Cognitive dysfunction at epilepsy onset as a marker for seizure recurrence.

ABSTRACT

BACKGROUND: Cognitive dysfunction has been correlated with seizure control in chronic epilepsy and in newly diagnosed epilepsy, which potentially makes it a good marker for predicting disease course and seizure control. However, there is a lack of prospective studies examining the role of cognitive dysfunction in predicting seizure recurrence at the earliest stages of the disease, such as following the first unprovoked seizure (UFS) or new onset epilepsy (NOE). METHODS: Thirty three adult participants (FS=18, NOE=15) from the Halifax First Seizure Clinic (HFSC) completed a cognitive screening assessment at baseline (typically 3 months following diagnosis); seizure-recurrence was evaluated one year after the initial HFSC visit. RESULTS: Cognitive impairment, defined as at least one z-score in the impaired range (≤-1.5) relative to published test norms, was documented in 76% of the patients with seizure recurrence at follow-up and in 55% without seizure recurrence. Speed/executive functions and Memory were the most frequently affected domains, with impaired performance noted in 35% and 29% of the entire sample, respectively. Although the seizure recurrence vs. non-recurrence groups did not differ significantly on likelihood of impairment in any specific cognitive domains, a regression model of seizure recurrence that included years of education, baseline mood and anxiety scores, normal vs. abnormal baseline MRI, and impaired (vs. unimpaired) function in six cognitive domains was significant overall (Χ2 (10) = 24.04, p =.007*, R2N =.77). The regression model was no longer significant with the cognitive variables removed. CONCLUSIONS: Subtle cognitive dysfunction, especially in the domains of executive functions and memory are prevalent in individuals at the earliest stages of epilepsy. In addition to abnormal MRI and EEG findings at baseline, which are far less prevalent in FS and NOE, cognitive factors show promise in helping predict seizure recurrence in these populations.