Richard W. Williamson

Stereotactic radiosurgery for vestibular schwannomas in patients with neurofibromatosis type 2: an analysis of tumor control, complications, and hearing preservation rates.

OBJECTIVEVestibular schwannomas present significant management challenges in patients with neurofibromatosis Type 2 (NF2). We evaluated the results of gamma knife radiosurgery for the management of these tumors, focusing on tumor response, hearing preservation, and other factors affecting outcomes. METHODSStereotactic radiosurgery was performed to manage 74 schwannomas in 62 patients. Ipsilateral serviceable hearing was present in 35% of tumors before the procedure. The mean tumor volume was 5.7 cm3. The mean margin and maximum dose used were 14 and 27.5 Gy, respectively. Cox regression analyses were performed to identify factors affecting outcomes. RESULTSThe median follow-up period was 53 months, and two patients were lost to follow-up. Actuarial local control rates at were 85, 81, and 81% at 5, 10, and 15 years, respectively. Tumor volume was significant as a predictor of local control. Since 1992, using current radiosurgery techniques (magnetic resonance imaging scan targeting and reduced margin dose to 14 Gy or less), the actuarial serviceable hearing preservation rate is 73% at 1 year, 59% at 2 years, and 48% at 5 years after radiosurgery. Facial neuropathy occurred in 8% of tumors, trigeminal neuropathy occurred in 4%, and vestibular dysfunction occurred in 4%. Radiation dose and tumor volume were predictive of development of new deficits. No radiosurgery-associated secondary tumors or atypical or malignant changes were noted. CONCLUSIONStereotactic radiosurgery is a safe and effective management modality for neurofibromatosis Type 2 vestibular schwannomas. Although results do not seem to be as good as for patients with sporadic unilateral tumors, gamma knife radiosurgery results seem favorable and indicate that radiosurgery should be strongly considered for primary tumor management in selected patients.

Adverse Radiation Effects after Radiosurgery May Benefit from Oral Vitamin E and Pentoxifylline Therapy: A Pilot Study

Background: Although uncommon, adverse radiation effects (ARE) are a potentially serious side effect of brain stereotactic radiosurgery (SRS). Corticosteroids are used to treat suspected ARE but side effects may be significant after long-term usage. Oral pentoxifylline (Ptx) and vitamin E therapy (VitE) are reported to benefit ARE seen in other organ systems. We treated 11 patients with suspected ARE after SRS with Ptx and VitE. Methods: To assess the response, edema was measured using fluid-attenuated inversion recovery magnetic resonance imaging (MRI). Edema volumes were calculated by first determining the three maximum measurements in the X, Y, and Z planes of the image with the largest signal change. Volume was plotted over time for each patient that had serial MRI scans available. Two patients had 2 separate radiosurgeries and 2 patients underwent 3. Three patients received adjuvant whole-brain radiation therapy. Results: The time until clinical detection of ARE after SRS varied from 3 to 18 months (median, 8 months). The change in edema volume varied from 59.6 ml in 1 patient (worse edema) to –324.2 ml (improvement). The average change in edema from pre- to post-treatment was –72.3 ml. One patient had more edema despite treatment; this patient was found to have tumor recurrence, and not an ARE. Two patients discontinued Ptx because of persistent nausea and abdominal discomfort. Conclusions: Ptx and VitE may be of benefit in the management of adverse radiation effects and should be studied further.

The relationship between ruptured aneurysm location, subarachnoid hemorrhage clot thickness, and incidence of radiographic or symptomatic vasospasm in patients enrolled in a prospective randomized controlled trial

