Landau-Kleffner syndrome: course and correlates with outcome

The presenting characteristics of 18 (11 female, seven male) children with Landau-Kleffner syndrome (LKS) were studied with respect to course and outc ome of their condition at a mean length of 67 (SD 46) months' follow-up. Al l had regression of receptive language (mean age of onset 4 years 9 months) and electrical status epilepticus in sleep (ESES). Length of ESES correlat ed strongly with length of period between onset of illness and onset of rec overy (p<0.006) and also with eventual receptive (p<0.001) and expressive ( p<0.007) language. Behaviour during the acute phase was severely affected i n nine children and associated with frontal lobe discharges in awake EEGs ( p<0.004). Age at onset was not correlated with outcome. All children had im paired shortterm memory at follow-up. Three children had language outcome w ithin the normal range. No child with ESES lasting longer than 36 months ha d normal language outcome. These data lend support for intervention in endi ng ESES by 36 months using multiple subpial transection (MST) if steroids a re ineffective or cause unacceptable side effects.