Acute cerebellar ataxia is a rare manifestation of Epstein–Barr virus (EBV) infection. We present a case of a 17-year-old male who presented with acute cerebellar ataxia occurring before the onset of tonsillitis and lymphadenopathy. Serological testing confirmed acute EBV infection.

A 17-year-old male college student complained of feeling ‘drunk’ and unsteady when walking. This progressed over a few days so that he could only crawl. By this time he had developed a sore throat and persistent nausea and vomiting. His general practitioner prescribed penicillin, without effect. On day 6, he presented to hospital bed-bound due to severe loss of balance with severe nausea and vomiting.

He was afebrile (37.2°C) but cardiovascular and respiratory examinations were normal. He had bilateral cervical lymphadenopathy and tonsillar enlargement, and there was no hepatosplenomegaly. He was dysarthric with truncal ataxia and dysmetria in all four limbs. He had no nystagmus.

His serum C reactive protein was raised at 24 mg/l (<10). Serum urea and electrolytes, full blood count and liver function tests were normal. Lymphocytosis developed on day 8, with reactive lymphocytes on a blood film. C reactive protein rose steadily and peaked at 88 mg/l on day 10, and then gradually returned …