Operative Epidemiology of the First Five Years in a New African Neurosurgery Training Center: The Experience in Rural Kenya at Tenwek Hospital 2016 to 2021.

BACKGROUND: One strategy to increase the availability of neurosurgical services in underserved regions within Sub-Saharan African countries is to create new residency training programs outside of cosmopolitan cities where programs may already exist. In 2016 Tenwek Hospital in rural western Kenya began offering full-time neurosurgical services and in 2020 inaugurated a residency training program. This review highlights the operative epidemiology of the first 5 years of the hospital's neurosurgical department. METHODS: A retrospective review of all cases performed by a neurosurgeon at Tenwek Hospital between September 2016 and February 2022 was performed. Patient demographics, surgical indications, length of stay, and in-hospital mortality rates were collected. RESULTS: A total of 1756 cases were retrievable. Of these, 1006 (57.3%) were male and mean age was 30 years (range 1 day to 97 years). Mean length of stay was 11 ± 2 days and in-hospital mortality rate was 4.4% (77 patients). The most common pathologies in children comprised hydrocephalus and spina bifida (42.5% and 21.1%, respectively); in adults, cranial trauma (28.2%), oncology (25.2%), and degenerative spine (18.5%) were most common. Trauma was the leading cause of death. CONCLUSIONS: The neurosurgical caseload of a rural hospital in an underserved area can provide not only an adequate neurosurgical volume, but a robust and varied exposure that is necessary for training safe and competent surgeons who are willing to remain in their countries of origin.

An online tumor board with international neurosurgical collaboration guides surgical decision-making in Western Kenya.

Telecollaboration via web-based platforms has emerged as a tool to relieve constraints on the establishment of tumor boards for neurosurgical oncology. Challenging tumor cases arising in low- and middle-income countries may benefit from the use of such models. The case of a 5-year-old boy presenting in Western Kenya with a challenging tumor and symptomatic hydrocephalus was presented on a novel web platform to a multi-national audience of neurosurgeons. The treating neurosurgeon invited a physician network to review the case vignette and radiographic images. Respondents independently offered input during a prescribed response period. Three respondents provided surgical opinions during a 24-h response period. The treating neurosurgeon utilized the pooled input to determine a course of action for the patient. When a web-based platform is available, lone neurosurgeons in low-resource settings may nevertheless apply multi-national, multi-institutional perspectives to challenging oncology cases.

The College of Surgeons of East, Central, and Southern Africa: Successes and Challenges in Standardizing Neurosurgical Training.

BACKGROUND: The College of Surgeons of East, Central, and Southern Africa (COSECSA) is a regional accrediting body for general and specialty surgical training programs that has recently expanded to include neurosurgery. As neurosurgical services expand in sub-Saharan Africa, the structure of training and accreditation has become a vital issue. METHODS: We review the founding and current structures of COSECSA neurosurgical training, identifying accomplishments and challenges facing the expansion of neurosurgical training in this region. RESULTS: The COSECSA model has succeeded in several countries to graduate qualified neurosurgeons, but challenges remain. Programs must balance the long duration of training required to promote surgical excellence against an overwhelming clinical need that seeks immediate solutions. CONCLUSION: Harnessing global collaboration, rapidly expanding local infrastructure, and a robust multinational training curriculum, COSECSA has emerged as a leader in the effort to train neurosurgeons and is anticipated to dramatically improve on the markedly unmet need for neurosurgical care in sub-Saharan Africa.

Spontaneous occult intracranial hypotension precipitating life-threatening cerebral venous thrombosis: case report.

Spontaneous intracranial hypotension (SIH) is an uncommon headache etiology, typically attributable to an unprovoked occult spinal CSF leak. Although frequently benign, serious complications may occur, including cerebral venous thrombosis (CVT). The objective of this study was to examine a highly complicated case of CVT attributable to SIH as a lens for understanding the heterogeneous literature on this rare complication, and to provide useful, evidence-based, preliminary clinical recommendations. A 43-year-old man presented with 1 week of headache, dizziness, and nausea, which precipitously evolved to hemiplegia. CT venography confirmed CVT, and therapeutic heparin was initiated. He suffered a generalized seizure due to left parietal hemorrhage, which subsequently expanded. He developed signs of mass effect and herniation, heparin was discontinued, and he was taken to the operating room for clot evacuation and external ventricular drain placement. Intraoperatively, the dura was deflated, suggesting underlying SIH. Ventral T-1 CSF leak was identified, which failed multiple epidural blood patches and required primary repair. The patient ultimately made a complete recovery. Systematic review identified 29 publications describing 36 cases of SIH-associated CVT. Among 31 patients for whom long-term neurological outcome was reported, 25 (81%) recovered completely. Underlying coagulopathy/risk factors were identified in 11 patients (31%). CVT is a rare and potentially lethal sequela occurring in 2% of SIH cases. Awareness of the condition is poor, risking morbid complications. Evaluation and treatment should be directed toward identification and treatment of occult CSF leaks. Encouragingly, good neurological outcomes can be achieved through vigilant multidisciplinary neurosurgical and neurocritical care.

