Neurosurgery Blog

J Neurosurg 118:884–888, 2013

The authors retrospectively analyzed data on brainstem gangliogliomas treated in their department and reviewed the pertinent literature to foster understanding of the preoperative characteristics, management, and clinical outcomes of this disease.

Methods. In 2006, the authors established a database of treated lesions of the posterior fossa. The epidemiology findings, clinical presentations, radiological investigations, pathological diagnoses, management, and prognosis for brainstem gangliogliomas were retrospectively analyzed.

Results. Between 2006 and 2012, 7 patients suffering from brainstem ganglioglioma were treated at the West China Hospital of Sichuan University. The mean age of the patients, mean duration of symptoms prior to diagnosis, and mean duration of follow-up were 28.6 years, 19.4 months, and 38.1 months, respectively. The main presentations were progressive cranial nerve deficits and cerebellar signs. Subtotal resection was achieved in 2 patients, and partial resection in 5. All tumors were pathologically diagnosed as WHO Grade I or II ganglioglioma. Radiotherapy and adjuvant chemotherapy were not administered. After 21–69 months of follow-up, patient symptoms were resolved or stable without aggravation, and MRI showed that the size of residual lesions was unchanged without progression or recurrence.

Conclusions. The diagnosis of brainstem ganglioglioma is of great importance given its favorable prognosis. The authors recommend the maximal safe resection followed by close observation without adjuvant therapy as the optimal treatment for this disease.

Neurosurgery 72:573–589, 2013

Cavernous malformations (CMs) in deep locations account for 9% to 35% of brain malformations and are surgically challenging.

OBJECTIVE: To study the clinical features and outcomes following surgery for deep CMs and the complication of hypertrophic olivary degeneration (HOD).

METHODS: Clinical records, radiological findings, operative details, and complications of 176 patients with deep CMs were reviewed retrospectively.

RESULTS: Of 176 patients with 179 CMs, 136 CMs were in the brainstem, 27 in the basal ganglia, and 16 in the thalamus. Cranial nerve deficits (51.1%), hemiparesis (40.9%), numbness (34.7%), and cerebellar symptoms (38.6%) presented most commonly. Hemorrhage presented in 172 patients (70 single, 102 multiple). The annual retrospective hemorrhage rate was 5.1% (assuming CMs are congenital with uniform hemorrhage risk throughout life); the rebleed rate was 31.5%/patient per year. Surgical approach depended on the proximity of the CM to the pial or ependymal surface. Postoperatively, 121 patients (68.8%) had no new neurological deficits. Follow-up occurred in 170 patients. Delayed postoperative HOD developed in 9/134 (6.7%) patients with brainstem CMs. HOD occurred predominantly following surgery for pontine CMs (9/10 patients). Three patients with HOD had palatal myoclonus, nystagmus, and oscillopsia, whereas 1 patient each had limb tremor and hemiballismus. At follow-up, 105 patients (61.8%) improved, 44 (25.9%) were unchanged, and 19 (11.2%) worsened neurologically. Good preoperative modified Rankin Score (98.2% vs 54.5%, P = .001) and single hemorrhage (89% vs 77.3%, P , .05) were predictive of good longterm outcome.

CONCLUSION: Symptomatic deep CMs can be resected with acceptable morbidity and outcomes. Good preoperative modified Rankin Score and single hemorrhage are predictors of good long-term outcome.

J Neurosurg 118:521–529, 2013

It has been over a decade since the introduction of the da Vinci Surgical System into surgery. Since then, technology has been advancing at an exponential rate, and newer surgical robots are becoming increasingly sophisticated, which could greatly impact the performance of surgery. NeuroArm is one such robotic system.

Methods. Clinical integration of neuroArm, an MR-compatible image-guided robot, into surgical procedure has been developed over a prospective series of 35 cases with varying pathology.

