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Foramen magnum meningiomas: experiences in 114 patients

Surgical Neurology 72 (2009) 376–382. doi:10.1016/j.surneu.2009.05.006

Background: Although there has been great development in the anatomical understanding and operative techniques for skull base tumors, controversy still exists regarding the optimal surgical strategies for the FMMs. We report clinical and radiologic features as well as the surgical findings and outcome for patients with FMM treated at our institution over the last 15 years.
Methods: We reviewed 114 consecutive cases of FMM operated between May 1993 and June 2008 in the neurosurgery department at Beijing Tiantan Hospital.
Results: There were 68 female and 46 male patients (mean age, 52.3 years; range, 28-76 years). Foramen magnum meningiomas were classified as anterior (80 cases), anterolateral (24 cases), and posterolateral (10 cases). Mean duration of symptoms was 11.7 months (ranging from 1.5 to 240 months). Cervico-occipital pain (80.7%) and headache and dizziness (42.1%) were the most common presenting symptoms. The preoperative KPS was 72.5 ± 8.3. Mean maximum diameter of the tumors on MRI was 3.35 cm (range, 1.5-4.7 cm). Posterior midline approach was performed in 10 cases, far-lateral retrocondylar approach in 97 cases, and extended far-lateral approach in 7 cases. Gross total resection was achieved in 86.0% of patients and subtotal resection in 14.0%. Surgical mortality was 1.8%. Follow-up data were available for 93 patients, with a mean follow-up of 90.3 months (range, 1-180 months), of which 59 (63.4%) lived a normal life (KPS, 80-100).
Conclusion: Our experience suggests that most anterior and anterolateral FMMs can be completely resected by a far-lateral retrocondylar approach without resection of the occipital condyle. Complete resection of the tumor should be attempted at the first operation. Postoperative management of FMM is important for the prognosis.

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Radiologically documented adjacent-segment degeneration after cervical arthroplasty

Surgical Neurology 72 (2009) 325–329. doi:10.1016/j.surneu.2009.02.013

Background: The authors retrospectively studied the incidence and characteristics of radiologically documented adjacent-segment degeneration after single-level diskectomy and subsequent cervical arthroplasty using the Bryan (Medtronic Sofamor Danek; Memphis, TN) disk prosthesis.

Methods: Seventy-two patients with single-level arthroplasty using the Bryan cervical disk prosthesis were evaluated. Radiological evidence of adjacent-disk disease included new formation or enlargement of anterior osteophyte, new or increasing ALL calcification, or narrowing of disk space documented on serial plain radiographs. We reported the characteristics of adjacent-segment degeneration and reviewed all of the cases.

Results: Among the 72 patients, 9 patients (12.5%) showed radiological evidence of adjacentsegment degeneration. The mean age was 43.3 years old, with a male-female ratio 1:3. The mean follow-up period was 24.2 (12.1-35.9) months. The mean period of onset was 16.3 months. Uppersegment degeneration was documented in 4 cases (3 new osteophyte, 1 enlargement of osteophyte), whereas lower-segment degeneration was noted in 5 cases (1 new osteophyte, 3 enlargement of osteophyte, 1 decreased disk height). Among the degenerated cases, 4 cases (44.4%) also showed various degrees of HO.

Conclusions: The rate of adjacent-segment degeneration was higher than that observed in previous studies. Adjacent-segment degeneration documented a tendency toward HO. A longer follow-up period is necessary to investigate and document the different types of degeneration seen at levels adjacent to artificial Bryan cervical disk prostheses.

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Indications for Brain Computed Tomography and Hospital Admission in Pediatric Patients with Minor Head Injury

Pediatr Neurosurg 2009;45:262–270. DOI: 10.1159/000228984

Objectives: The aim of this study was to describe the characteristics of patients with a minor head injury (MHI) who were admitted to a pediatric emergency unit and to identify the clinical signs and symptoms that most reliably predict the need for cranial computed tomography (CCT) and hospital admission following MHI.

Methods: All patients were retrospectively evaluated according to age, gender, details of injury, presenting symptoms, physical examination findings, radiological investigations ordered and results, length of stay, outcome of the injury and hospitalization rates.

