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Background Intracranial hypotension (IH) has a widely variable clinical and radiologic presentation. Secondary IH may be caused by degenerative spine disorders and in particular by thoracic disk herniations (TDHs). Methods We present 2 patients with a transdural TDH, a secondary IH, and superficial siderosis in 1. Results Case 1 presented with headache, cognitive decline, staggering gait, bilateral subdural effusions, cerebral sagging, an extradural spinal cerebrospinal fluid (CSF) collection suggesting secondary IH, and a calcified TDH at T9-T10. Case 2 presented with intermittent pain at the craniocervical junction provoked exclusively by specific physical activities, superficial siderosis mainly in the posterior fossa, an extradural spinal CSF collection, and a calcified TDH at T7-T8 yet no intracranial signs of IH. In both cases, using strict thoracoscopic technique, we removed a transdural TDH and reconstructed an underlying longitudinal slitlike dural defect with smooth lining. Follow-up magnetic resonance imaging scans confirmed a dramatically improved situation without residual extradural intraspinal CSF collection or signs of IH. Conclusions This paper adds to the evidence that some cases of IH and even superficial siderosis are caused by transdural erosion of a TDH that may be otherwise asymptomatic. The dura may degenerate due to chronic compression, and a longitudinal slitlike dural defect with smooth lining may develop, causing continuous (Case 1) or intermittent (Case 2) intraspinal CSF leakage. To the best of our knowledge, such dural defects closely resembling the ones observed in idiopathic spinal cord herniation have never been demonstrated on intraoperative endoscopic video in IH patients.

BACKGROUND: The pathophysiology of pain in patients with symptomatic thoracic disc herniation (TDH) remains poorly understood. Mere mechanical compression of the spinal cord and/or the exiting nerve root by a prolapsed disc cannot explain the pathogenesis of pain in all cases. Previous studies report a direct correlation between the levels of proinflammatory cytokines in disc biopsies and the severity of leg pain in patients with lumbar disc herniation. A similar correlation in patients with TDH has not been investigated.PURPOSE: To correlate the cerebrospinal fluid (CSF) expression of cytokines and pain-related amino acids with preoperative pain scores in patients with symptomatic TDH.STUDY DESIGN: A prospective human study of CSF samples and clinical outcome scores.METHODS: Using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC), we determined inflammatory cytokine levels (TNF-alpha, IL-1 beta, and IL-10) and amino acid levels (glutamate, aspartate, gamma-aminobutyric acid, glycine, and arginine) in CSF samples from 10 patients with TDH and 10 control subjects who did not suffer an inflammatory disease nor pain related to spinal cord compression and subsequently correlated these levels with preoperative pain scores. Differences between both groups were evaluated by a Mann-Whitney U test. In order to estimate the correlation between cytokine or amino acid expression and pain scores, data were analyzed using a linear regression analysis.RESULTS: No inflammatory cytokines were found in CSF samples from control subjects, whereas TNF-a, IL-1b, and IL-10 were detectable by ELISA in all CSF samples from patients with TDH. TNF-a and IL-10 but not IL-1b levels moderately correlated with preoperative pain scores. Elevated TNF-alevels positively correlated with high pain scores; elevated IL-10 levels negatively correlated with high pain scores. Amino acids were detectable in all samples from both groups. There were no significant differences between the groups in any of the amino acids measured with HPLC.CONCLUSION: Increased proinflammatory cytokine expression is associated with elevated pain scores in patients with symptomatic TDH. On the other hand, there is no conclusive correlation between the intensity of pain and the local or systemic presence of amino acids associated with pain transmission. (C) 2018 Elsevier Inc. All rights reserved.

We present a rare fatal complication of an occipital condylar fracture. The patient was initially neurologically intact, but showed secondary clinical deterioration. Imaging revealed extensive extra-axial hemorrhage at the craniocervical junction and an acute obstructive hydrocephalus. MR imaging demonstrated a T2 hyperintens signal in both the lower brainstem and upper cervical spinal cord, likely caused by the extra-axial hemorrhage. As prognosis was estimated infaust, supportive treatment was discontinued and the patient died soon thereafter. This case report illustrates a rare, delayed complication and unexpected death in a patient having sustained an occipital condylar fracture.

Introduction Childhood angular kyphosis is rare, as most children are affected by a mixed kyphotic and scoliotic deformity. Published series involving a mix of kyphosis and kyphoscoliosis, pediatric and adult, congenital and acquired cases are almost exclusively authored by orthopedic surgeons, suggesting that (pediatric) neurosurgeons are not involved.Case series We present five cases that illustrate the spectrum of angular kyphosis, and these were treated by a multidisciplinary team including child neurologist, orthopedic surgeon, and pediatric neurosurgeon as complementary partners.Discussion Angular kyphosis is a cosmetic problem but above all a serious threat to the spinal cord and as such to the child's ambulatory, sphincter, and genito-urinary functions. Spinal cord stretch over the internal kyphosis may cause pain and/or neurological deficit, often accompanied by myelomalacia or even segmental cord atrophy. Spinal cord function may be additionally affected by associated disorders such as syringomyelia or tethered cord, an orthopedic surgeon may be less familiar with. The decision when and how to proceed surgically should be made by a multidisciplinary team, including a pediatric neurosurgeon who actively participates in the operation and helps to safely achieve adequate spinal cord decompression and stabilization.Conclusion Childhood angular kyphosis is a complex, heterogeneous disorder that should be managed by a multidisciplinary team in specialized pediatric spine centers. While every case is truly unique, the spinal cord is always at risk, especially during decompression, stabilization, and eventual correction of deformity. Pediatric neurosurgeons have an important role to play in preoperative work-up, actual operation, and follow-up.

We report a child with Lennox–Gastaut syndrome with an increase in seizure frequency and loss of psychomotor skills due to a disintegrated cervical VNS lead, not detected during standard device monitoring. The lead was completely removed and replaced by a new 303 lead on the same nerve segment. After reinitiating VNS, side effects forced us to switch it off, resulting in immediate seizure recurrence. EEG recording demonstrated a non-convulsive status epilepticus that was halted by reinitiating VNS therapy. Thereafter, he remained seizure free for eight months, and regained psychomotor development., Highlights • Routine VNS device monitoring may not always detect lead dysfunction. • Seizure recurrence and loss of psychomotor skills may imply lead dysfunction. • Complete VNS revision may yield excellent results in LGS. • VNS revision can correct clinical deterioration associated with lead dysfunction.

Background Vagus nerve activation impacts inflammation. Therefore, we hypothesized that vagal nerve stimulation (VNS) influenced arterial wall inflammation as measured by 18F-FDG uptake. Results Ten patients with left-sided VNS for refractory epilepsy were studied during stimulation (VNS-on) and in the hours after stimulation was switched off (VNS-off). In nine patients, 18F-FDG uptake was measured in the right carotid artery, aorta, bone marrow, spleen, and adipose tissue. Target-to-background ratios (TBRs) were calculated to normalize the respective standardized uptake values (SUVs) for venous blood pool activity. Median values are shown with interquartile range and compared using the Wilcoxon signed-rank test. Arterial SUVs tended to be higher during VNS-off than VNS-on [SUVmax all vessels 1.8 (1.5–2.2) vs. 1.7 (1.2–2.0), p = 0.051]. However, a larger difference was found for the venous blood pool at this time point, reaching statistical significance in the vena cava superior [meanSUVmean 1.3 (1.1–1.4) vs. 1.0 (0.8–1.1); p = 0.011], resulting in non-significant lower arterial TBRs during VNS-off than VNS-on. Differences in the remaining tissues were not significant. Insulin levels increased after VNS was switched off [55.0 pmol/L (45.9–96.8) vs. 48.1 pmol/L (36.9–61.8); p = 0.047]. The concurrent increase in glucose levels was not statistically significant [4.8 mmol/L (4.7–5.3) vs. 4.6 mmol/L (4.5–5.2); p = 0.075]. Conclusions Short-term discontinuation of VNS did not show a consistent change in arterial wall 18F-FDG-uptake. However, VNS did alter insulin and 18F-FDG blood levels, possibly as a result of sympathetic activation.

