Sean O. McMenomey

The natural history of untreated acoustic neuromas

The emergence of magnetic resonance imaging with gadolinium has dramatically enhanced our ability to accurately detect the presence of acoustic tumors as small as 2 mm in diameter. Early diagnosis and improved surgical techniques continue to reduce the morbidity associated with surgical removal of these lesions. There exists, however, a select group of patients in whom no treatment may be the most appropriate management. Since 1979, a total of 51 patients with radiographic evidence of an acoustic neuroma have been prospectively followed for tumor growth and progression of symptoms. Patients were chosen for this conservative approach on the basis of age, medical condition, tumor size, audiometric data, and patient preference. This study reveals that a significant number of patients with acoustic tumors can be safely followed with regular imaging studies and may never require treatment. Discussed are tumor growth rates, epidemiology, and the impact of these factors on patient management.

A Meta-analysis Comparing Outcomes of Microsurgery and Gamma Knife Radiosurgery†

Objectives/Hypothesis Surgery has been the most common treatment for acoustic neuromas, but gamma knife radiosurgery has emerged as a safe and efficacious alternative to microsurgery. This meta‐analysis compares the outcomes of the two modalities.

Acoustic neuroma surgery outcomes.

Objective The outcomes of surgery for acoustic neuromas have improved dramatically since the development of modern surgical techniques, the operating microscope, magnetic resonance imaging (MRI), and cranial nerve monitoring. The goals of acoustic neuroma surgery are now preservation of facial nerve function and, when feasible, hearing preservation. Many large series do not report standardized hearing and facial function grading, and they include patients who did not benefit from the most modern techniques. The purpose of this study was to present the results of acoustic neuroma surgery using the most modern techniques and equipment, using standardized grading systems. Study Design Retrospective review. Setting Tertiary referral center. Patients 97 patients who underwent surgical removal of acoustic neuromas from 1992 to 1998. Intervention All patients underwent acoustic neuroma surgery and had preoperative audiograms and MRI with contrast. In addition, all patients had preoperative and postoperative facial function graded by the House-Brackmann scale and intraoperative facial nerve monitoring. Hearing preservation was attempted in patients with tumors of any size who had preoperative function of grade A or B according to the Committee on Hearing and Equilibrium guidelines for reporting results of acoustic neuroma surgery. Main Outcome Measures Hearing preservation was considered successful if the patient retained serviceable hearing grade A or B. House-Brackmann grade 1 or 2 was considered excellent facial function. Complications were recorded. Results Facial nerve integrity was preserved in 96 of 97 patients (99%). Eight of 8 (100%) patients with intracanalicular tumors had excellent facial nerve function (HB 1–2). Fifty-two of 55 (95%) of patients with small tumors had excellent facial nerve function, and 15 of 24 (63%) with medium tumors had HB grade 1–2. Hearing was preserved in 29% of patients with tumors under 2 cm. The overall complication rate was 20%; cerebrospinal fluid leak was the most common. Conclusion These results show that with modern imaging and surgical techniques, acoustic neuroma surgery is extremely safe and outcomes are very good. Surgery remains the treatment of choice for most tumors until alternative therapies, such as gamma knife, use uniform grading scales and show long-term facial and hearing results.

Spontaneous Middle Fossa Encephalocele and Cerebrospinal Fluid Leakage: Diagnosis and Management

Objective: To evaluate the clinical presentation, operative findings, and surgical management of patients with spontaneous middle fossa encephalocele (SMFE) and cerebrospinal fluid (CSF) leakage repaired using a middle fossa craniotomy (MFC) approach. Study Design: Retrospective. Setting: Tertiary referral center. Patients: Fifteen consecutive patients with 16 SMFE repaired using an MFC approach between January 1999 and April 2006 were included. Interventions: Patients were evaluated clinically and radiologically with computed tomography or magnetic resonance imaging. Encephaloceles were approached via MFC, and the cranial base was repaired in multilayered fashion using a variety of materials, including hydroxyapatite cement. Patients were followed clinically after discharge. Main Outcome Measures: Postoperative complications, including CSF leak and the need for surgical revision, are evaluated. Patient factors, diagnostic testing, and operative findings are reviewed. Results: Diagnosis was made using clinical and radiologic evaluation in most patients. β2-Transferrin testing was occasionally used in the diagnostic workup. Intraoperatively, multiple defects of the floor of the middle fossa were found in more than half of patients. Fifteen SMFE in 14 patients were successfully repaired via MFC alone. One patient required revision with a combined transmastoid/MFC approach due to recurrent CSF leakage. Hydroxyapatite cement was used for repair of the cranial base in 9 patients without complication. Conclusion: An MFC approach can be used to repair SMFE with CSF leakage with a high level of success. Hydroxyapatite cement is a safe and useful adjunct to aid in reconstruction of the cranial base defects in cases of SMFE.

