Extralabyrinthine manifestations of DFNA9.

DFNA9 is an autosomal dominant cause of non-syndromic adult-onset sensorineural hearing loss with associated variable vestibular dysfunction caused by mutations in the COCH gene. DFNA9 has previously been characterized by the presence of unique histopathologic features limited to the cochlear and vestibular labyrinth. This report describes newly discovered extralabyrinthine findings within the middle ear in DFNA9 and discusses their implications. The histopathologic anatomy of extralabyrinthine structures was reviewed in 12 temporal bones from seven individuals with DFNA9 and compared with age-matched controls. All temporal bones with DFNA9 had abnormal deposits within the tympanic membrane, incudomalleal joint, and incudostapedial joint. Hematoxylin and eosin stain and Movat's pentachrome stain both revealed different staining patterns of the extralabyrinthine deposits compared with the intralabyrinthine deposits suggesting that the composition of the deposits varies with location. The deposits within the tympanic membrane resembled cartilage morphologically and stained positively for aggrecan, an extracellular matrix protein found in cartilage. However, the cellular component of the tympanic membrane deposits did not stain with immunomarkers for chondrocytes (s100 and connective tissue growth factor). These novel findings in DFNA9 have implications for the phenotypic expression of the disorder and the clinical workup of adult-onset sensorineural hearing loss.

Imaging characteristics of children with auditory neuropathy spectrum disorder.

OBJECTIVE: To identify and define the imaging characteristics of children with auditory neuropathy spectrum disorder (ANSD). DESIGN: Retrospective medical records review and analysis of both temporal bone computed tomographic (CT) and magnetic resonance images (MRI) in children with a diagnosis of ANSD. SETTING: Tertiary referral center. PATIENTS: One hundred eighteen children with the electrophysiologic characteristics of ANSD with available imaging studies for review. INTERVENTIONS: Two neuroradiologists and a neurotologist reviewed each study, and consensus descriptions were established. MAIN OUTCOME MEASURES: The type and number of imaging findings were tabulated. RESULTS: Sixty-eight (64%) MRIs revealed at least 1 imaging abnormality, whereas selective use of CT identified 23 (55%) with anomalies. The most prevalent MRI findings included cochlear nerve deficiency (n = 51; 28% of 183 nerves), brain abnormalities (n = 42; 40% of 106 brains), and prominent temporal horns (n = 33, 16% of 212 temporal lobes). The most prevalent CT finding from selective use of CT was cochlear dysplasia (n = 13; 31%). CONCLUSION: Magnetic resonance imaging will identify many abnormalities in children with ANSD that are not readily discernable on CT. Specifically, both developmental and acquired abnormalities of the brain, posterior cranial fossa, and cochlear nerves are not uncommonly seen in this patient population. Inner ear anomalies are well delineated using either imaging modality. Because many of the central nervous system findings identified in this study using MRI can alter the treatment and prognosis for these children, we think that MRI should be the initial imaging study of choice for children with ANSD.

Radiation therapy for the treatment of vestibular schwannoma: a critical evaluation of the state of the literature.

OBJECTIVE: Review publications reporting radiation treatment of vestibular schwannomas (VS) and describe how data, patient characteristics, and study endpoints were reported. DATA SOURCES: PubMed search for English language articles on radiation treatment of VS published from January 2002 to July 2007. STUDY SELECTION: Studies presenting outcomes were selected, yielding 56 articles (58 studies) in journals of neurosurgery (30), oncology (18), otolaryngology (6), and other (2). DATA EXTRACTION/SYNTHESIS: Data included type of study, number of subjects, demographics, follow-up times, type of radiation, tumor size, tumor control definition, control rates, facial nerve function measure and outcome, type of hearing and vestibular testing and outcomes, and complications. Descriptive statistics were performed. RESULTS: Studies (72.9%) were retrospective reviews with stated sample sizes ranging from 5 to 829. Gamma-knife (49.2%), linear accelerator (35.6%), and proton beam (6.8%) were used with various doses. Average follow-up was less than 5 years in 79.6% of studies, and 67.4% included patients at less than or equal to 1 year. Tumor size was reported as diameter (23.7%), volume (49.2%), both (11.9%), other (3.4%), or not reported (11.9%). Definition of tumor control varied: less than or equal to 2 mm growth (22.0%), no visible/measurable change (16.9%), required surgery (10.2%), other (17.0%), and not clearly specified (33.9%). Facial nerve outcome was reported as House-Brackmann (64.4%), normal/abnormal (11.9%), other (1.7%), or was not reported (22%). CONCLUSION: The lack of uniform reporting criteria for tumor control, facial function and hearing preservation, and variability in follow-up times make it difficult to compare studies of radiation treatment for VS. We recommend consideration of reporting guidelines such as those used in otology for reporting VS resection results.

