[Development of Lennox-Gastaut syndrome in adulthood]

Lennox-Gastaut syndrome (LGS) is an epileptic encephalopathy that starts in childhood and has an unknown pathophysiological mechanism. Studies on the progress of LGS reveal a poor prognosis.

A retrospective study of 1629 patients with epilepsy was conducted. Patients included in the study were those with an age of onset during childhood, tonic seizures and atypical absences (who might also suffer from other types of seizures); electroencephalogram (EEG) showing generalised slow spike-wave and generalised fast activity; mental retardation and a follow-up time of at least 10 years.

The sample consisted of 12 patients, 9 of whom were males. Follow-up time: 20 years. Onset of seizures: 3 years. Cryptogenic LGS: 67%; symptomatic: 33%. Frequency of the seizures at onset: daily (83.3%) or weekly (16.7%). Types of seizures: tonic and atypical absences (100%); drop-attacks (83%); generalised tonic-clonic (75%); myoclonias (41.7%); partial (8.3%) and pseudo-epileptic (8.3%). EEG with slow background activity, generalised slow spike-wave and generalised fast activity: 100%. Fifty percent of the patients had at least one epileptic status. They used an average of 7.5 different antiepileptic drugs. At the end of the follow-up 33% were suffering from seizures on a daily basis; 17% were weekly and 42% monthly. A total of 8.3% were free from seizures. All of them were following combination therapy: 17% in bitherapy and 83% with an average of 3.8 drugs (range: 3-5). A total of 92% suffered from severe or very severe mental retardation. Fifty percent required neuroleptic drugs due to behavioural disorders.

Despite the fact that the diagnosis of LGS is serious, we observed a decrease in the number of seizures after several years of development, although the antiepileptic combination therapy remains constant. The mental retardation and behavioural disorders lead to a poor functional prognosis.