A 4-year-old boy with macrocephaly (+3 SD) was evaluated with MRI, which showed a subdural hygroma secondary to rupture of a left temporal arachnoid cyst and triventricular enlargement. Two years later, we repeated imaging to explore the possibility of a third ventriculostomy. There was a flow void across the floor of the third ventricle (figure). By using 3D cardiac-gated dynamic imaging, we demonstrated that a spontaneous ventriculostomy had already occurred (video, [links.lww.com/WNL/B217][1]). Spontaneous third ventriculostomy is rare and can occur in children and adults with chronic hydrocephalus.1 [1]: http://links.lww.com/WNL/B217

OBJECTIVE: To present our experience with anterior transthoracic surgery for high-risk thoracic disc herniations (TDHs) using motor evoked potential monitoring (MEPm).METHODS: We estimated surgical risk based on clinical and radiologic characteristics, including anteroposterior (AP) spinal canal occupation (SCO), AP spinal cord compression (SCC), residual AP spinal cord diameter (RSCD), and intramedullary signal changes (ISC). We analyzed Anand, ASIA, and Nurick scores, anesthesiologic, neurophysiological, and surgical reports. We considered > 50% MEP signal deterioration significant.RESULTS: Out of 435 anterior transthoracic procedures, 77 concerned high-risk TDH(s): 69 single-level, 8 multilevel, 61 with clinical myelopathy, 6 with merely ISC. Mean SCO and SCC were 55.4% and 54.0% for single-level, 31.8% and 33.9% for multilevel cases. ISC were present in 64% of single-level and 50% of multilevel cases, calcifications in 87% of single-level and 84% of multilevel TDHs. We initially performed 23 mini-transthoracic approaches (miniTTAs) and 24 thoracoscopic microdiscectomies (TMDs), more recently 29 TMDs (23 giant TDHs) and 1 transaxillary mini-TTA. Overall, 72 patients had reliable MEP signals. Isolated lower extremity MEP signal deteriorations (n = 21) correlated with maximal TDH AP diameter, SCO, SCC, and ISC. ASIA and Nurick scores improved in 45% and 66% respectively. One patient became paraplegic. MEP signal deterioration had 100% sensitivity, 75% specificity, and 19% positive predictive value during and 44% at the end of surgery.CONCLUSIONS: Maximal TDH AP diameter, SCO, SCC, (sub) total calcification, and ISC correlate with lower extremity MEP signal deterioration. In experienced hands, TMD with MEPm support is a safe, efficient procedure for high-risk TDHs.

Study Design. Retrospective analysis of a prospectively collected database of thoracoscopic microdiscectomies performed at the Maastricht University Medical Center. Objective. Many victims of a motor vehicle collision (MVC) report crippling upper back pain resistant to conservative treatment. Although this pain is often regarded as nonspecific or related to a whiplash type of cervical spine injury, this study demonstrates it may be caused by a thoracic disc herniation. Summary of Background Data. Recent literature on bodily pain after whiplash and other MVCs has shown that most patients rather than pain confined to the posterior neck area (0.4%) report pain in multiple body areas, the most frequently affected region being the posterior trunk region, including the posterior neck, posterior shoulder, upper back, lumbar, and buttock areas. Although several patterns determining most variance in pain localization in these patients have been identified, different pathoanatomical and pathophysiological substrates underlying these patterns have not been identified. However, a high incidence of posterior shoulder pain (75%) and upper back pain (66%) is striking. Methods. In a series of 326 thoracoscopic microdiscectomies for one or more symptomatic TDHs, we identified 10 patients whose symptoms had started after an MVC. We analyzed their clinical and radiological presentation, intraoperative findings, and postoperative outcome. Results. All patients (7 females, 3 males; age, 26-58 yr, including 4 with typical whiplash complaints) had reported substantial improvement of their complaints except for their upper back pain. Most hernias were small or medium sized (n = 8), at the apex of the kyphotic curvature (n = 6), and to some extent calcified (n = 7). One year postoperatively, results were excellent in 7, good in 2, and poor in 1. Conclusion. Crippling upper back pain after MVCs may be caused by a (previously asymptomatic) thoracic disc herniation. Although the exact pathophysiological mechanism has not been elucidated, results after thoracoscopic microdiscectomy are quite encouraging.

Purpose: The incidence of both symptomatic thoraco-lumbar junction disc herniation (TLJDH) and tight filum (TF) may be underestimated. Both conditions have a complex clinical presentation that may involve the distal spinal cord, conus medullaris, and/or cauda equina, including upper and/or lower motor neuron impairment, sensory impairment, urological and sexual dysfunction. The coexistence of both conditions has not been previously reported and may be a diagnostic and therapeutic challenge. Methods: We report three teenage girls, a 24-year-old woman, and two middle-aged women who were diagnosed with both conditions and treated at our institution. Results: Disc herniation level was T11-T12 in 2, T12-L1 in 3, and L1-L2 in one. All patients had a fatty filum (n = 5) and/or a low-lying CM (at or above L1-L2 in 2, at or below L2-L3 in 4), and were treated with filum sectioning first. All patients noted marked improvement of preoperative complaints including back pain (n = 5), leg pain and fatigue (n = 4), urological complaints (n = 4), and toe gait (n = 1). One 16-year-old girl successfully underwent a thoracoscopic microdiscectomy for persisting pain at the thoraco-lumbar junction two years after filum sectioning. Conclusions: Thoraco-lumbar junction disc herniation and tight filum both act on the distal spinal cord close to the transition to the cauda equina. Both conditions may coincide and may even act synergistically, the disc herniation acting as a fulcrum, aggravating the deleterious effect of the tethering force (and vice versa). This might explain why both conditions combined may present at a younger age. We suggest filum sectioning as the primary treatment option in all patients, however, more cases and a longer follow-up are needed to better understand their unique combination and interaction. Nevertheless, when confronted with a symptomatic TLJDH especially in young patients we advise to rule out a coinciding TF by careful consideration of all clinical, radiological, and urological data.

Purpose The purpose of this paper was to study the incidence and clinical significance of fever after intraventricular neuroendoscopic procedures in children. Methods We retrospectively assessed all children subjected to an intraventricular neuroendoscopic procedure between 2004 and 2015. Body temperature 6 days postoperatively, symptoms and signs, and eventual cerebrospinal fluid analysis were evaluated. Fever was defined as temperature above 38 °C. Results Fifty-five children (mean age 4.8 years) had 67 procedures. Forty-three children (47 procedures, 70 %) developed fever, mostly the day of surgery (n = 17; 25 %) or the next day (n = 33; 49 %). All children who were clinically ill (n = 9, including 7 with fever) suffered serious illness, as opposed to none of the children with fever without being clinically ill (n = 36). Fever was unrelated to gender, indication for, and type of procedure and did not influence ETV success rate at 3 months. Children under 1 year less frequently developed fever (p = 0.032). Conclusions Fever frequently develops after intraventricular neuroendoscopic procedures in children and follows a rather predictable course, peaking the day of surgery and/or the next day, and rapidly subsiding thereafter. Fever is not a cardinal symptom except when combined with other symptoms in children who are clinically ill (which most of them are not). Close observation avoiding invasive diagnostic tests may suffice for those who are not clinically ill, while extra attention should be paid to those whose temperature rises after day 2 especially when clinically ill, as they likely suffer serious illness. We recommend to closely observe children after any intraventricular neuroendoscopic procedure for at least 5 days.

