A case of cerebellar infarction presenting as thunderclap headache.

Thunderclap headache (TCH) refers to a sudden-onset, severe headache that features in subarachnoid hemorrhage, unruptured intracranial aneurysm, cerebral venous thrombosis, pituitary apoplexy, cervical artery dissection, and hypertensive reversible posterior leukoencephalopathy. TCH is a rare manifestation in cerebral or cerebellar infarctions. Herein, we report on a 60-year-old woman with a thunderclap headache as the first symptom of cerebellar infarction, in the absence of abnormal findings in the brain computed tomography (CT), CT angiography, and lumbar puncture. An urgent brain MRI showed an acute infarction of the right cerebellar hemisphere. The next day, the patient presented with right side ataxia. In emergency cases presenting with thunderclap headache, one should consider an expanded evaluation and/or close observation, with frequent neurological examinations, even though the findings are normal on the initial neurological examination, cerebrospinal fluid analysis, and brain CT.