OBJECT Cerebral vasospasm following subarachnoid hemorrhage (SAH) causes significant morbidity in a delayed fashion. The authors recently published a new scale that grades the maximum thickness of SAH on axial CT and is predictive of vasospasm incidence. In this study, the authors further investigate whether different aneurysm locations result in different SAH clot burdens and whether any concurrent differences in ruptured aneurysm location and maximum SAH clot burden affect vasospasm incidence. METHODS Two hundred fifty patients who were part of a prospective randomized controlled trial were reviewed. Most outcome and demographic variables were included as part of the prospective randomized controlled trial. Additional variables were also collected at a later time, including vasospasm data and maximum clot thickness. RESULTS Aneurysms were categorized into 1 of 6 groups: intradural internal carotid artery aneurysms, vertebral artery (VA) aneurysms (including the posterior inferior cerebellar artery), basilar trunk or basilar apex aneurysms, middle cerebral artery aneurysms, pericallosal aneurysms, and anterior communicating artery aneurysms. Twenty-nine patients with nonaneurysmal SAH were excluded. Patients with pericallosal aneurysms had the least average maximum clot burden (5.3 mm), compared with 6.4 mm for the group overall, but had the highest rate of symptomatic vasospasm (56% vs 22% overall, OR 4.9, RR 2.7, p = 0.026). Symptomatic vasospasm occurrence was tallied in patients with clinical deterioration attributable to delayed cerebral ischemia. There were no significant differences in maximum clot thickness between aneurysm sites. Middle cerebral artery aneurysms resulted in the thickest mean maximum clot (7.1 mm) but rates of symptomatic and radiographic vasospasm in this group were statistically no different compared with the overall group. Vertebral artery aneurysms had the worst 1-year modified Rankin scale (mRS) scores (3.0 vs 1.9 overall, respectively; p = 0.0249). A 1-year mRS score of 0-2 (good outcome) was found in 72% of patients overall, but in only 50% of those with pericallosal and VA aneurysms, and in 56% of those with basilar artery aneurysms (p = 0.0044). Patients with stroke from vasospasm had higher mean clot thickness (9.71 vs 6.15 mm, p = 0.004). CONCLUSIONS The location of a ruptured aneurysm minimally affects the maximum thickness of the SAH clot but is predictive of symptomatic vasospasm or clinical deterioration from delayed cerebral ischemia in pericallosal aneurysms. The worst 1-year mRS outcomes in this cohort of patients were noted in those with posterior circulation aneurysms or pericallosal artery aneurysms. Patients experiencing stroke had higher mean clot burden.

Technical considerations in the endovascular management of aneurysms of the posterior inferior cerebellar artery.

BACKGROUND: Aneurysms of the posterior inferior cerebellar artery (PICA) are rare, comprising 0.5% to 3% of intracranial aneurysms. Because their anatomic location relative to the PICA origin is variable, several endovascular techniques are used in their management. OBJECTIVE: To evaluate and discuss endovascular techniques for the treatment of PICA aneurysms. METHODS: We analyzed our prospectively maintained database to identify PICA aneurysms treated over a 12-year period from 1999 to 2011. RESULTS: Twenty patients were assessed angiographically for endovascular treatment. Treatment was successfully performed in 17, but 3 were deemed unsuitable and were referred for surgery. Patients ranged in age from 15 to 82 years (mean, 60.5); 85% (17/20) were women. Thirteen (65%) presented with subarachnoid hemorrhage, and 3 (15%) had been previously treated surgically. Although the aneurysms were located at the PICA origin in 13 (65%), their involvement with the PICA and vertebral artery was variable. Some arose distinctly from the origin, and others incorporated the PICA itself. Five patients were treated for distal PICA aneurysms. Treatment techniques included direct coiling, vertebral artery balloon remodeling with coiling, PICA balloon remodeling with coiling, and parent vessel sacrifice of PICA with either coiling or glue embolization. Complete occlusion was initially achieved in 11 of 17 patients. Of the 6 remaining patients, 3 improved to complete occlusion at follow-up, 2 underwent re-treatment, and 1 remained stable. No patient experienced posttreatment hemorrhage. CONCLUSION: A variety of endovascular techniques are required for the management of PICA aneurysms. Specific techniques vary according to the location of the aneurysm in relation to the PICA origin, distal course of the artery, and the vertebral artery. ABBREVIATIONS: BRAT, Barrow Ruptured Aneurysm Trial mRS, modified Rankin score nBCA, n-butyl cyanoacrylate PICA, posterior inferior cerebellar artery SAH, subarachnoid hemorrhage VA, vertebral artery

Malignant Transformation of a Vestibular Schwannoma After Gamma Knife Radiosurgery

OBJECTIVE To report a single case of malignant transformation of a vestibular schwannoma after radiosurgery and review the growing body of literature describing patients with malignant transformation of primary benign tumors after radiosurgery, including vestibular schwannoma. METHODS A 46-year-old woman presented with right facial paresthesias and imaging consistent with a right-sided vestibular schwannoma (volume approximately 18.5 cm(3)). RESULTS The patient underwent subtotal resection followed by Gamma Knife radiosurgery (GKRS) 6 months after surgery. Initial histology showed a benign vestibular schwannoma with an MIB-1 labeling index of 5.7%. At 43 months after GKRS, the patient underwent repeat subtotal resection of a benign vestibular schwannoma (MIB-1 labeling index 7.4%). At 59 months after GKRS, she underwent a third resection, and histology showed frank malignant transformation (MIB-1 labeling index 33.8%). CONCLUSIONS Malignant vestibular nerve tumors are extremely rare; only 18 cases have been reported in the literature. Our patient is the sixth pathologically confirmed case of malignant transformation after radiosurgery, supporting the contention that radiosurgery itself may play a causative role in transformation. In a histologically benign lesion, the presence of an elevated MIB-1 labeling index may predispose toward malignant transformation in the setting of adjuvant radiosurgery.

