Abstracts

RATIONALE: At the end of this activity, the participants should be able to discuss the differential effects of lamotrigine and carbamazepine on clinical EEG.
As newer antiepileptic medications (AEDs) have come into common use in the last decade, more patients treated with these new AEDs are undergoing EEG evaluation as part of their epilepsy management. While the effects of standard AEDs, such as carbamazepine (CBZ) have been recognized for some time, relatively little information is available with regard to the effects of the new AEDs on clinical EEG. This study looks at the effects of lamotrigine (LTG) and compares it to CBZ with regard to typical routine clinical EEG variables.
METHODS: Retrospective review of consecutive outpatient clinical EEGs over the last two years in the hospital based outpatient lab was performed to identify those records which listed LTG (n=14, mean age= 45) or CBZ (n=28, mean age=44) in the medication list as monotherapy. These patients were taking LTG or CBZ for the treatment of seizures. All EEGs were recorded with a Nicolet Voyageur or an XLTEK, Inc digital clinical EEG system. Visual inspection and interpretation was performed by board certified clinical neurophysiologists without knowledge that these studies were to be reviewed in the future for clinical data.
RESULTS: 79% of LTG, but only 54% of CBZ EEGs were interpreted as normal. The median alpha frequency was 9.5 hz in both groups (range LTG: 8-11 and CBZ: 8.5-11.5). The comparative abnormalities noted were as follows: Mild diffuse slowing: 7% LTG vs. 21% CBZ; Focal slowing: 0% LTG vs. 14% CBZ; Focal spikes: 0% LTG vs. 14% CBZ; Generalized spike-wave: 7% LTG vs. 11% CBZ; Seizure: 7% LTG vs. 4% CBZ; and Excessive beta: 7% LTG vs. 0% CBZ. None of the records revealed moderate or severe focal or diffuse slowing.
CONCLUSIONS: In this retrospective review of the differential effects of LTG vs. CBZ on clinical EEG, care was taken to eliminate the role of concomitant AEDs, comorbidities, and to limit the role of concomitant central nervous system agents on the results. With that in mind, the main findings suggest that in the routine clinical setting, that when compared to CBZ, LTG has relatively little effect on EEG background. Comparator clinical studies have revealed few differences between these medications in terms of efficacy of seizure control. However, the same studies suggest that LTG may be better tolerated, in terms of side effect profile. The present finding, that LTG has fewer effects on the EEG background seems to provide neurophysiological support of that notion. This information is important to the Neurologist who interprets EEGs of patients treated with these AEDs. A prospective evaluation, with the ability to randomize patients and control for variables such as dose and AED level, will likely provide more detailed information about the relationship of these agents to the EEG.
(Disclosure: Honoraria - GlaxoSmithKline Novartis)