Results:The factors affecting indications for computed tomography and hospitalization were retrospectively analyzed in 916 patients – 585 males and 331 females, aged between 1month and 15 years (mean: 5.01 8 3.58 years), with MHI. A multivariate analysis revealed significant correlations between CCT abnormalities and Glasgow Coma Scale scores of 13 or 14, headache, posttraumatic amnesia, blurred vision, cephalohematomas, periorbital ecchymoses, otorrhea and abnormal neurological findings. CCT abnormalities were identified in 67 (19.8%) of the 338 CCT scans. Twenty of the 67 patients (29.9%) with CCT scan abnormality had no clinical signs. Of all cases, 125 (13.6%) were hospitalized, 617 (67.4%) were treated as outpatients, and 174 (19.0%) left the emergency department based on a personal decision.

Conclusion: Some clinical risk factors can be used as predictors of abnormalities in CCT scans following MHI, but the absence of such clinical findings does not exclude the possibility of intracranial injuries.

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Risk of stereotactic biopsy in eloquent brain regions

J Neurosurg 111:820–824, 2009. DOI: 10.3171/2009.3.JNS081695

Object. Frameless stereotactic biopsy has been shown in multiple studies to be a safe and effective tool for the diagnosis of brain lesions. However, no study has directly evaluated its safety in lesions located in eloquent regions in comparison with noneloquent locations. In this study, the authors determine whether an increased risk of neurological decline is associated with biopsy of lesions in eloquent regions of the brain.
Methods. Medical records, including imaging studies, were reviewed for 284 cases in which frameless stereotactic biopsy procedures were performed by 19 neurosurgeons at 7 institutions between January 2000 and December 2006. Lesion location was classified as eloquent or noneloquent in each patient. The incidence of neurological decline was calculated for each group.
Results. During the study period, 160 of the 284 biopsies predominately involved eloquent regions of the brain. In evaluation of the complication rate with respect to biopsy site, neurological decline occurred in 9 (5.6%) of 160 biopsies in eloquent brain areas and 10 (8.1%) of 124 biopsies in noneloquent regions; this difference was not statistically significant (p = 0.416). A higher number of needle passes was associated with the presence of a postoperative hemorrhage at the biopsy site, although not with a change in the result of neurological examination.
Conclusions. Frameless stereotactic biopsy of lesions located in eloquent brain regions is as safe and effective as biopsy of lesions in noneloquent regions. Therefore, with careful planning, frameless stereotactic biopsy remains a valuable and safe tool for diagnosis of brain lesions, independent of lesion location.

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The motor-evoked potential threshold evaluated by tractography and electrical stimulation

J Neurosurg 111:785–795, 2009.DOI: 10.3171/2008.9.JNS08414

Object. To validate the corticospinal tract (CST) illustrated by diffusion tensor imaging, the authors used tractography-integrated neuronavigation and direct fiber stimulation with monopolar electric currents.
Methods. Forty patients with brain lesions adjacent to the CST were studied. During the operation, the motor responses (motor evoked potential [MEP]) elicited at the hand by the cortical stimulation to the hand motor area were continuously monitored, maintaining the consistent stimulus intensity (mean 15.1 ± 2.21 mA). During lesion resection, direct fiber stimulation was applied to elicit MEP (referred to as fiber MEP) to identify the CST functionally. The threshold intensity for the fiber MEP was determined by searching for the best stimulus point and changing the stimulus intensity. The minimum distance between the resection border and illustrated CST was measured on postoperative
isotropic images.
Results. Direct fiber stimulation demonstrated that tractography accurately reflected anatomical CST functioning. There were strong correlations between stimulus intensity for the fiber MEP and the distance between the CST and the stimulus points. The results indicate that the minimum stimulus intensity of 20, 15, 10, and 5 mA had stimulus points ~ 16, 13.2, 9.6, and 4.8 mm from the CST, respectively. The convergent calculation formulated 1.8 mA as the electrical threshold of the CST for the fiber MEP, which was much smaller than that of the hand motor area.
Conclusions. The investigators found that diffusion tensor imaging–based tractography is a reliable way to map the white matter connections in the entire brain in clinical and basic neuroscience applications. By combining these techniques, investigating the cortical-subcortical connections in the human CNS could contribute to elucidating the neural networks of the human brain and shed light on higher brain functions.

