ABR results in patients with posterior fossa tumors and normal pure-tone hearing

The prevalence and clinical characteristics of vestibular schwannoma among patients treated as sudden sensorineural hearing loss: A 10-year retrospective study in southern China

PURPOSE

To review the prevalence and clinical characteristics of vestibular schwannoma (VS) in patients with sudden sensorineural hearing loss (SSNHL) in southern China.

MATERIALS AND METHODS

This study examined the medical records and MRI findings of all the 1249 patients diagnosed with SSNHL between May 2009 and April 2019 in the Division of Otolaryngology at Peking University Shenzhen Hospital.

RESULTS

Among the 1249 patients with SSNHL, VS was found in 14 (1.12%). Among 14 patients, 11 (78.6%) complained of tinnitus and 3 patients (21.4%) complained of dizziness as accompanying symptoms. There was one patient with SSNHL in right ear who had an incidental finding of VS in the contralateral ear. 2 patients (14.3%) had normal auditory brainstem response (ABR) test and 3 patients (21.4%) had hearing recovery. The size of tumors ranged from 6.1 mm to 24.2 mm, with 7 grade 1 tumors, 4 grade 2 tumors, and 3 grade 3 tumors. The total MRI screening cost was $130,857 and the average MRI cost for identifying a VS patient was $9346.

CONCLUSION

The prevalence of VS among patients treated as SSNHL was 1.12%. Predicting the risk of VS in SSNHL by the audiogram patterns, pure tone audiometry or hearing recovery is not relivable. Compared with ABR, MRI is more suitable for the assessment of VS in patients with SSNHL in China.

Audiological Evaluation of Vestibular Schwannoma Patients with Normal Hearing

Objective: To evaluate the audiological aspects of vestibular schwannoma (VS) patients with normal hearing. Study Design: Retrospective study. Setting: Quaternary referral center for skull base pathologies. Patients: The records on 4,000 patients who had been diagnosed with VS between 1986 and December 2017 were retrospectively reviewed. The patients included in the study were the ones who complied with the strict audiological normality criteria, as follows: a pure tone hearing threshold (at the 6-octave-spaced frequencies from 250 to 8,000 Hz) ≤25 dBHL; a word recognition score >90%; and interaural differences ≤10 dB at each frequency. Interventions: Auditory brainstem response (ABR) testing and radiological imaging. Main Outcome Measures: The incidence of normal objective hearing among VS patients, and the diagnostic utility of the ABR and the effect of tumor size and site on the response. Results: The incidence of normal hearing among VS patients was 4.2%. Tinnitus and vertigo were the most common symptoms across tumor grades; 5.6% of the tumors were large and giant tumors. The ABR yielded a sensitivity of 73.6%, with a false negative rate of 26.3% using a cutoff point of 0.2 ms for interaural latency differences. Conclusions: The diagnosis of VS should not be based on audiometric thresholds alone. Alarming signs of VS should be clear to the physician in order not to miss or delay the diagnosis of the disease. The ABR is useful in the diagnosis of VS, but normal results do not exclude the occurrence of the disease in patients with normal hearing.

Atypical presentation of acoustic neuroma

Unilateral progressive sensorineural hearing loss, tinnitus, and unsteadiness are the usual initial symptoms of acoustic neuroma. Of the last 100 consecutive cases of acoustic neuroma detected at our Centre, 14 had atypical symptoms, Five patients manifested sudden hearing loss; one of these had complete recovery. Three patients reported long-standing unilateral hearing loss, ranging from 10 to 20 years. Six patients had normal hearing, one of whom was diagnosed incidently when the investigations were performed for contralateral glomus tumor. A second patient, a young woman, experienced weakness of lower limbs. The remaining four patients had only subjective symptoms of hearing loss or tinnitus. Acoustic tumors could have been overlooked easily in these patients. It is important to have a high index of suspicion in all cases of sudden hearing loss, asymmetric sensorineural loss of any duration, subjective sensation of hearing loss, and tinnitus. It is mandatory to investigate these cases with auditory brainstem responses, any abnormality of which makes it necessary to perform magnetic resonance imaging with gadolinium.