Anterior Extension of Tumor is as Important as Tumor Size to Facial Nerve Outcome and Extent of Resection for Vestibular Schwannomas.

Objectives We examined vestibular schwannoma tumor dimension and direction of growth to determine whether these correlate with facial nerve outcome as well as extent of resection (EOR). Design Retrospective review of prospectively maintained databases. Participants 206 patients were a part of this study. Main Outcome Measures Tumor dimensions were measured using preoperative magnetic resonance imaging, and a series of ratios were then calculated to further characterize tumor dimension. Regression analyses were performed to investigate correlation with facial nerve outcome and EOR. Results Patients with tumor extending >1.5 cm anterior to the internal auditory canal (IAC) (AB measurement) were three times more likely to have postoperative House-Brackman grades of 3 or worse. We also found that an EB/BF ratio (representing elongated growth parallel to the IAC axis) ≥1.1 was associated with half the risk of poor facial nerve outcome. Tumors with anterior-posterior diameter (AC measurement) >1.9 cm were five times less likely to undergo gross total resection (GTR). Furthermore, an increased degree of tumor extension into the IAC (DE measurement >2.4 cm) or an increased amount of brainstem compression (EB measurement >1.1 cm) were each associated with a nearly 3-fold decrease in the likelihood of GTR. Conclusion Our study demonstrates that anterior extent of the tumor is as important as tumor size to facial nerve outcome and degree of resection for vestibular schwannomas.

Microsurgery for Recurrent Vestibular Schwannoma After Previous Gross Total Resection.

OBJECTIVE: To present a single-institution experience and supportive systematic literature review examining outcomes after repeat microsurgery for recurrent vestibular schwannoma (VS) following previous gross total resection (GTR). STUDY DESIGN: Retrospective review of prospectively maintained VS database. Systematic literature review. SETTING: Tertiary referral center. PATIENTS: Six proven VS recurrences after primary GTR, treated via repeat microsurgery. INTERVENTION: Repeat microsurgery. MAIN OUTCOME MEASURES: Facial nerve function, extent-of-resection, time-to-repeat surgery, same versus alternate approach at repeat surgery (relative to primary operation). RESULTS: GTR was achieved in four (67%). House-Brackmann (HB) grade I-II facial nerve function was achieved in five (87%), including one that improved from preoperative HB grade V. An alternate surgical approach was chosen in four (67%). Systematic review identified four studies documenting 50 cases with patient-specific outcomes after repeat microsurgery for recurrent VS. Our cohort had significantly longer mean time-to-repeat surgery (117 vs. 64 months, p = 0.03), was significantly less likely to have HB III-VI function postrepeat (17% vs. 68%, p = 0.04), and was significantly less likely to undergo same approach surgery (33% vs. 90%, p = 0.0002); rates of GTR were nonsignificant (67% vs. 94%, p = 0.1). CONCLUSION: We report a six-patient series of microsurgery for recurrent VS after GTR, and the first systematic review of this rare and challenging entity. Anecdotally, our findings suggest that an alternate surgical approach may facilitate easier access to the tumor, with less scar encountered during the approach. Our results confirm that repeat microsurgery for recurrent VS is safe and effective, even for larger tumors not typically amenable to stereotactic radiosurgery.

Management of Residual Tumor After Limited Subtotal Resection of Large Vestibular Schwannomas: Lessons Learned and Rationale for Specialized Care.