False-positive magnetic resonance imaging in the diagnosis of vestibular schwannoma.

OBJECTIVE: To describe the case of a true false-positive finding on magnetic resonance imaging, mimicking a vestibular schwannoma, and review the pertinent literature. PATIENTS: The case of a single patient with a suspicion of a vestibular schwannoma. INTERVENTION: A middle fossa craniotomy was performed for resection of the presumed schwannoma. MAIN OUTCOME MEASURES: Intraoperative findings and postoperative magnetic resonance imaging (MRI). RESULTS: : Intraoperative findings and a postoperative MRI confirm the absence of a neoplasm. CONCLUSION: False-positive findings on MRI, though rare, do occur. The clinician should have a high index of suspicion and consider reimaging in some cases.

Minimally invasive pituitary surgery.

OBJECTIVES/HYPOTHESIS: Surgical approaches to the pituitary have undergone numerous refinements over the last 100 years. The introduction of the endoscope and the advent of minimally invasive pituitary surgery (MIPS) have revolutionized pituitary surgery. This study aims to compile and evaluate outcomes of all of the MIPS performed at our institution. STUDY DESIGN: Retrospective, cases series of 176 consecutive patients undergoing MIPS. METHODS: Patient demographics, tumor characteristics, and intraoperative or postoperative complications for of 176 consecutive patients undergoing MIPS were complied. Statistical analysis for categorical variables and incidence across series were conducted using Pearson's chi test and Fisher's exact tests. Odd ratios were calculated to relate the discrete variables to outcomes and designing clinical prediction of risk. RESULTS: One hundred seventy-six patients who underwent 193 procedures. Pathologic evaluation revealed 147 of the tumors to be pituitary adenomas. Only one death occurred (mortality rate of 0.5%). The rate of diabetes insipidus occurred in 20.2% of the procedures. Vascular complications occurred in 5.2% of the procedures. Intraoperative cerebrospinal fluid (CSF) leaks were identified in 19.7% whereas postoperative CSF leak was noted in 10.3%. Resection of Rathke's cleft cyst correlated higher risk of both intraoperative and postoperative CSF leak (OR = 2.6, P <.001). Resection of tumors other than adenomata correlated with significantly higher risk of CSF leak (OR = 9.0, P = <.001). Sinusitis occurred after eleven resections (5.7%). Meningitis occurred in 2 of 193 resections (1.0%) in our series. Two neurologic complications occurred in our series, pneumocephalus and cranial neuropathy (1.0%). No other complications occurred. CONCLUSIONS: MIPS is a safe and efficacious marriage of the endoscope to the transsphenoidal approach. Thus, a brightness and clarity of vision is combined with the unique ability to explore the tumor bed with angled views and hydroscopy. Outcomes and complication rates comparable to traditional transsphenoidal approaches have resulted but with less dissection and tissue manipulation, reduced need for packing, and greater patient comfort and acceptance.

Endoscopic anatomy of the parasellar region.

BACKGROUND: The aim of this study was to describe the endoscopic anatomy of the cavernous sinus and adjoining parasellar regions and their relationships to the sphenoid sinus. METHODS: An endoscopic transnasal transsphenoidal approach to the pituitary gland and posterior skull base was performed on three fresh frozen cadaver heads (six sides). Neural and vascular anatomic landmarks of the cavernous sinus and parasellar regions were identified and correlated with sphenoid surface anatomy. RESULTS: The posterior wall of the sphenoid sinus presents several surface landmarks allowing the identification of the sella, carotid artery, and optic nerve. Identification of the optic-carotid recess allows reflection of the internal carotid artery medially and access to the cavernous sinus. Further lateral dissection allows for easy identification of the oculomotor, trochlear, trigeminal, and abducens nerves. The ophthalmic artery then can be followed from its origin on the internal carotid artery coursing anteriorly into the orbit. The optic chiasm also can be easily identified superiorly. Posteriorly, careful dissection allows access to the basilar artery along the clivus. CONCLUSION: As endoscopic surgeons continue to expand their procedures to involve areas of the skull base outside the paranasal sinuses, knowledge of the endoscopic anatomy of the sella, parasellar, and adjacent areas is paramount. Critical landmarks are readily evident in the sphenoid sinus providing good access to neural and vascular structures of this region of the skull base.

