Case history

A 70-year-old woman presented to the hospital's general physicians with a 3-week exacerbation of pre-existing migrainous headache, speech and behavioural change. There was a 20-year history of slowly progressive bilateral sensorineural hearing loss, and a 10-year history of diabetes mellitus. On examination, there was marked receptive and expressive dysphasia, but no other abnormalities. She was afebrile. Her leucocyte count and inflammatory markers were normal. Uncontrasted CT scan of the brain showed bilateral temporal lobe low attenuation, more on the right side, with bilateral basal ganglia calcification (figure 1A, B). The lesions could not be characterised further as she could not tolerate MR imaging. Cerebrospinal fluid (CSF) examination was acellular, with normal protein and glucose. EEG showed generalised slowing, consistent with a diffuse disorder of cortical function. An autoimmune screen, including antinuclear antibodies, antithyroid peroxidase antibodies, antivoltage-gated potassium channel antibodies, anti-NMDA receptor antibodies and antineuronal antibodies was negative. Serum protein electrophoresis, carotid Doppler ultrasound and echocardiogram were normal.

She received intravenous aciclovir for a presumptive diagnosis of herpes simplex virus encephalitis. CSF PCR for herpes simplex virus was negative and aciclovir was stopped after 1 week. The following day she had a single generalised tonic-clonic seizure. Her clinician started phenytoin and reinstated aciclovir for a further week. She was discharged with a mild residual receptive dysphasia and short-term memory impairment, but independent for most activities of …