Maroun T. Semaan

The basic science of Meniere's disease and endolymphatic hydrops

Menieres disease is characterized by the triad of fluctuating hearing loss, episodic vertigo, and tinnitus and by endolymphatic hydrops found on post-mortem examination. The cause of Menieres disease remains unclear. Numerous factors play a role in the development of hydrops and in the pathogenesis of related cochleovestibular dysfunction. This review highlights recent advances in the understanding of the pathophysiology of symptom development in Menieres disease by detailing the role of genetics, autoimmunity, endolymphatic fluid homeostasis, excitotoxicity, oxidative stress, and cellular apoptosis. Emphasis is placed on reviewing the newly described animal models that exhibit endolymphatic hydrops. Recent findingsRecent evidence suggests that hearing loss might be explained in part by apoptosis of spiral ganglion neurons and that hydrops could represent an epiphenomenon rather than an initiating factor. In addition, the accepted guinea pig model described by Kimura has certain limitations. An animal model that would supplement and in some cases replace the surgically induced model is currently being sought. SummaryThese recent advances have expanded our understanding and will allow for the development of targeted therapeutic interventions aimed at preventing the progression oochleovestibular deterioration.

A mouse model with postnatal endolymphatic hydrops and hearing loss

Endolymphatic hydrops (ELH), hearing loss and neuronal degeneration occur together in a variety of clinically significant disorders, including Menieres disease (MD). However, the sequence of these pathological changes and their relationship to each other are not well understood. In this regard, an animal model that spontaneously develops these features postnatally would be useful for research purposes. A search for such a model led us to the Phex Hyp-Duk mouse, a mutant allele of the Phex gene causing X-linked hypophosphatemic rickets. The hemizygous male (Phex Hyp-Duk/Y) was previously reported to exhibit various abnormalities during adulthood, including thickening of bone, ELH and hearing loss. The reported inner-ear phenotype was suggestive of progressive pathology and spontaneous development of ELH postnatally, but not conclusive. The main focuses of this report are to further characterize the inner ear phenotype in Phex Hyp-Duk/Y mice and to test the hypotheses that (a) the Phex Hyp-Duk/Y mouse develops ELH and hearing loss postnatally, and (b) the development of ELH in the Phex Hyp-Duk/Y mouse is associated with obstruction of the endolymphatic duct (ED) due to thickening of the surrounding bone. Auditory brainstem response (ABR) recordings at various times points and histological analysis of representative temporal bones reveal that Phex Hyp-Duk/Y mice typically develop adult onset, asymmetric, progressive hearing loss closely followed by the onset of ELH. ABR and histological data show that functional degeneration precedes structural degeneration. The major degenerative correlate of hearing loss and ELH in the mutants is the primary loss of spiral ganglion cells. Further, Phex Hyp-Duk/Y mice develop ELH without evidence of ED obstruction, supporting the idea that ELH can be induced by a mechanism other than the blockade of longitudinal flow of endolymphatic fluid, and occlusion of ED is not a prerequisite for the development of ELH in patients.

Tissue-Engineered Calcium Alginate Patches in the Repair of Chronic Chinchilla Tympanic Membrane Perforations†

Objective: Chronic tympanic membrane perforations are a common problem in the United States. A high number of these cases results from placement of pressure equalization tubes. These perforations may initially be treated with paper patch techniques and although safe and well tolerated, the procedure demonstrates poor efficacy. The ideal treatment for small perforations should be rapid, minimally invasive, and efficacious. Calcium alginate‐based tissue engineered tympanic membrane patches represent an attractive option, but in vivo data are required.

Transmastoid extradural-intracranial approach for repair of transtemporal meningoencephalocele: a review of 31 consecutive cases.

To review the clinical presentation, surgical techniques, and outcomes of the transmastoid extradural–intracranial (TMEDIC) approach for the treatment of transtemporal meningoencephalocele.

Hearing results using the SMart piston prosthesis.

