Adverse effects of anti-epileptics in trigeminal neuralgiform pain.

BACKGROUND: Side effects of anti-epileptic drugs (AEDs) have not been adequately documented in trigeminal neuralgia and its variants. The aim of this observational cross-sectional study was to compare the A-B Neuropsychological Assessment Schedule (ABNAS), which measures cognitive side effects to the Adverse Events Profile (AEP), which looks at a broader range of side effects, and to investigate drug/dosage relationships with questionnaire scores to help determine a point at which a drug change would be indicated. METHODS: One hundred five patients were recruited from a facial pain clinic, over a 10-month period. Self-complete questionnaire scores were compared between patients using different AEDs. RESULTS: A-B Neuropsychological Assessment Schedule score correlated well with AEP indicating that cognitive side effects were a significant burden. Toxic range on the ABNAS was estimated to occur when scores were >43/72 (95% CI: 37.4-48.6). Polytherapy is weakly associated with the higher scores. Oxcarbazepine dosage was found to linearly correlate with AEP and ABNAS scores, better than carbamazepine dosage. Memory alteration was least common with lamotrigine and oxcarbazepine, and there was less association between fatigues with oxcarbazepine/pregabalin. CONCLUSION: Anti-epileptic drugs have significant side effects. The ABNAS questionnaire is a useful tool along with the AEP to recognize and monitor AEDs' side effects and to help to adjust medications to optimal dosage.