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Objective: Idiopathic intracranial hypertension (IIH) is a cerebrospinal fluid (CSF) disorder defect that is frequently treated with CSF shunts. Shunts utilizing the cisterna magna as a proximal reservoir have been described in literature; however, long-term outcomes are unknown. The present study aims to describe the long-term effectiveness, revision rates, and clinical outcomes of this shunt in 14 patients with IIH and slit ventricles., Methods: A single-center retrospective review of 14 IIH patients treated by cisterna magna shunts was performed. Shunt histories, including revision rate and time until first shunt failure for ventricular, lumbar, and cisterna magna shunts were recorded. "Revision rate" was calculated as the total number of shunt revisions over years of total shunt placement. The average follow-up time was 12.08 years., Results: The mean age at first cisterna magna shunt placement was 18.1 years (6.6-43.3 years) and all patients had radiological evidence of slit ventricles. Cisterna magna shunts improved or resolved clinical symptoms for all 14 patients and had a lower rate of revisions (0.42 revision/year) compared to ventricular (0.72 revision/year) and lumbar (1.30 revision/year) shunts. Of the 11 patients still requiring CSF diversion at the end of the study, eight had functioning shunts that utilized the cisterna magna., Conclusions: The cisterna magna shunt may be a suitable option for patients with IIH and slit ventricles. Further study is needed to understand the clinical utility of this shunt for the population in which it is indicated., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Cerebrospinal fluid (CSF) collection and its analysis are common medical practices useful in the diagnosis, therapy, and prevention of central nervous system (CNS) disorders. In recent years, several types of research have improved our insight into CSF and its role in health and disease. Yet, many characteristics of this fluid remain to be fully understood., New Methods: Here, we describe how to collect CSF from embryonic, postnatal, and adult stages of the rat. In adults, CSF can be collected through simple stereotaxic surgery to expose the membrane overlying the cisterna magna (CM) of an anesthetized rat and collection of CSF through micropipette puncture through the membrane. In embryos and pups, CSF is aspirated, using a fire-polished micro-capillary pipette, from the CM of animals., Results: Application of these methods provides the maximum volume of pure, uncontaminated CSF (embryonic day 19: 10-15 microliter, postnatal day 5: 20-30 microliter, adults: 100-200 microliter) with a success rate of approximately 95% in every age., Comparison With Existing Methods: Compared to the existing protocols, these methods obtain considerable volumes of CSF, which may accelerate the measurement of biological markers in this fluid. Also, these techniques do not require surgical skills and according to the practical points mentioned during sampling, the procedures can be performed in rapid fashion., Conclusion: We describe simple methods for collecting CSF in live rats. These protocols provide clean, uncontaminated CSF for experiments to understand the exact role of this fluid in the development and maintenance of the CNS health., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Stereotaxic surgery to target brain sites in mice is commonly guided by skull landmarks. Access is then obtained via burr holes drilled through the skull. This standard approach can be challenging for targets in the caudal brainstem and upper cervical cord due to specific anatomical challenges as these sites are remote from skull landmarks, leading to imprecision. Here we outline an alternative stereotaxic approach via the cisterna magna that has been used to target discrete regions of interest in the caudal brainstem and upper cervical cord. The cisterna magna extends from the occipital bone to the atlas (i.e., the second vertebral bone), is filled with cerebrospinal fluid, and is covered by dura mater. This approach provides a reproducible route of access to select central nervous system (CNS) structures that are otherwise hard to reach due to anatomical barriers. Furthermore, it allows for direct visualization of brainstem landmarks in close proximity to the target sites, increasing accuracy when delivering small injection volumes to restricted regions of interest in the caudal brainstem and upper cervical cord. Finally, this approach provides an opportunity to avoid the cerebellum, which can be important for motor and sensorimotor studies.

Background: Postoperative cerebrospinal fluid (CSF) fistula following cranial or spinal surgery is associated with increased morbidity and mortality. To prevent CSF fistulas, various techniques have been described. Here, we describe the arachnoid membrane continuous-running suture technique in cisterna magna reconstruction for preventing postoperative CSF leakage., Methods: After craniotomy and dural opening, the incision of the arachnoid of the cisterna magna was performed using a diamond blade. To prevent the arachnoid from drying out and shrinking during surgery, it was periodically irrigated with warm saline solution. Posterior fossa surgery was performed. When closing the membranes, the arachnoid membrane was closed with the running-suture technique. After the first surgical knot was made in the cranial end of the arachnoid opening, continuous suturing with a 2-mm distance between the stitches was performed without stretching them. After every 3 stitches, the free end of the thread was pulled gently along the suturing axis, and the edges of the arachnoid were closed. After the arachnoid edges were approximated, the surgical knot was tied. Watertight closure was checked by performing the Valsalva maneuver at the end of the surgery., Results: No CSF leakages were observed after surgery., Conclusions: Arachnoid membrane suturing seems to be safe and effective in preventing postoperative CSF leakage and CSF-related complications. Using continuous running suturing alone, without any sealant, might be effective in cases with untraumatized arachnoid membrane., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Cerebrospinal fluid (CSF) analysis is of significant clinical importance for the diagnosis of diseases. In humans, CSF is easily accessible and can be collected using minimally invasive methods. However, obtaining uncontaminated CSF from rats is still challenging., New Method: This study described a microsurgical technique for sampling large quantities (>200 μL) of clear and non-blood-contaminated CSF from the rat cisterna magna in a comprehensible step-by-step guide and provided a graphical visualization., Results: CSF was sampled in 5-10 min (n = 29 animals; average surgical time 7.6 min). In visual control, 28 samples (97 %) of clear and uncontaminated CSF were obtained. The volume of CSF collected was 124-337 μL, with an average volume of 207 μL/sample. Using the Valsalva maneuver, we could collect higher volumes (up to 400 μL) several times., Comparison With Existing Method(s): There is no need for special surgical skills to perform this method accurately. The method takes a few minutes longer than a percutaneous puncture (<1 min in pups). However, the volume of CSF obtained using the percutaneous approach in adult rats (50-70 μL) is comparatively low., Conclusions: We described a practical method of sampling CSF from rats that enables large volumes of CSF to be collected without blood contamination. No special surgical skills are required to use this method. With proper practice, the time between skin incision and CSF sampling is <10 min. Depending on the experimental design requirements, some additional time must be planned for wound closure., (Copyright © 2021. Published by Elsevier B.V.)

We present the case of a 42-year-old woman with a 5-week history of headache, progressive dysphagia, dysphonia, and hoarseness. A brain magnetic resonance imaging revealed an extra-axial cyst of the left lateral cerebellomedullary cistern. The subsequent histopathologic examination diagnosed a neuroenteric cyst. This case sheds light on the pivotal role of histologic identification of neuroenteric cyst, which could be crucial for further diagnostic investigations, especially in pediatric patients., (Copyright © 2020. Published by Elsevier Inc.)