Objective: SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or platinum piston prostheses. Hypothesis: Audiometric results using the SMart piston are identical to those obtained using a conventional piston prosthesis. Study Design: Retrospective chart review. Setting: Private neurotologic tertiary referral center. Patients: The 416 ears reviewed included 306 with a SMart prosthesis and 110 conventional prostheses. 61% were women. Mean follow-up time was 5.6 (standard deviation [SD], 6.3 mo) and 6.9 months (SD, 7.0 mo) for the 2 groups, respectively. Intervention: Stapedotomy using the SMart or a conventional (non-SMart) prosthesis. Main Outcome Measures: Audiometric hearing results, including pure-tone average (PTA) and air-bone gap (ABG), and prevalence of postoperative complications. Results: Mean postoperative PTA was 32.6 (SD, 16.8) dB for the SMart group and 29.4 (SD, 13.5) dB for the non-SMart group, with ABGs of 7.6 (SD, 8.9) and 6.0 (SD, 5.2) dB, respectively. Mean change (decrease) in ABG was 18.7 (SD, 13.1) dB for the SMart group and 19.9 (SD, 10.3) dB for the non-SMart group. High-frequency bone PTAs showed overclosure of 2.0 (SD, 7.9) dB for the SMart group and 3.6 (SD, 8.6) dB for the non-SMart group. Postoperative vertigo and tinnitus were infrequent. No significant differences in these audiometric outcomes or complication rates were noted between groups. There was no significant difference in rate of gap closure to within10 dB (78.3 versus 84.2%, SMart and non-SMart, respectively) or 20 dB (94.2 and 98.0%). Conclusion Compared with conventional stapes prostheses, the nitinol-based SMart is a safe and reliable stapes prosthesis that eliminates manual crimping without significantly altering the audiometric outcome. Complications are rare, but longer follow-up is needed before establishing long-term stability.

Geniculate ganglion hemangiomas: clinical results and long-term follow-up.

Objective: To review the clinical presentation, evaluation, and management of 18 patients with geniculate ganglion hemangiomas seen at the House Clinic. Study Design: Retrospective case review. Setting: Private neurotological tertiary referral center. Patients: Eighteen patients with geniculate ganglion hemangiomas treated at the House Clinic between 1986 and 2008. Intervention: Observation or surgical intervention using the middle fossa or translabyrinthine craniotomy for decompression or excision of the hemangioma with or without facial nerve resection and grafting. Main Outcome Measures: Postoperative facial function using the House-Brackmann grading system, postoperative audiograms and postoperative follow-up magnetic resonance imaging or computed tomographic scan of the temporal bone. Results: Approximately 13 patients (72%) were female subjects, and 5 (28%) were male subjects. Mean age was 54 years, and follow-up was 73 months. 17 (94%) of 18 patients presented with facial paresis or paralysis. Facial twitching was present in 10 (56%) of 18 cases. Four patients (22%) presented with hearing loss. Facial nerve function was House-Brackmann grade I/II in 7(38%), III/IV in 5 (28%), and V/VI in 6 (34%) patients, respectively. Approximately 13 patients (72%) underwent middle fossa craniotomy for excision or decompression of their hemangiomas, and 2 (11%) underwent translabyrinthine removal. The facial nerve was preserved in 11 (73%) of 15 patients and was excised and grafted in 4 (27%) of 15. Recovery to a House-Brackmann grade I/II was seen in 8 (72%) of 11 patients in whom the integrity of the facial nerve was preserved. In the surgical group, hearing remained stable in 64% of hearing preservation cases and worsened in 38%. Facial function remained stable in the nonsurgical group. Conclusion: Geniculate ganglion hemangiomas are rare vascular malformations that produce facial paralysis despite their relative small size at presentation. When possible, excision with neural preservation yields better long-term facial function. Recurrences are rare.

Staged Gamma Knife Radiosurgery after Tailored Surgical Resection

Object: Although benign and slow growing, glomus jugulare tumors can be locally aggressive because of their proximity to lower cranial nerves and major vascular structures. Surgical resection frequently leads to complications, and radiosurgery alone often does not relieve symptoms. We report a novel treatment paradigm of tailored surgical resection followed by staged radiosurgery that allows for tissue diagnosis and immediate improvement of symptoms and tumor control without the morbidity of radical surgical resection. Methods: Five patients with glomus jugulare tumors and contraindications to extensive surgery each underwent an outpatient otologic procedure to resect the portion of the tumor in the middle ear and mastoid with no attempt to remove tumor in the jugular bulb. Each patient returned 2–5 months later for Gamma Knife radiosurgery to the remainder of the tumor, which consisted of one 15-Gy dose prescribed to the 50% isodose curve. Patients were followed through outpatient visits and surveillance MR imaging for up to 3 years. Results: All patients were successfully treated as outpatients. Each had improvement or resolution of pulsatile tinnitus and otalgia and preserved or improved hearing. One patient developed a delayed facial palsy prior to radiosurgery that resolved completely; there were no other changes in cranial nerve function after either procedure. Tumor volume was stable or reduced in all patients at most recent follow-up, and there were no immediate or delayed complications. Conclusions: Staged outpatient microsurgical and radiosurgical therapy for glomus jugulare tumors in the symptomatic patient is safe and yields favorable results regarding tumor size, tinnitus, hearing and cranial nerve status.