Symptomatic thoracic disc herniations (TDHs) may severely incapacitate the patient while posing a significant challenge to the attending neurosurgeon. With the development of safer, less destructive surgical techniques, every symptomatic TDH may now be considered for surgical resection, provided it has enough impact on quality of life and conservative treatment has failed. While many open, endoscopic, or even percutaneous techniques have been developed using a posterior, posterolateral, or anterior route, today, thoracoscopic microdiscectomy (TMD) may be regarded as the golden standard because of its versatility, excellent results, and very low complication rates even in the most challenging cases. There are, however, a steep learning curve and a critical caseload to acquire and retain specific surgical skills. Moreover, close cooperation with a dedicated neuroradiologist, neuroanesthesiologist, and neurophysiologist is a prerequisite.

Object Thoracic disc herniations (TDHs) may occasionally present with an acute myelopathy, defined as a variable degree of motor, sensory, and sphincter disturbances developing in less than 24 hours, and resulting in a Frankel Grade C or worse. Confronted with such a patient, the surgeon has to decide whether to perform an emergency operation and whether to use an anterior or posterior approach. The authors analyze their own experience and the pertinent literature, focusing on clinical presentation, imaging findings, surgical timing, technique, and outcome. Methods Among 250 patients who underwent surgery for symptomatic TDH, 209 had at least 1 year of follow-up at the time of writing, including 8 patients who presented with an acute myelopathy. They were surgically treated using standard thoracoscopic microdiscectomy, careful blood pressure monitoring, and intravenous methylprednisolone. The authors analyzed pre- and postoperative neuroimaging, and Frankel scores preoperatively, at discharge, and 1 year postoperatively. Results Although 5 patients had multiple TDHs, the symptomatic TDH was invariably situated between T9–10 and T11–12. Seven TDHs were giant, 6 were calcified, 6 were accompanied by myelomalacia, and 4 were accompanied by segmental stenosis. Although sudden dorsalgia was the initial symptom in 6, a precipitating event was noted in only 1. All patients had severe neurological deficits by the time they underwent surgery. Frankel grades improved from B to D in 2 patients, from C to E in 4, and from C to D and B to E in 1 patient each. All patients regained continence and ambulation. Transient complications were CSF leak (in 2 patients), and intraoperative blood loss greater than 1000 ml, reversible ischemic neurological deficit, and subileus (in 1 patient each). Conclusions Approximately 4% of TDHs present with an acute myelopathy. They are often situated between T9–10 and T11–12, large or giant, and even calcified. They almost invariably cause important cord compression (sometimes aggravated by an associated segmental stenosis) and myelomalacia. Their clinical presentation may be misleading, and diagnosis may be delayed until other causes (especially vascular) have been excluded and the clinical picture has become more complete. Interestingly, whereas a precipitating event or trauma is rarely present, dorsalgia frequently precedes profound myelopathy and may help to make an early diagnosis. Remarkable recovery is possible even with profound neurological deficit, a delay of several days, in the elderly, and in the presence of myelomalacia, provided the spinal cord is adequately decompressed and intraoperative hypotension is strictly avoided. Although alternative approaches more familiar to most neurosurgeons may be used, the anterior transthoracic approach has the advantage of reaching the TDH in front of the compromised spinal cord, avoiding any manipulation. In experienced hands, thoracoscopic microdiscectomy combines the advantage and versatility of an anterior approach with minimal postoperative discomfort. The authors conclude that TDH-related acute myelopathy may have a favorable outcome when managed correctly, and they strongly recommend that every single patient should undergo surgical treatment.

Introduction Although Blake’s pouch cyst (BPC) is frequently mentioned in the spectrum of posterior fossa cysts and cystlike malformations since its first description in 1996, its natural history, clinical presentation, specific imaging characteristics, optimal treatment, and outcome are relatively unknown. Consequently, BPC may still be underdiagnosed. We therefore report six cases ranging from a fatal hydrocephalus in a young boy, over an increasing head circumference with or without impaired neurological development in two infants, to a decompensating hydrocephalus at an advanced age. Discussion We focus on their radiological uniformity, which should help making the correct diagnosis, and widely variable clinical presentation, which includes adult cases as well. Differentiating BPC from other posterior fossa cysts and cystlike malformations and recognizing the accompanying hydrocephalus are essentially noncommunicating, not only have important implications on clinical management but also on genetic counseling, which is unnecessary in case of BPC. In our experience, endoscopic third ventriculostomy is a safe and effective treatment option, avoiding the risks and added morbidity of open surgery, as well as many shunt-related problems.

Our goal was to validate the hypothesis that the lumbosacral angle (LSA) increases in children with spinal dysraphism who present with progressive symptoms and signs of tethered cord syndrome (TCS), and if so, to determine for which different types and/or levels the LSA would be a valid indicator of progressive TCS. Moreover, we studied the influence of surgical untethering and eventual retethering on the LSA.We retrospectively analyzed the data of 33 children with spinal dysraphism and 33 controls with medulloblastoma. We measured the LSA at different moments during follow-up and correlated this with progression in symptomatology.LSA measurements had an acceptable intra- and interobserver variability, however, some children with severe deformity of the caudal part of the spinal column, and for obvious reasons those with caudal regression syndrome were excluded. LSA measurements in children with spinal dysraphism were significantly different from the control group (mean LSA change, 21.0A degrees and 3.1A degrees respectively). However, both groups were not age-matched, and when dividing both groups into comparable age categories, we no longer observed a significant difference. Moreover, we did not observe a significant difference between 26 children with progressive TCS as opposed to seven children with stable TCS (mean LSA change, 20.6A degrees and 22.4A degrees respectively).We did not observe significant differences in LSA measurements for children with clinically progressive TCS as opposed to clinically stable TCS. Therefore, the LSA does not help the clinician to determine if there is significant spinal cord tethering, nor if surgical untethering is needed.

Juvenile xanthogranuloma (JXG) is a rare histiocytic disorder primarily observed during the first 2 years of life. Most patients present with a solitary cutaneous lesion; however, others present with extracutaneous manifestations or even with systemic involvement. The authors describe a 2-month-old boy in whom was diagnosed a unifocal extracutaneous JXG involving the temporal bone. Unlike 3 other cases of solitary JXGs of the temporal bone in the literature, the present case involved destruction of the dura mater and leptomeningeal enhancement surrounding the entire temporal lobe. The lesion did not regress after an initial biopsy procedure and had to be removed more radically because of progressive mass effect on the brain. The child recently underwent a reconstructive skull procedure and is doing well almost 2 years postoperatively without evidence of disease. This case demonstrates that even in instances of extensive disease a favorable outcome is possible without chemotherapy.

In contrast to what is commonly believed, thoracic disc herniations are not rare lesions. Their etiopathogenesis is largely unknown, but may be linked to trauma, Scheuermann’s disease or a degenerative back. We report two brothers with a symptomatic thoracic disc herniation at T11–T12 and address the possibility of a genetic factor as well as other factors in the etiopathogenesis of (symptomatic) thoracic disc herniations. Both brothers were in their early thirties and had a physically demanding job, however, only the first one was a smoker and was diagnosed with Scheuermann’s disease. The etiology of thoracic disc herniations is likely multifactorial. Their occurrence in siblings may reflect some genetic predisposition or may be merely coincidental, given the high prevalence of thoracic disc herniations in asymptomatic individuals. Further research, including genetic studies, is warranted.

