A 40-year-old right-handed British Asian engineer presented with a four-week history of nausea, persistent vomiting, anorexia and weight loss without abdominal pain or change in bowel habit. During a 10-day hospital admission, his full blood count (FBC), urea and electrolytes (U and E), liver function tests (LFT), C-reactive protein (CRP), calcium and thyroid function tests (TFT) were all normal. Gastroscopy showed Helicobacter pylori gastritis and he was discharged home after treatment with amoxicillin, clarithromycin and lansoprazole which resulted in symptomatic improvement.

He returned four weeks later with recurrence of nausea and vomiting, further weight loss (approximately 12 kg in three months) and progressive left leg weakness over 10 weeks which had not been apparent during the previous admission. He also described intermittent, mild, non-disabling headache without cranial nerve symptoms, photophobia, sphincter dysfunction or fever.

He did not have any significant past medical history. He was married with five children, had never smoked and did not drink alcohol. He had had regular contact with a relative treated for pulmonary tuberculosis in the UK five years ago and last travelled abroad three years previously (Saudi Arabia).

On examination he was apyrexial, with a normal systemic examination and no palpable lymphadenopathy. He had normal higher mental functions and cranial nerves with no papilloedema or signs of meningeal irritation, but he did have moderate left-sided pyramidal arm and leg weakness and brisk left-sided reflexes with an up going left plantar response. Sensory and cerebellar examination was normal. He was able to stand and walk with a Zimmer frame.

Normal investigations included FBC with differential, U and E, LFT, calcium, glucose, CRP, mid-stream specimen of urine, ECG and chest x ray. However, the CT brain scan with contrast showed hydrocephalus with no focal lesion.