Clinical characteristics and long-term outcomes in patients with ruptured posterior inferior cerebellar artery aneurysms: a comparative analysis

OBJECT Subarachnoid hemorrhage (SAH) from ruptured posterior inferior cerebellar artery (PICA) aneurysms is uncommon, and long-term outcome data for patients who have suffered such hemorrhages is lacking. This study investigated in-hospital and long-term clinical data from a prospective cohort of patients with SAH from ruptured PICA aneurysms enrolled in a randomized trial; their outcomes were compared with those of SAH patients who were treated for other types of ruptured intracranial aneurysms. The authors hypothesize that PICA patients fare worse than those with aneurysms in other locations and this difference is related to the high rate of lower cranial nerve dysfunction in PICA patients. METHODS The authors analyzed data for 472 patients enrolled in the Barrow Ruptured Aneurysm Trial (BRAT) and retrospectively reviewed vasospasm data not collected prospectively. In the initial cohort, 57 patients were considered angiographically negative for aneurysmal SAH source and did not receive treatment for aneurysms, leaving 415 patients with aneurysmal SAH. RESULTS Of 415 patients with aneurysmal SAH, 22 (5.3%) harbored a ruptured PICA aneurysm. Eight of them had dissecting/fusiform-type aneurysms while 14 had saccular-type aneurysms. Nineteen PICA patients were treated with clipping (1 crossover from coiling), 2 were treated with coiling, and 1 died before treatment. When comparing PICA patients to all other aneurysm patients in the study cohort, there were no statistically significant differences in age (mean 57.6 ± 11.8 vs 53.9 ± 11.8 years, p = 0.17), Hunt and Hess grade median III [IQR II-IV] vs III [IQR II-III], p = 0.15), Fisher grade median 3 [IQR 3-3] vs 3 [IQR 3-3], p = 0.53), aneurysm size (mean 6.2 ± 3.0 vs 6.7 ± 4.0 mm, p = 0.55), radiographic vasospasm (53% vs 50%, p = 0.88), or clinical vasospasm (12% vs 23%, p = 0.38). PICA patients were more likely to have a fusiform aneurysm (36% vs 12%, p = 0.004) and had a higher incidence of lower cranial nerve dysfunction and higher rate of tracheostomy/percutaneous endoscopic gastrostomy placement compared with non-PICA patients (50% vs 16%, p < 0.001). PICA patients had a significantly higher incidence of poor outcome at discharge (91% vs 67%, p = 0.017), 1-year follow-up (63% vs 29%, p = 0.002), and 3-year follow-up (63% vs 32%, p = 0.006). CONCLUSIONS Patients with ruptured PICA aneurysms had a similar rate of radiographic vasospasm, equivalent admission Fisher grade and Hunt and Hess scores, but poorer clinical outcomes at discharge and at 1- and 3-year follow-up when compared with the rest of the BRAT SAH patients with ruptured aneurysms. The PICAs location at the medulla and the resultant high rate of lower cranial nerve dysfunction may play a role in the poor outcome for these patients. Furthermore, PICA aneurysms were more likely to be fusiform than saccular, compared with non-PICA aneurysms; the complex nature of these aneurysms may also contribute to their poorer outcome.

Comparative Analysis of Surgical Freedom and Angle of Attack of Two Minimal-Access Endoscopic Transmaxillary Approaches to the Anterolateral Skull Base