Intraspinal dermoid and epidermoid tumors are two histopathological subtypes of cutaneous inclusion tumors of the spine. This classification is based on obsolete embryological knowledge. In fact, according to current embryology, both tumor types consist of ectodermal derivatives. Therefore, we hypothesized that dermoid and epidermoid tumors do not differ in clinical practice. To explore this hypothesis, we studied the clinical, radiological and intraoperative findings of 18 patients, and related these findings to the histopathological characteristics of the tumor. No differences were found between dermoid and epidermoid tumors regarding clinical presentation, radiological examination and outcome, while intraoperative diagnosis by the surgeon correlated with the histopathological diagnosis in only 8 of 18 cases. Therefore, the histopathological difference between intraspinal dermoid and epidermoid tumors is not important in clinical practice and should be avoided. A new nomenclature is proposed in which both tumor types are referred to as 'spinal cutaneous inclusion tumors'. Copyright (C) 2009 S. Karger AG, Basel

In recent years, video-assisted thoracoscopic microdiscectomy has gained acceptance as a minimally invasive, safe, and efficient technique suited for herniated thoracic discs from T4T5 until T11T12. However, correct localization is difficult and wrong level exploration is an ever-present threat. We present a reliable and time-efficient localizing technique.In 86 consecutive cases, 1 day preoperatively intrathecal contrast was administered and a computed tomography (CT) scan was performed in prone position. Using local anesthesia, a hollow needle was advanced above the corresponding rib and through the pleura. The inner wire and corresponding pathological level were easily identified endoscopically.Myelo-CT provides detailed anatomical information, which is often helpful in determining the side of operative approach and the extent of bone removal needed. Needle localization obviates fluoroscopy, saves OR time, and allows the surgeon to focus on the technically demanding procedure. Furthermore, it is a relatively simple and safe technique.

Cases of infected dermal sinus are scarce and detailed surgical anatomical descriptions are hardly found in literature. The clinical, radiological, and surgical findings in four cases of an infected dermal sinus located at the lower spine are presented to elucidate the pathological anatomical configuration. The first case showed two dermal sinuses with a parallel course extra- and intradurally, ending in a confluence of cavities connected to the conus. In this case, as well as in the fourth case, the signs and symptoms were those of meningitis. The second case presented with meningitis and a subdural empyema, while the third case presented with an intradermoid–intramedullary abscess at the junction between the DS and the conus. This child probably showed signs and symptoms of conus involvement as early as during pregnancy. The anatomy of the nervous elements in this congenital anomaly is heavily disturbed, more particularly in case of infection, due to extensive arachnoidal scarring. The latter renders dissection laborious and recognition of anatomical details difficult, resulting in complete excision of a dermal sinus in less than half of the cases. Despite their variability in presentation, most cases of an infected dermal sinus show similar characteristic features.

Study design Presented is a unique case report of a rare bone tumor: a benign fibrous histiocytoma (BFH) located in the posterior arch of C1 in a 6-year-old child. Objective To describe a benign fibrous histiocytoma of bone and the differential diagnostic considerations based on the authors' case report. Summary of background data A BFH is a rare tumor composed of varying degree of fibroblast-like spindle cells, foam cells, and multinucleated giant cells. Approximately 86 cases have been reported in literature. Its exact nature remains somewhat controversial. A lesion may be designated a benign fibrous histiocytoma based on clinical, radiographic, and microscopic criteria. Materials and methods The clinical symptoms, plain radiographs, computerized tomography (CT), magnetic resonance images (MRI), bone scintigraphy, and histologic section of the lesion are discussed, evaluated, and compared with other benign bone lesions. Results This case is, to the best of the authors' knowledge, the first benign fibrous histiocytoma to be reported in the cervical spine of a child. Various benign lesions such as nonossifying fibroma, giant-cell tumor, fibrous dysplasia, aneurysmal bone cyst, osteoblastoma, and eosinophilic granuloma are included in the differential diagnosis. Conclusion Benign fibrous histiocytoma is a rare skeletal tumor. Because of this and its nonpathognomonic microscopic features, the diagnosis can be somewhat troublesome. However, by systematically reviewing patient's symptoms, tumor location, and radiographic and microscopic characteristics, other benign lesions can be eliminated. The diagnosis of a BFH is one of exclusion.

Object. It remains uncertain if closure of a myelomeningocele at midgestation changes the neurological condition at birth in an infant born with spina bifida. The authors conducted a study to provide a detailed analysis of the morphology of the spinal cord with the myelomeningocele at the time fetal surgery usually is performed. Methods. The myelomeningocele of a 20-week-gestation-age fetus was examined, and data were compared with those obtained in a neurologically intact specimen of the same age. In vitro high-field 9.4-tesla magnetic resonance (MR) microscopy was used to examine the fetal material. High-field MR spectroscopy provided images in the three orthogonal planes with a resolution comparable with low-power optical microscopy. The authors observed that the fetal cord of the myelomeningocele specimen was tapered and tethered at S3–4 while the conus medullaris in the normal fetus reaches L-4. No neurulation defects were noted. The axial MR images clearly revealed the nonfusion of the mesodermal structures. The absence of neurulation defects suggests that at least in some cases of spina bifida the spinal cord initially is well developed but is damaged later on chemically and mechanically. This might be an argument in favor of intrauterine myelomeningocele repair. By 20 weeks' gestation, however, the deformation of the cord inside the myelomeningocele is severe. An optimization of the preoperative assessment by means of MR imaging therefore might be considered a valuable contribution to intrauterine surgery. The in vitro high-field MR microscopic findings of this study could be used as references for clinical intrauterine MR imaging. Conclusions. The detailed in vitro high-field MR analysis of a 20-week-gestation-age fetus with spina bifida demonstrated that an improvement of the preoperative intrauterine imaging should be pursued to detect those cases without neurulation defects and with minimal deformation of the spinal cord.

Dear Editor,We read with great interest the paper “Spinal dermal sinusand pseudo-dermal sinus tracts: two different entities” byMartinez-Lage et al. [1]. In fact, the term “sinus” may beused for (chronically) infected tracts connecting a deep-seated infection to the skin, and discharging pus to thesurface, except for those tracts connecting two epithelial-ized surfaces, which are called “fistula”.A spinal dermal sinus (DS) is a developmental anomalyof the dorsal midline axis, in which a hollow, epithelium-lined tract extends inward from the skin surface for avariable distance [1–3]. A key feature of a DS is an openskin defect; however, this may be minute and, as such,easily overlooked during routine neonatal examination [1].Occasional discharge from this orifice is a common finding,however, even in case of connection with the spinal cord,this never is cerebrospinal fluid [3, 4]. Another key featureof a DS is the accumulation of (epi)dermoid remnants,often presenting as tumors inside the tract or even insidethe spinal cord. Such tumors may produce manifestationsof spinal cord or cauda equina compression [1]. Moreover,due to an open connection with the skin surface, manycases present with meningitis and intraspinal, intramedul-lary, or more superficial intra-epidermoid abscesses, apotentially life-threatening condition, rather than with cordtethering (recurrent cases no longer connected to the skinsurface) [1, 3].A spinal dermal-sinus-like stalk (DSS) [4] or pseudo-dermal sinus tract as proposed by Martinez-Lage et al. [1]isa developmental anomaly of the dorsal midline axis, inwhich a solid tract extends outward from the intraduralspace to the skin. Key features of a DSS are a closed skindefect (a dimple, cigarette burn, or blister, all without anorifice) usually more obvious than in case of a DS, theabsence of a lumen, and the absence of (epi)dermoidremnants inside the tract [1, 4]. Consequently, a DSS willnever present with meningitis, but rather with cord tethering[1, 4]. To illustrate this point, we have included severalphotographs highlighting the essential surgical steps in caseof a DSS, which, in this particular case, was attached to alow-lying conus medullaris (Fig. 1a–f).In case of a DS, stratified squamous epithelium insidethe lumen, surrounded by dermal tissue, suggests anondisjunction of cutaneous and neural ectoderm withinward dragging of the epidermis. In case of a DSS,however, mesenchymal and neural elements inside the stalksuggest an embryologic development in the oppositedirection (inside-out rather than outside-in). This wouldexplain the absence of a skin orifice, the occasional dorsaltenting of the dura, and the presence of glioneural tissueinside the stalk. Thus, a DSS would represent an atrophicmesodermal-neural stalk [4] and, as suggested by Martinez-Lage et al., may indeed represent the spinal counterpart ofan atretic encephalocele [1].

