Clinical and electroencephalographical characterization of typical absence seizures

CLINICAL AND ELECTROENCEPHALOGRAPHICAL CHARACTERIZATION OF TYPICAL ABSENCE SEIZURES (ABSTRACT)^*. THESIS. SÃO PAULO, 1999.

LAURA MARIA DE FIGUEIREDO FERREIRA GUILHOTO^**

We recorded by video-EEG 455 typical absences in 43 patients aged 17 months to 53 years. Typical absence was defined as the Seizure Classification of the International League Against Epilepsy (ILAE) (1981) as follows: "sudden onset, interruption of activities, blank stare and possible upward rotation of the eyes". Syndromic diagnosis was possible in 60.46% of the cases according to the criteria of the Commission on Classification and Terminology of the ILAE (1989) and in 67.44% using the proposal of Panayiotopoulos (1997). In the remaining patients there was a wide spectrum of electro-clinical presentations that could not fit the described syndromic approach. In this series there were specific ictal syndromic characteristics in absence seizures as proposed by Panayiotopoulos et al. (1989).

Patients with childhood absence epilepsy (n=10) presented more severe ictal impairment of consciousness than the ones with juvenile absence epilepsy (n=14). Interictal occipital intermittent rhythmic delta activity, present in 90% of the cases with childhood absence epilepsy, was not recorded in the juvenile form.

Patients with myoclonic absence epilepsy (n=3) had pyknoleptic absences with severe alteration of consciousness accompanied by massive rhythmic myoclonic jerks of upper limbs and one patient with juvenile myoclonic epilepsy had absence seizures of short duration (mean 3.2sec) associated with irregular spike-wave complexes.

Finally, one patient with eyelid myoclonia with absences had seizures of short duration (mean 2.94sec) evoked by eye closure and intermittent photostimulation.

Ten patients older than 20 years had more often tonic-clonic associated seizures, difficulty in seizure control, subtle impairment of consciousness and irregular spike-wave complexes during the ictus, when compared to the ones younger than ten years. In four of these patients ictal electroencephalographical 10-20 Hz activity was associated.

Patients with severe ictal impairment of consciousness more often presented pyknolepsy (p=0.005) and earlier seizure onset (p=0.028) than those with partial impairment. Patients with regular electrographical patterns had more frequent pyknolepsy (p=0.028), earlier seizure onset (p=0.026), automatisms (p=0.047) and less often tonic-clonic seizures (p=0.011) than those with irregular spike-wave complexes.

Although there were a few photosensitive patients (n=3) in this series, seizure outcome was not correlated with photosensitivity in this group.

Neuropsychological evaluation of these patients showed a tendency to more frequent attention impairment than cognitive disorders.

KEY WORDS: typical absences, idiopathic generalized epilepsy, electroencephalography, classsification.

**Address: Rua Bom Jesus 864, 03344-000 São Paulo SP, Brasil.

*

Caracterização clínica e eletrencefalográfica de crises de ausência típica (Resumo). Tese de Doutorado, Faculdade de Medicina de da Universidade de São Paulo (Área Neurologia). Orientadora: Elza Márcia Targas Yacubian.

Publication Dates

• Publication in this collection
  03 Apr 2000
• Date of issue
  Mar 2000