John A. Rutka

Intratympanic Gentamicin for Menière's Disease: a Meta-Analysis

Objectives: To systematically review the published experience on intratympanic gentamicin treatment for intractable Menières disease.

Conservative management of vestibular schwannomas: third review of a 10-year prospective study.

•  Seventy‐two patients with a unilateral vestibular schwannoma have been treated conservatively for a median of 121 months. They have been followed prospectively by serial clinical examination, MRI scans and audiometry. •  Twenty‐five patients (35%, 95% CI: 24–47) failed conservative management and required active intervention during the study. No factors predictive of tumour growth or failure of conservative management could be identified. Seventy‐five per cent of failures occurred in the first half of the 10‐year study. •  The median growth rate for all tumours at 10 years was 1 mm/year (range −0.53–7.84). Cerebellopontine angle tumours grew faster (1.4 mm/year) than intracanalicular tumours (0 mm/year, P < 0.01); 92% had growth rates under 2 mm/year. •  Hearing deteriorated substantially even in tumours that did not grow, but did so faster in tumours that grew significantly (mean deterioration in pure tone average at 0.5, 1, 2 and 3 kHz was 36 dB; speech discrimination scores deteriorated by 40%). •  Patients who failed conservative management had clinical outcomes that were not different from those who underwent primary treatment without a period of conservative management.

Evidence of Vestibular and Balance Dysfunction in Children With Profound Sensorineural Hearing Loss Using Cochlear Implants

Objectives/Hypothesis: Similarities between the peripheral auditory and vestibular systems suggest that children with sensorineural hearing loss (SNHL) may demonstrate vestibular and balance impairments. This hypothesis was studied in 40 children with severe to profound SNHL and unilateral cochlear implants.

Management of hydrocephalus associated with vestibular schwannoma and other cerebellopontine angle tumors.

OBJECTIVEHydrocephalus (HCP) resulting from cerebellopontine angle (CPA) tumors is not rare. This retrospective study was designed to investigate the incidence of HCP and the clinical presentations, management options, and outcomes of HCP in 284 patients with CPA tumors. METHODSA retrospective study of 284 consecutive patients with CPA tumors (mostly vestibular schwannomas) treated from 1985 to 1996 at Toronto Western Hospital managed by one surgical team consisting of a neurosurgeon and a neuro-otologist. RESULTSThirty-nine patients (13.7%) had radiographic and/or clinical evidence of HCP, 37 preoperatively and 2 postoperatively. Tumor type distribution was 33 vestibular schwannomas, 5 meningiomas, and 1 cavernous hemangioma. Only five patients (12%) had obvious obstruction at the fourth ventricular level. In 36 patients (92%), symptoms were mostly chronic and mild, consistent with normal pressure hydrocephalus. Multivariate analysis confirmed the strong association of tumor size and incidence of HCP (P < .0001). Four patients underwent permanent shunting before microsurgical tumor excision, mainly because of florid symptoms of HCP. Microsurgical tumor excision without preoperative shunting was performed in 23 patients, 5 of whom required postoperative shunting in the first 2 months after tumor excision. Eighteen patients (78%) did not need shunts after tumor resection. With regard to tumor size, the postoperatively shunted group did not differ from the patients who had surgery but did not require shunt treatment (P < 0.50). The remaining 10 patients with preoperative HCP received shunts as the only treatment (3 patients), stereotactic radiosurgery (3 patients), or expectant management (4 patients). Two other patients without preoperative HCP developed postoperative HCP and required shunts. Postoperatively, we observed a significant (P < 0.001) increase in the incidence of pseudomeningocele and a nonsignificant (P < 0.1) increase in cerebrospinal fluid leaks (rhinorrhea and/or otorrhea) in patients without shunts as compared with postoperative patients without HCP. The patients were followed after any treatment for a mean of 3.2 years (range, 6 mo–10 yr). Follow-up in the patients who had surgery but did not require a shunt revealed a 61% decrease in clinical symptoms related to HCP and a 75% decrease in radiographic signs of HCP. CONCLUSIONIn the presence of HCP, operative resection of CPA tumors can be performed without permanent cerebrospinal fluid shunting. Precautionary measures to decrease the incidence of postoperative complications related to cerebrospinal fluid leak in patients with preoperative HCP include meticulous obliteration of any exposed air cells, including those around the internal auditory canal, accurate restoration of the dural barrier, and temporary lowering of intracranial pressure with a ventricular or lumbar drain. Patients with persistent symptomatic HCP after tumor excision should be treated with a ventriculoperitoneal shunt. Delaying this decision until the postoperative period is safe and avoids unnecessary shunting in the majority of patients.

