Abstracts

Rationale: Studies investigating the efficacy of pregabalin in adults have reported CNS-related adverse effects in up to 28.9% of patients. Most common are dizziness, somnolence, and ataxia. Concentration problems have been reported in about 7% of patients [1]. Only one study of the effectiveness of pregabalin in children has been conducted and reported CNS-related adverse effects in 21% of patients that included somnolence, dizziness, and behavioral changes [2]. Studies utilizing neuropsychological measures have been limited and have only been conducted with adults. In a 2005 study, Hindmarch, Trick, and Ridout found neurocognitive effects of pregabalin on reaction time and vigilance [3], and, in 2006, Ciesielski, Samson, and Steinhoff found evidence of increased memory problems in adults after initiating add-on pregabalin therapy [4]. The current case study provides evidence of fluctuations in verbal fluency in an adolescent treated with pregabalin for complex partial seizures. Methods: The subject of the current case study was an 18-year-old, right-handed, Caucasian male with a history of complex partial seizures that began at 10 years of age. He underwent placement of a VNS at 13 years of age and had an anterior two-thirds corpus callosotomy at 16 years of age. The patient was started on pregabalin (400 m.g./day) postsurgically because of on-going seizures and was found on neuropsychological assessment to have changes in verbal skills. He subsequently underwent repeat neuropsychological assessments after being removed from pregabalin for video-EEG monitoring, after being placed back on pregabalin, and after discontinuing pregabalin and started on a different AED. This clinical course provided observation of the patient’s verbal fluency performance on and off of pregabalin over 5 time points. Results: The patient’s raw score performance on a measure of verbal fluency fluctuated significantly during the course of being treated and withdrawn from pregabalin. After initiating pregabalin, the patient’s phonemic and semantic fluency declined 30% and 32%, respectively. Following discontinuation of pregabalin for EEG monitoring, his phonemic and semantic fluency increased 58% and 100%, respectively. After reinitiating pregabalin, phonemic and semantic fluency declined 33% and 32%, respectively. Follow-up neuropsychological assessment after discontinuing pregabalin and substituting clobazam revealed only a 5% increase in phonemic fluency but a more robust 78% increase in semantic fluency. Conclusions: Results of this case study reveal a relatively circumscribed change in the verbal fluency performance of an adolescent being treated with pregabalin for complex partial epilepsy. Discontinuation of pregabalin on 2 separate occasions repeatedly revealed a return to baseline performance. This pattern of performance suggests possible cognitive side effects with pregabalin therapy. Implications for treatment will be discussed.