Among strokes, subarachnoid hemorrhage (SAH) consecutive to the rupture of a cerebral arterial aneurysm represents 5-9% but is responsible for about 30% of the total stroke-related mortality with an important morbidity in terms of neurological outcome. A delayed cerebral vasospasm (CVS) may occur most often in association with a delayed cerebral ischemia. Different animal models of SAH are now being used including endovascular perforation and direct injection of blood into the cisterna magna or even the prechiasmatic cistern, each exhibiting distinct advantages and disadvantages. In this article, a standardized mouse model of SAH by double direct injection of determined volumes of autologous whole blood into the cisterna magna is presented. Briefly, mice were weighed and then anesthetized by isoflurane inhalation. Then, the animal was placed in a reclining position on a heated blanket maintaining a rectal temperature of 37 °C and positioned in a stereotactic frame with a cervical bend of about 30°. Once in place, the tip of an elongated glass micropipette filled with the homologous arterial blood taken from carotid artery of another mouse of the same age and gender (C57Bl/6J) was positioned at a right angle in contact with the atlanto-occipital membrane by means of a micromanipulator. Then 60 µL of blood was injected in the cisterna magna followed by a 30° downward tilt of the animal for 2 minutes. The second infusion of 30 µL of blood into the cisterna magna was performed 24 h after the first one. The individual follow-up of each animal is carried out daily (careful evaluation of weight and well-being). This procedure allows a predictable and highly reproducible distribution of blood, likely accompanied by intracranial pressure elevation that can be mimicked by an equivalent injection of an artificial cerebral spinal fluid (CSF), and represents an acute to mild-model of SAH inducing low mortality.

At the beginning of the 20th century, cerebrospinal fluid (CSF) collection and analysis emerged as a promising aid in the diagnosis of diseases of the central nervous system. It was obtained through the established procedure of lumbar puncture, described by Heinrich Quinke in 1891. The search for an alternative way to gather the CSF emerged in animal research, highlighting the cisterna magna as a promising source, with relative safety when performed by someone trained. Described initially and in detail by James Ayer in 1920, the procedure was widely adopted by neurologists and psychiatrists at the time, featuring its multiple advantages and clinical applications. After a period of great procedure use and exponential data collection, its complications and risks relegated the puncture of the cisterna magna as an alternative route that causes fear and fascination in modern Neurology.

Imbalance in extracellular ATP levels in brain tissue has been suggested as a triggering factor for several neurological disorders. Here, we describe the most sensitive and reliable technique for monitoring the ATP levels in mice cerebrospinal samples collected by cisterna magna puncture technique and quantified using a microplate reader.

Objective: To evaluate safety of stylet-in and stylet-out techniques for collection of CSF from the cisterna magna and to assess whether there were differences between techniques with regard to contamination of samples, sample quality, and efficiency of collection., Animals: 10 adult purpose-bred research Beagles., Procedures: A prospective crossover study was conducted. Preanesthetic physical and neurologic examinations and hematologic analyses were performed. Dogs were anesthetized, and collection of CSF samples from the cisterna magna by use of a stylet-in or stylet-out technique was performed. Two weeks later, samples were collected with the other sample collection technique. Samples of CSF were processed within 1 hour after collection., Results: Cellular debris was detected in higher numbers in stylet-in samples, although this did not affect sample quality. The stylet-out technique was performed more rapidly. No adverse effects were detected for either technique., Conclusions and Clinical Relevance: Both techniques could be safely performed in healthy anesthetized dogs. The stylet-out technique was performed more rapidly and yielded a sample with less cellular debris. Both techniques can be used in clinical practice to yield CSF samples with good diagnostic quality.

Objective: To present a hitherto unreported modification of the classic Torkildsen procedure: passing a catheter intracranially, between the third ventricle and cisterna magna., Methods: We applied our technique to a 56-year-old man who presented to our department for treatment of a pineal region mass., Results: The patient was placed in sitting position and the mass was gross totally removed through a supracerebellar infratentorial approach. After the completion of the tumor resection, the patency of the cerebral aqueduct was checked, but the permeability was doubtful. During the same procedure, a shunt was inserted, under direct microsurgical control, into the third ventricle and passed over the cerebellar surface into the cisterna magna. The postoperative course was uneventful, and the patient was discharged from our unit with no neurological deficits and able to carry on with his day-to-day life., Conclusions: Our case illustrates that ventriculocisternal shunting can successfully be used in selected cases. The variation we describe can be a valuable surgical strategy in patients with pineal region masses, in whom a supracerebellar infratentorial route is used and in whom uncertainty exists regarding the patency of the sylvian aqueduct., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: Focal hydrocephalus including trapped temporal horn (TTH), isolated lateral and fourth ventricles, is caused by obstruction and/or adhesion related to various etiologies. With the advent of the neuroendoscope, endoscopic procedures have become an alternative in selected cases., Case Report: A 2-year-old male from a rural town in México was referred to our institution because of multiple supra- and infra-tentorial abscesses and hydrocephalus. The patient had progressive deterioration and developed bilateral trapped temporal horn related to multi-septated hydrocephalus, so we performed an endoscopic ventricular-cistern-ventriculostomy through a single right temporal burr hole., Postoperative Course: Bilateral TTH and multi-septated hydrocephalus were effectively treated with a single external ventricular drainage (EVD) catheter, from the right temporal horn to the left temporal horn through the interpeduncular cistern; after clamping the EVD for 3 days with no evidence of hydrocephalus, the EVD was removed. The size of the ventricles remained stable afterwards, and no clinical or radiological evidence of hydrocephalus was observed after 3 months of follow-up., Discussion: Endoscopic ventriculocisternostomy is effective in selected cases of TTH. We know that dilatation of the temporal horn widens the window between the anterior choroidal artery and optic tract superiorly, and the posterior communicating and CN III inferiorly, making the described procedure feasible, even in the approach to the contralateral side. Even though this is a rare condition, we believe it is a safe and effective option to eliminate multiple shunts and/or to reduce the number of catheters needed to treat bilateral THH related to multi-septated hydrocephalus.

In this article, we present an optimized minimally invasive technique of ETV for children with occlusive hydrocephalus. The study comprises of 64 consecutive pediatric cases (34 boys and 30 girls aged from 1 month to 5 years) of occlusive hydrocephalus from various etiologies, which were treated with a modified technique of ETV. Mean clinical follow-up period after ETV was 24.2 ± 3.8 months. Application of the new technique made it possible to significantly reduce the length of the soft tissue incision for access, and the use of upgraded instruments allowed to perform a twist drill hole in the skull to less than half a usual size. Access to the brain and lateral ventricle was performed by blunt trephination of the dura without the need for significant corticectomy or coagulation, and yielded minimal damage to the brain, which is very important in patients of young age. Continued endoscopic control during the approach down to the lateral ventricle increases safety and decreases risk of injury, and can be performed in cases of pathologies affecting the anatomical relationships of the lateral and third ventricle. Mortality in our cohort was 0%, and there were no postoperative neurological, endocrinological, or infectious complications. Patency rates of the first ETV performed was 78%, with the remaining patients requiring additional surgical procedures for complicated settings. This new technique of minimally invasive ETV placement in pediatric patients is an effective and safe method to treat occlusive hydrocephalus and can be recommended for extensive clinical use.