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Outcome After Anterior Cervical Discectomy and Arthrodesis A Clinical Study of 368 Patients

Neurosurg Q 2009;19:164–170

Aim: To define the predictors for the clinical outcome after anterior cervical discectomy and arthrodesis for patients with degenerative diseases of the cervical spine. Does the subsidence of the intervertebral spacer in the adjacent vertebral have a negative influence on the outcome?
Materials and Methods: In a prospective clinical study, 368 patients underwent anterior cervical discectomy and arthrodesis with degenerative disease of the cervical spine. The patients were treated between September 1997 and January 2005. All patients were followed up 1 year after surgery.
Results: Young age of the patient, mono-segmental anterior cervical discectomy and arthrodesis of the lower cervical spine are predictors of a satisfactory outcome. We did not find statistical differences in the outcome between male and female patients or between patients with or without subsidence of the cage.
Conclusions: Good results can be achieved by early operative therapy. The subsidence of the cage does not affect the outcome.

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Intracranial-intracranial arterial by-pass for complex aneurysms

Neurosurgery 65:670–683, 2009 DOI: 10.1227/01.NEU.0000348557.11968.F1

OBJECTIVE: Bypass surgery for brain aneurysms is evolving from extracranial-intracranial
(EC-IC) to intracranial-intracranial (IC-IC) bypasses that reanastomose parent arteries,
revascularize efferent branches with in situ donor arteries or reimplantation, and reconstruct bifurcated anatomy with grafts that are entirely intracranial. We compared results with these newer IC-IC bypasses to conventional EC-IC bypasses.
METHODS: During a 10-year period, 82 patients underwent bypass surgery as part of their aneurysm management. A quarter of the patients presented with ruptured aneurysms and two-thirds presented with compressive symptoms from unruptured aneurysms. Most aneurysms (82%) had non-saccular morphology and 56% were giant sized. Common locations included the cavernous internal carotid artery (23%), middle cerebral artery (20%), and posteroinferior cerebellar artery (12%).
RESULTS: Forty-seven patients (57%) received EC-IC bypasses and 35 patients (43%)received IC-IC bypasses, including 9 in situ bypasses, 6 reimplantations, 11 reanastomoses, and 9 intracranial grafts. Aneurysm obliteration rates were comparable in ECIC and IC-IC bypass groups (97.9% and 97.1%, respectively), as were bypass patency rates (94% and 89%, respectively). Three patients died (surgical mortality, 3.7%), and 4 patients were permanently worse as a result of bypass occlusions (neurological morbidity,4.9%). At late follow-up (mean duration, 41 months), good outcomes (Glasgow Outcome Scale score 5 or 4) were measured in 68 patients (90%) overall, and were similar in EC-IC and IC-IC bypass groups (91% and 89%, respectively). Changes in Glasgow Outcome Scale score were slightly more favorable with IC-IC bypass (6% worse or dead after IC-IC bypass versus 14% with EC-IC bypass).
CONCLUSION: IC-IC bypasses compare favorably to EC-IC bypasses in terms of aneurysm obliteration rates, bypass patency rates, and neurological outcomes. IC-IC bypasses can be more technically challenging to perform, but they do not require harvest of extracranial donor arteries, spare patients a neck incision, shorten interposition grafts, are protected inside the cranium, use caliber-matched donor and recipient arteries, and are not associated with ischemic complications during temporary arterial occlusions. IC-IC bypass can replace conventional EC-IC bypass with more anatomic reconstructions for selected aneurysms involving the middle cerebral artery, posteroinferior cerebellar artery, anterior cerebral artery, and basilar apex.

