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Chiari zero malformation is a relatively new and rare subtype of Chiari malformations. Most of the patients present with signs and symptoms of Chiari malformation without actual cerebellar tissue herniation, with or without syringomyelia. Furthermore, Chiari zero cases can be associated with syringobulbia in rare instances. We present a case of a 39-year-old patient diagnosed with Chiari zero associated with syringomyelia and syringobulbia.

There is an absent systematic analysis or review that has been conducted to clarify the topic of nomenclature history and terms misuse about Chiari malformations (CMs). We reviewed all reports on terms coined for CMs for rational use and provided their etymology and future development. All literature on the nomenclature of CMs was retrieved and extracted into core terms. Subsequently, keyword analysis, preceding and predicting (2023–2025) compound annual growth rate (CAGR) of each core term, was calculated using a mathematical formula and autoregressive integrated moving average model in Python. Totally 64,527 CM term usage was identified. Of these, 57 original terms were collected and then extracted into 24 core-terms. Seventeen terms have their own featured author keywords, while seven terms are homologous. The preceding CAGR of 24 terms showed significant growth in use for 18 terms, while 13, three, three, and five terms may show sustained growth, remain stable, decline, and rare in usage, respectively, in the future. Previously, owing to intricate nomenclature, Chiari terms were frequently misused, and numerous seemingly novel but worthless even improper terms have emerged. For a very basic neuropathological phenomenon tonsillar herniation by multiple etiology, a mechanism-based nosology seems to be more conducive to future communication than an umbrella eponym. However, a good nomenclature also should encapsulate all characteristics of this condition, but this is lacking in current CM research, as the pathophysiological mechanisms are not elucidated for the majority of CMs. [ABSTRACT FROM AUTHOR]

Background: Surgical treatment of syringomyelia is directed at the reconstruction of the subarachnoid space and restoration normal cerebrospinal fluid flow. Direct intervention on the syrinx is a rescue procedure and should be offered to patients with refractory syringomyelia. Methods: We provide an overview on indications and technique of syringopleural shunt (SPS). The procedure involves the connection of syrinx with the pleural space using a lumboperitoneal shunt. The occurrence of a negative pressure inside the pleural compartment offers an appropriate gradient for drainage from the syrinx. Conclusions: The SPS allows for a safe and effective treatment of persistent syringomyelia when management of the underlying cause does not yield substantial improvement. [ABSTRACT FROM AUTHOR]

Background: Chiari malformations are a spectrum of posterior cranial fossa anomalies characterized by herniation of the cerebellar tonsils through the foramen magnum. Surgery is the treatment of choice for selected patients with good postoperative outcomes. Methods: We describe foramen magnum decompression (FMD) with dural opening and a "drum skin" duraplasty technique. Conclusions: In our experience, FMD with "drum skin" duraplasty is a safe and effective procedure, reducing the risk of CSF leakage and arachnoidal adhesions and yielding better long-term clinical and radiological outcomes than other traditional techniques. [ABSTRACT FROM AUTHOR]

Background: Excess flexion or extension during occipitocervical fusion (OCF) can lead to postoperative complications, such as dysphagia, respiratory problems, line of sight issues, and neck pain, but posterior fossa decompression (PFD) and OCF require different positions that require intraoperative manipulation. Objective: The objective of this study was to describe quantitative fluoroscopic morphometrics in Chiari malformation (CM) patients with symptoms of craniocervical instability (CCI) and demonstrate the intraoperative application of these measurements to achieve neutral craniocervical alignment while leveraging a single axis of motion with the Mayfield head clamp locking mechanism. Methods: A retrospective cohort study of patients with CM 1 and 1.5 and features of CCI who underwent PFD and OCF at a single-center institution from March 2015 to October 2020 was performed. Patient demographics, preoperative presentation, radiographic morphometrics, operative details, complications, and clinical outcomes were analyzed. Results: A total of 39 patients met the inclusion criteria, of which 37 patients (94.9%) did not require additional revision surgery after PFD and OCF. In this nonrevision cohort, preoperative to postoperative occipital to C2 angle (O-C2a) (13.5° ± 10.4° vs. 17.5° ± 10.1°, P = 0.047) and narrowest oropharyngeal airway space (nPAS) (10.9 ± 3.4 mm vs. 13.1 ± 4.8 mm, P = 0.007) increased significantly. These measurements were decreased in the two patients who required revision surgery due to postoperative dysphagia (mean difference – 16.6°° in O C2a and 12.8°° in occipital and external acoustic meatus to axis angle). Based on these results, these fluoroscopic morphometrics are intraoperatively assessed, utilizing a locking Mayfield head clamp repositioning maneuver to optimize craniocervical alignment prior to rod placement from the occipital plate to cervical screws. Conclusion: Establishing a preoperative baseline of reliable fluoroscopic morphometrics can guide surgeons intraoperatively in appropriate patient realignment during combined PFD and OCF, and may prevent postoperative complications. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation (CM) is a cluster of related developmental anomalies of the posterior fossa ranging from asymptomatic to fatal. Cranial and spinal decompression can help alleviate symptoms of increased cerebrospinal fluid pressure and correct spinal deformity. As surgical intervention for CM increases in frequency, understanding predictors of reoperation may help optimize neurosurgical planning. Materials and Methods: This was a retrospective analysis of the prospectively collected Healthcare Cost and Utilization Project's California State Inpatient Database years 2004–2011. Chiari malformation Types 1–4 (queried with ICD-9 CM codes) with associated spinal pathologies undergoing stand-alone spinal decompression (queried with ICD-9 CM procedure codes) were included. Cranial decompressions were excluded. Results: One thousand four hundred and forty-six patients (29.28 years, 55.6% of females) were included. Fifty-eight patients (4.01%) required reoperation (67 reoperations). Patients aged 40–50 years had the most reoperations (11); however, patients aged 15–20 years had a significantly higher reoperation rate than all other groups (15.5% vs. 8.2%, P = 0.048). Female gender was significantly associated with reoperation (67.2% vs. 55.6%, P = 0.006). Medical comorbidities associated with reoperation included chronic lung disease (19% vs. 6.9%, P < 0.001), iron deficiency anemia (10.3% vs. 4.1%, P = 0.024), and renal failure (3.4% vs. 0.9%, P = 0.05). Associated significant cluster anomalies included spina bifida (48.3% vs. 34.8%, P = 0.035), tethered cord syndrome (6.9% vs. 2.1%, P = 0.015), syringomyelia (12.1% vs. 5.9%, P = 0.054), hydrocephalus (37.9% vs. 17.7%, P < 0.001), scoliosis (13.8% vs. 6.4%, P = 0.028), and ventricular septal defect (6.9% vs. 2.3%, P = 0.026). Conclusions: Multiple medical and CM-specific comorbidities were associated with reoperation. Addressing them, where possible, may aid in improving CM surgery outcomes. [ABSTRACT FROM AUTHOR]