BACKGROUND: In an era where subtotal resection (STR) is increasingly used, we have encountered a growing number of patients referred to our institution with limited resection of large vestibular schwannomas (VSs), sometimes associated with grave complications. Our aim was to highlight lessons learned in the management of large VSs and provide a rationale for specialized care. METHODS: A prospectively maintained database of >2000 patients with VSs evaluated at our institution between 2000 and 2016 was reviewed. Details of 10 patients with residual tumor after limited subtotal resection were reviewed, with 3 presented in detail to illustrate key aspects of management. RESULTS: All but 1 patient underwent initial surgery at private hospitals without a designated skull base team. The median posterior fossa tumor diameter at the time of initial operation was 4.0 cm, whereas median diameter of residual tumor at the time of our evaluation was 3.5 cm. Before referral, 3 patients had undergone fractionated radiation therapy after their initial operation; 1 had undergone stereotactic radiosurgery. Four patients had moderate to severe facial weakness; 2 had permanent sequelae from stroke, including hemiparesis and blindness; and 7 had ongoing symptomatic brainstem compression and/or hydrocephalus. CONCLUSIONS: Management of large VSs remains challenging, including treating presenting hydrocephalus, maximizing extent of resection while optimizing facial nerve outcome, and avoiding complications. Most cases should be approached with the intent of complete resection, realizing that subtotal resection may become necessary based on intraoperative findings.

Histology of the distal dural ring.

The distal dural ring (DDR) is a conserved intracranial anatomic structure marking the boundary point at which the internal carotid artery (ICA) exits the cavernous sinus (CS) and enters the subarachnoid space. Although the CS has been well described in a range of anatomic studies, to our knowledge no prior study has analyzed the histologic relationship between the ICA and DDR. Correspondingly, our objective was to assess the relationship of the DDR to the ICA and determine whether the DDR can be dissected from the ICA and thus divided, or can only be circumferentially trimmed around the artery. The authors examined ten fresh-frozen, adult cadaveric specimens. A standard frontotemporal craniotomy, orbito-optic osteotomy, and extradural anterior clinoidectomy was performed bilaterally. The cavernous ICA, DDR, and supraclinoid ICA were harvested as an en bloc specimen. Specimens formalin-fixed and paraffin-embedded prior to routine histochemical staining with hematoxylin and eosin and Masson trichrome. In all specimens, marked microscopic investment of the DDR throughout the ICA adventitia was noted. Dural collagen fibers extensively permeated the arterial layers superficial to the muscularis propria, with no evidence of a clear separation between the DDR and arterial adventitia. Histologic analysis suggests that the ICA and DDR are highly interrelated, continuous structures, and therefore attempted intraoperative dissection between these structures may carry an elevated risk of injury to the ICA. We correspondingly recommend careful circumferential trimming of the DDR in lieu of direct dissection in cases requiring mobilization of the clinoidal ICA. Clin. Anat. 30:742-746, 2017. © 2017Wiley Periodicals, Inc.

Synchronous ipsilateral cavernous malformations of the trochlear nerve.

BACKGROUND: Cranial nerve cavernous malformations (CM) are rare benign congenital vascular anomalies, with approximately 44 preceding cases in the literature. We report the fifth case of trochlear CM, as well as the first instance of two discrete CM occurring simultaneously along the same cranial nerve. METHODS: Case report. RESULTS: A fifty-seven year-old man presented with several years of diplopia; physical examination identified a complete left trochlear nerve paralysis. MRI revealed a 1cm enhancing lesion within the left ambient cistern, and the patient underwent left pretemporal transcavernous resection. Intraoperatively, a second, discrete CM of the trochlear nerve was also discovered; wide excision of the intrinsic trochlear lesions was completed, allowing both tumors to be removed en bloc with negative margins. Pathologic analysis confirmed both to be CM of the trochlear nerve. The patient recovered with a persistent left trochlear paralysis only, and follow-up MRI was negative for residual or recurrent disease. CONCLUSION: Cranial nerve CM are rare but potentially morbid mass lesions, with the capacity to precipitate significant neuropathies. Differential diagnosis includes schwannoma and hemangioblastoma. Definitive diagnosis may not be possible preoperatively; however, resection is recommended in symptomatic patients, potentially accompanied by nerve repair.

Delayed Cerebrospinal Fluid Rhinorrhea After Gamma Knife Radiosurgery with or without Preceding Transsphenoidal Resection for Pituitary Pathology.