OBJECTIVE Surgical freedom and the angle of attack influence approach selection for open cranial base approaches, but these concepts have not been well studied in minimal-access endoscopic approaches. We therefore developed a methodology to study surgical freedom and angle of attack in two endoscopic transmaxillary transpterygoid approaches, the endonasal ipsilateral uninostril medial maxillotomy and the sublabial Caldwell-Luc anterior maxillotomy. METHODS Dissections were performed bilaterally in three formalin-fixed cadaver heads (six sides). For each approach, three progressively lateral and posterior anatomic targets were identified. Utilizing frameless stereotaxy, surgical freedom using the vector cross-product method was calculated for both approaches for each target. The mean and maximum possible angles of attack were calculated in the axial and sagittal planes. RESULTS Compared to the endoscopic endonasal-transmaxillary approach, the endoscopic Caldwell-Luc approach offered significantly greater surgical freedom to the genu of the internal carotid artery (P=0.02), foramen rotundum (P=0.03), and foramen ovale (P=0.03). Mean and maximum possible angles of attack were also significantly different between the two approaches for each target. The Caldwell-Luc approach offered a more bottom-up approach in the sagittal plane and a more head-on approach in the axial plane to each target (P<0.05). CONCLUSIONS We have successfully developed a model for comparing endoscopic skull base approaches. Both the endonasal medial maxillotomy approach and Caldwell-Luc approach provided endoscopic access to each target. However, the sublabial Caldwell-Luc approach offered greater surgical freedom and a more head-on approach than the endonasal medial maxillotomy. These differences in surgical freedom and angles of attack may be useful to consider when planning minimal-access approaches.

Concussion 101: the current state of concussion education programs.

Concussion is an important cause of morbidity in young student athletes. The prevention, accurate diagnosis, and prompt management of concussions require that players, parents, coaches, and medical personnel are accurately educated on current concussion data and guidelines. All states have laws that mandate concussion education for high school athletes. There is currently no uniform educational program to disseminate information to student athletes regarding concussions. This article highlights a few nationally recognized educational programs that aim to accurately and effectively inform all members of the athletic, academic, and medical communities about the importance and urgency of concussion.Concussion is an important cause of morbidity in young student athletes. The prevention, accurate diagnosis, and prompt management of concussions require that players, parents, coaches, and medical personnel are accurately educated on current concussion data and guidelines. All states have laws that mandate concussion education for high school athletes. There is currently no uniform educational program to disseminate information to student athletes regarding concussions. This article highlights a few nationally recognized educational programs that aim to accurately and effectively inform all members of the athletic, academic, and medical communities about the importance and urgency of concussion.

Transvenous coil embolization of an intraorbital arteriovenous fistula: case report and review of the literature.

BACKGROUND AND IMPORTANCE Purely intraorbital arteriovenous fistulas (AVFs), which are rare vascular malformations that clinically mimic carotid-cavernous fistulas (CCFs), involve a fistula from the ophthalmic artery to 1 of the draining ophthalmic veins. We describe a case of an intraorbital AVF treated with transvenous endovascular coil embolization via the inferior petrosal sinus (IPS) route and review the literature on this rare entity. CLINICAL PRESENTATION An 81-year-old woman sought treatment after 7 days of progressive left-sided visual acuity loss, chemosis, and lateral rectus palsy. Magnetic resonance imaging demonstrated dilated vascularity in the left orbit raising suspicions for a CCF. Cerebral angiography showed a purely intraorbital AVF with a fistula between the left ophthalmic artery and superior ophthalmic vein (SOV). Transvenous selective catheterization of the fistula was performed by successfully navigating the ipsilateral IPS to the cavernous sinus and SOV. The fistula was then embolized using detachable coils. The patient was discharged the next day. Three weeks after embolization, her ocular symptoms and findings had resolved. CONCLUSION Intraorbital AVFs are a rare type of AVF that can be treated by direct surgical ligation, transarterial embolization, or transvenous embolization. We successfully navigated the IPS, which is frequently stenotic or occluded secondary to chronically increased fistulous drainage, and utilized this route to embolize the fistula with detachable coils.

Histopathological features of the outer membrane of chronic subdural hematoma and correlation with clinical and radiological features.

We compared the histopathological features of the outer membrane of a chronic subdural hematoma (CSH) with its clinico-radiological presentation in patients. One hundred and fifty-six patients undergoing surgery for CSH were prospectively included in this study. Histopathological specimens of the outer neomembrane obtained intraoperatively were studied. Histological features were classified into four types and analyzed in relation to the Glasgow Coma Scale (GCS) score at presentation and radiological features. On histopathological examination, there were no cases of type I, 42.3% cases of type II and 34.6% cases of type III and 23.1% cases of types IV CSH neomembranes. Patients presenting with a GCS <13 exclusively had type II neomembranes. Increased radiodensity and thickness of the hematoma correlated with type IV neomembranes. This study may serve as an incentive to investigate the histopathology of CSH membranes in predicting outcomes and the recurrence of subdural hemorrhage after drainage surgery.