Sudden hearing loss due to internal auditory canal metastasis of Her2-positive gastric cancer: A case report.

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.