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Occipital condyle fractures: clinical decision rule and surgical management

JNS Spine DOI: 10.3171/2009.5.SPINE08866

Object. Occipital condyle fractures (OCFs) are rare injuries and their treatment remains controversial. Several classification systems have been proposed, first by Anderson and Montesano and more recently by Tuli and colleagues and Hanson and associates, who sought to stratify these fractures in a manner that would guide treatment that has typically ranged from semirigid collar immobilization to halo fixation or occipitocervical fusion. It has been the authors’ impression, based on experience with OCFs at their institution, that classification is cumbersome and contributes little to the clinical decision-making process, while the identification of craniocervical misalignment and neural element compromise is paramount, and sufficient, for the planning of treatment.

Methods. The authors performed a retrospective review of 24,745 consecutive trauma presentations to a single Level I trauma center (UPMC Presbyterian Hospital) over a 6-year period, identifying 100 patients with 106 OCFs. All patients were evaluated by the spine trauma service and underwent imaging of the craniocervical junction using reconstructed CT scans. Patient characteristics, fracture characteristics (including fracture classification according to the 2 major classification systems), initial management, and status at follow-up were recorded.

Results. The incidence of OCF in this trauma population was 0.4%. Two patients had evidence of craniocervical misalignment on reconstructed CT imaging at the time of admission; both patients underwent occipitocervical fusion. One patient underwent occipitocervical fusion for unrelated C1–2 fractures. The remainder of those surviving to discharge, whose fractures represented all fracture subtypes, received treatment with a rigid cervical collar or counseling alone. No patients, including 4 patients with bilateral OCFs, were found to have developed delayed craniocervical instability or misalignment on follow-up, or to require further neurosurgical intervention for an OCF. Neural element compression was not identified in any of the patients, and there were no cases of delayed cranial neuropathy.

Conclusions. Beyond the identification of craniocervical misalignment on reconstructed CT scans at admission, further classification of OCFs is unnecessary. Management should consist of up-front occipitocervical fusion or halo fixation in cases demonstrating occipitocervical misalignment, or of immobilization in a rigid cervical collar followed by delayed clinical and radiographic evaluation in a spine trauma clinic if misalignment is not present.

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Meningiomas of the ventral foramen magnum and lowerclivus

Acta Neurochir DOI 10.1007/s00701-009-0511-2

Purpose To identify an appropriate surgical approach for meningiomas of the foramen magnum and lower clivus and determine the factors influencing the surgical outcomes. Method The study involved 23 patients with foramen magnum or lower clival meningiomas (8 men, 15 women; average age, 56 years; range, 26–70 years) treated at Keio University Hospital between 1991 and 2008. Their clinical data were retrospectively reviewed with regard to the surgical approaches and outcomes. The average follow-up duration was 42.8 months, the mean tumour size, 25.9 mm (range, 12.0–50.0 mm).

Findings The tumours most commonly originated in the anterolateral rim of the foramen magnum. In 12 cases with lateral compression of the brain stem, the tumours were resected via the suboccipital approach with C1 laminectomy. The transcondylar approach was adopted in 11 cases where the tumour was located on the anterior rim of the foramen magnum. Four patients required epidural drilling of the jugular tubercle. Gross total resection was achieved in 15 cases (62.5%), the resection rate being lowest in cases of tumour extension to the lower clivus. The transient and permanent morbidity rates were 30.4% and 17.4%, respectively. Logistic regression analysis revealed that extension to the lower clivus (noted in 6 of 23 patients) was a statistically significant, independent factor influencing the permanent morbidity rate (p = 0.005)

Conclusions Selecting an appropriate surgical approach considering the tumour location resulted in a good surgical outcome. However, tumour extension to the lower clivus strongly influenced the morbidity and tumour radicality

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Aneurysmal subarachnoid hemorrhage diagnosis with computed tomographic angiography and OsiriX

Acta Neurochir DOI 10.1007/s00701-009-0508-x

Purpose Recent advances in computed tomographic angiography (CTA) have resulted in its replacing digital subtraction angiography (DSA). However, CTA requires a powerful workstation and experienced technicians for image postprocessing. OsiriX, a free open-source medical imaging software with powerful three-dimensional (3D) capability, enables neurosurgeons to perform 3D rendering without extensive training. In this study, we examined the sensitivity and specificity of CTA with OsiriX as the primary diagnostic tool for intracranial aneurysms.

