Hashimoto encephalopathy presenting as acute unilateral vestibulopathy: a case report

Hashimoto encephalopathy (HE) is a rare neurological disorder characterized by encephalopathy associated with autoimmune thyroiditis. While common manifestations include altered mental status, seizures, myoclonus, and neuropsychiatric symptoms, vestibular manifestations as the initial presentation are exceedingly rare. We report a case of a 49-year-old man with a history of hyperthyroidism who initially presented with acute unilateral vestibulopathy. Neurological examination revealed right-beating nystagmus with a negative head impulse test, and caloric testing showed 29.4% left canal paresis. He later developed confusion, ataxia, dysarthria, and psychiatric symptoms. HE was diagnosed based on the clinical features and supportive laboratory findings, including elevated anti-thyroid antibodies and cerebrospinal fluid pleocytosis. The patient showed significant improvement following intravenous methylprednisolone treatment. This case highlights the importance of considering HE in patients with atypical vestibular symptoms, especially those with underlying autoimmune thyroid disease, as timely diagnosis and treatment can lead to a favorable outcome.