An unusual cause of cerebellovestibular symptoms.

Hashimoto encephalopathy (HE) is a controversial autoimmune disorder, probably underdiagnosed, that causes a wide variety of neurological manifestations. Symptoms differ among patients and may be very severe in some cases. However, it can be treated, with a very good prognosis. In our case, a teenaged girl with a family history of migraine, vitiligo and benign paroxysmal positional vertigo presented with severe ataxia, vomiting and hypotension. She had a history of similar, but milder, symptoms and was misdiagnosed several times. She had subclinical hypothyroidism, and high levels of antithyroid antibodies. There were abnormal MRI and visual evoked potential findings. After excluding other more common causes, we diagnosed her as having 'Hashimoto Encephalopathy', and started treatment with corticosteroids, on which she showed dramatic improvement. After about 2 years of presentation, the patient is able to continue her life independently.