Results. Only 1 adverse event was encountered in the first 35 neuroArm cases, with no patient injury. The adverse event was uncontrolled motion of the left neuroArm manipulator, which was corrected through a rigorous safety review procedure. Surgeons used a graded approach to introducing neuroArm into surgery, with routine dissection of the tumor-brain interface occurring over the last 15 cases. The use of neuroArm for routine dissection shows that robotic technology can be successfully integrated into microsurgery. Karnofsky performance status scores were significantly improved postoperatively and at 12-week follow-up.

Conclusions. Surgical robots have the potential to improve surgical precision and accuracy through motion scaling and tremor filters, although human surgeons currently possess superior speed and dexterity. Additionally, neuroArm’s workstation has positive implications for technology management and surgical education. NeuroArm is a step toward a future in which a variety of machines are merged with medicine.

Neurosurgery 72:42–46, 2013

Jugular foramen schwannomas are uncommon and surgically challenging lesions.

OBJECTIVE: To determine the importance of surgical technique on morbidity and recurrence of jugular foramen schwannomas.

METHODS: A retrospective review and case-control analysis of a single-senior-surgeon series of 81 patients with surgically treated jugular foramen schwannomas was performed, focusing on operative technique. Patients undergoing an aggressive, total tumor resection (series 1) were compared with those undergoing more conservative resection focusing on preserving the pars nervosa (series 2).

RESULTS: There was a statistically significant (P = .04) decrease in permanent deficits of the cranial nerve 9/10 complex with a conservative technique. Recurrence was seen in 3 patients (5.7%) in series 1 and in 3 patients (10.7%) in series 2 (P = .36). Recurrence was treated with reoperation in 1 patient, radiation in 1 patient, and observation in the others.

CONCLUSION: Although radical gross total resection is desirable, it is not optimal for cranial nerve preservation in patients with jugular foramen schwannomas. A more conservative approach resulted in a statistically significant decrease in lower cranial nerve deficits. There was a nonstatistically significant trend toward increasing recurrence, which may be treated with multiple modality therapy in the modern era.

Acta Neurochir (2012) 154:1407–1412 

The authors assessed the usefulness of intraoperative near-infrared indocyanine green videoangiography (ICG-VA) in the microscopic resection of hemangioblastomas.

Methods From January 2009 to February 2012, nine consecutive patients (seven men, two women) who underwent surgery for hemangioblastomas using intraoperative ICGVA were included in this study. Surgery was performed on four cystic cerebellar lesions with mural nodules, two solid tumors (one in the cerebellar hemisphere and one in the medulla oblongata), one spinal tumor and multiple tumors in two patients with von Hippel-Lindau disease. Of the nine patients, three were treated for recurrent tumor. The ICGinduced fluorescence images of hemangioblastomas with variable presentation were evaluated.

Results All tumors could be completely removed en bloc. Blood flow in the tumor and tumor-related vessels at the brain surface were clearly detected by ICG-VA in all cases, except one recurrent tumor where postoperative adhesive scar tissue obstructed ICG-induced fluorescence resulting in poor delineation of the blood flow patterns and tumor margins. ICG-VAwas also helpful for detecting the multiple small mural nodules within the cyst or the tumors buried under thin gliotic neural tissue despite reduced fluorescence.

Conclusion Intraoperative ICG-VA is a safe and easy modality for confirming the vascular flow patterns in hemangioblastomas. In addition, ICG-VA provided useful information for intracystic small lesions or lesions concealed under thin brain tissue in order to accomplish total resection of these tumors.

J Neurosurg 117:295–301, 2012

Cavernomas in the occipital lobe are relatively rare. Because of the proximity to the visual cortex and incoming subcortical tracts, microsurgical removal of occipital cavernomas may be associated with a risk of visual field defects. The goal of the study was to analyze long-term outcome after operative treatment of occipital cavernomas with special emphasis on visual outcome.

Methods. Of the 390 consecutive patients with cavernomas who were treated at Helsinki University Central Hospital between 1980 and 2011, 19 (5%) had occipital cavernomas. Sixteen patients (4%) were surgically treated and are included in this study. The median age was 39 years (range 3–59 years). Seven patients (56%) suffered from hemorrhage preoperatively, 5 (31%) presented with visual field deficits, 11 (69%) suffered from seizures, and 4 (25%) had multiple cavernomas. Surgery was indicated for progressive neurological deterioration. The median follow-up after surgery was 5.25 years (range 0.5–14 years).

