ASSESSMENT OF DROWSINESS IN EPILEPSY PATIENTS RECEIVING CHRONIC ANTIEPILEPTIC DRUG-THERAPY

Drowsiness is a common complaint among patients with epilepsy taking a ntiepileptic drugs (AEDs) and may be of particular importance because of the potential effects on cognitive abilities. We used a novel EEG-b ased measure (the Awake Maintenance Task, AMT) to determine objectivel y whether patients on chronic, stable AED therapy had impaired ability to maintain wakefulness. Thirty patients receiving AEDs [carbamazepin e (CBZ), phenytoin (PHT), phenobarbital (PB), valproate (VPA)] were co mpared to 35 healthy controls, 12 seizure patients not taking AEDs, an d 16 patients with multiple sclerosis. A structured EEG recording was conducted under controlled conditions, and subjects were tested to det ermine their ability to maintain wakefulness during a 6-min unstimulat ed trial. Testing also included Digit Symbol, auditory reaction time, and subjective measures of fatigue or sleepiness [Profile of Mood Stat es (POMS), Stanford Sleepiness Scale (SSS)]. Patients receiving AEDs h ad a mean total drowsiness score of 101 s compared with less than or e qual to 12 s for each of the three control groups (p < 0.001). One thi rd of the AED-treated patients had >120 s of drowsiness, in contrast t o only 1 of 63 controls (p < 0.001). Among patients receiving AEDs, ob jective EEG drowsiness did not correlate with AED levels or performanc e measures. Untreated seizure patients had significantly greater compl aints of lack of vigor despite a near absence of objective drowsiness on the AMT. These results suggest that epilepsy patients receiving chr onic AED therapy have impaired ability to maintain wakefulness. Patien t self-reports of AED-related sleepiness may not accurately represent this problem.