Method From May 2006 to March 2009, 121 patients with spontaneous subarachnoid hemorrhage (SAH) underwent CTA. The CTA source images were 3D rendered by neurosurgeons using OsiriX. All the possible locations for aneurysms were carefully reviewed. DSA was performed on every patient in any of the following conditions: for negative CTA findings, after surgical clipping of aneurysms or before transarterial embolization of aneurysms.

Results Of the 121 patients, 8 were excluded because DSA data were not available. In the remaining 113 patients, 20 patients had negative CTA findings. CTA with OsiriX detected 106 aneurysms in 93 patients, of which 103 were confirmed by DSA or postoperative DSA; 3 infundibular dilated pouches of small arteries were mistaken for aneurysms. Two anterior communicating artery aneurysms (1.5 mm and 1 mm) were missed by CTA from among all 113 patients. The sensitivity and specificity of CTA for detecting aneurysms on a per-patient basis were 98.9% and 100%, respectively. The sensitivity and specificity of CTA for detecting aneurysms on a per-aneurysm basis for detecting aneurysms were 98.1% and 86.3%, respectively.

Conclusion CTA with OsiriX enables accurate detection of intracranial aneurysms. Cerebral DSA should be reserved for those patients with negative CTA findings.

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Bevacizumab Alone and in Combination With Irinotecan in Recurrent Glioblastoma

Journal of Clinical Oncology. DOI:10.1200/JCO.2008.19.8721

Purpose

We evaluated the efficacy of bevacizumab (Avastin TM), alone and in combination with irinotecan, in patients with recurrent glioblastoma in a phase II, multicenter, open-label, noncomparative trial.

Patients and Methods

One hundred sixty-seven patients were randomly assigned to receive bevacizumab 10 mg/kg alone or in combination with irinotecan 340 mg/m2 or 125 mg/m2 (with or without concomitant enzyme-inducing antiepileptic drugs, respectively) once every 2 weeks. Primary end points were 6-month progression-free survival and objective response rate, as determined by independent radiology review. Secondary end points included safety and overall survival.

Results

In the bevacizumab-alone and the bevacizumab-plus-irinotecan groups, estimated 6-month progression-free survival rates were 42.6% and 50.3%, respectively; objective response rates were 28.2% and 37.8%, respectively; and median overall survival times were 9.2 months and 8.7 months, respectively. There was a trend for patients who were taking corticosteroids at baseline to take stable or decreasing doses over time. Of the patients treated with bevacizumab alone or bevacizumab plus irinotecan, 46.4% and 65.8%, respectively, experienced grade  3 adverse events, the most common of which were hypertension (8.3%) and convulsion (6.0%) in the bevacizumab-alone group and convulsion (13.9%), neutropenia (8.9%), and fatigue (8.9%) in the bevacizumab-plus-irinotecan group. Intracranial hemorrhage was noted in two patients (2.4%) in the bevacizumab-alone group (grade 1) and in three patients (3.8%) patients in the bevacizumabplus-irinotecan group (grades 1, 2, and 4, respectively).

Conclusion

Bevacizumab, alone or in combination with irinotecan, was well tolerated and active in recurrent glioblastoma.

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Prognostic factors in intramedullary astrocytomas

Eur Spine J (2009) 18:1397–1422 DOI 10.1007/s00586-009-1076-8

Astrocytomas affect a significant portion of patients with intramedullary tumors. These infiltratively growing tumors are treated by a variety of methods—biopsy and decompressive surgery, maximal safe resection, adju- vant oncological therapy. Also, numerous prognostic factors are reported in the literature. Better understanding of factors that influence prognosis may help in treatment planning with the goal of prolonging survival. We have thus undertaken an extensive literature review in order to define factors affecting prognosis. A total of 38 articles were studied. Only tumor grade was consistently reported as the major factor affecting prognosis. The influence of other clinical factors (age, gender, history length, functional status, tumor location or extent, syrinx or cyst presence) can be speculated upon, but cannot be assessed adequately from the available literature. For both low- and high-grade (HG) astrocytomas, maximal safe tumor resection should be the primary treatment objective but is often not feasible in contrast to other intramedullary and spinal neoplasms. Since the biological nature of spinal cord HG glioma is identical to that of the brain, the same treatment algorithm of maximal safe resection followed by concomitant radio and chemotherapy would be sensible to implement.