Results. All patients underwent thorough neuroophthalmological assessment to determine visual outcome after surgery. Visual fields were classified as normal, mild homonymous visual field loss (not disturbing the patient, driving allowed), moderate homonymous visual field loss (disturbing the patient, driving prohibited), and severe visual field loss (total homonymous hemianopia or total homonymous quadrantanopia). At the last follow-up, 4 patients (25%) had normal visual fields, 6 (38%) had a mild visual field deficit, 1 (6%) complained of moderate visual field impairment, and 5 (31%) had severe homonymous visual field loss. Cavernomas seated deeper than 2 cm from the pial surface carried a 4.4-fold risk of postoperative visual field deficit relative to superficial ones (p = 0.034). Six (55%) of the 11 patients presenting with seizures were seizure-free postoperatively. Eleven (69%) of 16 patients had no disability during the long-term follow-up.

Conclusions. Surgical removal of occipital cavernomas may carry a significant risk of postoperative visual field deficit, and the risk is even higher for deeper lesions. Seizure outcome after removal of these cavernomas appeared to be worse than that after removal in other supratentorial locations. This should be taken into account during preoperative planning.

Neurosurg Focus 32 (5):E7, 2012. (http://thejns.org/doi/abs/10.3171/2012.1.FOCUS127)

Microsurgical resection of arteriovenous malformations (AVMs) is facilitated by real-time image guidance that demonstrates the precise size and location of the AVM nidus. Magnetic resonance images have routinely been used for intraoperative navigation, but there is no single MRI sequence that can provide all the details needed for characterization of the AVM. Additional information detailing the specific location of the feeding arteries and draining veins would be valuable during surgery, and this detail may be provided by fusing MR images and MR angiography (MRA) sequences.

The current study describes the use of a technique that fuses contrast-enhanced MR images and 3D time-of-flight MR angiograms for intraoperative navigation in AVM resection.

Methods. All patients undergoing microsurgical resection of AVMs at the Dartmouth Cerebrovascular Surgery Program were evaluated from the surgical database. Between 2009 and 2011, 15 patients underwent surgery in which this contrast-enhanced MRI and MRA fusion technique was used, and these patient form the population of the present study.

Results. Image fusion was successful in all 15 cases. The additional data manipulation required to fuse the image sets was performed on the morning of surgery with minimal added setup time. The navigation system accurately identified feeding arteries and draining veins during resection in all cases. There was minimal imaging-related artifact produced by embolic materials in AVMs that had been preoperatively embolized. Complete AVM obliteration was demonstrated on intraoperative angiography in all cases.

Conclusions. Precise anatomical localization, as well as the ability to differentiate between arteries and veins during AVM microsurgery, is feasible with the aforementioned MRI/MRA fusion technique. The technique provides important information that is beneficial to preoperative planning, intraoperative navigation, and successful AVM resection.

Neurosurg Focus 32 (5):E7, 2012. http://thejns.org/doi/abs/10.3171/2012.1.FOCUS127

Microsurgical resection of arteriovenous malformations (AVMs) is facilitated by real-time image guidance that demonstrates the precise size and location of the AVM nidus. Magnetic resonance images have routinely been used for intraoperative navigation, but there is no single MRI sequence that can provide all the details needed for characterization of the AVM. Additional information detailing the specific location of the feeding arteries and draining veins would be valuable during surgery, and this detail may be provided by fusing MR images and MR angiography (MRA) sequences. The current study describes the use of a technique that fuses contrast-enhanced MR images and 3D time-of-flight MR angiograms for intraoperative navigation in AVM resection.

Methods. All patients undergoing microsurgical resection of AVMs at the Dartmouth Cerebrovascular Surgery Program were evaluated from the surgical database. Between 2009 and 2011, 15 patients underwent surgery in which this contrast-enhanced MRI and MRA fusion technique was used, and these patient form the population of the present study.

