William R. Copeland

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.

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.

Use of Preoperative MRI to Predict Vestibular Schwannoma Intraoperative Consistency and Facial Nerve Outcome

Objectives We sought to identify if preoperative schwannoma magnetic resonance imaging (MRI) intensities might predict intraoperative consistency. We then determined whether consistency correlated with facial nerve outcomes. Design Operative reports from 2000 to 2010 were searched for tumor description as either soft and/or suckable or firm and/or fibrous. Preoperative T1 and T2 sequences were then reviewed to identify intensities relative to gray matter. Facial nerve function was recorded at the time of most recent follow-up. Results Forty-six patients were included. No tumors were T1 hyperintense. Soft and firm schwannomas were equally likely to be T1 hypointense. On T2 sequences, however, soft schwannomas were more likely to be hyperintense (88% versus 14%, p < 0.005) whereas firm schwannomas were more likely to be hypointense (86% versus 6%, p < 0.005). There was a tendency for firm schwannomas to have worse facial nerve outcomes (43% versus 19%, p = 0.14). Conclusions Prediction of vestibular schwannoma intraoperative consistency based on T2 intensity seems promising. Furthermore, though not statistically significant, in this small pilot study firm schwannomas tended to have worse facial nerve outcomes. This potential ability to predict consistency and its correlation with facial nerve outcome may assist the surgeon in preoperative planning and patient counseling, though further data needs to be accumulated.

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.

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.

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.

A modification to the fascia-bone-fascia technique for repair of the middle fossa floor.

A commonly used method for resurfacing of the middle fossa floor is the fascia-bone-fascia technique. One disadvantage of this technique however is the occasional migration of the bone graft. To prevent this, we have modified the technique to include securing of the graft using simple craniotomy fixation materials. We have now used this method in five patients, all of whom have had satisfactory clinical outcomes. Follow-up imaging has demonstrated the grafts to have remained in their original position.

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.

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.

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.