Atypical central nervous system lymphoma at the cranial base : Report of four cases

OBJECTIVE AND IMPORTANCE Primary central nervous system lymphoma is a disease with increasing incidence. Atypical presentations are becoming more frequent. CLINICAL PRESENTATION Three patients bearing cavernous sinus lesions presented initially with periorbital pain and diplopia. Tolosa-Hunt syndrome was the initial presumptive diagnosis for two patients, and meningioma was the diagnosis for the third patient. A fourth patient presented with left ear pain, and a mass in the left internal auditory canal was thought to represent an acoustic neuroma. INTERVENTION For all four patients, an operative pathological diagnosis was obtained and was compatible with central nervous system lymphoma. All patients were treated with osmotic blood-brain barrier disruption with intra-arterial chemotherapy using a methotrexate-based regimen. CONCLUSION All four cases included atypical presentations of lymphoma. These cases again illustrate that a correct diagnosis cannot be obtained based only on imaging and clinical findings.

Cochlear Implantation: Current and Future Device Options

Today most cochlear implant users achieve above 80% on standard speech recognition in quiet testing, and enjoy excellent device reliability. Despite such success, conventional designs often fail to provide the frequency resolution required for complex listening tasks. Furthermore, performance variability remains a vexing problem, with a select group of patients performing poorly despite using the most recent technologies and processing strategies. This article provides a brief history of the development of cochlear implant technologies, reviews current implant systems from all 3 major manufacturers, examines recently devised strategies aimed at improving device performance, and discusses potential future developments.

Congenital Encephalocele of the Medial Skull Base

Meningoencephaloceles of the temporal bone are rare. Although most often seen following otologic surgery or trauma, congenital meningoencephaloceles can exist. The clinical presentation, diagnostic evaluation, and surgical management of three patients with congenital meningoencephalocele are presented. Two of the three patients presented to our institution with recurrent episodes of meningitis; one presented with partial complex seizures. Diagnostic evaluation included temporal bone computed tomography with magnetic resonance imaging. In two patients, defects were imaged following high‐pressure subarachnoid cisternography with computed tomography. All three patients were found to have congenital defects in the area of Meckels cave. Early recognition of congenital meningoencephalocele is important to avoid delay of definitive surgical management and neurologic sequelae.

Cochlear Implant Fixation Using Polypropylene Mesh and Titanium Screws

Hypothesis: Fixation of cochlear implants using prosthetic mesh is an improvement of the traditional fixation methods.

Hearing preservation with the transcrusal approach to the petroclival region.

Objective: We studied the hearing results and outcomes after transcrusal craniotomy. Study Design: We conducted a retrospective review. Setting: This study was conducted at a tertiary care hospital. Patients: We studied 10 consecutive patients, including two men and eight women, who underwent transcrusal craniotomy for petroclival masses or tumors. Intervention: The intervention consisted of therapeutic removal of petroclival meningioma. Main Outcome Measure: The main outcome measure of this study was hearing preservation as measured by standard audiogram. Results: There were six meningiomas, one eighth nerve schwannoma, one fifth nerve schwannoma, one chordoma, and one midbasilar artery aneurysm. Postoperative hearing was measured according to the AAOHNS criteria. Complications and further therapies were recorded. Postoperative hearing was measured in eight. The cochlear nerve was severed in one patient. One was unavailable for follow up. Eight patients retained hearing at or near preoperative levels, seven with SRT within 10 dB and speech discrimination within 10% of preoperative levels. Four patients presented with trigeminal symptoms, one with third nerve palsy and two with facial weakness. Postoperative deficits included fourth, sixth, seventh, and eighth nerve palsies in three patients. Complications included one wound infection, two cerebrospinal fluid leak, and two cases of meningitis, both of which were sterile. There were secondary procedures in five patients—three radiosurgery, two shunts, one tracheotomy, and one g-tube. Conclusions: Transcrusal craniotomy is a safe and effective approach to the petroclival region. Excellent hearing results can be expected with this technique.

Stria vascularis ultrastructural pathology in the C3H/lpr autoimmune strain mouse: a potential mechanism for immune-related hearing loss.

The stria vascularis in the C3H/lpr autoimmune strain mouse was ultrastructurally examined in order to better understand the potential mechanisms by which systemic autoimmune disease affects the ear. The inner ears from C3H/lpr mice before disease onset and C3H/HeJ controls showed no apparent pathology. However, the stria vascularis from older C3H/lpr mice after systemic autoimmune disease onset showed considerable intercellular edema around the stria capillaries and thickening of the capillary basement membrane, compared to controls. These observations suggest that perivascular abnormalities, which are the hallmark of systemic autoimmune diseases, may underlie the stria dysfunction and hearing loss seen in autoimmune diseases in humans.