Results. Image fusion was successful in all 15 cases. The additional data manipulation required to fuse the image sets was performed on the morning of surgery with minimal added setup time. The navigation system accurately identified feeding arteries and draining veins during resection in all cases. There was minimal imaging-related artifact produced by embolic materials in AVMs that had been preoperatively embolized. Complete AVM obliteration was demonstrated on intraoperative angiography in all cases.

Conclusions. Precise anatomical localization, as well as the ability to differentiate between arteries and veins during AVM microsurgery, is feasible with the aforementioned MRI/MRA fusion technique. The technique provides important information that is beneficial to preoperative planning, intraoperative navigation, and successful AVM resection.

J Neurosurg Spine 16:308–314, 2012. DOI: 10.3171/2011.11.SPINE11536

Intramedullary spinal cord cavernous malformations (CMs), once thought to be extremely rare, have been diagnosed more frequently since the advent of MR imaging. In the literature, however, only a few studies include more than 10 cases. The aim of this study was to discuss the clinical presentation of intramedullary spinal cord CMs and the outcome of microsurgery for these histologically benign but clinically progressive lesions.

Methods. The authors retrospectively reviewed the records of 20 patients who underwent microsurgery for intramedullary spinal cord CMs. All patients had undergone pre- and postoperative MR imaging, and they were all treated using microsurgical resection. The diagnosis of spinal cord CMs was based on pathological criteria. The pre- and postoperative neurological states of the patients were classified according to the McCormick scale and Frankel scale. The microsurgical outcomes are presented and discussed.

Results. In most cases, CMs can be diagnosed on the basis of MR imaging findings, since these lesions have certain characteristic imaging patterns. Patients with intramedullary spinal cord CMs may present with either a rapid, acute onset of symptoms or slow, progressive neurological decline. The CMs in 19 of 20 patients in this series were totally resected, and most patients neurologically improved postoperatively. As previously reported, the authors confirm that the treatment of choice for symptomatic intramedullary CMs is total removal of the lesion to avoid recurrence and the possibility of further hemorrhage.

Conclusions. This study has defined the clinical features of symptomatic intramedullary spinal cord CMs. Surgery is the mainstay treatment. Surgical outcome is associated with low mortality with a high probability of functional recovery, especially when symptoms are not severe and are of relatively recent onset.

Neurosurgery 70[ONS Suppl 1]:ons132–ons144, 2012 DOI: 10.1227/NEU.0b013e31822efb21

Trigeminal schwannomas make up 0.8% to 8% of all intracranial schwannomas.

OBJECTIVE: To analyze our surgical experience with trigeminal schwannomas.

METHODS: We performed 107 operations on 105 patients harboring trigeminal schwannomas over the past 30 years. We classified the tumors as peripheral, ganglion cavernous, posterior fossa root, and dumbbell types according to the portion of the nerve that gave rise to the tumor.

RESULTS: Fourteen were peripheral-type tumors (13.1%), 39 (36.4%) were ganglion cavernous type, 22 (20.6%) were posterior fossa root type, and 32 (30.0%) were dumbbell type. Sixty-five tumors were solid, 35 were mixed, and only 7 were cystic. Among solid tumors, 14 were vascular, fibrous, and adherent to adjacent structures. Total or near-total removal was performed in 86 cases (81.9%), and subtotal removal was achieved in 18 (17.1%). The most common symptom was facial hypesthesia, occurring in 69 patients. This symptom improved in 11 patients, persisted in 50 patients, and worsened in 8 patients after surgery. New postoperative hypesthesia was observed in 8 patients. The second most common symptom was facial pain, observed in 24 patients. Facial pain subsided in 22 and persisted in 2 patients after surgery. Diplopia was observed in 21 patients. This symptom improved postoperatively in 14 patients, persisted in 6 patients, and worsened in 1 patient.

CONCLUSION: The present series demonstrates acceptable results using microsurgical treatment to remove trigeminal schwannomas. Pain and diplopia may be relieved after surgery; however, hypesthesia frequently remains or may be worsened by surgery.