BACKGROUND: Skull base cerebrospinal fluid (CSF) leak after gamma knife radiosurgery (GKRS) is a very rare complication. In patients who were treated with both GKRS and transsphenoidal resection (TSR) for pituitary lesions, early CSF leak occurs at a comparable rate with the general TSR population (4%). Delayed CSF leak occurring more than a year after TSR, GKRS, or dual therapy is exceedingly rare. METHODS: Retrospective chart review and review of the literature. RESULTS: We present 2 cases of delayed CSF leak after GKRS to treat pituitary adenoma. One patient developed CSF rhinorrhea 16 years after GKRS for growth hormone-producing pituitary adenoma. The patient had previously undergone TSR surgery 7 years prior to GKRS without complication. Additionally, a second patient developed high-flow CSF rhinorrhea 2 years after GKRS for a prolactinoma that failed dopamine agonist therapy. Both patients underwent a complicated clinical course after presentation, requiring multiple revisions for definitive CSF leak repair. CONCLUSIONS: Delayed CSF leak is a rare but serious complication after GKRS independent of TSR status; urgent repair is the treatment of choice. Based on our experience, these leaks have the potential to be refractory, and we recommend aggressive reconstruction, preferably with a vascularized flap, and potentially supplemented by placement of a lumbar drain and acetazolamide. Current evidence is scant and provides little insight regarding an underlying mechanism, which may include bony destruction by the tumor, delayed radiation necrosis, or a secondary empty sella syndrome.

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression.

OBJECTIVES/HYPOTHESIS: To report two patients with a history of microvascular decompression (MVD) for hemifacial spasm who presented with Teflon granulomas (TG) mimicking cerebellopontine angle (CPA) tumors and to perform a systematic review of the English-language literature. STUDY DESIGN: Case series at a single tertiary academic referral center and systematic review. METHODS: Retrospective chart review with analysis of clinical, radiological, and histopathological findings. Systematic review using PubMed, Embase, MEDLINE, and Web of Science databases. RESULTS: Two patients with large skull base TGs mimicking CPA tumors clinically and radiographically were managed at the authors' institution. The first presented 4 years after MVD with asymmetrical sensorineural hearing loss, multiple progressive cranial neuropathies, and brainstem edema due to a growing TG. Reoperation with resection of the granuloma confirmed a foreign-body reaction consisting of multinucleated giant cells containing intracytoplasmic Teflon particles. The second patient presented 11 years after MVD with asymmetrical sensorineural hearing loss and recurrent hemifacial spasm. No growth was noted over 2 years, and the patient has been managed expectantly. Only one prior case of TG after MVD for hemifacial spasm has been reported in the English literature. CONCLUSIONS: TG is a rare complication of MVD for hemifacial spasm. The diagnosis should be suspected in patients presenting with a new-onset enhancing mass of the CPA after MVD, even when performed decades earlier. A thorough clinical and surgical history is critical toward establishing an accurate diagnosis to guide management and prevent unnecessary morbidity. Surgical intervention is not required unless progressive neurologic complications ensue. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:715-719, 2017.

Synchronous Tumors of the Cerebellopontine Angle.

BACKGROUND: Synchronous tumors of the cerebellopontine angle (CPA) are very rare and inconsistently described. We present 2 cases of contiguous vestibular schwannoma (VS) and meningioma and a systematic literature review of all multiple CPA tumors. METHODS: Retrospective chart review and systematic literature review were performed. RESULTS: A 64-year-old woman and a 42-year-old man presented with symptoms referable to the CPA. Magnetic resonance imaging in both patients revealed 2 separate contiguous tumors. Retrosigmoid craniotomy and tumor removal in each case confirmed VS and meningioma. Systematic literature review identified 42 previous English-language publications describing 46 patients with multiple CPA tumors. Based on Frassanito criteria, there were 4 concomitant tumors (8%), 16 contiguous tumors (33%), 3 collision tumors (6%), 13 mixed tumors (27%), and 11 tumor-to-tumor metastases (23%). Extent of resection was gross total in 16 cases and subtotal in 16 cases (50% each). Unfavorable House-Brackmann grade III-VI function was documented in 27% overall and in 33% of patients with VS and meningioma, a marked increase from the observed range in isolated VS. CONCLUSIONS: Multiple CPA tumors are rare, heterogeneous lesions with a marked predisposition toward poor facial nerve outcomes, potentially attributable to a paracrine mechanism that simultaneously drives multiple tumor growth and increases invasiveness or adhesiveness at the facial nerve-tumor interface. Preceding nomenclature has been confounding and inconsistent; we recommend classifying all multiple CPA tumors as "synchronous tumors," with "schwannoma with meningothelial hyperplasia" or "tumor-to-tumor metastases" reserved for rare, specific circumstances.