Treatment of patients with the simultaneous presence of Chiari malformation type I (MC I) and hydrocephalus may include both one-stage and two-stage surgical interventions. The article describes the two-stage surgical treatment experience performed for the first time in the Republic of Tajikistan. Description of the case. A 50-year-old female patient with a three-year history of bursting headache, dizziness, nausea, and vomiting developed impaired coordination of movements and decreased visual acuity. Computed tomography (CT) revealedsigns of MC I: descent of the cerebellar tonsils 5 mm below the level of the foramen magnum and occlusive triventricular hydrocephalus with symmetrical enlargement of the lateral and third ventricles. The patient underwent surgery – endoscopic third ventriculocisternostomy (ETV) in combination with decompressive suboccipital craniectomy, which was supplemented by CI laminectomy. After the surgery, the symptoms regressed. According to the control CT scan, there was a moderate decrease in the size of the lateral and third ventricles, restoration of the normal anatomical structure of the posterior cranial fossa.

Eight syndrome is defined as the combination of a unilateral conjugate gaze palsy and ipsilateral seventh cranial nerve palsy. It may occur as a result of demyelinating, vascular, infectious, or compressive lesions of the brainstem localized to the caudal pontine tegmentum. A 43-year-old woman was admitted to our clinic with complaints of headache, inability to look to the left, and weakness on the left side of her face. The complaints had begun abruptly about a month before her admission. Suboccipital decompression surgery for type I Chiari malformation had been performed 10 years earlier. Neuro-ophthalmological examination revealed left-sided horizontal gaze palsy and anisocoria. Cranial and cervical magnetic resonance images revealed cerebellar tonsillar herniation and syringomyelia, the latter of which was considered to be the cause of eight syndrome. No interventions were performed, and periodic follow-up was advised on neurosurgical consultation. Left gaze palsy and facial palsy recovered almost completely in three months, while the anisocoria persisted. Syringomyelia should be considered among the causes of horizontal gaze palsy plus ipsilateral seventh nerve palsy, termed as eight syndrome. Clinical suspicion and appropriate radiological examination can aid in the diagnosis.

Children with Chiari Malformation type II (CM-II) have an increased risk of sleep apnoea. The aim of the study was to describe the management of patients with CM-II in relation to sleep apnoea syndrome, clinical symptoms and magnetic resonance imaging (MRI) findings. The paper reports 8 consecutive patients with CM-II followed between September 2013 and April 2017. The prevalence of sleep apnoea syndrome was high with 6 out of 8 patients having mild-to-severe sleep apnoea. Patients with severe sleep apnoea syndrome (3 patients) were treated with upper airway surgery and/or noninvasive ventilation. Our findings highlight the importance of respiratory polygraphy in the management of patients with CM-ΙΙ. Poly(somno)graphy is recommended in the follow-up care of children with CM-II. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation type 1 (CM-1) is characterized by cerebellar tonsil herniation through the foramen magnum and can be associated with additional craniovertebral junction anomalies (CVJA). The pathophysiology and treatment for CM-1 with CVJA (CM-CVJA) is debated. Objective: To evaluate the trends and outcomes of surgical interventions for patients with CM-CVJA. Methods: A systematic review of the literature was performed to obtain articles describing surgical interventions for patients with CM-CVJA. Articles included were case series describing surgical approach; reviews were excluded. Variables evaluated included patient characteristics, approach, and postoperative outcomes. Results: The initial query yielded 403 articles. Twelve articles, published between 1998-2020, met inclusion criteria. From these included articles, 449 patients underwent surgical interventions for CM-CVJA. The most common CVJAs included basilar invagination (BI) (338, 75.3%), atlantoaxial dislocation (68, 15.1%) odontoid process retroflexion (43, 9.6%), and medullary kink (36, 8.0%). Operations described included posterior fossa decompression (PFD), transoral (TO) decompression, and posterior arthrodesis with either occipitocervical fusion (OCF) or atlantoaxial fusion. Early studies described good results using combined ventral and posterior decompression. More recent articles described positive outcomes with PFD or posterior arthrodesis in combination or alone. Treatment failure was described in patients with PFD alone that later required posterior arthrodesis. Additionally, reports of treatment success with posterior arthrodesis without PFD was seen. Conclusion: Patients with CM-CVJA appear to benefit from posterior arthrodesis with or without decompressive procedures. Further definition of the pathophysiology of craniocervical anomalies is warranted to identify patient selection criteria and ideal level of fixation.

Syringomyelia can be associated with multiple etiologies. The treatment of the underlying causes is first-line therapy; however, a direct approach to the syrinx is accepted as rescue treatment. Any direct intervention on the syrinx requires a myelotomy, posing a significant risk of iatrogenic spinal cord (SC) injury. Intraoperative neurophysiological monitoring (IONM) is crucial to detect and prevent surgically induced damage in neural SC pathways. We retrospectively reviewed the perioperative and intraoperative neurophysiological data and perioperative neurological examinations in ten cases of syringomyelia surgery. All the monitored modalities remained stable throughout the surgery in six cases, correlating with no new postoperative neurological deficits. In two patients, significant transitory attenuation, or loss of motor evoked potentials (MEPs), were observed and recovered after a corrective surgical maneuver, with no new postoperative deficits. In two cases, a significant MEP decrement was noted, which lasted until the end of the surgery and was associated with postoperative weakness. A transitory train of neurotonic electromyography (EMG) discharges was reported in one case. The surgical plan was adjusted, and the patient showed no postoperative deficits. The dorsal nerve roots were stimulated and identified in the seven cases where the myelotomy was performed via the dorsal root entry zone. Dorsal column mapping guided the myelotomy entry zone in four of the cases. In conclusion, multimodal IONM is feasible and reliable and may help prevent iatrogenic SC injury during syringomyelia surgery. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid overdrainage in long-lasting shunted hydrocephalus is a well recognized complication. It may lead to different clinical syndromes which may occur over time, namely cranioencephalic disproportion and hindbrain herniation. Among the latter, Chiari malformation type 1 classically refers to one of the mildest form. When symptomatic, the patients generally exhibit a chronic, slowly progressive disease course. Although well documented in Chiari type II malformation and hydrocephalus, ventriculo-peritoneal shunt malfunction causing acute neurological deterioration in acquired Chiari malformation type 1 has been described only in three cases. All these patients underwent urgent shunt revision and suboccipital decompression in two of them, achieving good clinical improvement. We report on a 20-year-old woman harboring a previously asymptomatic Chiari malformation type 1, who experienced an acute foramen magnum syndrome with ventriculo-peritoneal shunt malfunction. We performed an endoscopic third-ventriculo-cisternostomy and definite removal of the shunt, obtaining the complete resolution of symptoms and shunt independence at 2 years follow-up. The phisiopathogenetic mechanisms and surgical management are discussed. [ABSTRACT FROM AUTHOR]