Neurosurgery 69:1261–1271, 2011 DOI: 10.1227/NEU.0b013e31822bb8a6

Many significant microsurgical series of patients with giant aneurysms predate changes in practice during the endovascular era.

OBJECTIVE: A contemporary surgical experience is presented to examine changes in management relative to earlier reports, to establish the role of open microsurgery in the management strategy, and to quantify results for comparison with evolving endovascular therapies.

METHODS: During a 13-year period, 140 patients with 141 giant aneurysms were treated surgically. One hundred aneurysms (71%) were located in the anterior circulation, and 41 aneurysms were located in the posterior circulation.

RESULTS: One hundred eight aneurysms (77%) were completely occluded, 14 aneurysms (10%) had minimal residual aneurysm, and 16 aneurysms (11%) were incompletely occluded with reversed or diminished flow. Three patients with calcified aneurysms were coiled after unsuccessful clipping attempts. Eighteen patients died in the perioperative period (surgical mortality, 13%). Bypass-related complications resulted from bypass occlusion (7 patients), aneurysm hemorrhage due to incomplete aneurysm occlusion (4 patients), or aneurysm thrombosis with perforator or branch artery occlusion (4 patients). Thirteen patients were worse at late follow-up (permanent neurological morbidity, 9%; mean length of follow-up, 23 6 1.9 months). Overall, good outcomes (Glasgow Outcome Score 5 or 4) were observed in 114 patients (81%), and 109 patients (78%) were improved or unchanged after therapy.

CONCLUSION: A heavy reliance on bypass techniques plus indirect giant aneurysm occlusion distinguishes this contemporary surgical experience from earlier ones, and obviates the need for hypothermic circulatory arrest. Experienced neurosurgeons can achieve excellent results with surgery as the ‘‘first-line’’ management approach and endovascular techniques as adjuncts to surgery.

J Neurosurg 115:875–884, 2011. DOI: 10.3171/2011.6.JNS101958

In large vestibular schwannoma (VS), microsurgery is the main treatment option, and complete resection is considered the primary goal. However, previous studies have documented suboptimal facial nerve outcomes in patients who undergo complete resection of large VSs. Subtotal resection is likely to reduce the risk of facial nerve injury but increases the risk of lesion regrowth. Gamma Knife surgery (GKS) can be performed to achieve long-term growth control of residual VS after incomplete resection. In this study the authors report on the results in patients treated using planned subtotal resection followed by GKS with special attention to volumetric growth, control rate, and symptoms.

Methods. Fifty consecutive patients who underwent the combined treatment strategy of subtotal microsurgical removal and GKS for large VSs between 2002 and 2009 were retrospectively analyzed. Patients with neurofibromatosis Type 2 were excluded. Patient charts were reviewed for clinical symptoms. Audiograms were evaluated to classify hearing pre- and postoperatively. Preoperative and follow-up contrast-enhanced T1-weighted MR images were analyzed using volume-measuring software.

Results. Surgery was performed via a translabyrinthine (25 patients) or retrosigmoid (25 patients) approach. The median follow-up was 33.8 months. Clinical control was achieved in 92% of the cases and radiological control in 90%. One year after radiosurgery, facial nerve function was good (House-Brackmann Grade I or II) in 94% of the patients. One of the two patients who underwent surgery to preserve hearing maintained serviceable hearing after resection followed by GKS.

Conclusions. Considering the good tumor growth control and facial nerve function preservation as well as the possibility of preserving serviceable hearing and the low number of complications, subtotal resection followed by GKS can be the treatment option of choice for large VSs.

J Neurosurg 114:984–993, 2011. DOI: 10.3171/2010.12.JNS101297

Parafalcine arteriovenous malformations (AVMs) have a midline plane in common, but differ in their location (anterior, middle, or posterior) and depth (superficial or deep). Surgical management varies with AVM location and depth in terms of patient position, head position, craniotomy, and surgical approach. This study examined surgical strategies, patient outcomes, and regional factors influencing results.