MEMS Capacitive Accelerometer-Based Middle Ear Microphone

The design, implementation, and characterization of a microelectromechanical systems (MEMS) capacitive accelerometer-based middle ear microphone are presented in this paper. The microphone is intended for middle ear hearing aids as well as future fully implantable cochlear prosthesis. Human temporal bones acoustic response characterization results are used to derive the accelerometer design requirements. The prototype accelerometer is fabricated in a commercial silicon-on-insulator (SOI) MEMS process. The sensor occupies a sensing area of 1 mm × 1 mm with a chip area of 2 mm × 2.4 mm and is interfaced with a custom-designed low-noise electronic IC chip over a flexible substrate. The packaged sensor unit occupies an area of 2.5 mm × 6.2 mm with a weight of 25 mg. The sensor unit attached to umbo can detect a sound pressure level (SPL) of 60 dB at 500 Hz, 35 dB at 2 kHz, and 57 dB at 8 kHz. An improved sound detection limit of 34-dB SPL at 150 Hz and 24-dB SPL at 500 Hz can be expected by employing start-of-the-art MEMS fabrication technology, which results in an articulation index of approximately 0.76. Further micro/nanofabrication technology advancement is needed to enhance the microphone sensitivity for improved understanding of normal conversational speech.

Conservative management of vestibular schwannoma: expectations based on the length of the observation period.

Objective Evaluate long-term prevalence of tumor growth and need for further treatment in patients with a vestibular schwannoma treated with conservative management. Study Design Retrospective chart review. Setting Private neurotologic tertiary referral center. Patients Vestibular schwannoma patients undergoing conservative management and previously studied (N = 114). Mean time to last magnetic resonance imaging was 4.8 years and to last follow-up was 6.4 years (maximum, 18.5 yr). Intervention Serial gadolinium-enhanced magnetic resonance imaging with size measurement. Main Outcome Measures Change in maximum tumor dimension of 2 mm or higher (growth), further treatment, audiologic measures—pure-tone average, word recognition, AAO-HNS (American Academy of Otolaryngology-Head and Neck Surgery) hearing class. Results Thirty-eight percent of tumors demonstrated growth; an average of 6.5 mm (SD, 3.8) at a mean rate of 3.1 mm per year. Of patients with no growth at 1 year or less, 20% grew by last follow-up. Overall, 31% had further treatment after a mean of 3.8 years (SD, 3.5; maximum, 18.5 yr). Of those followed for 5 to 10 years, 18% eventually had further treatment. Only 56% of growing tumors had further treatment by last follow-up; 14.8% with nongrowing tumors also had further treatment. Pure-tone average declined more in tumors that grew (mean &Dgr; = 28.8 dB) than those that did not (mean &Dgr; = 16.5 dB) (p ⩽ 0.025), but there was no correlation between the amount of change in hearing and in the size of the tumor. Of patients with an initial AAO-HNS hearing Class A, 85.7% retained serviceable hearing. Conclusion For patients electing an observation approach to treatment of vestibular schwannoma, about 31% may eventually undergo further treatment. Of those followed for 5 to 10 years, 18% eventually had further treatment. However, some patients are followed with radiologic evaluations for many years without necessity for further treatment.

Ménière's Disease: A Challenging and Relentless Disorder

Ménières disease (MD) is characterized by episodic vertigo, fluctuating hearing loss and tinnitus, and by the presence of endolymphatic hydrops on postmortem examination. This disease continues to be a diagnostic and therapeutic challenge. Patients with MD range from minimally symptomatic, highly functional individuals to severely affected, disabled patients. Current management strategies are designed to control the acute and recurrent vestibulopathy but offer minimal remedy for the progressive cochlear dysfunction. Recent research highlights the role of neurotoxicity in the pathogenesis of the cochleovestibular deterioration. This article discusses a patient with MD, and provides an algorithm for the management of this disease.