Cisterna magna cannulation (CMc) is a straightforward procedure that enables direct access to the cerebrospinal fluid (CSF) without operative damage to the skull or the brain parenchyma. In anesthetized rodents, the exposure of the dura mater by blunt dissection of the neck muscles allows the insertion of a cannula into the cisterna magna (CM). The cannula, composed either by a fine beveled needle or borosilicate capillary, is attached via a polyethylene (PE) tube to a syringe. Using a syringe pump, molecules can then be injected at controlled rates directly into the CM, which is continuous with the subarachnoid space. From the subarachnoid space, we can trace CSF fluxes by convective flow into the perivascular space around penetrating arterioles, where solute exchange with the interstitial fluid (ISF) occurs. CMc can be performed for acute injections immediately following the surgery, or for chronic implantation, with later injection in anesthetized or awake, freely moving rodents. Quantitation of tracer distribution in the brain parenchyma can be performed by epifluorescence, 2-photon microscopy, and magnetic resonance imaging (MRI), depending on the physico-chemical properties of the injected molecules. Thus, CMc in conjunction with various imaging techniques offers a powerful tool for assessment of the glymphatic system and CSF dynamics and function. Furthermore, CMc can be utilized as a conduit for fast, brain-wide delivery of signaling molecules and metabolic substrates that could not otherwise cross the blood brain barrier (BBB).

Objective: A pseudomeningocele and an incisional cerebrospinal fluid leak are considered frequent complications following neurosurgical operations. The rate of these complications especially increases following neurosurgical procedures on the posterior cranial fossae. According to some publications, the rate of pseudomeningoceles has been reported as high as 40%, whereas that of incisional cerebrospinal fluid leaks is up to 17%. For the purposes of reducing the risk of these complications after a midline suboccipital craniotomy, we propose suturing the arachnoid membrane of the cisterna magna. In this paper, we present a retrospective analysis of arachnoid membrane suturing., Methods: Seventy patients underwent midline suboccipital craniotomy by the first author between 2012 and 2016 at Burdenko Neurosurgery Institute. In this group was included a consecutive group of patients with posterior fossae tumors where the approach was performed through the cisterna magna arachnoid membrane following midline suboccipital craniotomy and dural opening. The patients were divided into two groups. Group 1 included 38 patients to whom cisterna magna arachnoid membrane suturing was performed with monofilament nonabsorbable suture 7.0., and additionally, the suture was sealed with fibrin adhesive sealant TachoComb®. Group 2 included 32 patients without arachnoid membrane suturing. There was no other significant difference in terms of clinical signs and surgical procedures between these groups. In the postoperative period, the frequency of developing a pseudomeningocele and an incisional cerebrospinal fluid leak was assessed in these two groups. The results were evaluated on the basis of clinical, CT, and MRI data performed in the postoperative period., Results: In the patients who underwent arachnoid membrane suturing (group I), pseudomeningocele formation was observed in one (2.6%) and CSF leak in one (2.6%) of the 38 patients. In group II, in which patients had no arachnoid membrane suturing, we observed pseudomeningocele formation in 11 (34.4%) patients and a CSF leak in 7 (25.0%) out of 28 patients with known follow-up. Statistical analysis of the data indicates a significantly higher risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in a group of patients who did not undergo arachnoid membrane suturing (p < 0.05)., Conclusions: Suturing of the arachnoid membrane of the cisterna magna and its further sealing with fibrin adhesive sealant TachoComb® create an additional barrier for preventing cerebrospinal fluid collection in the extradural space. This technique significantly reduces the risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in patients with midline suboccipital craniotomy.

Background: Lesions lateral to the lower brainstem in an area extending from the foraminae of Luschka to the foramen magnum are rare and include different pathologies. There is no consensus on an ideal surgical approach., Method: To gain access to this area, we use the midline suboccipital subtonsillar approach (STA). This midline approach with unilateral retraction of the cerebellar tonsil enables entry into the cerebellomedullary cistern., Conclusions: The STA offers excellent access with a panoramic view of the cerebellomedullary cistern and its structures and therefore can be useful for a number of different pathologies in the lower petroclival area.

Background: Intraventricular and subarachnoid forms represent the relatively complex, albeit uncommon, manifestations of central nervous system involvement by cysticercal cysts. Cysticercal encystation inside the Blake's pouch remnant of mega cisterna magna (MCM) remains an extremely rare clinical scenario that, to the best of our knowledge, has not been reported previously., Case Presentation: A 12-year-old boy presented with acute worsening and subsequent spontaneous resolution of his compensated hydrocephalus. Neuroimaging revealed features consistent with a MCM with septum inside, indicating remnants of the embryologic fourth ventricular diverticulum, the Blake's pouch. It also revealed a free-floating intact cysticercal cyst inside the MCM limited by the septum with aqueductal stenosis. The spontaneous clinicoradiologic resolution of hydrocephalus raised the possibility of ball valve obstruction of the cerebrospinal fluid outflow, i.e., Bruns syndrome. We successfully treated this patient with endoscopic extraction of the viable cysticercal cyst through a suboccipital burrhole., Conclusions: The clinical scenario presented here has not been described previously. Endoscopic cyst removal in such a situation is an effective and low-risk procedure that obviates the further need for antihelminthic medications., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Meningiomas within the cisterna magna without dural attachment are extremely rare. To the best of our knowledge, only three cases of meningiomas within the cisterna magna have been reported in the literature. The authors present two cases of patient with the cisterna magna meningioma without dural attachment. (Case 1) A 36-year-old female presented with a 10-month history of numbness in the left hand. Magnetic resonance imaging (MRI) disclosed the presence of a contrast-enhanced tumor in the posterior fossa. A suboccipital craniectomy was performed, and the tumor located within the cisterna magna with no attachment to the dura. Diagnosis is made as clear cell meningioma. The postoperative course was uneventful, and a recurrence has not been observed for three years. (Case 2) A 58-year-old man presented with a well-circumscribed mass in the posterior fossa. At surgery, the tumor located within the cisterna magna with a connection to the right tenia. The tumor was totally removed without neurological deficits. At a 7-year follow-up, no evidence of a recurrence was observed. It is quite difficult to preoperatively diagnose as a cisterna magna meningioma without dural attachment. However, complete removal of the tumor should be achieved., (Copyright © 2017 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Background: Component analysis of cerebrospinal fluid (CSF) is frequently required to probe the causes and pathologic mechanisms of disease and effective drugs in experimental studies of the central nervous system. Rat and mouse are two kinds of most frequently used animals in experimental studies. Rats are considered to be the most suitable animal for experimental analysis of CSF both on cost and manipulability as mice are too small for drawing CSF. However, drawing CSF from rats is still not easy, which makes many researchers choose bigger animals, such as rabbits. This paper introduced a highly applicable technique of CSF collection from cerebellomedullary cistern (CC) in rats., Methods: CSF collection with this technique was performed by direct CC puncture using a collection apparatus with negative pressure. The apparatus consists of a 1ml syringe, a disposable intravenous infusion needle and a clip. The needle was cut and made less sharp than the original one to avoid injury to the brain and spinal cord., Results: We have collected CSF multiple times from each rat with this approach and the collection lasted less than 30s each time on average. The length of the collection needles of the CSF was conformed to the different body sizes (weight) of the rats in the 3 groups. Compared with currently existing methods, this is faster, safer, simpler and repeatable., Conclusions: CSF collection by CC puncture using a negative pressure collection apparatus is fast to operate, safe to the rats, and maximum amount of CSF can be collected., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Neuroendoscopy is currently recommended as the first choice to treat posterior fossa arachnoid cysts. It has proven to be effective, providing improved outcome, and safe, having a low complication rate. Compared to craniotomy and shunt placement, it has lower surgical morbidity, minimizing or avoiding risks of subdural fluid collections, shunt infection, malfunction, overdrainage, and dependence. Usually, rigid scopes maneuvered through a suboccipital approach are used. When symptomatic obstructive hydrocephalus develops, CSF diversion is the first aim of surgery., Methods: In these patients, a flexible scope introduced through a frontal burr hole allows not only immediate and efficient management of hydrocephalus with endoscopic third-ventriculostomy, but in selected cases also direct cyst inspection and fenestration. Navigation of an enlarged cerebral aqueduct is actually safe when performed by experienced neurosurgeons., Results: We describe the cystocisternostomy of a cisterna magna arachnoid cyst using a transaqueductal trans-Magendie approach., Conclusions: This minimally invasive technique gives the possibility of performing both endoscopic third-ventriculostomy and cyst fenestration, which alone may not be enough to efficiently treat hydrocephalus.

