Complete blood count, urinalysis, and electrolytes were normal except for 10,800 leucocytes/mm3.Lumbar puncture showed opening pressure of 300 mm water, closing pressure of 180 mm with 1,952 leucocytes/mm3 (58% polymorphonuclear cells, 42% mononuclear cells), protein 0.74 g/l, and glucose 4.11 mmol/l. Gram stain and India ink preparations were negative; bacterial, fungal, and tuberculosis cultures showed no growth. EEG, skull radiograph, and brain isotope scan were normal.The patient was treated with intravenous ampicillin, and what had been assumed to be a meningitis cleared. Repeat lumbar puncture one week later showed only 9 lymphocytes/mm3; protein and sugar were normal. She was discharged and remained stable for the next two months, when she had a sudden onset of diplopia and was found to have a left sixth nerve palsy. Over the next two months she developed progressive ataxia of gait, dysarthria, and further weakness of her left limbs. Vertical nystagmus appeared and a diminished gag reflex and dysphagia. A four-vessel cerebral angiogram was performed and was normal. She continued to deteriorate and died six months after her initial admission.NECROPSY Findings at necropsy included a large pulmonary embolus which was considered to be the immediate cause of death. The basis pontis, surrounding structures, and meninges were replaced and infiltrated by a diffuse, focally necrotic mass