title: Pharmacological tests of hypotheses for acquired pendular nystagmus.
abstract: Acquired pendular nystagmus (APN) occurs with multiple sclerosis (MS) and oculopalatal tremor (OPT); distinct features of the nystagmus have led to the development of separate models for their pathogenesis. APN in MS has been attributed to instability in the neural integrator, which normally ensures steady gaze. APN in OPT may result from electrotonic coupling between neurons in the hypertrophied inferior olivary nucleus, which induces maladaptive learning in cerebellar cortex. We tested these two hypotheses by analyzing the effects of gabapentin, memantine, and baclofen on both forms of nystagmus. No drug changed the dominant frequency of either form of APN, but the variability of frequency was affected with gabapentin and memantine in patients with OPT. The amplitude of APN in both MS and OPT was reduced with gabapentin and memantine, but not baclofen. Analyzing the effects of drug therapies on ocular oscillations provides a novel approach to test models of nystagmus.
authors.affiliation: Neurology Service, Veterans Medical Center and Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: Aasef G
authors.initials: AG
authors.lastname: Shaikh
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Thurtell
authors.forename: Lance M
authors.initials: LM
authors.lastname: Optican
authors.forename: R John
authors.initials: RJ
authors.lastname: Leigh
mesh_terms: D000588:Amines / Q000494:pharmacology; D001418:Baclofen / Q000494:pharmacology; D002525:Cerebellar Cortex / Q000503:physiopathology; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D005133:Eye Movements / Q000187:drug effects; D000077206:Gabapentin; D006801:Humans; D008559:Memantine / Q000494:pharmacology; D008959:Models, Neurological; D009103:Multiple Sclerosis / Q000150:complications / Q000503:physiopathology; D009207:Myoclonus / Q000150:complications / Q000503:physiopathology; D009759:Nystagmus, Pathologic / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D009847:Olivary Nucleus / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D000588:Amines; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D001418:Baclofen; D008559:Memantine