Cisternostomy is defined as opening the basal cisterns to atmospheric pressure. This technique helps to reduce the intracranial pressure in severe head trauma as well as other conditions when the so-called sudden "brain swelling" troubles the surgeon. We elaborated the surgical anatomy of this procedure as well as the proposed physiology of how cisternostomy works. This novel technique may change the current trends in neurosurgery.

Background: Endoscopic ventriculostomy is an attractive surgical alternative to ventriculoperitoneal shunt in the treatment of focal hydrocephalus, including trapped temporal horn (TTH). The major concern of this surgical approach is closure of a stoma, the risk of which may be minimized by placement of a stent after ventriculostomy., Case Description: The authors report a case of a 60-year-old man with glioblastoma in the corpus callosum and the parietal lobe who developed TTH after partial tumor resection. After the failure of a ventriculoperitoneal shunt, endoscopic ventriculocisternostomy was chosen over the revision of the shunt. A stoma was placed at the medial wall of the dilated temporal horn. Endoscopic inspection confirmed communication with the interpeduncular cistern, but the collapsed lateral ventricle after fenestration suggested the risk of stoma closure. Therefore, a ventricular tube was placed through the stoma as a stent to secure its flow. No further surgical intervention was needed, and the patient was able to complete radiochemotherapy without cessation., Conclusions: The risk of recurrence of TTH after endoscopic ventriculocisternostomy may be minimized by combining ventriculostomy with stent placement. This surgical procedure would be beneficial, particularly in cases of TTH associated with malignant brain tumors, where the risk of delay or interruption of adjuvant oncologic treatments may negatively impact patient prognosis., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: We used microscopy with endoscopic assistance to conduct an objective analysis of 4 surgical approaches commonly used in the surgery of the ambient cistern: infratentorial supracerebellar (SC), occipital interhemispheric (OI), subtemporal (ST), and transchoroideal (TC). In addition, we performed a parahippocampalis gyrus resection in the ST context., Methods: Each approach (SC, OI, ST, TC) was performed on 3 cadaveric heads (6 sides). After the microscopic anatomic dissection, the 30-degree endoscope was used to explore the exposure. The parahippocampalis gyrus was resected through an ST approach and the exposure was evaluated. The quantitative analysis was based on linear exposure of the vascular structures (linear exposure), such as the posterior choroidal artery (PChA), the P2 and P3 segments of the posterior cerebral artery (PCA) with their branches, the basal vein of Rosenthal, and the area of exposure of the ambient cistern region (area of exposure) limited by points on its superior, mesial, and anterior walls. In all cases, a P value of less than 0.05 was considered significant., Results: There was a significant difference (P < 0.05) in linear exposure of the PCA and medial PChA between microsurgery and endoscopic assistance using the ST approach. This approach also improved the medial, superior, and total exposure of the ambient cistern region., Conclusions: This study demonstrates that endoscope assistance improved exposure of the ambient cistern region when using the ST approach. Endoscopic assistance provided similar surgical exposure compared with ST associated with parahippocampalis resection., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Aneurysmal subarachnoid hemorrhage comprises of an early phase after the bleeding and a late phase of delayed consequences of the bleeding. The development of delayed injury mechanisms, like the reduction of cerebral blood flow (CBF) due to cerebral vasospasm (CVS), seems mainly to depend on the amount and the duration of the subarachnoid blood clot. The reduction of CBF may lead to cerebral ischemia and delayed neurological deterioration. The rat double cisterna magna injection model reproduces the time course of the delayed consequences of CVS and imitates the clinical setting more precise than other rodent subarachnoid hemorrhage models. Therefore, the rat double cisterna magna injection model seems to be predisposed to be used to mimick the delayed consequences of subarachnoid hemorrhage. We reviewed the existing literature on this animal model and propose a standard protocol including technical considerations, as well as advantages and limitations of this model.

Cisternal puncture in dogs and cats is commonly carried out. This article describes the percutaneous ultrasound anatomy of the cisternal region in the dog and the cat and an indirect technique for ultrasound-guided cisternal puncture. Ultrasound images obtained ex vivo and in vivo were compared with anatomic sections and used to identify the landmarks for ultrasound-guided cisternal puncture. The ultrasound-guided procedure was established in cadavers and then applied in vivo in seven dogs and two cats. The anatomic landmarks for the ultrasound-guided puncture are the cisterna magna, the spinal cord, the two occipital condyles on transverse images, the external occipital crest and the dorsal arch of the first cervical vertebra on longitudinal images. Using these ultrasound anatomic landmarks, an indirect ultrasound-guided technique for cisternal puncture is applicable in the dog and the cat., (© 2014 Blackwell Verlag GmbH.)

