Multiple types of auras in patients with partial epilepsy can emerge from a single epileptogenic focus, according to a report in the August 21st issue of
Neurology."Having multiple auras does not necessarily mean there are multiple seizure foci, so they may very well benefit from a detailed evaluation with subdural grid electrodes and eventually resection of the focus," Dr. Prakash Kotagal from the Cleveland Clinic Epilepsy Center, Ohio told Reuters Health.
Dr. Kotagal and colleagues investigated the nature of the underlying epileptogenic region, and the success of epilepsy surgery, in 31 patients with partial epilepsy who experienced multiple aura types -- e.g., abdominal, auditory, gustatory, olfactory, and visual -- during a seizure.
For most patients, there was no correlation between aura types or combinations and the lobar or sublobar localization of the epilepsy, the authors report.
Most of the patients, however, and all of the patients with at least three auras had localized epilepsy originating in the right or nondominant hemisphere. "We found that multiple auras are more common in seizures arising from the nondominant hemisphere when there is greater likelihood of preserved awareness," Dr. Kotagal explained.
Ten of 19 patients (53 per cent) who had resective epilepsy surgery achieved freedom from seizures, the researchers report.
Subdural EEG recordings in six patients revealed a march of sequential auras in five of them. "The auras in our patients occurred as the discharge spread to various symptomatogenic zones," Dr. Kotagal said. In one case, several ictal onset zones resulted in separate isolated auras.
SPECT in six patients with right-sided seizures showed no brainstem activation during the seizures.
"We are planning a more detailed investigation of all patients with auras using subdural grid electrodes hoping to identify the symptomatogenic zones for various types of auras," Dr. Kotagal added. "We expect our paper will draw attention to this interesting phenomenon, which is probably more common than observed in our retrospective study.