Methods. Patients with AVMs located on the medial surface of the cerebral hemisphere were identified retrospectively from a consecutive, single-neurosurgeon series that is registered prospectively as part of the UCSF Brain Arteriovenous Malformation Study Project. During a 12-year period, 443 patients with AVMs were treated surgically. Of these 443 patients, 132 (30%) had parafalcine AVMs, which were distributed in zones as follows: superficialanterior, 25 (18.9%); superficial-middle, 26 (19.7%); superficial-posterior, 39 (29.5%); deep-anterior, 25 (18.9%); deep-posterior, 17 (12.9%). Five different surgical strategies were used depending on AVM zone.

Results. Complete AVM resection was achieved in 123 (93.2%) of 132 patients. Overall, neurological condition improved in 74 patients (56.1%) and remained unchanged in 41 patients (31.1%). Neurological condition deteriorated in 12 patients (9.1%), and 5 patients (3.8%) died. Patients with AVMs in the superficial-middle zone had the highest rate of neurological deterioration (26.9%).

Conclusions. Parafalcine AVMs lie on a midline surface that, when exposed with a bilateral craniotomy across the superior sagittal sinus and a wide opening of the interhemispheric fissure, makes them superficial. However, unlike convexity AVMs, which are approached perpendicularly, parafalcine AVMs are approached tangentially. Gravity retraction is useful with deeply located AVMs (those in the deep-anterior and deep-posterior zones), because it widens the interhemispheric fissure and accesses deep arterial feeding vessels from the anterior and posterior cerebral arteries. Surgical risks were increased in the superficial-middle zone, which is likely explained by the proximity of sensorimotor cortex. The authors’ regional classification of parafalcine AVMs may serve as a guide to surgical planning.

Neurosurg Focus 30 (2):E2, 2011.(DOI: 10.3171/2010.11.FOCUS10250)

Hypothalamic hamartomas (HHs) are devastating lesions causing refractory epilepsy, rage attacks, social ineptitude, and precocious puberty. Microsurgical and/or endoscopic resection offers an excellent risk/benefit profile for cure or improvement of epilepsy.

Methods. The authors reviewed a prospective database maintained during the first 7 years of the Barrow Hypothalamic Hamartoma program. They describe and illustrate their surgical methods, and they review data from several previous publications regarding surgical outcome.

Results. To date, the authors have performed surgery in 165 patients for symptomatic HHs. Patients underwent an endoscopic, transcallosal, or skull base approach, or multiple approaches. Twenty-six patients (15.8%) required more than 1 treatment for their HH.

Conclusions. Microsurgical and endoscopic resection of symptomatic HHs are technically demanding but can be performed safely with excellent results and an acceptable risk profile. Meticulous attention to the subtleties of surgical management helps optimize outcomes.

Acta Neurochir (2011) 153:261–270. DOI 10.1007/s00701-010-0812-5

Cavernomas of the temporal lobe occur in 10– 20% of patients with cerebral cavernomas. They frequently cause epileptic seizures, some of which tend to become refractory to medical therapy. Surgical removal of safely achievable symptomatic lesions has been frequently consistent with good long-term outcome. In the present study, a postoperative outcome is assessed.

Methods Of our 360 consecutive patients with cerebral cavernomas, 53 (15%) had a single cavernoma in the temporal lobe. Forty-nine patients were treated surgically and were included in the study. All data were analyzed retrospectively. The cavernomas were allocated into three groups based on the temporal lobe site: medial, anterolateral, and posterolateral. To collect follow-up data, all available patients were interviewed by phone. Seizure outcome was assessed using the Engel classification and general outcome using the Glasgow Outcome Scale (GOS).