BackgroundHuman brown adipose tissue (BAT) activity is inversely related to obesity and positively related to energy expenditure. BAT is highly innervated and it is suggested the vagus nerve mediates peripheral signals to the central nervous system, there connecting to sympathetic nerves that innervate BAT. Vagus nerve stimulation (VNS) is used for refractory epilepsy, but is also reported to generate weight loss. We hypothesize VNS increases energy expenditure by activating BAT.Methods and findingsFifteen patients with stable vns therapy (age: 45 ± 10 yrs; body mass index; 25.2 ± 3.5 kg/m(2)) were included between January 2011 and June 2012. Ten subjects were measured twice, once with active and once with inactivated VNS. Five other subjects were measured twice, once with active VNS at room temperature and once with active VNS under cold exposure in order to determine maximal cold-induced BAT activity. BAT activity was assessed by 18-Fluoro-Deoxy-Glucose-Positron-Emission-Tomography-and-Computed-Tomography. Basal metabolic rate (BMR) was significantly higher when VNS was turned on (mean change; +2.2%). Mean BAT activity was not significantly different between active VNS and inactive VNS (BAT SUV(Mean); 0.55 ± 0.25 versus 0.67 ± 0.46, P = 0.619). However, the change in energy expenditure upon VNS intervention (On-Off) was significantly correlated to the change in BAT activity (r = 0.935, PConclusionsVNS significantly increases energy expenditure. The observed change in energy expenditure was significantly related to the change in BAT activity. This suggests a role for BAT in the VNS increase in energy expenditure. Chronic VNS may have a beneficial effect on the human energy balance that has potential application for weight management therapy.Trial registrationThe study was registered in the Clinical Trial Register under the ClinicalTrials.gov Identifier NCT01491282.

Objective Based on the assumption that children with spinal dysraphism are exposed to a large amount of ionising radiation for diagnostic purposes, our objective was to estimate this exposure, expressed in cumulative effective dose. Design Retrospective cohort study. Settings The Netherlands. Patients 135 patients with spinal dysraphism and under 18 years of age treated at our institution between 1991 and 2010. Results A total of 5874 radiological procedures were assessed of which 2916 (49.6%) involved ionising radiation. Mean cumulative effective dose of a child with spinal dysraphism during childhood was 23 mSv, while the individual cumulative effective dose ranged from 0.1 to 103 mSv. Although direct radiography accounted for 81.7% of examinations, the largest contributors to the cumulative effective dose were fluoroscopic examinations (40.4% of total cumulative effective dose). Conclusions Exposure to ionising radiation and associated cancer risk were lower than expected. Nevertheless, the use of ionising radiation should always be justified and the medical benefits should outweigh the risk of health detriment, especially in children.

The natural history of pediatric intramedullary cavernomas (ImCs) is essentially unknown, however, they tend to present at a mean age between 9.1 and 13.2 years with an acute neurological deficit, often followed by rapid deterioration due to hematomyelia. Imaging of the entire neuraxis is warranted, as those affected by multiple lesions and the familial form of the disease (12–40%) tend to suffer a more aggressive behaviour and earlier age of clinical onset. The cumulative literature is inconclusive with regard to indications for surgical treatment, thus supporting the concept of highly individualized decision making. However, considering the lifetime risks in children, surgical treatment to prevent future hemorrhage should strongly be considered, at least for those lesions that are surgically accessible. Except for the very young child, most authors would favor the use of intraoperative neuromonitoring during resection using either a posterior midline, dorsal root entry zone, or lateral myelotomy approach. With adequate surgical treatment either in the acute phase or after clinical recuperation, prognosis may be surprisingly good. Incompletely resected lesions and/or syndromal cases tend to recur, requiring further treatment. Definite answers await more cases with longer follow-up especially after subtotal resection, however, as long as the child remains in a stable condition, careful clinical and radiological follow-up may be an alternative to reoperation.

Positioned anatomically between the spinal epidural space and the intramedullary compartment, the spinal subdural space remains the least common area of localized infection in the central nervous system. Infectious processes of the subdural spinal space include subdural spinal empyema, subdural spinal abscess, infected spinal subdural cyst, and infectious spinal subdural cyst. To date, there has been no systematic review of these entities in children, with the cumulative knowledge of the pathophysiologic, microbiologic, and demographic characteristics of these infections relegated solely to few small series and case reports. A series of 11 recent cases culled from the collaboration of international authors are presented. In addition, an exhaustive MEDLINE search and manual review of the international literature was performed, identifying a total of 73 cases of spinal subdural infections in patients under the age of 21. Data of interest include the age, sex, signs, and symptoms at presentation, spinal location of infection, presence of spinal dysraphism, and other comorbidities, offending organism, treatment, outcome, and follow-up. Patients ages ranged from 4 weeks to 20 years (mean, 6.5 years). Males outnumbered females by a ratio of 2:1. Over half (53 %) of spinal subdural infections in children were associated with spinal dysraphism or other congenital abnormalities of the spine. The commonest organism to infect the spinal subdural space in children is mycobacterium tuberculosis and the thoracic spinal region was most commonly infected. The disease is usually treated surgically, although a more expectant approach consisting of antibiotics and observation has also been proposed.

The aim of this study was to evaluate the effects of vagus nerve stimulation (VNS) in children with intractable epilepsy on seizure frequency and severity and in terms of tolerability and safety.In this study, the first randomized active controlled trial of its kind in children, 41 children (23 males; 18 females; mean age at implantation 11y 2mo, SD 4y 2mo, range 3y 10mo-17y 8mo) were included. Thirty-five participants had localization-related epilepsy (25 symptomatic; 10 cryptogenic), while six participants had generalized epilepsy (four symptomatic; two idiopathic). During a baseline period of 12 weeks, seizure frequency and severity were recorded using seizure diaries and the adapted Chalfont Seizure Severity Scale (NHS3), after which the participants entered a blinded active controlled phase of 20 weeks. During this phase, half of the participants received high-output VNS (maximally 1.75mA) and the other half received low-output stimulation (0.25mA). Finally, all participants received high-output stimulation for 19 weeks. For both phases, seizure frequency and severity were assessed as during the baseline period. Overall satisfaction and adverse events were assessed by semi-structured interviews.At the end of the randomized controlled blinded phase, seizure frequency reduction of 50% or more occurred in 16% of the high-output stimulation group and in 21% of the low-output stimulation group (p=1.00). There was no significant difference in the decrease in seizure severity between participants in the stimulation groups. Overall, VNS reduced seizure frequency by 50% or more in 26% of participants at the end of the add-on phase The overall seizure severity also improved (p0.001).VNS is a safe and well-tolerated adjunctive treatment of epilepsy in children. Our results suggest that the effect of VNS on seizure frequency in children is limited. However, the possible reduction in seizure severity and improvement in well-being makes this treatment worth considering in individual children with intractable epilepsy.