A method is described for chronic cannulation of the cisterna magna to enable repeated sampling of cerebrospinal fluid from conscious, ambulatory sheep by means of a flexible vinyl tube. Ease of sampling and duration of cannula patency are similar to those obtained with rigid, metal cannulae, but this modified method minimizes the degree of surgical intervention, and possible trauma, occurring during placement of the cannula., (© The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Objective: To clarify microsurgical anatomic features of the cerebellomedullary fissure (CMF), the natural cleavage plane between the cerebellum and the medulla, and its relationship to the cerebellomedullary cistern (CMC) and to describe a surgical technique that uses the unilateral trans-CMF approach for CMC surgeries., Methods: In the anatomic study, 2 formalin-fixed cadaver heads were used. In the clinical study, 3 patients with vertebral artery-posterior inferior cerebellar artery aneurysms and 3 patients with glossopharyngeal neuralgia were surgically treated through the unilateral trans-CMF approach combined with the transcondylar fossa approach, which is a lateral foramen magnum approach., Results: The CMC was present at the lateral end of the CMF. The CMF was closed by arachnoidal adhesion, and the cerebellar hemisphere was superiorly attached to the cerebellar peduncle. After the unilateral CMF was completely opened, the cerebellar hemisphere was easily retracted rostrodorsally. Clinically, almost completely opening the unilateral CMF markedly enabled the retraction of the biventral lobule to obtain a wide surgical field safely for vascular CMC lesions. We present 2 representative cases., Conclusion: Combined unilateral trans-CMF/lateral foramen magnum approaches provide a wide and close surgical field in the CMC, allowing easy and safe CMC surgery., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: The optimal extent of resection for surgical treatment of lesional epilepsy is a controversial issue., Objective: For patients with mesial temporal lobe lesions visible on magnetic resonance imaging, we compared the surgical outcome of selective lesionectomy with that of standard anterior temporal lobectomy (ATL) and amygdalohippocampectomy., Methods: We conducted a retrospective analysis of the seizure outcome of 40 patients treated for lesional mesial temporal lobe epilepsy between 1993 and 2008. Before 2006, patients were managed by ATL (n=29) and from 2006 onward, by selective lesionectomy via the transsylvian-transcisternal approach (n=11)., Results: The postoperative seizure-free rates for the 2 groups were comparable: 93% (27/29) for the ATL group and 91% (10/11) for the selective lesionectomy group (P=.814). In both groups, patients with persistent seizures commonly showed incomplete lesion resection, with complete resection often improving seizure outcome. Postoperative visual field defects were more common in the ATL group (21%) than in the selective lesionectomy group (0%) (P=.102)., Conclusion: Transsylvian-transcisternal selective lesionectomy is an effective and safe therapeutic modality in children with lesional mesial temporal lobe epilepsy. Completeness of resection is an important variable for seizure control regardless of surgical modality.

In 1994, we started cisternal washing therapy (CWT) using urokinase combined with head-shaking method in order to prevent cerebral vasospasm. In this paper, we showed the surgical procedure for CWT and reported the effect of this therapy in preventing vasospasm following SAH. A total of 332 consecutive cases with Fisher group 3 SAH since 1988 were analyzed. Of these patients, 118 cases (56 cases before 1994 and 62 cases after 1994) had not CWT, and, 214 cases after 1994 had this therapy. All of these patients had clipping surgery within 3 days following SAH, and had postoperative management both with normovolemia and normal to mild hypertension. In these two groups, the incidence of symptomatic vasospasm (transiently symptomatic vasospasm without infarction), cerebral infarction due to vasospasm on CT, and mortality and morbidity (M&M) due to vasospasm were analyzed. In the group without CWT, the incidences of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm were 4.2%, 28.8%, and 17.8%, respectively. On the other hand, in the group with CWT, they were 3.7%, 6.5%, and 2.8%, respectively. In the patients with CWT, the incidence of cerebral infarction on CT due to vasospasm and M&M due to vasospasm were significantly (p < 0.05) decreased. CWT was effective in preventing cerebral vasospasm.

Cerebrospinal fluid (CSF) is commonly used for assessing biomarkers of drug efficacy or disease progression in the central nervous system. Studies of CSF from pre-clinical species can characterize biomarkers for use in clinical trials. However, obtaining CSF from pre-clinical species, particularly rodents, can be challenging due to small body sizes, and consequently, low volumes of CSF. Surgical cannulation of rats is commonly used to allow for CSF withdrawal from the cisterna magna. However, cannulae do not remain patent over multiple days, making chronic studies on the same rats difficult. Moreover, CSF biomarkers may be affected by cannulation. Thus cannulation may contribute confounding factors to the understanding of CSF biomarkers. To determine the potential impact on biomarkers, CSF was analyzed from cannulated rats, surgically implanted with catheters as well as from non-cannulated rats. Brain protein biomarkers (αII-spectrin SBDP150 and total tau) and albumin, were measured in the CSF using ELISA assays. Overall, cannulated rat CSF had elevated levels of the biomarkers examined compared to non-cannulated rat CSF. Additionally, the variation in biomarker levels observed among CSF from cannulated rats was greater than that observed for non-cannulated rat CSF. These results demonstrate that in some cases, biomarker assessment using CSF from cannulated rats may differ from that of non-cannulated animals and may contribute confounding factors to biomarker measurements and assay development for clinical use., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background: Dermoid tumors are rare congenital lesions and account for 0.2% to 1.8% of all intracranial tumors. Dermoid tumor with diastematobulbia is very rare., Case Description: We report a dermoid tumor in an adult female with an unusual location and morphology. The lesion had 2 major components with different material within the cysts. The posterior part of the dermoid had presented on the floor of the fourth ventricle and had split the pons into 2 distinct halves. The anterior part of the lesion was situated in the prepontine cistern and encircling the anterior half of the brainstem. The lesion was radically excised, and the postoperative images showed return of the 2 halves of the pons to appose each other in the midline., Conclusion: This case report demonstrates the anatomical peculiarities of this extremely unusual presentation of a dermoid cyst with diastematobulbia. Total excision of the lesion through a dorsal approach resulted in a good outcome., (Copyright 2009 Elsevier Inc. All rights reserved.)

