Symptoms in focal sensory seizures. Clinical and electroencephalographic features

Aura is a brief subjective symptom that may represent the initial manifestation of a partial epileptic seizure with objective signs or constitute the entire epileptic attack (focal sensory seizure (FSS)). We studied the electro-clinical features of FSSs recorded in 28 patients.

Using long-term surface video-EEG recordings, we examined 28 patients (from a consecutive series of 64) with stereotyped FSSs and complex partial seizures (CPS) preceded in at least one instance by identical subjective manifestations (overall 255 FSSs and 39 CPS were recorded). FSSs were subdivided according to the type of sensation into somatosensory, visual or oculosensory, viscerosensory, experiential, cephalic and diffuse warm sensations. The EEG discharges accompanying FSSs were examined by two of the authors either blinded as to the type and timing of the seizure, or unblinded, i.e. after receiving complete clinical information including timing of the patient's warning.

The ictal pattern accompanying FSSs was identified blind in 13 patients and unblind in 8 patients. In seven patients, the ictal discharge remained undetected. In the cases with recognizable ictal abnormalities, two main patterns could be distinguished, static and dynamic. FSSs whose ictal discharge could be recognized by blind EEG examination more frequently consisted of somatosensory and visual or oculosensory manifestations, and the discharge generally involved the centro-parieto-occipital regions. The ictal discharge of viscerosensory and experiential FSSs more easily remained undetected; when identified, it generally involved the fronto-temporal regions.

FSSs are often accompanied by ictal abnormalities recognizable on surface EEG. A thorough knowledge of their EEG accompaniments may be a useful diagnostic aid in patients with partial epilepsy.