Objective: Pathomorphological alterations of the central nervous system in dogs, such as syringomyelia and Chiari-like malformation, can cause cranial and cervical hyperesthesia and neuropathic pain. The long-term activity of the pain network can induce functional alteration and eventually even morphological changes in the pain network. This may happen especially in the prefrontal and cingulate cortex, where atrophy of the gray matter (GM) was observed in humans with chronic pain, irrespective of the nature of the pain syndrome. We tested the hypothesis that Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation and associated syringomyelia (SM) and pain show cerebral morphological differences compared to animals without signs of syringomyelia and pain. Methods: Volumetric datasets of 28 different brain structures were analyzed in a retrospective manner, including voxel-based morphometry, using magnetic resonance imaging data obtained from 41 dogs. Results: Volumetric analyses revealed a decrease in GM volumes in the cingulate gyrus (CG) in CKCS with SM and chronic pain when normalized to brain volume. This finding was supported by voxel-based morphometry, which showed a cluster of significance within the CG. Conclusion: GM atrophy in the CG is associated with chronic pain and thus may serve as an objective readout parameter for the diagnosis or treatment of canine pain syndromes. [ABSTRACT FROM AUTHOR]

Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management. [ABSTRACT FROM AUTHOR]

Patients with Chiari malformation (CM) associated with atlantoaxial dislocation (AAD) and basilar invagination (BI) may present with a small posterior cranial fossa, but data on the volumetric analysis are lacking. Additionally, whether additional foramen magnum decompression (FMD) is needed together with atlantoaxial fusion remains controversial. This study evaluated the volumetric alterations of the posterior cranial fossa in these patients and analyzed the radiological and clinical outcomes after posterior C1-C2 reduction and fixation plus C1 posterior arch resection. Thirty-two adult CM patients with AAD and BI (CM-AAD/BI group) and 21 AAD and BI patients without CM (AAD/BI-only group) who received posterior atlantoaxial fusion plus C1 posterior arch resection were retrospectively studied. The clinical and radiological outcomes and volumetric measurements of the posterior cranial fossa were evaluated. The majority of CM-AAD/BI patients (94%) improved clinically and radiologically at 12 mo postoperatively, and none required additional FMD. Morphological analysis revealed a significant reduction in the bony posterior cranial fossa volumes of the CM-AAD/BI group (P < 0.01) and the AAD/BI-only group (P < 0.01) relative to those of the CM group. No significant differences were observed between the CM-AAD/BI and AAD/BI groups. Compared with patients with simple CM, patients with AAD/BI with or without CM demonstrated a considerably and equally reduced bony posterior cranial fossa volume. No additional FMD is needed in the treatment of CM-AAD/BI patients after posterior reduction and fusion plus C1 posterior arch resection. [ABSTRACT FROM AUTHOR]

The Chiari malformations present heterogeneous entities, raising many questions regarding their natural history, pathophysiology, treatment options, and prognosis. Bibliometric analyses have emerged as a method to assess the impact of articles in current clinical practice. The most cited articles were identified via Scopus Library by using the keywords "Chiari," "Arnold-Chiari," and "Chiari malformation." The 100 most cited articles were then assembled and analyzed in detail. The top 100 articles yielded a mean of 155,28 citations per article, ranging from 87 to 896 citations, and from 1.63 to 38.96 per year. Years of publications ranged from 1950 to 2015. Oakes was the most cited author (n = 7), followed by Tubbs and Milhorat. The country with the highest cited articles was the United States (n = 63), followed by the United Kingdom (n = 6), Italy (n = 5), Spain (n = 5), Japan (n = 4), and Germany (n = 3). Neurosurgery is the journal with the most highly cited articles (n = 21), followed by Journal of Neurosurgery (n = 19). Most articles focused on Chiari malformation type I (n = 83). The topic discussed most often was imaging (n = 63), followed by the evaluation of treatment outcome (n = 58), clinical signs and symptoms (n = 57), and the role of surgery (n = 56). The present bibliometric analysis provides a succinct appraisal of the most cited articles concerning Chiari malformation, allowing a deeper insight in this area and its main influential articles with their impact on current clinical practice and future research. [ABSTRACT FROM AUTHOR]

