Rationale: Achievement of maximum seizure control with preservation or even improvement of patient's cognitive capabilities is the major aim of epilepsy therapy. EpiTrack is a brief screening tool for the tracking of cognitive side effects of antiepileptic drugs. Test selection was based on recent studies on the effects of topiramate on cognition and retrospective inspection of results from patients with antiepileptic drug (AED) side effects.
Methods: The 15-minute screening tool comprises six subtests: the Trail-Making Test (parts A and B), a test of response inhibition, digit span backward, written word fluency, and a maze test. These tests were standardized in 220 healthy subjects, 100 of whom were reevaluated after 5.3 months to obtain information on reliability and practice effects. Criterion validity was determined by correlation to other neuropsychological measures. For a first clinical evaluation, the impact of epilepsy (seizures) and medication on EpiTrack scores was evaluated cross-sectionally in 184 consecutive inpatients with chronic epilepsy.
Results: According to the normative data, we developed an easy scoring scheme assigning test scores on a 7-point scale. The EpiTrack is suitable for patients between 18 and 60 years of age. Age corrections were included for patients between 40 and 60 years. EpiTrack scores on subtests for both controls and patients were submitted to principal component analysis. VARIMAX rotation yielded a two-factor solution (verbal/visuo-spatial) that accounted for 63.8% of the total variance in controls. In the patient group, only one factor emerged accounting for 54.7% of variance. EpiTrack correlates with global scores of attention (r=0.85) and language (r=0.67) (P's<0.001). At a cutoff score of 25, only 2.7% of the controls were classified as impaired, while impairment was indicated in 48.4% of the patients. The score is sensitive to monthly frequency of complex partial seizures and to number of AEDs. It shows negative cognitive effects of valproate and topiramate given in mono/polytherapy.
Conclusion: EpiTrack is a promising 15-minute screening tool for the detection and tracking of cognitive side effects of AEDs and adverse effects of seizures in patients with epilepsy. Future application will show its value in prospective follow-up studies on AED side effects.