Incidence and Risk Factors of Delayed Facial Palsy After Vestibular Schwannoma Resection.

BACKGROUND: Preservation of facial nerve function following vestibular schwannoma surgery is a high priority. Even those patients with normal to near-normal function in the early postoperative period remain at risk for delayed facial palsy (DFP). OBJECTIVE: To evaluate the incidence and prognosis of DFP and to identify risk factors for its occurrence. METHODS: A retrospective cohort study of 489 patients who underwent vestibular schwannoma resection at our institution between 2000 and 2014. Delayed facial palsy was defined as deterioration in facial function of at least 2 House-Brackmann (HB) grades between postoperative days 5 to 30. Only patients with a HB grade of I to III by postoperative day 5 were eligible for study inclusion. RESULTS: One hundred twenty-one patients with HB grade IV to VI facial weakness at postoperative day 5 were excluded from analysis. Of the remaining 368, 60 (16%) patients developed DFP (mean 12 days postoperatively, range: 5-25 days). All patients recovered function to HB grade I to II by a mean of 33 days (range: 7-86 days). Patients that developed DFP had higher rates of gross total resections (83% vs 71%, P = .05) and retrosigmoid approaches (72% vs 52%, P < .01). There was no difference in recovery time between patients who received treatment with steroids, steroids with antivirals, or no treatment at all (P = .530). CONCLUSION: Patients with a gross total tumor resection or undergoing a retrosigmoid approach may be at higher risk of DFP. The prognosis is favorable, with patients likely recovering to normal or near-normal facial function within 1 month of onset.

Can Preoperative Imaging Predict Tumor Involvement of the Anterior Clinoid in Clinoid Region Meningiomas?

BACKGROUND: Anterior clinoid region meningiomas may infiltrate the bone over which they arise, therefore requiring an anterior clinoidectomy to achieve a Simpson grade 1 resection. A clinoidectomy, however, is not without risks. OBJECTIVE: We performed a study of diagnostic accuracy investigating whether preoperative imaging could predict tumor involvement of the clinoid, and thereby tailor the degree of bony removal. METHODS: Patients having undergone resection of a clinoid region meningioma between 2001 and 2011 were identified. Included in further analysis were those patients in whom a clinoidectomy was performed with subsequent pathologically confirmed presence or absence of tumor in the clinoid process on decalcified specimens. Two neuroradiologists, blinded to pathology results, independently reviewed available preoperative imaging and stated whether or not they anticipated the clinoid to be involved by tumor. Interobserver agreement and the ability to accurately predict tumor involvement of the clinoid were then analyzed. RESULTS: Sixty-two patients were included in the final analysis. Interobserver agreement was 100%. Sensitivity and specificity of preoperative imaging to predict tumor involvement was 89% and 52%, respectively, with positive and negative likelihood ratios of 1.85 and 0.20. Positive and negative predictive values were 73% and 76%, respectively. CONCLUSION: Preoperative imaging of clinoid region meningiomas can accurately predict the presence or absence of tumor involvement of the clinoid in only approximately 75% of cases. In light of the fact that a quarter of patients with radiographically negative clinoids will have tumor present on pathological analysis, we recommend a clinoidectomy for all clinoid region meningiomas.

Are there modifiable risk factors to prevent a cerebrospinal fluid leak following vestibular schwannoma surgery?