Radiation dose to the eyes and parotids during CT of the sinuses.

OBJECTIVE: To measure the radiation dose to the lens and parotid during high-resolution computed tomography scan of the sinuses. STUDY DESIGN AND SETTING: Nine cadaver heads were scanned in the axial plane by means of a fine-cut (0.75 mm) protocol. Images were then reconstructed in the coronal and sagittal planes for use with the image guidance software. Thermoluminescent dosimeters were taped over the eyes and parotids and used to measure the radiation dose absorbed by these organs. RESULTS: Doses obtained were 29.5 mGy for the lens and around 30 mGy for the parotid. CONCLUSION: The measured doses are lower than the reported acute thresholds of 500-2000 mGy for lens opacities and well below the threshold of 2500 mGy for damage to the parotid. SIGNIFICANCE: These results demonstrate minimal risk from radiation through the use of high-resolution computed tomography and support the use of such a protocol for diagnosis and preoperative planning.

MED-EL Combi40+ cochlear implantation in adults.

OBJECTIVE/HYPOTHESIS: Cochlear implantation is currently the treatment of choice for severe to profound sensorineural hearing loss. The MED-EL Combi40+ (Innsbruck, Austria) cochlear implant system was approved for use in the United States in 2001. This device employs a 31-mm-long electrode array, ceramic case, and continuous interleaved sampling with Hilbert transformation for envelope extraction. A single institution's experience with the Combi40+ implant in adult patients was reviewed. STUDY DESIGN: Retrospective chart review. METHODS: Medical-surgical and audiological data were collected from 112 patients who received a MED-EL Combi40+ cochlear implant between December 1998 and April 2004. RESULTS: The rate of surgical complications and speech perception testing results compared favorably with those of other cochlear implant systems. For postlingually deafened adults, mean CNC word, HINTQ, CUNY, and HINT + 10 dB signal-to-noise ratio scores after 1 year of implant usage were 54%, 87%, 96%, and 64%, respectively. Prelingually deafened adults also derived significant benefit, but plateau performance for these patients was well below that for patients with later onset of deafness and significant variability was seen in this group. Repeat implantation for suspected device malfunction was undertaken in seven cases (6% of devices) (mean duration of use, 28 +/- 12 mo) with ultimate resolution of the presenting problem. CONCLUSION: The study results support the safety and efficacy of cochlear implantation with the MED-EL Combi40+ cochlear implant system.

Tympanostomy tube obstruction related to ototopical drug therapy.

Obstruction of tympanostomy tubes is a potentially significant complication, sometimes requiring replacement of the nonfunctioning tube. Early blockage can occur secondary to bleeding during the tube placement procedure. Delayed obstruction is usually caused by inspissated secretions or epithelial casts. We briefly report our treatment of 9 cases of delayed ventilation tube obstruction that were associated with the use of an ototopical antibiotic/steroid suspension.

Rapid adaptation of the 2f1-f2 DPOAE in humans: binaural and contralateral stimulation effects.

The present data were collected in humans to characterize the effects of monaural and binaural stimulation and contralateral noise on the 2f1-f2 distortion-product otoacoustic emission (DPOAE) adaptation response. DPOAE levels (f2/f1=1.21, L1=70 dB SPL, L2=65 dB SPL) were measured in both ears for a range of f2 frequencies (1.2 to 10.0 kHz). The f2 frequency producing the largest amplitude DPOAE was used for further testing employing three different stimulus conditions: the primary tones were presented to only one ear for 4 s; the two tones were presented simultaneously in both ears; and, contralateral broadband noise (60 dB SPL) was presented for 5 s, beginning 4 s after the onset of the monaural primaries in the test ear. Acoustic reflex thresholds were measured to verify that the middle-ear muscles played no systematic role in the measured DPOAE reductions. Estimates of monaural rapid adaptation levels and time constants agreed well with previous human findings. The magnitude of the rapid adaptation under binaural stimulation, as compared with monaural primaries, was 25% greater on average, though adaptation time constants were comparable. With added contralateral noise, the average DPOAE suppression was 1.1 dB (0.3-2.7 dB). The magnitude of the monaural adaptation and the effects of binaural and contralateral stimulation, however, were smaller than those measured previously in experimental animals, though the time constants were in good agreement.