Patients with herpes zoster oticus (HZO) may commonly show symptoms associated with 7th and 8th cranial nerve (CN VII and CN VIII) dysfunction. The aim of this study is to investigate the characteristics of hearing loss in patients with HZO and discuss possible mechanisms.Ninety-five HZO patients who showed at least one of the symptoms of CN VII and CN VIII dysfunction between January 2007 and October 2014 were included in this study. Hearing loss was defined when the mean thresholds of pure tone audiometry (PTA) in speech frequency (0.5 kHz + 1 kHz + 2 kHz/3) or isolated high frequency (4 kHz + 8 kHz/2) were greater than 10 dB in the affected ear compared with the healthy ear, and a total of 72 patients were classified as the hearing loss group.The difference of mean PTA thresholds between affected and healthy ears was significantly greater in the high frequency range than in low range (20.0 ± 11.5 dB vs. 12.9 ± 15.7 dB, P = 0.0026) in patients with hearing loss (n = 72). The difference between affected and healthy ear was significantly greater in patients with vertigo (n = 34) than those without vertigo (n = 38) in both the high (P = 0.033) and low (P = 0.024) frequency ranges. In contrast, the differences between affected and healthy ears were not significantly different between patients with facial palsy (n = 50) and those without facial palsy (n = 22) in both the high (P = 0.921) and low (P = 0.382) frequency ranges.In patients with HZO, hearing loss is more severe in the high frequency range than in the low frequency range. Hearing impairment is more severe in patients with vertigo than in those without vertigo in both the high and low frequency ranges, even though the degree of hearing impairment is not significantly different between patients with and without facial palsy. These findings indicate that the mechanisms of viral spread from CN VII to CN VIII may differ between vestibular and audiologic deficits.

Conclusion The patients with serous labyrinthitis caused by acute otitis media (AOM) exhibited various patterns of nystagmus in which direction-fixed irritative-type nystagmus was the most common pattern. Differential effects on inner ear function by toxic or inflammatory mediators may be responsible for the various manifestation of nystagmus. Objective This study aimed to investigate nystagmus patterns in patients with serous labyrinthitis, and discuss possible mechanisms. Methods From October 2011 to March 2014, 13 consecutive patients with serous labyrinthitis were included. Eye movements of the patients were serially examined using video-nystagmography, and patterns of nystagmus were investigated. Results The most commonly observed pattern was direction-fixed nystagmus (nine of 13 patients). Of these, eight showed irritative-type, and one showed paretic-type. Direction of nystagmus, although the intensity gradually decreased, was not changed during the course of treatment. One patient showed direction-changing spontaneous nystagmus, which changed into paretic-type direction-fixed nystagmus 1 day after myringotomy. Three patients exhibited persistent direction-changing positional nystagmus in a supine head-roll test. Of them, two showed apogeotropic and one showed geotropic type. In all 13 patients, vertigo and hearing loss were improved after the treatment.

The etiology of sudden sensorineural hearing loss (SSNHL) remains unclear in most cases. This study aimed to assess abnormal magnetic resonance imaging (MRI) findings in patients with SSNHL and evaluate the value of MRI in identifying the cause of SSNHL.A retrospective analysis of the charts and MRI findings of 291 patients with SSNHL was performed.In 291 patients, MRI abnormality, which was considered a cause of SSNHL, was detected in 13 patients. Vestibular schwannoma involving the internal auditory canal (IAC) and/or cerebellopontine angle was observed in 9 patients. All 9 patients had intrameatal tumors, and 6 of the 9 patients displayed extrameatal extension of their tumors. The tumor was small (<1 cm) or medium-sized (1.1-2.9 cm) in these 6 patients. Intralabyrinthine schwannoma, labyrinthine hemorrhage, IAC metastasis, and a ruptured dermoid cyst were each observed in 1 patient.The most commonly observed MRI abnormality in patients with SSNHL was vestibular schwannoma, and all of the lesions were small or medium-sized tumors involving the IAC.

Benign paroxysmal positional vertigo (BPPV) is the most common type of positional vertigo. A canalolithiasis-type of BPPV involving the lateral semicircular canal (LSCC) shows a characteristic direction-changing positional nystagmus (DCPN) which beats towards the lower ear (geotropic) on turning the head to either side in a supine position. Because geotropic DCPN in LSCC canalolithiasis is transient with a latency of a few seconds, the diagnosis can be challenging if geotropic DCPN is persistent without latency. The concept of "light cupula" has been introduced to explain persistent geotropic DCPN, although the mechanism behind it requires further elucidation. In this review, we describe the characteristics of the nystagmic pattern in light cupula and discuss the current evidence for possible mechanisms explaining the phenomenon.