Background/Aims In addition to effects on seizure frequency in intractable epilepsy, multiple studies report benefits of vagus nerve stimulation (VNS) on behavioural outcomes and quality of life. The present study aims to investigate the effects of VNS on cognition, mood in general, depression, epilepsy-related restrictions and psychosocial adjustment in children with intractable epilepsy, as well as the relation between these effects and seizure reduction. Methods We conducted a randomized, active-controlled, double-blinded, add-on study in 41 children (age 4–18) with medically refractory epilepsy. We performed cognitive and behavioural testing at baseline (12 weeks), at the end of the blinded phase (20 weeks) in children receiving either high-output or low-output (active control) stimulation, and at the end of the open label phase (19 weeks) with all children receiving high-output stimulation. Seizure frequency was recorded using seizure diaries. Results VNS did not have a negative effect on cognition nor on psychosocial adjustment. At the end of the follow-up phase we noted an improvement of mood in general and the depression subscale for the entire group, unrelated to a reduction of seizure frequency. At the end of the blinded phase a ≥50% reduction of seizure frequency occurred in 16% of the high-stimulation group and 21% of the low-stimulation group. At the end of the open-label follow-up phase, 26% of the children experienced a seizure frequency reduction of 50% or more (responders). Conclusions VNS has additional beneficial effects in children with intractable epilepsy. As opposed to anti-epileptic drugs, there are no negative effects on cognition. Moreover, we observed an improvement of mood in general and depressed feelings in particular, irrespective of a reduction in seizure frequency. These beneficial effects should be taken into account when deciding whether to initiate or continue VNS treatment in these children.

Introduction We analyze our preliminary experience using the PoleStar N20 mobile intraoperative MR (iMR) system as an adjunct for pediatric brain tumor resection. Methods We analyzed 11 resections in nine children between 1 month and 17 years old. After resection, we acquired iMR scans to detect residual tumor and update neuronavigation. We compared final iMR interpretation by the neurosurgeon with early postoperative MR interpretation by a neuroradiologist. Results Patient positioning was straightforward, and image quality (T1 7-min 4-mm sequences) sufficient in all cases. In five cases, contrast enhancement suspect for residual tumor was noted on initial postresection iMR images. In one case, a slight discrepancy with postoperative imaging after 3 months was no longer visible after 1 year. No serious perioperative adverse events related to the PoleStar N20 were encountered, except for transient shoulder pain in two. Conclusions Using the PoleStar N20 iMR system is technically feasible and safe for both supra- and infratentorial tumor resections in children of all ages. Their small head and shoulders favor positioning in the magnet bore and allow the field of view to cover more than the area of primary interest, e.g., the ventricles in an infratentorial case. Standard surgical equipment may be used without significant limitations. In this series, the use of iMR leads to an increased extent of tumor resection in 45 % of cases. Correlation between iMR and early postoperative MR is excellent, provided image quality is optimal and interpretation is carefully done by someone sufficiently familiar with the system.

Thoracic disc herniations (TDHs) may occasionally present with an acute myelopathy, defined as a variable degree of motor, sensory, and sphincter disturbances developing in less than 24 hours, and resulting in a Frankel Grade C or worse. Confronted with such a patient, the surgeon has to decide whether to perform an emergency operation and whether to use an anterior or posterior approach. The authors analyze their own experience and the pertinent literature, focusing on clinical presentation, imaging findings, surgical timing, technique, and outcome.Among 250 patients who underwent surgery for symptomatic TDH, 209 had at least 1 year of follow-up at the time of writing, including 8 patients who presented with an acute myelopathy. They were surgically treated using standard thoracoscopic microdiscectomy, careful blood pressure monitoring, and intravenous methylprednisolone. The authors analyzed pre- and postoperative neuroimaging, and Frankel scores preoperatively, at discharge, and 1 year postoperatively.Although 5 patients had multiple TDHs, the symptomatic TDH was invariably situated between T9-10 and T11-12. Seven TDHs were giant, 6 were calcified, 6 were accompanied by myelomalacia, and 4 were accompanied by segmental stenosis. Although sudden dorsalgia was the initial symptom in 6, a precipitating event was noted in only 1. All patients had severe neurological deficits by the time they underwent surgery. Frankel grades improved from B to D in 2 patients, from C to E in 4, and from C to D and B to E in 1 patient each. All patients regained continence and ambulation. Transient complications were CSF leak (in 2 patients), and intraoperative blood loss greater than 1000 ml, reversible ischemic neurological deficit, and subileus (in 1 patient each).Approximately 4% of TDHs present with an acute myelopathy. They are often situated between T9-10 and T11-12, large or giant, and even calcified. They almost invariably cause important cord compression (sometimes aggravated by an associated segmental stenosis) and myelomalacia. Their clinical presentation may be misleading, and diagnosis may be delayed until other causes (especially vascular) have been excluded and the clinical picture has become more complete. Interestingly, whereas a precipitating event or trauma is rarely present, dorsalgia frequently precedes profound myelopathy and may help to make an early diagnosis. Remarkable recovery is possible even with profound neurological deficit, a delay of several days, in the elderly, and in the presence of myelomalacia, provided the spinal cord is adequately decompressed and intraoperative hypotension is strictly avoided. Although alternative approaches more familiar to most neurosurgeons may be used, the anterior transthoracic approach has the advantage of reaching the TDH in front of the compromised spinal cord, avoiding any manipulation. In experienced hands, thoracoscopic microdiscectomy combines the advantage and versatility of an anterior approach with minimal postoperative discomfort. The authors conclude that TDH-related acute myelopathy may have a favorable outcome when managed correctly, and they strongly recommend that every single patient should undergo surgical treatment.

BACKGROUND: The purpose of this study is to demonstrate the added value of intraoperative MRI in treating secondary empty sella syndrome. CASE REPORT: We describe the case of a 66-year-old woman who was diagnosed with a prolactinoma stage IIIb. During treatment with cabergoline she presented with a secondary empty sella syndrome resulting in visual symptoms. We performed intraoperative MRI-guided packing of the secondary empty sella. We explain why this is useful in surgical treatment of secondary empty sella syndrome. CONCLUSION: Intraoperative MRI helps to achieve adequate sellar packing while avoiding insufficient packing as well as overpacking.

A 20 year old male patient who had been successfully treated for epilepsy with vagus nerve stimulation (VNS) for 7 years (50% seizure frequency reduction), had experienced multiple episodes of severe hoarseness, throat pain and impaired breathing during physical exercise. As malfunctioning of the pulse generator was suspected, it was decided to replace the device. During surgery, the pulse generator was found to have broken in two, due to an unstable connection between the battery subunit and the connector subunit. With a new pulse generator seizure frequency reduction was restored. No side effects occurred.

Study design This study analyzes the mobility of the aorta relative to the spine in patients with a herniated thoracic disc requiring surgical intervention. Objectives To determine the mobility of the aorta relative to the spine with the patient in prone and supine position. Summary of background data In anterior scoliosis surgery, safe screw placement is important and knowledge of the position of the aorta relative to the spine is crucial. To the authors' knowledge, there are no studies on the mobility of the aorta relative to the spine with the patient in different positions. Methods All 50 patients before surgery had a computed tomography (CT) and/or magnetic resonance (MR) scans of the involved spinal segment in supine position, as well as a CT with intrathecal contrast in prone position. The aorta-vertebral angle and the aorta-vertebral distance were measured on as many levels as possible. Results In supine position, the aorta is positioned left lateral to the vertebral body at midthoracic levels (T4-T8) and more anterior to the vertebral body at lower thoracic levels (T9-L2). In prone position, the aorta moves to a more anteromedial position relative to the vertebra, which is most significant at levels T4 to T8. The mediolateral aorta-vertebral distance according to Sevastik is shorter in prone position, whereas the anterior-posterior distance according to Sucato is larger, especially at levels T5 to T10. Conclusions We demonstrate a substantial difference in the position of the aorta relative to the spine in prone and in supine position, which is most markedly seen at levels T4 to T8. The aorta is positioned posterolateral to the spine in supine position and more anteromedial in prone position. Before performing anterior thoracolumbar spine surgery, we suggest to measure vertebral body width, as well as the position of the aorta in the prone and in the supine patient to decide if his approach is technically feasible, or if an alternative (contralateral) approach is preferable.

