Hypothalamic hamartomas and ictal laughter: Evolution of a characteristic epileptic syndrome and diagnostic value of magnetic resonance imaging

Abstract

Detailed study of 4 patients and review of the literature allowed us to delineate further the epileptic syndrome associated with hypothalamic hamartomas, which characteristically begins in infancy with laughing seizures. Because early childhood psychomotor development is usually normal, the condition appears benign and may not even be recognized. The episodes of laughter are brief, frequent, and mechanical in nature. These features distinguish it from other forms of epileptic laughter, particularly that which occurs in temporal lobe epilepsy. Subsequently, the seizures become longer, other seizure types appear, and between the ages of 4 and 10 years, the clinical and electroencephalographic features of secondary generalized epilepsy develop. Cognitive deterioration occurs and severe behavior problems are frequent. Prognosis for seizure control and social adjustment is poor. Cortical abnormality occurs in association with the hypothalamic hamartoma. The lesions are best detected by magnetic resonance imaging but may be difficult to identify by computed tomographic scanning.

Interictal spike EEG source analysis in hypothalamic hamartoma epilepsy

“…The overall data is consistent with the postulated progressive cognitive deterioration of the syndrome (Berkovic et al, 1988), with the oldest patients showing clear learning and behavioural problems. The fact that cognitive and behavioural disturbances usually appear after long standing and refractory seizures suggests that they are causally related.…”

“…A clear trend was apparent in the described cases for a progressive slowing of the background activity with age, a feature already described in the literature (Berkovic et al, 1988). No such progression could be found for the spike activity, which exhibited great inter-individual variability independent of age.…”

“…The reported cases express the main characteristics described for the epilepsy associated with hypothalamic hamartomas (Berkovic et al, 1988): they all started with seizures in the first years of life which were refractory to medical therapy, developmental problems were present in the two oldest patients, and gelastic fits were the predominant seizure type (3 of 4 cases).…”

“…No such progression could be found for the spike activity, which exhibited great inter-individual variability independent of age. The multifocal spike activity is a common finding in previously described cases (Striano et al, 1999) and has been taken as suggestive of secondary epileptogenesis involving multiple neocortical areas (Berkovic et al, 1988). We are not aware of studies trying to establish the sources of such spike activity, but the uniformly poor results of surgical cortical resections (Cascino et al, 1993) strongly suggests that the primary epileptic focus lies at a subcortical location.…”

“…The early onset, peculiar type of seizures, usually associated with progressive cognitive deterioration, and behavioural problems makes this a distinct epileptic syndrome (Berkovic et al, 1988).…”