Purpose: To describe the clinical characteristics of pre- and postnatal care of children born with myelomeningocele in Costa Rica from 2004 to 2022 after the introduction of mandatory fortification of four major staple foods, describing the clinical features of this cohort including the size of the meningomyelocele, neurological level, presence of symptomatic Chiari II at birth, kyphosis, and the severity of hydrocephalus requiring cerebrospinal fluid (CSF) shunting. These results were compared against the pre-fortification historical data to determine favorable outcomes from this health policy. Methods: We performed a retrospective review of the clinical records of patients with myelomeningocele at the spina bifida clinic from the National Children's Hospital of Costa Rica who were born between 2004 and 2022, a period when staple food fortification was implemented in the country for four food staples (wheat and corn flour, rice, and dairy products). Pre and postnatal care data pertaining to the number of obstetric ultrasound studies, the trimester in which they were performed, the detection of myelomeningocele and associated hydrocephalus, gestational age and route of delivery, neurological level, myelomeningocele defect size, associated kyphosis and symptomatic Chiari II malformation at birth, time periods of myelomeningocele repair, and CSF shunting were examined. A descriptive comparative frequency analysis between myelomeningocele (MMC) defect size, CSF shunt insertion, symptomatic Chiari II, and kyphosis between the different functional levels was performed with the estimation of the Fisher's exact chi-square test by contingency tables, and 0.05 was set as significance level. Additionally, the postnatal features of this cohort were compared against pre-fortification historical data obtained from 100 live-born patients between 1995 and 1996. Results: A total of 215 patients that were live born between 2004 and 2022 were eligible for analysis with a follow up ranging from 1 to 19 years (median follow up: 7.9 years). Among 99.1% of the mothers of patients who had prenatal consultations, 95.8% had an average of 3.8 obstetric ultrasound studies which led to a 59% prenatal detection rate of myelomeningocele. The pre and post fortification features showed a male/female ratio that changed from 0.92 to 1.25 respectively. Among these newborns, there was an increase from 54 to 64% cesarean sections as method for delivery. Only 26% of the pre fortification patients had the MMC defect repaired in the first 24 h, 32% from 24 to 72 h, 20% from 72 h to 1 week, and 22% later than 10 days respectively which deeply contrasted with the post fortification cohort where 7.5% had the MMC defect repaired in less than 8 h, 12.2% from 8 to 12 h, 66.5% 12–24 h, and 12.7% from 24 to 48 h and 1% later than 48 h, respectively (P < 0.01). Regarding the post fortification myelomeningocele anatomic and functional characteristics, defect size was measured as less than 3 cm in 7% of cases, 3 to 5 cm in 50% of cases, 5 to 7 cm in 42% of cases, and greater than 7 cm in 1% of cases. Thirteen percent of the cases had paraplegia due to a thoracic level, 10% had a high lumbar level, 58% had a middle lumbar level, 13% a lower lumbar level, and 6% only sacral compromise. When the data from the pre and post fortification cohorts were adjusted and compared, there was a reduction from thoracic/high lumbar cases from 26 to 23% (P < 0.56), with an increase of middle lumbar cases from 43 to 58% and a reduction from 25 to 13% of low lumbar cases (P < 0.01) while there was no change in the 6% percentage of sacral cases respectively. Lesions that were considered too extensive or larger than 7 cm decreased from 7 to 1% while associated kyphotic deformities decreased from 6 to 1.4% (P < 0.01); symptomatic Chiari II malformation at birth also decreased from 7 to 2% in the pre- and post-fortification cohorts respectively with all these changes being statistically significant (P < 0.01). Seventy-nine percent and 80% of the pre and post FAF cohorts required CSF VP shunting with a mean time for insertion of 10 days after spinal defect closure with no significant statistical change between the two groups. Conclusions: This study describes a four-staple folate fortified population of live-born patients with myelomeningocele lesions whose neurological level, defect size, and associated deformities such as spinal kyphosis and symptomatic Chiari II at birth suggest that folate fortification could have diminished the severity of this congenital disease. [ABSTRACT FROM AUTHOR]

Background: Scoliosis is a spinal deformity that usually manifests as a structural curve determining a variable deformity of the trunk. According to some published series, 4 to 26% of scoliosis initially classified as idiopathic show neurological alterations when studied with nuclear magnetic resonance, such as syringomyelia and Chiari malformation, among the most frequent. Chiari malformations are characterized by descending herniation of the cerebellar tonsils, brainstem, and IV ventricle into the spinal canal. Case report: We present the case of a patient whose first symptomatic manifestation was early-onset scoliosis. The overlapping of some physical examination signs, such as postural lateralization and scoliosis, reinforced the active suspicion of neuroaxis alterations. Conclusions: Early childhood-onset scoliosis should raise a high degree of suspicion for association with neuro-spinal diseases. Although the frequency of Chiari malformation is low, its early approach could reduce the progression of associated comorbidities. An early detection could change the prognosis of the disease. [ABSTRACT FROM AUTHOR]

• Evaluation of patients after Chiari surgery can require repeat imaging, usually CT or MRI. • The need exists for a less expensive, more convenient, and radiation free alternative. • Transcutaneous posterior fossa ultrasound is feasible to show anatomy. • Novel Chiari-specific cranioplasties that allow ultrasound transmission are safe. Evaluation after posterior fossa decompression for Chiari malformation can require repeated imaging, particularly with persistent symptoms. Typically, CT or MRI is used. However, CT carries radiation risk and MRI is costly. Ultrasound is an inexpensive, radiation-free, point-of-care modality that has, thus far, been limited by intact skull and traditional cranioplasty materials. Ultrasound also allows for imaging in different head positions and body postures, which may lend insight into cause for persistent symptoms despite adequate decompression on traditional neutral static CT or MRI. We evaluate safety and feasibility of ultrasound as a post-operative imaging modality in patients reconstructed with sonolucent cranioplasty during posterior fossa decompression for Chiari malformation. Outcomes were analyzed for 26 consecutive patients treated with a Chiari-specific sonolucent cranioplasty. This included infection, need for revision, CSF leak, and pseudomeningocele. Ultrasound was performed point-of-care in the outpatient clinic by the neurosurgery team to assess feasibility. In eight months mean follow up, there were no surgical site infections or revisions with this novel sonolucent cranioplasty. Posterior fossa anatomy was discernable via transcutaneous ultrasound obtained point-of-care in the clinic setting at follow up visits. We demonstrate proof of concept for ultrasound as a post-operative imaging modality after posterior fossa decompression for Chiari malformation. With further investigation, ultrasound may prove to serve as an alternative to CT and MRI in this patient population, or as an adjunct to provide positional and dynamic information. Use of sonolucent cranioplasty is safe. This technique deserves further study. [ABSTRACT FROM AUTHOR]