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Neurosurgical management of intractable rolandic epilepsy in children: role of resection in eloquent cortex

J Neurosurg Pediatrics 4:199-216, 2009. DOI: 10.3171/2009.3.PEDS08459

Object. The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable  epilepsy.
Methods. The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative   electroencephalography (EEG), MRimaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores.
Results. There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis.
Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3–6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child’s age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024).
Conclusions. Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

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Endoscopic treatment of third ventricular colloid cysts

Neurosurg Rev (2009) 32:395–402. DOI 10.1007/s10143-009-0208-2

The surgical treatment of colloid cysts has been traditionally difficult with high rate of postoperative complications. The variety of surgical options reflects the technical difficulty in removing these benign lesions with low morbidity. Microsurgical removal has for years been considered the “gold standard” of treatment, with the use of either a transcortical–transventricular or a transcallosal approach. Neuroendoscopic management is emerging as a safe, effective alternative to microsurgery. The present review discusses the role

of endoscopy in the surgical treatment of third ventricular colloid cysts focusing on some factors, which might influence the outcome. The results have been presented from the literature and supplemented by the results of treating ten personal cases of third ventricular colloid cysts who were operated endoscopically in the Neurosurgical Department, Cairo University. This study aims at evaluating the endoscopic approach as a surgical line of treatment in the management of third ventricular colloid cysts and to see if it has already become superior over microsurgery.

Conclusions: Endoscopic approach to third ventricular colloid cysts is a minimally invasive procedure, which achieves both total evacuation of the cyst and at least near-total resection of the cyst wall with a low surgical morbidity. The available results document less radical excisions as compared to microsurgical group; this is counterbalanced by the lower incidence of complications and shorter operative, hospitalization, and rehabilitation time in the endoscopic group. This conclusion makes endoscopy an alternative and not a better choice than microsurgery. Consequently, the ongoing debate between both procedures remains unresolved. This dispute will become resolved only when long-term studies (mean follow-up for 10 years or greater) are available for a substantial number of patients who have undergone endoscopic resection.

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Do children and adults differ in survival from medulloblastoma? A study from the SEER registry

J Neurooncol (2009) 95:81–85 DOI 10.1007/s11060-009-9894-4

Studies investigating whether adults have diminished survival from medulloblastoma (MB) compared with children have yielded conflicting results. We sought to determine in a population-based registry whether adults and children with MB differ in survival, and to examine whether dissimilar use of chemotherapy might contribute to any disparity.

1,226 MB subjects were identified using the Surveillance Epidemiology and End Results (SEER-9) registry (1973–2002) and survival analysis performed. MB was defined strictly to exclude non-cerebellar primitive neuro- ectodermal tumors. Patients were stratified by age at diagnosis: <3 years (infants), 3–17 years (children) and >18 years (adults). Because the SEER-9 registry lacks treatment data, a subset of 142 patients were identified using the San Francisco-Oakland SEER registry (1988–2003) and additional analyses performed.

There was no significant difference in survival between children and adults with MB in either the SEER-9 (P = 0.17) or SFO (P = 0.89) cohorts but infants fared worse compared to both children (P < 0.01) and adults (P < 0.01). In the SFO sample, children and adults who received chemotherapy plus radiation therapy (XRT) did not differ in survival. Among patients treated with XRT alone, children showed increased survival (P = 0.04) compared with adults. Children and adults with MB do not differ with respect to overall survival, yet infants fare significantly worse.

For children and adults with MB treated with both XRT and chemotherapy, we could not demonstrate a survival difference. Similar outcomes between adult and childhood MB may justify inclusion of adults in pediatric cooperative trials for MB.