Objective: To assess the suboccipital median transcerebellomedullary fissure keyhole approach in a cadaver model by using a neuronavigation system and explore its feasibility and operative indications., Methods: Six 10% formaldehyde-fixed adult cadaveric head and neck specimens injected with colored latex were chosen for the study. First the suboccipital median transcerebellomedullary fissure keyhole approach was performed and the anatomical structures were observed under operative microscope. The exposed floor area of the fourth ventricle and the vertical and transverse angles at the point where the line between the lateral apertures crossing the median sulcus, vertical angle at the apertures of midbrain aqueduct and the obex were measured with the aid of a frameless stereotactic navigation device. Parameters were compared with those when C1 posterior arch was removed, and also with those under conventional approach with or without C1 arch., Results: By means of adjusting specimen positions and the angle of operative microscope, as tela choroidea and inferior medullary velum were dissected gradually, the structures of floor, lateral recesses and lateral apertures of the fourth ventrical, vermian and aperture of midbrain aqueduct were exposed. There were no significant difference in the exposed floor area of the fourth ventricle between the keyhole approach and conventional approach (P = 0.06), and the C1 arch removal can't increase the exposed area (P = 0.84). The conventional approach have wider angles than the keyhole approach (P < 0.01), and the C1 arch removal increased the vertical angle (P < 0.05), but not the horizontal angle (P > 0.05)., Conclusion: The suboccipital median transcerebellomedullary fissure keyhole approach can expose similar anatomic architectures as that of the conventional approach. Thus it can be used to remove the tumors located in the fourth ventricle, dorsum of pons and medullary oblongata and cerebellar vermis.

Objective: To explore the surgical approaches, microsurgical techniques and therapeutic effect of modified cistern magna reconstruction for treating of syringomyelia with Chiari malformations., Methods: The clinical data of 35 patients with syringomyelia complicated by Chiari malformations were retrospectively reviewed, and the patients' chief complaints, presenting symptoms, neurological and radiographic findings, surgical approaches, outcomes, and complications were analyzed., Results: The radiographs revealed type I Chiari in 18 and type II Chiari malformations in these patients. Surgical treatment resulted in symptomatic improvements in 29 patients, and 6 patients showed no obvious changes in the symptoms after the surgery; 3 patients received subarachnoid shunting for syringomyelia. During the follow-up for a mean of 2 years, 32 patients showed obvious clinical improvement, and magnetic resonance imaging demonstrated complete spontaneous resolution of syringobulbia in 25 patients., Conclusion: Modified cistern magna reconstruction relieves brainstem compression and restores the pulsatile flow of the cerebrospinal fluid at the cervicomedullary junction. Cerebellar tonsil reduction is performed chiefly by electric coagulation and cauterization combined with subpial resection, and the integrity of the pia mater should be maintained as much as possible to avoid potential adhesion and recurrence. The median foramens and Luschka of the fourth ventricle have to be opened to recover normal CSF circulation. Arachnoidal suspension and placement of a patulous dural graft are also important. Modified reconstruction of the cistern magna can be a good option for treatment of syringomyelia complicated by Chiari malformations.

Objective: Cerebrospinal fluid diversion from the cisterna magna has been described previously but has largely been abandoned because of high complication rates and anatomic constraints. Situations still remain in which this may be the best or only alternative. We describe the use of interventional magnetic resonance imaging (iMRI) for the application of this largely forgotten procedure., Presentation: A 28-year-old woman with a previously diagnosed malignant peripheral nerve sheath tumor of the thoracic spine presented with a refractory postoperative cerebrospinal fluid leak complicated by diffuse meningeal carcinomatosis. External lumbar drainage was unsuccessful because of complete tumor obliteration. An attempt at primary closure augmented with muscle flaps was also ineffective. Ventricular drainage was deferred because of concern for tumor seeding, thus necessitating a more aggressive approach., Technique: The patient was intubated and placed in the open iMRI portal in a lateral decubitus position. Under direct image guidance, a closed-tip lumbar catheter was inserted into the cisterna magna through an iMRI-compatible biopsy needle and then connected for external drainage., Conclusion: To our knowledge, this is the first described use of iMRI technology for catheterization of the cisterna magna for cerebrospinal fluid diversion. Moreover, iMRI technology should be considered in future applications of complex posterior fossa shunting procedures.

The access of transplanted cells to large areas of the CNS is of critical value for cell therapy of chronic diseases associated with widespread neurodegeneration. Intrathecal cell application can match this requirement. Here we describe an efficient method for cell injection into the cisterna magna and the assessment of the cell distribution within subarachnoidal space in mice. In order to maximize cell distribution we applied a "concord-like" position, where the cisterna magna is nearly the highest point of the animal's body. A drop of saline on the needle insertion site avoided the outflow of transplanted cells from subarachnoidal space with CSF during surgery. Twenty-four hours later the preparation of the CNS with an intact dura mater by a suitable dissection technique (described in detail) revealed approx. 80% of the injected cells (100,000 cells per animal) within the subarachnoidal space ranging from the skull base (olfactory nerve to premedullary cisterns) to the IV ventricle, and to both the ventral and dorsal surfaces of the spinal cord. Thus the "concorde-like" position proved to be very useful for intrathecal cell application leading to a widespread cell distribution within the subarachnoidal space.

A 29-year-old woman with acute lancinating headache, throbbed nuchal pain and subacute paraparesis underwent brain MRI in supine position that depicted: the absence of the cisterna magna, filled by non herniated cerebellar tonsils and compression of the brain stem and cisternae of the posterior fossa, which are aspects of the impacted cisterna magna without syringomyelia and without hydrocephalus. During eight days, pain was constant and resistant to drug treatment. Osteodural-neural decompression of the posterior fossa, performed with the patient in sitting position, revealed: compression of the brainstem, fourth ventricle and foramen of Magendie by herniated cerebellar tonsils, which were aspirated. Immediately after surgery, the headache and nuchal pain remmited. MRI depicted the large created cisterna magna and also that the cerebellar tonsils did not compress the fourth ventricle, the foramen of Magendie and the brainstem, besides the enlargement of posterior fossa cisternae. Four months after surgery, headache, nuchal pain and paraparesis had disappeared but hyperactive patellar and Achilles reflexes remained.

Object: Interhemispheric arachnoid cysts are very rare, and they are often associated with complex brain malformations such as corpus callosum agenesis and hydrocephalus. Debate remains concerning the proper management of these lesions. Placement of shunts and microsurgical marsupialization of the cyst are the traditional options. Using endoscopic methods to create areas of communication between the cyst, the ventricular system, and/or the subarachnoid space is an attractive alternative to the use of shunts and microsurgery., Methods: Between 2000 and 2005, seven consecutive pediatric patients with interhemispheric arachnoid cysts underwent neuroendoscopic treatment involving cystoventriculostomy in two patients, cystocisternostomy in two, and cystoventriculocisternostomy in three. There were three cases of associated hydrocephalus, six cases of corpus callosum agenesis, and one case of corpus callosum hypogenesis. The follow-up period ranged from 12 to 49 months (mean 31.6 months). Endoscopic procedures were completely successful in all but two patients. In one of the remaining two patients, a repeated endoscopic cystocisternostomy was performed with success because of closure of the previous stoma. In the other, a subcutaneous collection of cerebrospinal fluid (CSF) was managed by insertion of an lumboperitoneal shunt. A subdural collection of CSF developed in three patients; it was treated with insertion of a subduroperitoneal shunt in one patient and managed conservatively in the other two patients, resolving spontaneously without further treatment. Neurodevelopmental evaluation performed in six patients showed normal intelligence (total intelligence quotient [IQ] > 80) in three patients, mild developmental delay (total IQ 50-80) in two, and severe developmental delay (total IQ < 50) in one., Conclusions: Endoscopic treatment of interhemispheric cysts can be considered a useful alternative to traditional treatments, even if some complications are to be expected, such as subdural or subcutaneous CSF collections and CSF leaks due to thinness of cerebral mantle and to the often-associated multifactorial hydrocephalus.