Background. The incidence of CM-I is estimated to be 1/1,000 births. In rare cases, CM-I is complicated by associations with other malformations of the craniocervical junction, including mainly Basilar invagination (BI). Chiari malformation (CM) is characterized by a congenital malformation of the posterior cranial fossa with cerebellar tonsils herniation through the foramen magnum, probably due to the underdevelopment of the posterior bony skeleton (exo-occipital and supraoccipital bones). CM may be complicated by a variety of other malformations, including platybasia, basilar invagination and occipitalization, although syringomyelia (SM) is the most commonly observed. Case Report. A girl, 14 years old came with a chief complaint of headache, which is exacerbated whenever the patient coughed or sneezed. The patient also complained about neck pain and a tingling sensation in her hand. A history of vomiting or seizure has not been found. A history of muscle weakness was not found. On physical examination, the patient has a GCS score of 15 on admission, with normal muscle tone and normal reflexes. The patient has a sensory deficit, on the level below C4. The patient underwent CT Scan and MRI whole spine, Chiari 1 malformation and platybasia were diagnosed. The patient underwent posterior fossa decompression, and postoperatively symptoms of Chiari and sensory deficit gradually improved. Discussion. As an association with this syndrome, there is also basilar invagination as shown by flat basioccipt (platybasia) and upward odontoid projection. hydrocephalus [3]. Virchow coined the term 'platybasia' to describe an abnormal flattening of the skull base, a defect which he attributed to abnormal bone development. In addition to the flattening of the base of the skull, there was upward displacement (impression) of the basilar and condylar portions of the occipital bone, which caused infolding, or impression of the foramen magnum, reduction of the posterior fossa, and consequent protrusion of the upper cervical spine into the anterior brainstem, with neurological signs. The symptomatology presented by CM-1 patients is diverse, and its severity does not correlate with the degree of TH, with some asymptomatic cases presenting with prominent TH. The onset of symptoms generally develops gradually, however, trauma, coughing/sneezing or pregnancy can also precipitate the event. The most common treatment for these patients is surgical PCF decompression (alone or with duraplasty), although cerebellar tonsillectomy, cervical laminectomy, and suboccipital cranioplasty are also applied. The goal of these surgical procedures is to decompress the foramen magnum and increase the subarachnoid space in order to avoid the impaction of the cerebellar tonsils, reestablish the CSF flow and reverse the symptoms. Conclusion. This patient was diagnosed with Chiari 1 malformation and platybasia, as suggested in the literature, posterior fossa decompression was done and the patient improved clinically. [ABSTRACT FROM AUTHOR]

Purpose: Chiari malformation type 1 (CM-1) is a posterior fossa anomaly characterized by herniation of the cerebellar tonsils from the foramen magnum (FM). This study compares FM, medulla spinalis (MS), and herniated cerebellar tonsils ratios by making area measurements from axial plane MRI in CM-1 patients and the control group. Methods: Our study evaluated 30 pediatric patients with CM-1 and 30 people in the control group. The lengths of the McRae line, twining line, and clivus line were measured on the posterior cranial fossa evaluation. The areas of FM (AFM), MS (AMS), and herniated cerebellar tonsils (ATONSILS) were measured by axial images. Results: As a result of area measurements obtained from axial cross-sectional MRI, a statistically significant difference was found between CM-1 patients and the control group. According to the results of the ROC analysis, if an individual's AMS/AFM value is above 17.9% or the ATONSILS/AFM value is above 18.4%, it can be interpreted as a CM-1 patient. Conclusion: It will be easier to diagnose the patient with the new approach we obtained from axial MR images in addition to sagittal MR images. This method can be a guide in some cases when the surgeons are undecided. [ABSTRACT FROM AUTHOR]

Chiari Malformations are a group of conditions defined in 1891 with 5 degrees being described. These malformations present with several symptoms such as cervical protrusion and are associated with hydrocephalus. Also, they can also present with different clinical signs and symptoms, such as deafness and tinnitus. We present a case of a 45-year-old man with unilateral tinnitus evaluated in otolaryngology office. No other symptoms on otolaryngological physical exam were detected in the audiogram performed it was described a significant unilateral sensorineural hearing loss. During the study of this patient, Magnetic Resonance Imaging was requested, showing a type I Chiari malformation. The patient was then observed by Ophthalmology, Neurology, and Neurosurgery. No other neurological symptoms of malformation Chiari syndrome or cranial nerve abnormalities were presented at the respective exam. The surgical management of these pathologies takes into account an adequate CSF and venous blood flow - that was seen in this patient, therefore, there was no surgical indication for decompression. The patient maintains its follow-up in the otolaryngology, neurology, and neurosurgery office, and tinnitus was minimized after prosthetic adaptation was recommended to optimize the quality of life, which was achieved. [ABSTRACT FROM AUTHOR]

BACKGROUND: Previous case-control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known. METHODS: Eighteen CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group. RESULTS: CMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group. CONCLUSIONS: Diffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.

BackgroundPrevious case-control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known.MethodsEighteen CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group.ResultsCMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group.ConclusionsDiffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.

Background: Chiari malformation (CM) is a cluster of related developmental anomalies of the posterior fossa ranging from asymptomatic to fatal. Cranial and spinal decompression can help alleviate symptoms of increased cerebrospinal fluid pressure and correct spinal deformity. As surgical intervention for CM increases in frequency, understanding predictors of reoperation may help optimize neurosurgical planning. Materials and Methods: This was a retrospective analysis of the prospectively collected Healthcare Cost and Utilization Project's California State Inpatient Database years 2004–2011. Chiari malformation Types 1–4 (queried with ICD-9 CM codes) with associated spinal pathologies undergoing stand-alone spinal decompression (queried with ICD-9 CM procedure codes) were included. Cranial decompressions were excluded. Results: One thousand four hundred and forty-six patients (29.28 years, 55.6% of females) were included. Fifty-eight patients (4.01%) required reoperation (67 reoperations). Patients aged 40–50 years had the most reoperations (11); however, patients aged 15–20 years had a significantly higher reoperation rate than all other groups (15.5% vs. 8.2%, P = 0.048). Female gender was significantly associated with reoperation (67.2% vs. 55.6%, P = 0.006). Medical comorbidities associated with reoperation included chronic lung disease (19% vs. 6.9%, P < 0.001), iron deficiency anemia (10.3% vs. 4.1%, P = 0.024), and renal failure (3.4% vs. 0.9%, P = 0.05). Associated significant cluster anomalies included spina bifida (48.3% vs. 34.8%, P = 0.035), tethered cord syndrome (6.9% vs. 2.1%, P = 0.015), syringomyelia (12.1% vs. 5.9%, P = 0.054), hydrocephalus (37.9% vs. 17.7%, P < 0.001), scoliosis (13.8% vs. 6.4%, P = 0.028), and ventricular septal defect (6.9% vs. 2.3%, P = 0.026). Conclusions: Multiple medical and CM-specific comorbidities were associated with reoperation. Addressing them, where possible, may aid in improving CM surgery outcomes.