OBJECT: The following study was conducted to identify risk factors for a postoperative CSF leak after vestibular schwannoma (VS) surgery. METHODS: The authors reviewed a prospectively maintained database of all patients who had undergone resection of a VS at the Mayo Clinic between September 1999 and May 2013. Patients who developed a postoperative CSF leak within 30 days of surgery were compared with those who did not. Data collected included patient age, sex, body mass index (BMI), tumor size, tumor side, history of prior tumor treatment, operative time, surgical approach, and extent of resection. Both univariate and multivariate regression analyses were performed to evaluate all variables as risk factors of a postoperative CSF leak. RESULTS: A total of 457 patients were included in the study, with 45 patients (9.8%) developing a postoperative CSF leak. A significant association existed between increasing BMI and a CSF leak, with those classified as overweight (BMI 25-29.9), obese (BMI 30-39.9), or morbidly obese (BMI≥40) having a 2.5-, 3-, and 6-fold increased risk, respectively. Patients undergoing a translabyrinthine (TL) approach experienced a higher rate of CSF leaks (OR 2.5, 95% CI 1.3-4.6; p=0.005), as did those who had longer operative times (OR 1.04, 95% CI 1.02-1.07; p=0.0006). The BMI, a TL approach, and operative time remained independent risk factors on multivariate modeling. CONCLUSIONS: Elevated BMI is a risk factor for the development of a postoperative CSF leak following VS surgery. Recognizing this preoperatively can allow surgeons to better counsel patients regarding the risks of surgery as well as perhaps to alter perioperative management in an attempt to decrease the likelihood of a leak. Patients undergoing a TL approach or having longer operative times are also at increased risk of developing a postoperative CSF leak.

Single-fraction stereotactic radiosurgery of meningeal hemangiopericytomas.

Meningeal hemangiopericytomas (M-HPC) are challenging tumors with a high rate of recurrence despite surgical resection and external beam radiotherapy (EBRT). To better understand the role of single-fraction stereotactic radiosurgery (SRS) for patients with M-HPC, we reviewed our experience with 22 patients (12 men, 10 women) from 1990 until 2010. Twelve patients (55%) underwent a single SRS procedure, whereas 10 patients (45%) had more than one SRS procedure (range 2-6). In total, 47 SRS procedures were performed to treat 64 tumors. Fourteen patients (64%) had undergone prior EBRT (median dose, 56.0 Gy). Follow-up after the initial SRS (median, 66 months) was censored at the time of death (n = 15) or last clinical evaluation (n = 7). Eleven patients (50 %) died of intracranial tumor progression (n = 10) or treatment-related complications (n = 1). One patient (5%) died of systemic disease progression. Disease-specific survival (DSS) at 1-, 3- and 5-years after SRS was 96, 82, and 61%, respectively. Prior EBRT (HR 9.0, 95% CI 1.1-78.1, p < 0.05) and larger initial tumor volume (HR 1.09, 95% CI 1.02-1.2, p = 0.02) were associated with worse DSS. Local tumor control (LTC) after SRS at 1-, 3-, and 5-years was 89, 68, and 59%, respectively. Improved LTC was noted in patients who had not undergone prior EBRT (HR 6.3, 95% CI 2.1-19.5, p = 0.001). One patient (5%) had symptomatic radiation-relation complications after SRS. Overall, single-fraction SRS was effective in providing LTC for more than half of recurrent or residual M-HPC at 5-years after the procedure. Repeat SRS is often required secondary to either distant or local tumor progression.

Temporal bone encephalocele and cerebrospinal fluid fistula repair utilizing the middle cranial fossa or combined mastoid-middle cranial fossa approach.

OBJECT: The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome. METHODS: A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid-middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers. RESULTS: Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%). Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m(2), and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance. Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid-middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up. CONCLUSIONS: Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid-middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.

A radiation-induced meningioma "cures" a complex dural arteriovenous fistula.

OBJECTIVE: We report a case of spontaneous thrombosis of an extremely complex dural arteriovenous fistula (DAVF), believed to be previously incurable, after the development of a radiation-induced meningioma resulting from prior attempts to treat the fistula with radiosurgery. METHODS: A very large DAVF was treated over the course of 3 decades with a combination of partial embolization and stereotactic radiosurgery with no angiographic or clinical treatment response at long-term follow-up. However, with the development of new neurologic symptoms 13 years after radiosurgery, a meningioma was found to have arisen in the previously irradiated field, and surprisingly, the fistula had spontaneously thrombosed. The meningioma was successfully removed. RESULTS: We discuss the unique pathophysiology of the radiation-induced meningioma causing this previously incurable DAVF progressing to obliteration. We also review the natural history of DAVFs, including reported rates of spontaneous occlusion, as well as the success of radiosurgery in their treatment. Finally, the incidence of radiosurgery-induced tumors, particularly meningiomas, is reviewed. CONCLUSION: The relationship between the spontaneous thrombosis of a DAVF and the radiation-induced meningioma is unique and has not previously been reported.