A previously well 6-year-old boy presented with steadily increasing twitching of the face and eyes for 3 months. These were initially thought to represent tics, but it became increasingly clear that he could not control the movements. On examination, the twitching involved the right orbital muscles and face, resulting in partial eye closure and hemi-grimacing. The motions were very jerky and arrhythmic, occurring every second or so, and appeared to continue in sleep. There was no associated pain or change in awareness or consciousness. 30-minute EEG showed left frontal epileptic discharges, occurring every second on average, with mild slowing in the same region, but no other abnormalities. Carbamazepine was started and increased to 15 mg/kg/day without clear effect.

Over the following 6 months, the focal facial seizures continued, and the child started to have focal clonic seizures affecting the right arm with some alteration of awareness. These seizures lasted 30 to 40 seconds and tended to occur in clusters, worsening with infection. Medical trials of lamotrigine, topiramate, clobazan, and clonazepam failed. In between seizures, during this period, the right arm and hand were less coordinated, resulting in changes in handwriting and dropping objects. School performance also deteriorated with reduced focus, concentration, and completion of tasks. His speech became less distinct, and he became quieter and less able to find words. Formal neurological examination revealed mild right-sided hemiplegia and a right hemianopia.

Brain MRI ( Fig. 50.1 ) showed asymmetric volume loss in the left cerebral hemisphere, particularly periinsular region.

Rasmussen disease. Brain MRI, (A) axial T2 and (B) T1 show left hemispheric atrophy greatest in the periinsular region with ex vacuo enlargement of ventricles and subarachnoid spaces. (C) Axial T2 following left hemispherectomy.

Cerebrospinal fluid examination showed intrathecal oligoclonal bands without pleocytosis. All peripheral blood investigations, including inflammatory markers and lupus serology, were normal.

Brain biopsy showed diffuse microglia and astrocyte gliosis, neuronal loss, and occasional perivascular lymphocytic infiltration. There was no evidence of viral inclusions.