Hearing preservation in acoustic neuroma surgery.

This article reviews the Montreal experience of hearing preservation in acoustic neuroma surgery. The medical records since 1995 of 36 patients who underwent acoustic neuroma extirpation with the intent to preserve hearing were examined. Intraoperative monitoring was conducted using auditory brainstem response measurement with electrocochleography via a transtympanic electrode. The role of intraoperative monitoring in guiding surgical technique and its correlation with postoperative hearing outcome are discussed. A review of the literature regarding hearing preservation in acoustic neuroma surgery is included.

Intratympanic cholesteatoma.

Cholesteatomas occurring behind an intact TM are relatively unusual, and intratympanic keratomas are even less common. This article presents the case of a Baffin Zone Inuit gentleman with an intratympanic cholesteatoma confined to the membranous portion of his TM. Although it is generally accepted that many native populations, including the Inuit, demonstrate an elevated preponderance of aural disease, cholesteatoma formation, particularly within the TM, in an individual from this area of the high Arctic is extremely rare.

Spontaneous vertebral artery dissection mimicking acute vertigo. Case report.

A patient with acute vertigo, and normal findings on neurologic examination, was found to have vertebral artery dissection (VAD). This case shows that the clinical picture of VAD can mimic vertigo of labyrinthine (i.e, peripheral) origin.

Standardized format for depicting hearing preservation results in the management of acoustic neuroma.

The Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery recently published guidelines for reporting hearing preservation in the treatment of acoustic neuromas. These suggestions included pretreatment and posttreatment pure-tone hearing thresholds, word recognition scores, and hearing classification. We present a standardized reporting format that addresses the Committee's recommendations and displays individual patient audiologic data as a simple, concise plot of posttreatment hearing results. To illustrate the use of the recommended format, preoperative and postoperative hearing data from our institution are reported. Such reporting criteria will facilitate comparative reviews of studies of hearing preservation after surgical or radiotherapeutic management of acoustic neuromas, while providing specific data for individual patient outcome analysis.

Electron microscopic temporal bone histopathology in experimental pneumococcal meningitis.

Bacterial meningitis is one of the most common causes of acquired profound sensorineural deafness in children. Measurement of hearing and examination of the cochlea is limited in patients suffering from acute meningitis. A rabbit model of pneumococcal meningitis was developed to identify the temporal bone histopathologic changes that occur in meningogenic labyrinthitis caused by Streptococcus pneumoniae. Light microscopy was previously performed on temporal bones from acutely meningitic rabbits with profound hearing loss as determined electrophysiologically. Extensive inflammation of the cochlea with endolymphatic hydrops was observed. The organ of Corti, however, showed preserved architecture in the majority of these animals. In order to further investigate these findings, a protocol was used to create meningitic rabbits with hearing loss ranging from early high-frequency loss to profound deafness. The temporal bones from 7 rabbits were examined by transmission electron microscopy. In cases of mild hearing loss, partial degeneration of the inner row of outer hair cells, as well as edema of efferent cochlear nerve endings and marginal cells of the stria vascularis, was seen. With increasing degrees of hearing loss, the remainder of the organ of Corti and intermediate cells of the stria showed ultrastructural abnormalities. Spiral ganglion cells and basal cells of the stria vascularis remained intact in all subjects. This study provides unique information regarding the histology and pathophysiology of meningogenic deafness. The clinical implications of these findings are discussed, with an emphasis on potentially reversible changes and therapeutic intervention.

Prevention of hearing loss in experimental pneumococcal meningitis by administration of dexamethasone and ketorolac.

Pneumococcal meningitis remains a significant cause of morbidity, particularly sensorineural hearing loss. Recent literature has suggested that a vigorous host immune response to Streptococcus [corrected] pneumoniae is responsible for much of the neurologic sequelae, including deafness, after bacterial meningitis. This study used a rabbit model of hearing loss in experimental pneumococcal meningitis to evaluate the therapeutic effect of two anti-inflammatory agents, dexamethasone and ketorolac, coadministered with ampicillin. Both adjunctive drugs minimized or prevented sensorineural hearing loss compared with placebo. Dexamethasone, administered 10 min before ampicillin, was particularly effective in minimizing mean hearing threshold change compared with placebo for both clicks (dexamethasone: 6.7-dB sound pressure level [SPL] vs. placebo: 33. 4-dB SPL, P=.0078) and 10-kHz tone bursts (dexamethasone: 8.4-dB SPL vs. placebo: 53.4-dB SPL, P=.0003). These findings support the beneficial role of anti-inflammatory agents in reducing the incidence of hearing loss from pneumococcal meningitis, especially if therapy is instituted early in the course of infection.

Pneumocephalus in frontal sinus osteoma: a case report.

Osteomas are the most commonly encountered neoplasms of the frontal sinus. Extension of these lesions through the posterior table can result in life-threatening complications. We present the case of a 70-year-old man with yellow nail syndrome who complained of persistent rhinorrhea and the sensation of "sloshing" when moving his head. Radiographic investigation revealed a frontal mucocele that had extended to a dramatic intracerebral pneumatocele. This occurred secondary to a frontal sinus osteoma that had been incidentally noted seven years earlier. Surgical exploration via an osteoplastic flap approach allowed us to excise both the osteoma and the associated pneumatomucocele. The resulting dural defect was resurfaced using a flap of pericranium to facilitate anterior cranialization. The features of this interesting case are discussed as an illustration of the potential complications of frontal sinus osteomas. The literature is reviewed regarding management of these lesions and their complications.

Auditory temporal resolution in multiple sclerosis.