Results Patients’ median age at presentation was 37 (range, 7–64) years, with a female/male ratio of 2.5:1. Epileptic seizures occurred in 40 patients (82%). Median duration of seizures preoperatively was 3 (range, 0.1–23) years. In addition, four patients (10%) had memory disorder. Three patients without history of seizures (6%) complained of headache and two (4%) had memory problems. Three patients (6%) had an incidental cavernoma. Hemorrhage occurred in nine patients (18%) preoperatively. Median postoperative follow-up time was 6 (range, 0.2–26) years. Favorable seizure outcome (Engel class I and II) was registered in 35 patients (90%). Ten patients (25%) who had only a single seizure before surgery were seizure free during postoperative follow-up. Good general outcome (GOS, 4.5) was detected in 46 patients (96%). Two patients (4%) developed a new mild memory deficit after surgery, and in two patients existing memory deficits worsened.

Conclusions Microsurgical removal of temporal lobe cavernomas is a safe and effective method to improve seizure outcome in patients with medically intractable epilepsy and to prevent deterioration caused by hemorrhage.

Neurosurgery 67:1646–1654, 2010 DOI: 10.1227/NEU.0b013e3181f8d3d3

There are few published prospective data sets specifically focusing on patients younger than 40 years old undergoing microsurgery for vestibular schwannoma.

OBJECTIVE: We describe functional outcomes and long-term tumor control after surgery in patients younger than 40 years old enrolled in a prospectively collected database over a 25-year period.

METHODS: We selected all vestibular schwannoma patients from a prospectively collected database who were younger than 40 years old at the time of surgical resection for a vestibular schwannoma. Rates of tumor control and hearing preservation were analyzed using Kaplan-Meier analysis, and risk factors for facial nerve palsy, hearing loss, and trigeminal neuropathy were analyzed using multivariate logistic regression.

RESULTS: A total of 204 patients younger than 40 years of age met our inclusion criteria and were included in the analysis. Our data indicate that surgical resection leads to durable long-term freedom from tumor recurrence or progression in 89% of young patients at 15 years of follow-up. Consistent with other published series, hearing was preserved in 68% of patients with smaller tumors (,3 cm). Facial nerve function was preserved in 76% of patients with smaller tumors and 52% of patients with larger tumors (P , .001). On multivariate logistic regression, tumor size was a significant predictor of hearing loss, whereas gross total resection was nearly a significant predictor of hearing loss controlling for other variables (P = .06).

CONCLUSION: We present the largest prospectively studied cohort of young patients undergoing microsurgical resection of vestibular schwannoma. These data suggest that surgical resection provides excellent long-term tumor control in these patients

J Neurosurg 113:1106–1111, 2010. DOI: 10.3171/2010.3.JNS09513

Resident duty-hours restrictions have now been instituted in many countries worldwide. Shortened training times and increased public scrutiny of surgical competency have led to a move away from the traditional apprenticeship model of training. The development of educational models for brain anatomy is a fascinating innovation allowing neurosurgeons to train without the need to practice on real patients and it may be a solution to achieve competency within a shortened training period. The authors describe the use of Stratathane resin ST-504 polymer (SRSP), which is inserted at different intracranial locations to closely mimic meningiomas and other pathological entities of the skull base, in a cadaveric model, for use in neurosurgical training.

Methods. Silicone-injected and pressurized cadaveric heads were used for studying the SRSP model. The SRSP presents unique intrinsic metamorphic characteristics: liquid at first, it expands and foams when injected into the desired area of the brain, forming a solid tumorlike structure. The authors injected SRSP via different passages that did not influence routes used for the surgical approach for resection of the simulated lesion. For example, SRSP injection routes included endonasal transsphenoidal or transoral approaches if lesions were to be removed through standard skull base approach, or, alternatively, SRSP was injected via a cranial approach if the removal was planned to be via the transsphenoidal or transoral route. The model was set in place in 3 countries (US, Italy, and The Netherlands), and a pool of 13 physicians from 4 different institutions (all surgeons and surgeons in training) participated in evaluating it and provided feedback.

Results. All 13 evaluating physicians had overall positive impressions of the model. The overall score on 9 components evaluated—including comparison between the tumor model and real tumor cases, perioperative requirements, general impression, and applicability—was 88% (100% being the best possible achievable score where the evaluator strongly agreed with the proposed factor). Individual components had scores at or above 80% (except for 1). The only score that was below 80% was related to radiographic visibility of the model for adequate surgical planning (score of 74%). The highest score was given to usefulness in neurosurgical training (98%).