The incidence and distribution of cupular deposits in the labyrinth

Findings of large basophilic staining deposits on the cupula of the posterior semicircular canal ampulla have been used in part to explain the clinical phenomenon of benign positional vertigo (BPV). Although it is generally agreed that cupulolithiasis may involve other canal ampullae, the precise nature, distribution, and origin of these deposits remains unclear. In order to provide a better understanding of this finding, a series of 566 temporal bone specimens from the Ear Pathology Research Laboratory at the University of Toronto were reviewed. The results from this survey and speculations concerning the nature and formation of these deposits are discussed.

Vestibular end-organ dysfunction in children with sensorineural hearing loss and cochlear implants: an expanded cohort and etiologic assessment.

Introduction Similarities between the peripheral auditory and vestibular systems suggest that children with sensorineural hearing loss (SNHL) may demonstrate associated vestibular impairments. The current study examines vestibular function in a previously reported cohort (n = 40) augmented by 113 children with profound SNHL. Methods The current study is prospective and cross-sectional with repeated measures. Horizontal canal function was assessed in response to caloric and rotational stimuli. Saccular function was examined using vestibular evoked myogenic potentials (VEMP). One hundred fifty-three children were tested; 119 had unilateral cochlear implants (CIs) at time of testing, and 34 were evaluated before CI. Results Horizontal semicircular canal function was abnormal in response to caloric stimuli in 50% (69/139), with a proportion (18/69, 26%) reflecting mild to moderate unilateral abnormalities. Severe hypofunction or areflexia occurred in 37% (51/139). Horizontal semicircular canal function in response to rotation was abnormal in 47% (64/139). Bilateral reduction in VOR gain was seen across frequencies in 29% (40/139) and 13% (18/139) demonstrated isolated high-frequency (≥2 Hz) loss. Saccular function was absent bilaterally in 21% (32/135) and unilaterally in 30% (40/135). All children with meningitis (n = 11) and 46% with radiologic cochleovestibular anomalies (n = 31) had horizontal canal dysfunction, whereas 45% and 46%, respectively, displayed saccular dysfunction. Unilateral dysfunction of the horizontal canal or the saccule was equally distributed between the implanted and nonimplanted ear (14:9 and 22:18, respectively), and the differences in proportions were not statistically significant. Conclusion Vestibular end organ dysfunction occurred in half of all children with profound SNHL. Approximately one-third of the subjects displayed severe abnormalities(bilateral and/or severe loss). The likelihood of vestibular end-organ dysfunction is highly dependent on etiology, with meningitis and cochleovestibular anomalies having the highest rates of severe dysfunction.

Consequences to hearing during the conservative management of vestibular schwannomas.

Objective: To estimate the risk of loss of serviceable hearing during the conservative management of vestibular schwannomas.

Vestibular end-organ and balance deficits after meningitis and cochlear implantation in children correlate poorly with functional outcome.