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Dura splitting decompression in Chiari type 1 malformation: clinical experience and radiological findings

Neurosurg Rev (2009) 32:465–470. DOI 10.1007/s10143-009-0214-4

To restore the cerebrospinal fluid (CSF) flow at the craniocervical junction in Chiari I malformation (CM-I), most surgeons practice a suboccipital craniectomy with duraplasty. To reduce the risk of CSF leak, a dura splitting decompression is created removing only the dural outer layer. We report on a series of 11 patients with CM-I (five with syringomyelia) operated on between 2000 and 2007 using this technique. Neurological examination and cerebro-spinal MRI scan were performed before and after surgery. Symptoms improved completely in six patients. Headaches and cervicalgias disappeared for all patients. Dizziness and paresthesia in the upper limb remained unchanged for three and two patients, respectively. We observed no complications such as CSF leak, meningocele, or meningitis. Postoperative MRI scan showed a significant craniocervical decompression in ten patients. Four patients had a new cisterna magna. Two syringomyelias completely disappeared, two decreased, and one was stable. Dural splitting can be practiced to treat CM-I. Clinical results are similar to the other techniques with less complications. Radiological findings show satisfying posterior fossa decompression.

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Trigeminal neurinomas: clinical features and surgical experience in 84 patients

Neurosurg Rev (2009) 32:435–444.DOI:10.1007/s10143-009-0210-8

Trigeminal neurinomas are the second most common intracranial neurinomas next to the vestibular neurinomas. Eighty-four patients with trigeminal neurinomas were treated between 2003 and 2007. There were 40 women and 44 men (mean age 43 years). The most frequent symptoms were headache or numbness of the ipsilateral hemiface. There were 24 type A, nine type B, 45 type C, and six type D tumors. Dextroscope virtual reality technology was used for preoperative planning in recent eight cases. Gross total resection was achieved in 63 patients. We found that the major impediments to complete removal were adherent to the brainstem and skull base vascular structure, the frontotemporal approach with zygomatic or orbitozygomatic osteotomy or subtemporal approach could offer excellent exposure of the middle fossa and access to the posterior fossa, and Dextroscope virtual reality technology was a very useful tool to identify surgical and anatomic nuances and enhance preoperative planning in trigeminal neurinomas resection.

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Intraoperative X-Ray Detection and MRI-Based Quantification of Brain Shift Effects Subsequent to Implantation of the First Electrode in Bilateral Implantation of Deep Brain Stimulation Electrodes

Stereotact Funct Neurosurg 2009;87:322-329 (DOI:10.1159/000235804)

After implantation of the first electrode in bilateral deep brain stimulation (DBS) lead implantation, brain shift effects in the target region and along the implantation trajectory of the second electrode are quantified with intraoperative magnetic resonance imaging (MRI). We investigated intraoperative X-ray imaging for its feasibility in indirect detection of brain shift.

Methods: In 25 patients who underwent bilateral DBS lead implantation, X-ray and MRI were performed before and after implantation of the first electrode. Two parameters of brain shift were assessed with nonrigid free-form deformation field analysis of the MRI data: global brain shift along the anterior and posterior commissure (AC-PC) line and specific brain shift along the implantation trajectory of the second electrode. Pre- and intraoperative X-ray images were geometrically and intensity corrected for detection of significant signal changes through intracranial air accumulation during implantation of the first electrode.

Results: After implantation of the first electrode, brain shift greater than 1 mm (maximum 1.3 mm) was observed at the AC and brain shift greater than 2 mm (maximum 2.5 mm) was observed along the planned implantation trajectory of the second electrode. In 1 patient, the implantation trajectory of the second electrode went through a sulcus after cortical brain shift. In 9 patients, intracranial air volume between 0.1 and 38.5 ml was observed with MRI after implantation of the first electrode. Significant X-ray absorption changes were induced by an intracranial air volume of greater than 8 ml.

Conclusion: In bilateral DBS implantation, brain shift effects can cause misallocation of the second electrode with the risk of adverse or no stimulation effects as well as unnecessary cortical damage. A lack of X-ray signal changes caused by intracranial air invasion during DBS lead implantation indicates a lack of clinically relevant brain shift.