Objective: The purpose of this work is to present our endoscopic neuroanatomical findings of a series of myelomeningocele and hydrocephalus patients, treated with endoscopic third ventricular cisternostomy (ETVC), in order to describe ventricular configuration abnormalities in this group of patients, in which this neurosurgical procedure has limited performance., Method: We checked the videos of 10 endoscopic third ventricular cisternostomies of myelomeningocele patients taken during 24 months as from December 1998. A previous guideline is designed to record anatomic variables in the lateral ventricles, IIIrd ventricle, and basal cisterns. The topic is analyzed in view of the necropsy and imaging background data., Results: The ETVC of lateral ventricles showed: absence of septum (9/10); absence of anteroseptal vein (8/10); absence of choroid plexus and thalamostriate vein (0/10); absence of fornix (1/10): small foramen of Monro (4/10). The ETVC of the IIIrd ventricle showed: impossibility of recognizing any mammillary bodies (4/10); presence of septations (5/10); presence of atypical veins in the floor (6/10); translucent floor (5/10); floor umbilications (5/10); absence of infundibulum (4/10); arachnoid adherences (7/10); and visual contact of basilar artery (4/10)., Conclusion: There are categorical structural alterations in the ventricular system of myelomeningocele patients that are well correlated with previous necropsy and imaging reports. The ventricular system of dysraphic children presents severe anatomic alterations, which alter the reference points of the classical endoscopic third ventricular cisternostomy.

Object: Severely increased intracranial pressure (ICP) can be life threatening in patients who had previously undergone shunt treatment but who do not experience ventricular enlargement. The authors analyzed the utility of placing shunts into the cisterna magna concurrently with ventricular shunts in patients who were not candidates for lumboperitoneal (LP) shunt placement., Methods: Ten patients treated with cisterna magna-ventricle-peritoneum (CMVP) shunts for complex problems of shunt function were reviewed retrospectively. All patients had documented increases in ICP and ventricles that did not expand despite life-threatening increases (> 80 mm Hg in one case) in ICP. Between 1995 and 2003, 10 patients (four males and six females, age range 4-32 years) were identified as having life-threatening increases in ICP despite small or slit-like ventricles on imaging studies. Each episode was documented with intraparenchymal pressure monitoring. All patients had documented ventricular catheter failures at the time of the intervention, and all had undergone at least one previous attempt to treat the condition with a valve upgrade and replacement of the ventricular catheter. Three patients had achondroplasia, four had spina bifida, and three had a preexisting Chiari malformation Type I. All patients improved after the procedure, and none suffered permanent complications. For at least 48 hours after surgery, all patients underwent intraparenchymal monitoring of ICP (an intraparenchymal monitor was used that documented normal ICP)., Conclusions: The CMVP shunts are an excellent option for patients who are not candidates for LP shunts but who have high ICP and ventricles that do not enlarge at shunt failure. The ability to access the spinal fluid in the cortical subarachnoid space presumably accounts for this success.

We report a rare intracisternal C1 posterior root neurinoma in a 35-year-old man without neurofibromatosis who presented with headache, nuchal pain, bilateral motor weakness of the upper extremities, and numbness in the right distal upper extremity. CT and MRI study showed a 20-mm intracisternal lesion at the foramen magnum. At surgery, there was an anastomosis between the C1 posterior root and a spinal accessory nerve at the site of the tumor; the root from the collateral sulcus of this C1 root was absent. Postoperatively, the patient remains free of symptoms. Foramen magnum neurinomas have been described as accessory nerve tumors. We present new anatomical consideration regarding this lesion.

Background: The authors introduce the transsylvian trans-limen insular approach to the crural, ambient and interpeduncular cisterns., Method: The transsylvian trans-limen insular approach was performed in 7 patients; 3 for aneurysm, 2 for isolated temporal horn hydrocephalus, one for tumour and one for an arteriovenous malformation. This approach is summarized in 4 procedures; the exposure of the inferior limiting sulcus of the insular cortex, the exposure of the inferior horn of the lateral ventricle, the dissection of the inferior part of the choroidal fissure and the splitting of the inferior border of the limen insula., Findings: Four among 7 patients underwent surgery for the lesions in the crural or ambient cistern. The other 3 patients underwent surgery for the lesion in the interpeduncular cistern. Two patients of the latter group postoperatively had temporal lobe infarction., Conclusions: The transsylvian trans-limen insular approach may be indicated for lesions in the crural and the anterior ambient cisterns, and the lesions which need wider exposure of the interpeduncular cistern. For the former lesions, this approach can afford good results. For the latter lesions, careful brain retraction and some other techniques to avoid temporal lobe infarction are necessary. Further neuropsychological assessment should be also necessary to prove the validity of this approach.

Case Report: A 20-year-old female born with a thoracic level myelomeningocele, Chiari II malformation, and hydrocephalus treated at birth developed clinical features of increased intracranial pressure (ICP) due to shunt malfunction. The patient became comatose. Her ICP remained high despite a functioning shunt and even after the ventricular catheter was exteriorized. Diagnostic imaging consistently demonstrated slit-like ventricles, a Chiari II malformation, and a tethered spinal cord. We attributed her neurological condition either to brainstem compression or increased ICP related to venous outlet obstruction at the foramen magnum., Outcome: The patient improved rapidly after undergoing a Chiari II decompression and placement of a shunt from the cisterna magna and upper cervical subarachnoid space to the peritoneum connected by a "Y" connector to the ventricular catheter., Conclusion: The complex hydrocephalus was effectively treated by this concurrent ventricular and cisterna magna-to-peritoneum shunt.

Objective: Shunting of cerebrospinal fluid (CSF) to an extracranial site is the mainstay of treatment of absorptive hydrocephalus and pseudotumor cerebri. On occasion, both lateral ventricles and the lumbar space become unsuitable for placement of a functioning CSF drainage catheter. We have encountered several such patients and describe our strategy of shunting from the cisterna magna to the pleural space or cardiac atrium., Methods: We report a retrospective review of the clinical course of five patients with cisternal shunts and intracranial pressure telemonitoring devices., Results: Cisternal shunting was able to successfully drain CSF to a normal pressure in all five patients. CSF pressure data collected from those patients indicate that the CSF pressure dynamics in cisternal shunts is similar to that of ventricular shunts. However, the cisternal shunting and subsequent high revision rate did result in a significant number of complications and two shunt infections., Conclusion: Shunting CSF from the cisterna magna in the absence of another suitable drainage site does result in acceptable reduction of elevated intracranial pressure. However, the technique is associated with a high complication rate that may reflect the population of patients in whom this technique is required.