✓ The authors present a rare case of fatal cerebral and cerebellar hemorrhagic infarction following an uneventful thoracoscopic microdiscectomy. They hypothesize that this complication was associated with cortical venous thrombosis secondary to intracranial hypotension, which was caused by an unnoticed leak of cerebrospinal fluid (CSF) into the thoracic cavity. Cortical venous thrombosis and intrathoracic CSF were confirmed at autopsy. The former disorder is the most severe manifestation of the pathophysiological mechanism occurring to a lesser degree in patients affected by mild intracranial hypotension, and occurs more frequently in these patients. Intracranial hypotension (of an orthostatic nature or not) must be considered in the differential diagnosis of every patient who complains of headaches after thoracoscopic or open transthoracic microdiscectomy.

A patient is described in which a complete osteofibrotic dorsally implanted septum was found in combination with a split cord malformation in a single dural tube. This case cannot be explained using the widely used theory as proposed by Pang et al. [Pang D, Dias MS, Ahab-Barmada M (1992) Split cord malformation, part I: A unified theory of embryogenesis for double spinal cord malformations. Neurosurgery 31:451-480] but must be regarded as a combination of type I and II split cord malformation.The authors state that all types of split cord malformation can be reduced to a single derailment during development, with various degrees of severity.The configuration of the malformation is determined by the way the median parts of the mesoderm come to development. Type I and II split cord malformation are not distinct entities.

To prospectively investigate the feasibility of contrast material-enhanced magnetic resonance (MR) angiography for visualization of the spinal vasculature in patients referred for video-assisted thoracoscopic surgical treatment of a thoracic herniated disk and to prospectively assess the influence of preoperative imaging of the spinal vasculature on the choice of surgical approach.Eight patients (three men and five women; mean age, 58 years; range, 42-83 years) with a thoracic herniated disk underwent contrast-enhanced MR angiography of the thoracoabdominal aorta and posterior branches. Imaging was performed with three-dimensional first-pass contrast-enhanced MR angiographic technique and a triple dose of gadolinium-based contrast agent. Images were analyzed by two observers in consensus to localize the Adamkiewicz artery (AKA) and its connections to the aorta and the anterior spinal artery (ASA). This information was used to determine any change in surgical approach.In all eight patients, the AKA, the ASA, and the connections with the aorta were identified. The AKA originated between T9 and L2 in all patients and derived from the left side of the aorta in 75% (six of eight) of the patients. In three patients in whom the AKA was observed on the left side, the surgical approach was changed to the right side to preserve spinal cord integrity.Preoperative imaging of the AKA is feasible with contrast-enhanced MR angiography. Contrast-enhanced MR angiography can be used to image the main feeding arteries of the spinal cord in patients undergoing thoracoscopic spinal surgery, and results can be used to change the side of surgical approach.

The Arnold-Chiari malformation type II (ACMII) is reported to be reversible after closure of a myelomeningocele at midgestation. To elucidate the developmental state of the ACMII malformation at the approximate time fetal surgery is performed, the ACMII of a 20-week human fetus was investigated in vitro using high-field magnetic resonance microscopy at 9.4 T and compared with the hindbrain of a neurologically intact fetus of the same gestational age. Up to 20 weeks of gestation, the developmental failures caused by the early embryonic herniation of the posterior fossa contents are the dominant feature of fetal ACMII, but after 20 weeks, the accelerated and disproportionate growth of the cerebellum dominates. As midgestational surgery stops the leakage of cerebrospinal fluid, the posterior fossa will expand in time to allow further normal growth of both the cerebellum and brain stem. Some early developmental anomalies already present in the primitive rhombencephalon due to early embryonic hindbrain herniation as well as some intra-axial anomalies are probably not reversible.

We describe two cases of peripheral primitive neuroectodermal tumor-Ewing's sarcoma (PNET-ES) arising intracranially in the leptomeninges. Both tumors exhibited a primitive undifferentiated round-cell morphology. Immunohistochemical stains revealed strong membrane expression of CD99 in both cases. A t(11;22)(q24;q12) could be demonstrated with reverse transcriptase-polymerase chain reaction in one case, whereas fluorescence in situ hybridization analysis performed in the second case showed a rearrangement of the EWS gene. The occurrence of PNET-ES at this site is very unusual. Immunophenotypical as well as genetic analysis play a key role in the diagnosis and the distinction from central PNET.

✓ The authors report on four third ventriculostomy procedures in which upward ballooning of the third ventricular floor occurred immediately after perforation of the floor and withdrawal of a Fogarty catheter. The floor herniated into the third ventricle, hindering the endoscopic view. Preoperative magnetic resonance imaging demonstrated a similar anatomy in all four cases, consisting of hydrocephalus, extreme dilation of the third ventricle, and disappearance of the interpeduncular cistern due to a very thin, membranous floor of the third ventricle, which herniated downward, draping over the basilar artery. The authors suggest that excessive rinsing in combination with this anatomical configuration provoked the phenomenon of upward ballooning of the third ventricular floor, which is described in this report.

Dear Editor, We thank Rueda-Franco et al. for their interest in our paper [1]. They suggest the yellowish material covering the occipital lobes as well as the cerebellum may point to a purulent process rather than a massive cerebral necrosis. Indeed, we agree Fig. 1d in the original paper may suggest a thin layer of pus covering the brain; however, this certainly was not the case as we will now explain. The clinical presentation and laboratory findings did not point to an infection. The boy had no fever on admission nor in the days immediately before and after admission until his death 14 days postoperatively. Blood leukocyte count and C-reactive protein were within normal range, and routine cerebrospinal fluid cultures were negative. Moreover, postmortem macroscopic and microscopic examination of the child’s meninges, cerebral and cerebellar cortex pointed to a massive necrosis (ischemic encephalopathy) as a result of prolonged, dramatically elevated intracranial pressure, the clinical symptoms and signs of which were very clear when the child was transferred to our hospital [1]. As such, the yellowish aspect of the surface of both brain and cerebellum corresponded to an ischemic liquefaction and infiltration with sporadic neutrophilic granulocytes, sporadic lymphocytes, and numerous iron-loaded macrophages, as illustrated in Fig. 1a–c. This is to be regarded as a reactive process after dramatic intracranial hypertension and secondary hypoperfusion, aggravated by a suboptimal coagulation status resulting in widespread microhemorrhage. Fig. 1 a Microscopic view of cerebellar meninges. Note that there are few neutrophilic granulocytes, few lymphocytes, and many iron-loaded macrophages. b Microscopic view of cerebral meninges. Again, note the absence of a purulent infiltrate. c Microscopic view ...

Objective We quantified the impact of chorioamnionitis on both the white and gray matter structures of the preterm ovine central nervous system (CNS). Study Design The CNS was studied at 125 days of gestation, either 2 or 14 days after the intraamniotic administration of 10 mg of lipopolysaccharide (LPS) ( Escherichia coli ) or saline. Apoptotic cells and cell types were analyzed in the brain, cerebellum, and spinal cord using flow cytometry. Results Apoptosis and microglial activation increased in all regions with prolonged exposure to LPS-induced chorioamnionitis. Astrocytes were increased in the brain and cerebellum of LPS-exposed fetuses but not in the spinal cord. Mature oligodendrocytes decreased in the cerebral and cerebellar white matter, the cerebral cortex, caudate putamen, and hippocampus 14 days after LPS. Neurons in the cerebral cortex, hippocampus, and substantia nigra were reduced 14 days after LPS. Conclusion Fetal inflammation globally but differentially affected the CNS depending on the maturational stage of the brain region.