Objective: Assess vestibular and balance function in meningitis-induced profound sensorineural hearing loss (SNHL). Study Design: Prospective cohort study. Setting: Tertiary pediatric referral center. Patients: Nine pediatric participant with profound SNHL after bacterial meningitis with (8) and without (1) unilateral Cochlear implant. Main Outcome Measure(s): Horizontal canal function in response to caloric and high-frequency rotation (0.25-5 Hz). Saccular function assessed by the vestibular evoked myogenic potential. Static and dynamic balance performance on the balance subset of the Bruininsk-Oseretsky Test of Motor Proficiency 2. Labyrinthine ossification on computed tomography preimplant, with follow-up imaging in a subset (n = 7). Results: Horizontal canal function in response to caloric stimulation was abnormal in all children, with 5 of 8 demonstrating bilateral areflexia and 3 of 8 having asymmetric hypofunction with better function on the implanted side. In response to rotation, horizontal canal function was abnormal in all but 1 child (8 of 9). Saccular function, assessed by VEMP, was intact in most of the children (5 of 7). Static and dynamic balance (Bruininsk-Oseretsky Test of Motor Proficiency 2 scores) were significantly poorer in the meningitis group compared with both normal-hearing controls (p < 0.01) and children with SNHL of variable etiology and Cochlear implant (p < 0.01). Labyrinthine ossification was present in all cases, with variable extent, location, and progression. Conclusion: Vestibular function and balance are compromised in children with SNHL after meningitis. Whereas vestibular loss seems well compensated at low frequency through an overreliance on visual inputs, deficits surface during high-frequency rotation, particularly in dark. Saccular function seems less susceptible to damage from meningitis. Extent, location, and progression of ossification were variable. Despite profound dysfunction on objective testing, subjective limitations in functional balance were not reported, demonstrating the significant ability of children to compensate for even the most severe vestibular losses.

Ototoxicity of Topical Gentamicin Preparations

Objective: To document that commercially available topical gentamicin‐containing eardrops carry a risk of ototoxicity if they reach the middle ear through a tympanic membrane defect. Study Design: Clinical study, retrospective case‐note review. Setting: Department of Otolaryngology, The Toronto Hospital, University of Toronto. Patients: Sixteen patients were identified with well‐documented histories, physical findings and laboratory investigations consistent with topical gentamicin‐induced ototoxicity. One patient with incapacitating unilateral Menieres disease underwent successful intentional vestibular ablation using topical gentamicin/steroid drops. Results: In all cases of inadvertent ototoxicity, patients had used the drops for longer than 7 days (average 20.7 d) prior to symptoms developing. All patients developed vestibulotoxicity that was confirmed on ENG testing. Only 1 patient had a noticeable worsening of cochlear reserve. Deliberate and successful therapeutic ablation of vestibular function in a patient with unilateral Menieres disease confirms the vestibulotoxic nature of commercially available topical gentamicin preparations. Conclusions: Physicians should consider the potential for ototoxicity if gentamicin‐containing eardrops (and by extrapolation all topical aminoglycoside drops) are used for longer than 7 days in patients with a tympanic membrane defect. These preparations should not be used in the presence of healthy middle ear mucosa and should be discontinued shortly after the discharge has stopped. It is important to recognize that toxicity is primarily vestibular rather than cochlear.

Significance of Head-shaking Nystagmus in the Evaluation of the Dizzy Patient

In a series of studies, the phenomenon of head-shaking nystagmus (HSN) was assessed in 50 control subjects and 1364 consecutive dizzy patients who underwent formal electronystagmography (ENG) at the Toronto Hospital Center for Advanced Hearing and Balance Testing. HSN was compared in a series of 30 patients who underwent conventional electro-oculography (EOG) vs magnetic (scleral) coil eye movement recordings. Clinical correlation of HSN to other parameters of the ENG test battery was performed in another sub-series of 300 patients with known diagnoses. HSN was identified in 31.7% of dizzy patients vs 24% of control subjects. No significant difference in its manifestation was noted between active vs passive head-shaking tests or on EOG vs magnetic (scleral) coil eye movement recordings. When compared to other aspects of the ENG test battery, HSN was neither specific nor sensitive for vestibular dysfunction. It nevertheless correlated well with the presence of a caloric reduction and with increasing R/L excitability differences on ENG testing. When present, HSN was characteristically monophasic in 76.8%, biphasic in 22.7% and triphasic in 0.5% of subjects. The initial direction of HSN generally obeyed Ewalds second law, but the reverse was noted in 27% with monophasic and 17.6% of patients with biphasic HSN. In the subseries of 300 patients with known diagnoses, the presence of HSN was statistically significant (p < 0.05) in patients with peripheral vestibular dysfunction vs psychogenic dizziness. Its presence was also significant in well-documented peripheral vestibular disorders such as Menieres disease (p < 0.01), vestibular neuronitis (p < 0.05) and acoustic neuroma (p < 0.05). Localization of the disease involvement based on the initial direction of HSN was especially unpredictable in patients with Menieres disease. The significance and usefulness of the head-shake test in the otoneurological evaluation of the dizzy patient is further commented on.