Background: The pathogenesis of cerebral vasospasm is likely to be multifactorial. Exposure of the adventitia of large cerebral arteries to blood breakdown products initiates a cascade of changes in both morphology and vasomotor regulation of the exposed vessels. The role of nitric oxide (NO) in development of cerebral vasospasm process is controversial. Basal cerebral vascular tone requires the continuous release of NO, nevertheless NO is involved in free radical mediated injury of endothelial cell membrane. Concentrations of nitrate/nitrite (stabile endproducts of NO metabolism) were studied in cisternal cerebrospinal fluid (cCSF) in patients suffering from aneurysmal subarachnoid haemorrhage (SAH)., Method: 21 patients suffering from aneurysmal SAH were investigated. Treatment included aneurysm clipping, cisternal drainage of CSF and intravenous nimodipine in all patients as well as tripple H therapy when indicated. TCDS was performed on a daily basis. A mean flow velocity of more than 150 cm/sec and the development a delayed neurological deficit was defined as vasospasm. CSF samples were collected on the day of surgery and for the 7 days following. NO-M (nitrite and nitrate) were measured using a commercially available test kit., Findings: 5 of 21 patients developed clinically symptomatic vasospasm. There was a significant difference in NO levels between the groups. Patients with cerebral vasospasm showed significantly higher levels of NO-M in CSF than patients with a uncomplicated follow-up between day 2 and 8., Interpretation: Our preliminary results indicate that SAH leads to an increase in NO-M in CSF. This increase of NO-M significantly correlates with the flow velocities in TCDS measurement suggesting that NO plays an important role in the pathogenesis of cerebral vasospasm.

Background: Intracranial schwannoma of the accessory nerve can be divided into two types. One is a jugular foramen type arising from the accessory nerve of the jugular foramen, while the other is an intracisternal type, which arises from the spinal root of the accessory nerve and is separate from the jugular foramen. The latter type is rare, and only 9 cases have been reported previously., Case Description: A 46-year-old female presented with a large, midline mass lesion in the posterior fossa manifesting as foramen magnum syndrome. Magnetic resonance imaging (MRI) revealed a huge tumor with cystic lesion located in the cisterna magna with extension to the C1 spinal level. The tumor was totally removed by a suboccipital craniectomy and C1 laminectomy. It originated from the spinal root of the right accessory nerve. Temporary slight atrophy of the right sternocleidomastoid muscle was observed, but the patient was free of disease 2 years after treatment., Conclusions: We report a schwannoma of the spinal accessory nerve in the cisterna magna. The clinical and neuroradiological findings are discussed with a review of the literature. The initial symptoms were variable without loss of function of the cranial nerve, and the tumor tended to grow in the cisterna magna without laterality. Because of the absence of typical neurologic symptoms, early neuroradiological investigation by MRI is recommended for accurate diagnosis of these tumors.

We herein describe a case of an isolated multilocular hydatid cyst occurring in the basilar cisterns, with nondependent levels of different signal intensities shown on MR images. Three portions were visualized on T1-weighted images: the hyperintense inferior aspect, the isointense central part, and the superior aspect of lower signal intensity. The inferior portion was hypointense on T2-weighted images. This unusual appearance was caused by layering of hydatid sand and may represent a characteristic feature of hydatid disease.

Objective: To describe the anatomy of the cisternal segment of the trochlear nerve as seen through different neurosurgical approaches., Methods: The cisternal course of ten trochlear nerves was observed in five cadaveric embalmed heads, through the view afforded by the median infratentorial-supracerebellar, the extreme-lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. The relationships of the trochlear nerve with the surrounding neuro-vascular structures were analyzed., Results: We identified 3 segments of the cisternal trochlear nerve: quadrigeminal, ambient and tentorial. The median infratentorial-supracerebellar approach allowed exposure of the quadrigeminal segment, including the origin of the nerve. The extreme-lateral supracerebellar and the combined presigmoid-subtemporal transtentorial approaches provided visualization of the ambient and tentorial segments of the nerve. The tentorial segment runs in a dural canal contained in the free edge of the tentorium, surrounded by its own arachnoidal sleeve., Conclusion: The trochlear nerve is a very delicate structure that can be easily injured during approaches to the tentorial incisura. Accurate knowledge of its anatomy as seen through different operative windows is helpful in maintaining its integrity during surgery.

Object: Craniopharyngiomas frequently grow from remnants of the Rathke pouch, which is located on the cisternal surface of the hypothalamic region. These lesions can also extend elsewhere in the infundibulohypophyseal axis. The aim of this study was to establish the usefulness of the frontobasal approach made through a relatively small craniotomy window for the removal of tumors protruding from the sellar-suprasellar region into the third and basal cistern., Methods: Thirty-one patients who were surgically treated for craniopharyngiomas extending outside the sellar-suprasellar region were evaluated. The diagnoses were established in all cases by using magnetic resonance and computerized tomography imaging. The initial symptoms and signs were increased intracranial pressure in eight, vision impairment or visual field defect in 16, hypopituitarism in 17, and psychological disturbances in three cases. All patients underwent surgery via the frontobasal interhemispheric approach, and the average follow-up period was 30 months. Total removal of the lesion was achieved in 22 cases, six patients underwent subtotal resection, and three underwent partial removal due to tumor recurrence after previous surgeries performed with or without adjunctive radiotherapy. Major complications, including impairment of the cranial nerves, were not observed in the immediate postoperative period. One patient exhibited transient memory disturbance due to infarction of the perforating vessels; after 3 months this symptom was ameliorated. None of the patients died during long-term follow up; however, four of the 22 who underwent total removal and six of the nine patients who underwent subtotal or partial removal suffered recurrence. Of the 10 patients with recurrence, six experienced a small recurrence of the lesion (average 3 months postsurgery); after gamma knife surgery (GKS), the size of two of the lesions was unchanged and in four reoperation was performed due to tumor enlargement during the follow-up period. Ultimately, a total of eight patients (four with recurrence and four who had been treated with GKS) underwent reoperation, with gross-total removal via the same approach or combined with the orbitozygomatic approach in patients with very short optic nerves. In no patient was deterioration of visual acuity and visual field observed after surgery. Although all patients except four children and one adult were receiving some form of hormone replacement therapy, their endocrine status was stably controllable., Conclusions: In the authors' experience, the frontobasal interhemispheric approach, even made through a small craniotomy window, is a valid choice for the removal of craniopharyngiomas extending outside the sellar-suprasellar region. Via this approach, tumors can be removed without significant sequelae related to the surgical method, due to ease of preservation of the pituitary stalk, hypothalamic structures, and perforating vessels. This approach offers a safe and minimally invasive means of treating craniopharyngiomas.