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Tentorial meningiomas: operative nuances and perioperative management dilemmas

Acta Neurochir (2009) 151:1037–1051.DOI 10.1007/s00701-009-0421-3

Tentorial meningiomas (TM), comprising approximately 3–6% of all intracranial meningiomas, are complex entities with an intricate relationship to surrounding structures and require multiple surgical approaches. In the present study, the rationale for deciding the approaches for TMs and the perioperative management dilemmas were evaluated.
Methods  Thirty-seven patients (28 primary [supratentorial (2), infratentorial (20) and both (6)] and nine complex [cerebellopontine (CP) angle (5) and petroclival (4)] TM) underwent surgery using the occipital transtentorial, supracerebellar infratentorial, subtemporal transtentorial, bioccipital suboccipital, midline suboccipital, retrosigmoid, and combined pre and retrosigmoid approaches. The extent of excision was categorized according to Simpson’s grade.
Results  Simpson’s grade of excision was I in six, II in 11, III in nine and IV in 11 patients, respectively. Follow-up assessment (2 months to 9 years) in 27 patients (72.9%) showed that 23 patients returned to their previous activity level with either no or minimal symptoms, three returned to previous activity level with major cranial nerve palsy, and one patient required permanent assistance. One patient had recurrence and four others underwent resurgery for residual tumor. Two patients with petroclival lesions died due to aspiration pneumonitis and meningitis, respectively; one with CP angle TM presented in a poor general condition and expired following emergency ventriculoperitoneal shunt and subsequent definite surgery. Pseudomeningocele, cerebrospinal fluid leak, and cranial nerve palsy were the major morbidities.
Conclusions  Classifying TM into medial and lateral, supra and infratentorial groups helps in deciding an appropriate and safe approach. Meticulously preserving venous sinuses is important since the risk of venous infarction cannot be predicted even with radiological good venous collaterization and apparent venous sinus blockade by tumor. Laterally situated tumors carry a better prognosis when compared to the medially situated ones. Leaving a small residual tumor in an effort to preserve important neurovascular structures does not obviate the expectation of a good long-term prognosis with minimal morbidity and low recurrence rates.

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Experiences with a gravity-assisted valve in hydrocephalic children

J Neurosurg Pediatrics 4:020880–200930, 2009. (DOI: 10.3171/2009.4.PEDS08204)

Over the past decade, a gravity-assisted valve (GAV) has become a standard device in many European pediatric hydrocephalus centers. Because past comparative clinical outcome studies on valve design have not included any GAV, the authors in this trial evaluated the early results of GAV applications in a pediatric population.

Methods. For a minimum of 2 years the authors monitored 169 of 182 hydrocephalic children who received a pediatric GAV at their first CSF shunt insertion (61.5%) or as a substitute for any differential pressure valve (38.5%) at 1 of 7 European pediatric hydrocephalus centers. Outcomes were categorized as valve survival (primary outcome) or shunt survival (secondary outcome). The end point was defined as valve explantation.

Results. Within a follow-up period of 2 years, the valve remained functional in 130 (76.9%) of 169 patients. One hundred eight of these patients (63.9%) had an uncomplicated clinical course without any subsequent surgery, and 22 (13%) were submitted to a valve-preserving catheter revision without any further complications during the follow- up period. Thirty-nine patients (23.1%) reached an end point of valve explantation: 13 valve failures from infection (7.7%), 8 (4.7%) from overdrainage, and 18 (10.6%) from underdrainage.

Conclusions. Compared with nongravitational shunt designs, a GAV does not substantially affect the early complication rate. Valve-preserving shunt revisions do not increase the risk of subsequent valve failure and therefore should not be defined as an end point in studies on valve design. A significant impact of any well-established valve design on the early complication rate in shunt surgery is not supported by any current data; therefore, this correlation should be dismissed. As overdrainage-related complications have been shown to occur late, the presumed advantages of a pediatric GAV remain to be shown in a long-term study.

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