Conclusions. The skull base tumor model is an effective tool to provide more practice in preoperative planning and technical skills.

Neurosurgery 66:702-713, 2010. DOI: 10.1227/01.NEU.0000367555.16733.E1

Patient age, hemorrhagic presentation, nidal diffuseness, and deep perforating artery supply are important factors when selecting patients with brain arteriovenous malformations (AVMs) for surgery.

OBJECTIVE: We hypothesized that these factors outside of the Spetzler-Martin grading system could be combined into a simple, supplementary grading system that would accurately predict neurologic outcome and refine patient selection.

METHODS: A consecutive, single-surgeon series of 300 patients with AVMs treated microsurgically was analyzed in terms of change between preoperative and final postoperative modified Rankin Scale scores. Three different multivariable logistic models (full, Spetzler- Martin, and supplementary models) were constructed to test the association of combined predictor variables with the change in modified Rankin Scale score. A simplified supplementary grading system was developed from the data with points assigned according to each variable and added together for a supplementary AVM grade.

RESULTS: Predictive accuracy was highest for the full multivariable model (receiver operating characteristic curve area, 0.78), followed by the supplementary model (0.73), and least for the Spetzler-Martin model (0.66). Predictive accuracy of the simplified supplementary grade was significantly better than that of the Spetzler-Martin grade (P = .042), with receiver operating characteristic curve areas of 0.73 and 0.65, respectively.

CONCLUSION: This new AVM grading system supplements rather than replaces the wellestablished Spetzler-Martin grading system and is a better predictor of neurologic outcomes after AVM surgery. The supplementary grading scale has high predictive accuracy on its own and stratifies surgical risk more evenly. The supplementary grading system is easily applicable at the bedside, where it is intended to improve preoperative risk prediction and patient selection for surgery.

Neurosurgery 64:654–663, 2009 DOI: 10.1227/01.NEU.0000340684.60443.55

OBJECTIVE: To conduct a prospective, open, nonrandomized study of treatment- associated morbidity in patients undergoing microsurgery or gamma knife radiosurgery (GKRS) for vestibular schwannomas.

METHODS: Ninety- one patients with vestibular schwannomas with a maximum tumor diameter of 25 mm in the cerebellopontine angle were treated according to a prospective protocol either by GKRS (63 patients) or open microsurgery (28 patients) using the suboccipital approach. Primary end points included hearing function, according to the Gardner- Robertson scale, and facial nerve function, according to the House- Brackmann scale at 2 years. Clinical data included a balance platform test, score for tinnitus and vertigo using a visual analog scale, and working ability. Patients responded to the qualityof- life questionnaires Short- Form 36 and Glasgow Benefit Inventory.

RESULTS: Three elderly GKRS patients withdrew; all remaining patients were followed for 2 years. Both primary end points were highly significant in favor of GKRS (P<0.001). Evidence of reduced facial nerve function (House- Brackmann grade 2 or poorer) at 2 years was found in 13 of 28 open microsurgery patients and 1 of 60 GKRS patients. Thirteen of 28 patients who underwent surgery had serviceable hearing (Gardner- Robertson grade A or B) preoperatively, but none had serviceable hearing postoperatively. Twentyfive of 60 GKRS patients had serviceable hearing before treatment, and 17 (68%) of them had serviceable hearing 2 years after treatment. The tinnitus and vertigo visual analog scale score, as well as balance platform tests, did not change significantly after treatment, and working status did not differ between the groups at 2 years. Quality of life was significantly better in the GKRS group at 2 years, based on the Glasgow Benefit Inventory questionnaire. One GKRS patient required operative treatment within the 2-year study period.

CONCLUSION: This is the second prospective study to demonstrate better facial nerve and hearing outcomes from GKRS than from open surgery for small- and medium- sized vestibular schwannomas.

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.