Background: Excess flexion or extension during occipitocervical fusion (OCF) can lead to postoperative complications, such as dysphagia, respiratory problems, line of sight issues, and neck pain, but posterior fossa decompression (PFD) and OCF require different positions that require intraoperative manipulation. Objective: The objective of this study was to describe quantitative fluoroscopic morphometrics in Chiari malformation (CM) patients with symptoms of craniocervical instability (CCI) and demonstrate the intraoperative application of these measurements to achieve neutral craniocervical alignment while leveraging a single axis of motion with the Mayfield head clamp locking mechanism. Methods: A retrospective cohort study of patients with CM 1 and 1.5 and features of CCI who underwent PFD and OCF at a single-center institution from March 2015 to October 2020 was performed. Patient demographics, preoperative presentation, radiographic morphometrics, operative details, complications, and clinical outcomes were analyzed. Results: A total of 39 patients met the inclusion criteria, of which 37 patients (94.9%) did not require additional revision surgery after PFD and OCF. In this nonrevision cohort, preoperative to postoperative occipital to C2 angle (O-C2a) (13.5° ± 10.4° vs. 17.5° ± 10.1°, P = 0.047) and narrowest oropharyngeal airway space (nPAS) (10.9 ± 3.4 mm vs. 13.1 ± 4.8 mm, P = 0.007) increased significantly. These measurements were decreased in the two patients who required revision surgery due to postoperative dysphagia (mean difference – 16.6°° in O C2a and 12.8°° in occipital and external acoustic meatus to axis angle). Based on these results, these fluoroscopic morphometrics are intraoperatively assessed, utilizing a locking Mayfield head clamp repositioning maneuver to optimize craniocervical alignment prior to rod placement from the occipital plate to cervical screws. Conclusion: Establishing a preoperative baseline of reliable fluoroscopic morphometrics can guide surgeons intraoperatively in appropriate patient realignment during combined PFD and OCF, and may prevent postoperative complications.

Study Design: Prospective human anatomical study. Objective: Occipitocervical fusion with occipital plate or condyle screws has shown higher failure rates in those with skeletal dysplasia. The modified occipital condyle screw connects the occipital condyle to the pars basilaris of the occipital bone that may achieve fortified bony purchase and serve as a more rigid fixation point. We evaluate anatomical feasibility of a novel cranial fixation technique designed to decrease risk of pseudarthrosis. Materials and Methods: Occipital condyles were analyzed morphologically using multiplanar three-dimensional reconstructed, ultra-thin section computed tomography. The following parameters were obtained: occipital condyle length, maximal cross section, location of hypoglossal canal, axial and sagittal orientation of the long axis, occipital condyle pedicle (OCP) diameter, maximal length of OCP screw, and entry point. Results: Forty patients with total of 80 occipital condyles were analyzed and the following measurements were obtained: occipital condyle length 24.1 mm (20.5–27.7, standard deviation [SD]: 2.2); condyle maximum axial cross-section 12.6 mm (9–15.8, SD: 1.9); length of OCP screw 38.9 mm (29.3–44, SD: 5.7); diameter of OCP 3.4 mm (3.2–3.6, SD: 0.2); clearance below hypoglossal canal 4.5 mm (3.4–7, SD: 1.1); and distance of screw entry point from condylar foramen 2 mm (range 0-4, SD 1.6). Conclusion: The modified occipital condyle screw connects the condyle with the clivus through the pars basilaris and represents a safe and technically feasible approach to achieve craniocervical fusion in skeletally mature individuals. This cephalad anchor point serves as an alternate fixation point of the occipitocervical junction with increased strength of construct and decreased risk of hardware failure or pseudarthrosis given cortical bone purchase and longer screw instrumentation.

Introduction: Ehlers–Danlos syndrome (EDS) is a connective tissue disorder that has been linked to several neurological problems including Chiari malformations, atlantoaxial instability (AAI), craniocervical instability (CCI), and tethered cord syndrome. However, neurosurgical management strategies for this unique population have not been well-explored to date. The purpose of this study is to explore cases of EDS patients who required neurosurgical intervention to better characterize the neurological conditions they face and to better understand how neurosurgeons should approach the management of these patients. Methods: A retrospective review was done on all patients with a diagnosis of EDS who underwent a neurosurgical operation with the senior author (FAS) between January 2014 and December 2020. Demographic, clinical, operative, and outcome data were collected, with additional radiographic data collected on patients chosen as case illustrations. Results: Sixty-seven patients were identified who met the criteria for this study. The patients experienced a wide array of preoperative diagnoses, with Chiari malformation, AAI, CCI, and tethered cord syndrome representing the majority. The patients underwent a heterogeneous group of operations with the majority including a combination of the following procedures– suboccipital craniectomy, occipitocervical fusion, cervical fusion, odontoidectomy, and tethered cord release. The vast majority of patients experienced subjective symptomatic relief from their series of procedures. Conclusions: EDS patients are prone to instability, especially in the occipital-cervical region, which may predispose these patients to require a higher rate of revision procedures and may require modifications in neurosurgical management that should be further explored.

INTRODUCTION: Cervical meningomyelocele (MMC) is rarely seen compared to lumbosacral and thoracolumbar meningomyelocele. There are only a few series related to cervical MMC in the literature. This study presents one of the most extensive series of cervical meningomyelocele, reviewing its clinical features, surgical management, and management strategies. METHODS: A total of 520 spina bifida patients, 25 of whom were diagnosed with cervical meningomyelocele, from January 2010 to September 2022, were included in the study. RESULTS: 88% (22) of the patients included in the study were newborns. The mean age was 3 days. Of the patients, 52% (13) were female and 48% (12) were male. The most common sites of cervical meningomyelocele were C4-C5, C5-C6, and C7-T1 regions with similar rates of 24%. There was a cranial anomaly in 56% (14) of the patients. The most common cranial anomalies were Chiari II with 24% (6), hydrocephalus, and Chiari type II with hydrocephalus and syringomyelia with 16% (4). All patients underwent surgical resection of the sac and intradural exploration. DISCUSSION AND CONCLUSION: Cervical meningomyelocele is structurally and clinically different from thoracolumbar and lumbosacral meningomyelocele and has more favorable outcomes after surgery. Preoperative magnetic resonance imaging and detailed patient evaluation are recommended to identify the cervical meningomyelocele's sac and spinal cord structure and additional anomalies. Surgical treatment should be done early and intradural exploration is recommended in addition to resection of the sac.

The use of live animal models for testing new therapies for brain and spinal cord repair is a controversial area. Live animal models have associated ethical issues and scientific concerns regarding the predictability of human responses. Alternative models that replicate the 3D architecture of the central nervous system have prompted the development of organotypic neural injury models. However, the lack of reliable means to access normal human neural tissue has driven reliance on pathological or post-mortem tissue which limits their biological utility. We have established a protocol to use donor cerebellar tonsillar tissue surgically resected from patients with Chiari malformation (cerebellar herniation towards the foramen magnum, with ectopic rather than diseased tissue) to develop an in vitro organotypic model of traumatic brain injury. Viable tissue was maintained for approximately 2 weeks with all the major neural cell types detected. Traumatic injuries could be introduced into the slices with some cardinal features of post-injury pathology evident. Biomaterial placement was also feasible within the in vitro lesions. Accordingly, this ‘proof-of-concept’ study demonstrates that the model offers potential as an alternative to the use of animal tissue for preclinical testing in neural tissue engineering. To our knowledge, this is the first demonstration that donor tissue from patients with Chiari malformation can be used to develop a benchtop model of traumatic brain injury. However, significant challenges in relation to the clinical availability of tissue were encountered, and we discuss logistical issues that must be considered for model scale-up.

