Ammar Alkawi1, Jorge C Kattah, Katie Wyman. 1. Department of Neurology, University of Illinois College of Medicine at Peoria, OSF Saint Francis Medical Center, 530N.E. Glen Oak Avenue, Peoria, IL 61637, USA. alkawi@uic.edu
Abstract
BACKGROUND: Downbeat nystagmus (DBN) has been reported with phenytoin and carbamazepine toxicity. DBN has not been described as a result of lamotrigine toxicity. METHODS: Clinical records, neuroimaging and video recordings were obtained in two patients diagnosed with intractable epilepsy who developed oscillopsia and incoordination while being treated with lamotrigine. One patient had a videonystagmographic (VNG) study. DISCUSSION: Lamotrigine's half-life is extended when used with valproic acid; hence, the increased chance of neurotoxicity associated with DBN. In our cases, DBN and truncal ataxia occurred in conjunction with toxic lamotrigine serum levels. CONCLUSION: Anticonvulsant toxicity should be considered as a cause of DBN. Lamotrigine toxicity may be an unusual cause.
BACKGROUND: Downbeat nystagmus (DBN) has been reported with phenytoin and carbamazepinetoxicity. DBN has not been described as a result of lamotriginetoxicity. METHODS: Clinical records, neuroimaging and video recordings were obtained in two patients diagnosed with intractable epilepsy who developed oscillopsia and incoordination while being treated with lamotrigine. One patient had a videonystagmographic (VNG) study. DISCUSSION: Lamotrigine's half-life is extended when used with valproic acid; hence, the increased chance of neurotoxicity associated with DBN. In our cases, DBN and truncal ataxia occurred in conjunction with toxic lamotrigine serum levels. CONCLUSION: Anticonvulsant toxicity should be considered as a cause of DBN. Lamotriginetoxicity may be an unusual cause.