Pleomorphic adenoma arising in the external auditory canal is rare. We report the case of a 38-year-old man. To better grasp the clinical features and natural history of this uncommon tumour, we also reviewed the world wide literature and found 24 similar cases, which we analysed together with our own.

Schwannoma arising in the posterior pharyngeal wall is rare. We report on a 60-year-old man who complained of discomfort in his pharynx, from whom a tumour was excised via an intraoral approach. No recurrence was seen after an 11-year follow-up. The nerve origin of the tumour is most likely to be the peripharyngeal plexus. This is the third such case reported.

The effects of the stimulus rate on the auditory brainstem reponses (ABRs) of acoustic neuroma (AN) patients were studied. Ninety-decibel click stimuli at a normal hearing level were delivered at stimulus rates of 9.5,20,40 and 90 Hz, and ABRs were recorded of 40 AN patients (40 ears) at each stimulus rate. Subjects with normal hearing (42 ears) and patients with sensorineural hearing loss (30 ears) were also studied to obtain normative data. The following two parameters were examined: the interpeak latency difference between wave I and wave V (IPLI-V) at each stimulus rate, and the increase in IPLI-V (ΔIPL I-V) when the stimulus rate was increased from 9.5 Hz. AN patients showed significantly larger values for both parameters at all stimulus rates compared to those of the control groups. Among 6 AN patients with normal ABRs at 9.5 Hz, 5 showed abnormal IPL I-V or abnormal ΔIPL I-V at 90 Hz, when the upper normal limits of both parameters were defined as the mean plus 2 SD of the group with normal hearing. These results suggest that recording ABR at high stimulus rates provides valuable information for detecting AN patients with normal ABRs.

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