Objective Combined with different configuration types of syringomyelia, to analyze the correlation between syrinx resolution and changes in cervical sagittal alignment following Foramen magnum and Magendie dredging (FMMD) for syringomyelia associated with Chiari I malformation (CM-I), and to further explore the respective relationship with clinical outcome. Methods A consecutive series of 127 patients with CM-I and syringomyelia who underwent FMMD in our center met the inclusion criteria of this study. Their clinical records and radiologic data were retrospectively reviewed. The Japanese Orthopedic Association (JOA) scoring system and the Chicago Chiari Outcome Scale (CCOS) were used to evaluate the surgical efficacy. The phenotypes of syringomyelia and the clinical characteristics of the patients were analyzed according to grouping by cervical curvature at baseline. Results The preoperative straight or kyphotic cervical alignment is more common in the moniliform syrinx. After surgery, the syrinx resolution and cervical sagittal realignment in the moniliform group are more obvious, and the corresponding prognosis is relatively better. Spearman correlation analysis showed that the ΔS/C ratio (the change ratio of syrinx/cord) was positively correlated with the CCOS (p = 0.001, r = 0.897) and ΔC2–7A (the change of lower cervical angle) (p = 0.002, r = 0.560). There was also a correlation between the ΔJOA score (the change rate of the JOA score) and ΔC2–7A (p = 0.012, r = 0.467). Conclusion After decompression surgery, syrinx resolution may coexist with the changes in the subaxial lordosis angle, especially for syrinx in moniliform type, and the relationship between syrinx resolution and cervical sagittal realignment might be valuable for evaluating the surgical outcome.

Background: Despite several hypotheses, our understanding of syringomyelia’s pathophysiology remains limited. The hypothesis proposed by Oldfield et al. suggests that piston-like movement of the cerebellar tonsils propels the cerebrospinal fluid (CSF) into the syrinx via the spinal perivascular space. However, a significant question remains unanswered: how does the CSF enter and stay in the syrinx, which has a higher pressure than the subarachnoid space. In the current study, we attempted to verify Oldfield’s hypothesis using phase-contrast magnetic resonance imaging (MRI) data from patients with syringomyelia. Methods: We analyzed phase-contrast MRI scans of 18 patients with Chiari-I malformation associated with syringomyelia, all of whom underwent foramen magnum decompression, and 21 healthy volunteers. We obtained velocity waveforms for CSF and brain tissue from regions of interest (ROI) set at the various locations. These waveforms were synchronized at the peak timing of downward CSF flow. We compared the preoperative patient data with the control data and also compared the preoperative patient data with the postoperative patient data. Results: The syrinx shrank in 17 (94%) of the patients, and they experienced significant clinical improvement. When comparing pre- and postoperative MRI results, the only significant difference noted was the preoperative elevated velocity of the cerebellar tonsil, which disappeared post-surgery. The CSF velocities in the subarachnoid space were higher in the preoperative patients than in the controls, but they did not significantly differ in the postoperative MRI. The tonsillar velocity in the preoperative MRI was significantly lower than that of the CSF, suggesting that the elevated tonsillar velocity was more of an effect, rather than the cause, of the elevated CSF velocity. Conclusions: Given these findings, a completely new paradigm seems necessary. We, therefore, propose a novel hypothesis: the generative force of syringomyelia may be the direction-selective resistance to CSF flow in the subarachnoid space.

Purpose: The aim of this study is to evaluate the morphological changes in Magnetic Resonance Images (MRI) of Chiari Malformation Type-1 (CMI) patients by performing morphometric measurements of fossa cranii posterior (FCP) and cranium. Materials and Methods: Our study is retrospective and included a control group of 32 (16 females, 16 males) and 12 patients (6 males, 6 females) with CMI between the ages of 21 and 47 years. Measurements were made on T2-weighted cranial MR images of the patient with CMI and the control group. Results: Maximum cranial length, maximum cranial height, sagittal diameter of foramen magnum, cranium base length, supraocciput, clivus length, anterior-posterior diameter of fossa cranii posterior, occipital cord length, cerebellum height, amount of herniation in CMI were found 164.13±10.67mm, 134.60±10.71mm, 36.89±5.28mm, 108.5±7.9mm, 38.5±3.7 mm, 36.7±7.1mm, 84.9±8.8mm, 79.7±11.5mm, 53.3±4.2mm, 7.8±4.9mm respectively. Conclusion: In our study, the measurements of the CMI and the control group were compared and a decrease in the length of the supraocciput, the length of the clivus and the length of the occipital cord has been found and an increase in the length of the cranial base and the sagittal diameter of the foramen magnum has been found in CMI patients. As a result of the data obtained in our study, FCP morphometry of patients with CMI can contribute to patient follow-up and surgery.

Chiari malformation Type 1 (CMI) is traditionally characterized as a descent of the cerebellar tonsils more than 5mm below the foramen magnum. In some patients with CMI, there is aberrant pulsatile movement of the tonsils downward during cardiac systole which can affect cerebrospinal fluid (CSF) flow at the foramen magnum. Here, we present an 18-year-old female patient with CMI who presented with worsening symptoms of her CMI. Magnetic resonance imaging (MRI) at this time indicated an increase in cerebellar tonsil movement and decreased CSF flow at the foramen magnum. At her follow-up appointment, she had complete resolution of the aberrant motion of her tonsils and CSF flow returned to baseline without surgical intervention. Her symptoms also improved during this time, and she is now able to be followed by her primary care physician. The increased pulsatile movement of cerebellar tonsils in patients with CMI has been linked to diminished CSF flow at the foramen magnum and symptom severity. Spontaneous resolution of CMI is rare and has only ever been documented as ascension of the cerebellar tonsils. This case describes restoration of normal tonsil movement and baseline CSF flow corresponding with a resolution of symptoms where a complete resolution in tonsillar ectopia was not present.

