Internal auditory canal (IAC) metastasis due to leptomeningeal carcinomatosis (LMC) from gastric cancer (GC) has rarely been reported. Early manifestation of symptoms, such as hearing loss, vertigo and facial paralysis, in cases of IAC metastasis due to LMC may facilitate the early detection of brain metastasis. To the best of our knowledge, the present study is the first to report IAC metastasis due to LMC in human epidermal growth factor receptor 2 (Her2)-positive GC. This study reports a case of an Her2-positive GC patient with LMC including IAC metastasis, who presented with acute sensorineural hearing loss, ipsilateral facial paralysis and vertigo during trastuzumab containing chemotherapy. The current study also discusses the early diagnosis and management of this complicated condition, demonstrating that clinical suspicion is key for a prompt diagnosis and proper management of LMC including IAC metastasis in Her2-positive GC.

Objective. This study aimed to investigate the incidence of spontaneous nystagmus (SN) in posterior semicircular canal (PSCC) benign paroxysmal positional vertigo (BPPV) and its effect on treatment outcomes.Study Design. Retrospective case series. Setting. Tertiary referral center.Methods. This study included 50 patients with idiopathic unilateral PSCC BPPV between July 2021 and May 2022. The presence of SN was investigated, and the results of the bithermal caloric test and video head impulse test (vHIT) were compared.Results. SN was observed in 13 (26%) of the 50 patients presenting PSCC BPPV. The direction of SN was mainly unidirectional and horizontal in 12 of the 13 patients with a slow-phase velocity ranging from 2 to 4°/s. One patient presented an upbeating torsional SN at the initial evaluation. The mean vHIT gain of the PSCC on the affected side was significantly lower in patients with SN than those without SN (p = .004, Mann-Whitney U test). The proportion of patients who recovered within 2 sessions of the repositioning maneuver was significantly higher in those without SN than that in those with SN (p < .001, Fisher's exact test). Conclusion.This study demonstrated that the treatment outcomes of PSCC BPPV were significantly worse in patients with SN than those without SN. Examining the presence of SN in patients with PSCC BPPV may be helpful in counseling the patients on prognosis, and it is expected that more sessions of canalith repositioning maneuver may be required to treat PSCC BPPV in patients with SN than those without SN.