Intractable seizures of frontal lobe origin: clinical characteristics, localizing signs, and results of surgery.

PURPOSE

We analyzed the clinical characteristics of seizures of frontal lobe (FL) origin with particular emphasis on establishing different categories and determining if these categories had any localizing or lateralizing value. In addition, results of surgery are reported.

METHODS

Seizure characteristics were established by historical review and electroencephalographic/videotape analysis of 449 seizures in 26 adult patients with refractory seizures of FL origin.

RESULTS

No outstanding risk factor was identified for seizures of FL origin. Seizures were frequent (7.1 per week), brief (mean duration, 48.3 seconds), and had a nocturnal preponderance in 58% of the patients. Status epilepticus was reported in 54%, and generalized convulsions as a prominent seizure type were reported in 26% of patients. The most common reported aura was a nonspecific sensation, often localized to the head (35%). Early forced head and eye deviation was not a consistent lateralizing sign, whereas late head and eye deviation always occurred contralateral to the site of seizure origin. Early asymmetric tonic posturing occurred consistently contralateral to the side of seizure origin. Clinical seizure patterns did not consistently localize to specific regions of the frontal lobe, although there were some noticeable trends: focal clonic seizures were associated with seizure origin in the frontal convexity; tonic seizures were most often associated with origin in the supplementary motor area but also occurred with origin in other parts of the frontal lobe; seizures resembling typical temporal lobe seizures with oroalimentary automatisms were observed with seizure origin in the orbitofrontal region; and seizures with hyperactive, frenetic automatisms were not associated with any specific region within the frontal lobes. Eighty percent of patients had favorable seizure outcome after surgery (class I/II).

CONCLUSION

Although certain clinical features are characteristic for seizures of frontal lobe origin and some have lateralizing value, they do not localize to specific areas within the FL. After careful presurgical evaluation, both lesional and nonlesional patients benefit from epilepsy surgery.