Objects In this study, a disjunction anomaly mimicking the spinal congenital dermal sinus (DS) is described. This anomaly is referred to as the dermal-sinus-like stalk. Dissimilarities between a true dermal sinus and a dermal-sinus-like stalk are discussed. Clinical material Three cases in which a spinal congenital dermal sinus was suspected are presented. A similar anatomical configuration, different from that of a dermal sinus, was found. All cases presented with a skin-covered dimple from which a solid tract was seen continuing intramedullary in two cases and intraspinally in one case. None of the patients presented with signs of infection or an associated dermoid–epidermoid tumor. Clinical, radiological, and surgical findings are discussed. A hypothesis is made on the pathological genesis of this malformation. Conclusion A dermal-sinus-like stalk is a malformation similar to a spinal congenital dermal sinus but is not associated with DS-related complications. Despite important clinical, radiological, surgical, and histopathological differences, it is difficult to distinguish this malformation from a true DS based on clinical and radiological examination alone. Therefore, surgical intervention, at the time of diagnosis, is recommended in all cases.

Dear Editor, We wish to thank Professor Raybaud for his valued comments [7] with regards to the embryology of the fourth ventricular outlet and the history of the terminology currently in use for cystic malformations of the posterior fossa [2, 4, 10]. In his original, well-illustrated paper published at the turn of the century, Blake states that “his investigations on the subject were prompted by the contradictory opinions and the lack of absolute knowledge concerning the nature of the communications between the cavity of the fourth ventricle and the subarachnoid space” [2]. Interestingly, to date, there are still “contradictory opinions and a lack of absolute knowledge” with regard to the spectrum of posterior fossa cysts and cyst-like malformations, including the one supposedly related to the embryological entity known as Blake's pouch, which is referred to as Blake's pouch cyst by some, and persisting Blake's pouch by others. Because of our incomplete understanding of normal and abnormal embryological development in the posterior fossa, there are many descriptive terms, eponyms, classifications, and revised classifications [1, 5, 6, 9] that lack uniformity and add to the confusion. A great deal of answers may be in anatomical and embryological studies that may nowadays include such sophisticated techniques as ultra high-field strength MR imaging, or phase-contrast cine MR imaging to evaluate cerebrospinal fluid flow [11]. However, in our opinion, everyday clinical practice requires a more practical approach, which was exactly the purpose of our paper [3]. Modern MR imaging techniques enable us to recognize distinct imaging features that may help identify subgroups in the spectrum of posterior fossa cysts and cyst-like malformations, as suggested by Barkovich et al. as early as 1989 [1]. Moreover and possibly of greater importance to clinicians, these techniques may enable us to identify children who may benefit from a specific surgical intervention (i.e., cyst fenestration, cyst shunting, ventricular shunting, endoscopic third ventriculostomy). In this regard, the most important questions might be (1) whether there is fourth ventricular outflow obstruction and resulting hydrocephalus and (2) whether there are associated (developmental) anomalies. We were inspired by the paper of Tortori-Donati et al. [9] who proposed a practical classification for those cystic malformations of the posterior cranial fossa originating from a defect of the posterior membranous area. According to these authors, in the absence of anomalies of the anterior membranous area (i.e., when vermis, cerebellar hemispheres, and fourth ventricle are roughly normal) a defect of the posterior membranous area may produce two distinct malformations: mega cisterna magna and persisting Blake's pouch. Still according to these authors, a mega cisterna magna should be clinically silent (no symptoms or signs secondary to compression of the nervous and ventricular structures of the posterior fossa), should not produce hydrocephalus, and should never be treated. Differential diagnosis in case of a dilated retrocerebellar subarachnoid space and an associated hydrocephalus should be either an arachnoid cyst (produced by an entirely different mechanism that does not involve the posterior membranous area), an acquired encystment of the fourth ventricle (e.g., posthemorrhagic, postinfectious, or postoperative), or a Blake's pouch cyst. The latter is defined as a failure of regression of Blake's pouch (hence the term “persisting Blake's pouch”) secondary to non-perforation of the foramen of Magendi, resulting in a posterior ballooning of the superior medullary velum into the cisterna magna. As such, according to these authors, a persisting Blake's pouch should communicate freely with the fourth ventricle, and should always be accompanied by hydrocephalus. Moreover, it may (or may not) produce symptoms early or late in life [3] pretty much in the same way as in congenital aqueductal stenosis. Tortori-Donati et al. [9] continue that shunting of either the lateral ventricles or the pouch restores the ventricular system to a normal size and allows re-expansion of the compressed cerebellum, while the pouch diminishes in size or completely collapses. Such practical radiological classifications are appealing and easy to apply in everyday clinical practice. As such, we reported six cases with a retrocerebellar cyst that appeared to communicate freely with the fourth ventricle, an associated hydrocephalus, and a roughly normal vermis, cerebellar hemispheres, and fourth ventricle configuration [3]. We admit we had some discussions about the first child who died and had an autopsy, but decided to include the case for several reasons. First, it did look like an acute bleeding into a pre-existent posterior fossa cyst-like malformation that may have acted as a locus minoris resistentiae when (for unrelated reasons) the child developed a coagulation disorder. Second, to attract the readers' attention underscoring the wide clinical spectrum of Blake's pouch cyst, that may on the other end of the spectrum remain asymptomatic throughout life. Moreover, whereas Tortori-Donati et al.[9] suggested a treatment involving some kind of shunting, we successfully treated three symptomatic cases by means of an endoscopic third ventriculostomy, and suggest this may be regarded the best current treatment option for symptomatic Blake's pouch cyst. Also of interest, some years earlier than Tortori-Donati, Strand et al. [8] proposed a unified embryological theory with regard to posterior fossa cysts and cyst-like malformations. These authors emphasize that it is more important to describe the morphologic findings (using a kind of checklist proposed in their material and methods section) than to label the retrocerebellar cyst with an eponym. They point out that it is of particular importance whether the retrocerebellar cyst is associated with a malformed hindbrain (i.e., true cerebellar hypoplasia), a deformed hindbrain (i.e., merely mass effect on a roughly normal cerebellum), or both, as the two may actually coexist, illustrating every classification in the end is somewhat arbitrary. Moreover, of equal importance is the detection and delineation of other central nervous system anomalies, as well as aqueductal patency in case of an associated hydrocephalus [8]. Finally, we fully agree with Professor Raybaud's comment [7] that an extraventricular hydrocephalus caused by arachnoid encystment after an intraventricular hemorrhage should be included in the differential diagnosis. However, because imaging as well as therapeutic options are pretty much the same for both entities, again from a practical standpoint, distinguishing both entities despite their different etiology (one congenital, the other one acquired) may not be necessary. In conclusion, over the years, the eponyms Blake's pouch cyst and persisting Blake's pouch have been used inconsequently in the literature on posterior fossa cysts and cyst-like malformations. From a practical standpoint, however, as well as for the sake of clarity, we would agree with Tortori-Donati et al. [9] that Blake's pouch cyst should be regarded as a separate entity, involving a retrocerebellar cyst that appears to communicate freely with the fourth ventricle, an associated hydrocephalus that may or may not become symptomatic, and a roughly normal vermis, cerebellar hemispheres, and fourth ventricle configuration. Importantly, not all posterior fossa cysts and cyst-like malformations with an associated hydrocephalus are a Dandy–Walker or a Dandy–Walker variant (defect of the anterior membranous area). They may be a Blake's pouch cyst (defect of the posterior membranous area), or may even be acquired (secondary arachnoidal adhesions causing fourth ventricular outflow obstruction). We suggest that endoscopic third ventriculostomy may be regarded the best current treatment option for symptomatic Blake's pouch cyst.