We investigated the mechanism underlying Chiari malformation type I (CM-I) and classified it according to the morphometric analyses of posterior cranial fossa (PCF) and craniocervical junction (CCJ). Three independent subtypes of CM-I were confirmed (CM-I types A, B, and C) for 484 cases and 150 normal volunteers by multiple analyses. CM-I type A had normal volume of PCF (VPCF) and occipital bone size. Type B had normal VPCF and small volume of the area surrounding the foramen magnum (VAFM) and occipital bone size. Type C had small VPCF, VAFM, and occipital bone size. Morphometric analyses during craniocervical traction test demonstrated instability of CCJ. Foramen magnum decompression (FMD) was performed in 302 cases. Expansive suboccipital cranioplasty (ESCP) was performed in 102 cases. Craniocervical posterolateral fixation (CCF) was performed for CCJ instability in 70 cases. Both ESCP and FMD showed a high improvement rate of neurological symptoms and signs (84.4%) and a high recovery rate of the Japanese Orthopaedic Association (JOA) score (58.5%). CCF also showed a high recovery rate of the JOA score (69.7%), with successful joint stabilization (84.3%). CM-I type A was associated with other mechanisms that caused ptosis of the brainstem and cerebellum (CCJ instability and traction and pressure dissociation between the intracranial cavity and spinal canal cavity), whereas CM-I types B and C demonstrated underdevelopment of the occipital bone. For CM-I types B and C, PCF decompression should be performed, whereas for small VPCF, ESCP should be performed. CCF for CCJ instability (including CM-I type A) was safe and effective.

Despite extensive investigations, the choice of graft material for reconstructive duraplasty after foramen magnum decompression for Chiari type I malformation (CMI) is still a topic of discussion. The authors performed a systematic review and meta-analysis of the literature examining the post-operative complications in adult patients with CMI after foramen magnum decompression and duraplasty (FMDD) using different graft materials. Our systematic review included 23 studies with a total of 1563 patients with CMI who underwent FMDD with different dural substitutes. The most common complications were pseudomeningocele (2.7%, 95% CI 1.5–3.9%, p < 0.01, I2 = 69%) and CSF leak (2%, 95% CI 1–2.9%, p < 0,01, I2 = 43%). The revision surgery rate was 3% (95% CI 1.8–4.2%, p < 0.01, I2 = 54%). A lower rate of pseudomeningocele was observed with autologous duraplasty when compared with synthetic duraplasty (0.7% [95% CI 0–1.3%] vs. 5.3% [95% CI 2.1–8.4%] p < 0.01). The rate of CSF leak and revision surgery was lower after autologous duraplasty than after non-autologous dural graft (1.8% [95% CI 0.5–3.1%] vs. 5.3% [95% CI 1.6–9%], p < 0.01 and 0.8% [95% CI 0.1–1.6%] vs. 4.9% [95% CI 2.6–7.2%] p < 0.01, respectively). Autologous duraplasty is associated with a lower rate of post-operative pseudomeningocele and reoperation. This information should be considered when planning duraplasty after foramen magnum decompression in patients with CMI. [ABSTRACT FROM AUTHOR]

In patients with Chiari malformation type 1 (CMI) presenting with low intracranial compliance (ICC), foramen magnum decompression (FMD) often fails and the complication rate may be higher. We therefore routinely perform a preoperative assessment of ICC from intracranial pressure measurement. Patients with low ICC are treated with ventriculoperitoneal shunt (VPS) before FMD. In this study, we assess the outcome of patients with low ICC, compared with patients with high ICC treated with FMD alone. We reviewed the clinical and radiologic data of all consecutive patients with CMI treated between April 2008 and June 2021. ICC was assessed by overnight measurement of the pulsatile intracranial pressure: mean wave amplitude (MWA) above a previously defined threshold for abnormality was considered a surrogate marker for low ICC. The outcome was scored by Chicago Chiari Outcome Scale. Of 73 patients, 23 with low ICC (average MWA 6.8 ± 1.2 mm Hg) received VPS before FMD, whereas 50 with high ICC (average MWA 4.4 ± 1.0 mm Hg) received only FMD. After a mean follow-up of 78.7 ± 41.4 months, 96% of all patients subjectively improved. The mean Chicago Chiari Outcome Scale score was 13.1 ± 2.2. Enlargement of cerebrospinal fluid space in the foramen magnum was achieved in 95% and regression of syringomyelia in 74% of cases. We found no significant difference in outcome between the patients with low and high ICC. By identifying patients with CMI associated with low ICC and tailoring their treatment by VPS before FMD, we achieved favorable clinical and radiologic outcomes comparable to those with high ICC. [ABSTRACT FROM AUTHOR]

Craniofacial encephaloceles are rare, yet highly debilitating neuroanatomical abnormalities that result from herniation of neural tissue through a bony defect and can lead to death, cognitive delay, seizures, and issues integrating socially. The etiology of encephaloceles is still being investigated, with evidence pointing towards the Sonic Hedgehog pathway, Wnt signaling, glioma-associated oncogene (GLI) transcription factors, and G protein-coupled receptors within primary cilia as some of the major genetic regulators that can contribute to improper mesenchymal migration and neural tube closure. Consensus on the proper approach to treating craniofacial encephaloceles is confounded by the abundance of surgical techniques and parameters to consider when determining the optimal timing and course of intervention. Minimally invasive approaches to encephalocele and temporal seizure treatment have increasingly shown evidence of successful intervention. Recent evidence suggests that a single, two-stage operation utilizing neurosurgeons to remove the encephalocele and plastic surgeons to reconstruct the surrounding tissue can be successful in many patients. The HULA procedure (H = hard-tissue sealant, U = undermine and excise encephalocele, L = lower supraorbital bar, A = augment nasal dorsum) and endoscopic endonasal surgery using vascularized nasoseptal flaps have surfaced as less invasive and equally successful approaches to surgical correction, compared to traditional craniotomies. Temporal encephaloceles can be a causative factor in drug-resistant temporal seizures and there has been success in curing patients of these seizures by temporal lobectomy and amygdalohippocampectomy, but magnetic resonanceguided laser interstitial thermal therapy has been introduced as a minimally invasive method that has shown success as well. Some of the major concerns postoperatively include infection, cerebrospinal fluid (CSF) leakage, infringement of craniofacial development, elevated intracranial pressure, wound dehiscence, and developmental delay. Depending on the severity of encephalocele prior to surgery, the surgical approach taken, any postoperative complications, and the age of the patient, rehabilitation approaches may vary [ABSTRACT FROM AUTHOR]