Disturbances of hearing in multiple sclerosis patients have been variably reported, likely because standard audiologic testing emphasizes assessment of peripheral, rather than central, auditory function. This study investigated a group of patients with multiple sclerosis (MS), prospectively selected on the basis of magnetic resonance imaging (MRI) scans. Five of these patients had demyelinating lesions that included the rostral auditory fibre tracts, while another seven patients had lesions restricted to brainstem auditory sites. A further four had no lesions in the distribution of their auditory pathways. A comprehensive battery of audiometric tests, including standard audiometry and retrocochlear testing, was performed. In addition, their findings on electrophysiologic testing, including auditory brainstem responses (ABR) and middle latency responses (MLR), were studied. Finally, their performances in gap detection and speech recognition in continuous and interrupted background noise were examined to assess their auditory temporal resolution. The MS patients were found to be selectively impaired under the interrupted masker of this speech-in-noise paradigm, confirming a temporal processing defect. Furthermore, these patients' performances suggested a predominant role of forebrain pathways in mediating auditory temporal resolution.

Impaired word recognition in noise by patients with noise-induced cochlear hearing loss: contribution of temporal resolution defect.

Fifteen patients with mild noise-induced cochlear hearing loss reported a selective difficulty in understanding speech in noisy settings. To examine the hypothesis that a temporal resolution defect was responsible for this difficulty, the patients were tested for their recognition of monosyllabic words presented against continuous and interrupted wide-band noise backgrounds, at each of seven signal-to-noise ratios. Their recognition performance was compared with that of normal listeners studied with the same paradigms. By comparison with the controls, the group with cochlear hearing loss showed a significant recognition impairment only for words presented against the interrupted masker. This finding was in keeping with the existence of a temporal resolution defect in cochlear disease, though it need not indicate a stimulus timing defect at the level of individual cochlear neurons.

Disturbed speech intelligibility in noise despite a normal audiogram: a defect in temporal resolution?

Patients with complaints of disturbed speech intelligibility in noise, despite normal standard audiograms, constitute a unique yet not uncommon population of listeners. The literature on this patient group is reviewed, and the term Idiopathic Discriminatory Dysfunction (IDD) is introduced in an attempt to standardize and qualify the distinct characteristics of this entity. Preliminary studies of these patients have hypothesized both frequency and temporal resolution deficits underlying this impairment. A representative group of 15 patients suffering from IDD were tested using a new speech-in-noise paradigm designed to test temporal resolution. These patients were found to have near-normal temporal resolving capacity as determined by this task.

Cerebrospinal fluid leaks and meningitis in acoustic neuroma surgery.

Cerebrospinal fluid leaks and associated meningitis are the most common life-threatening complications of surgery for acoustic neuromas. This retrospective study reviews 319 patients who had surgery for 321 acoustic tumors at the Sunnybrook Health Sciences Center, University of Toronto, from April 1975 to March 1990. Cerebrospinal fluid leaks occurred after 13.4% of primary tumor operations. Surgical repair was required in 6.2% of all patients; 4.4% needed more than one operation. Meningitis occurred in 5.3% of all patients. These complications were more common in larger tumors and after the combined translabyrinthine middle fossa approach. Transnasopharyngeal eustachian tube obliteration was used to stop recurrent cerebrospinal fluid leaks in two patients.

Cyclophosphamide, carmustine, and etoposide with autologous bone marrow transplantation in refractory Hodgkin's disease and non-Hodgkin's lymphoma: a dose-finding study.

Cyclophosphamide, carmustine (BCNU), and etoposide (VP-16) (CBV) is a widely used conditioning regimen in autologous bone marrow transplantation (ABMT) of patients with refractory and relapsed lymphoma. However, the maximum-tolerated dose (MTD) of these agents when used in combination has not been systematically explored. We treated 58 patients (28 with non-Hodgkin's lymphoma [NHL], 30 with Hodgkin's disease [HD]) at seven dose levels of CBV. Doses were cyclophosphamide 4,500 to 7,200 mg/m2, BCNU 450 to 600 g/m2, and VP-16 1,200 to 2,000 mg/m2. The MTD was cyclophosphamide 7,200 mg/m2, BCNU 450 mg/m2, and VP-16 2,000 mg/m2. Six hundred milligrams per square meter of BCNU was associated with five of 18 cases of interstitial pneumonitis versus two of 40 at 450 mg/m2 (P = .02). Treatment-related mortality was 5% at dose levels less than or equal to the MTD and 22% at the highest dose. In this heavily pretreated patient population, most of whom had high volume residual disease, complete responses (CRs) to CBV and ABMT occurred in 25% of assessable patients with NHL and 43% of patients with HD. Thirteen of 28 patients with NHL and 14 of 30 with HD remain free from disease progression with median follow-up of 212 and 215 days, respectively. CBV can be administered with acceptable toxicity over a wide range of doses to patients with refractory and relapsed lymphoma.

Increased serum immunoglobulin E levels following allogeneic bone marrow transplantation.

IgE levels were determined before and serially after allogeneic bone marrow transplantation (BMT) in 12 patients. Six patients had aplastic anemia, four leukemia, and one each Wiskott-Aldrich syndrome and infantile agranulocytosis. IgE levels increased sharply (7- to 2,000-fold) in 10 of the 12 as early as 14 days after BMT. They all returned to baseline levels by 60 days. In six of these patients, the rise accompanied clinical and biochemical evidence of acute graft-versus-host disease (GVHD). All of the patients who received rabbit antihuman thymocytic serum (ATS) in preparation for transplantation and were tested for IgE antirabbit serum antibody by radioallergosorbent test (RAST) (n = 6) developed a strongly positive RAST which paralleled their total IgE levels. These high IgE levels detected during the period of acute GVHD may be a manifestation of a transient lack of suppressor T cell activity.