title: The effects of baclofen and cholinergic drugs on upbeat and downbeat nystagmus.
abstract: The GABAergic drug baclofen and the cholinergic drug physostigmine were administered to patients with upbeat and downbeat nystagmus. Baclofen (orally, 5 mg three times daily) reduced nystagmus slow phase velocity and distressing oscillopsia by 25-75% in four out of five patients (two upbeat nystagmus; two downbeat nystagmus). Physostigmine (1 mg single intravenous injection) increased nystagmus in five additional patients with downbeat (1) or positional downbeat nystagmus (4) for a duration of 15-20 minutes. The different interactions of baclofen and physostigmine on neurotransmission subserving vertical vestibulo-ocular reflex could account for these effects. The response to baclofen appears to be a GABA-B-ergic effect with augmentation of the physiological inhibitory influence of the vestibulo-cerebellum on the vestibular nuclei. Similarly baclofen has an inhibitory effect on the velocity storage mechanism. Cholinergic action may cause the increment of nystagmus by physostigmine.
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Dieterich
authors.forename: A
authors.initials: A
authors.lastname: Straube
authors.forename: T
authors.initials: T
authors.lastname: Brandt
authors.forename: W
authors.initials: W
authors.lastname: Paulus
authors.forename: U
authors.initials: U
authors.lastname: Büttner
mesh_terms: D000328:Adult; D000368:Aged; D001418:Baclofen / Q000627:therapeutic use*; D001712:Biperiden / Q000008:administration & dosage; D002531:Cerebellum / Q000187:drug effects / Q000503:physiopathology; D004585:Electrooculography / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D009759:Nystagmus, Pathologic / Q000188:drug therapy* / Q000503:physiopathology; D010830:Physostigmine; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000187:drug effects / Q000502:physiology; D014726:Vestibular Nuclei / Q000187:drug effects / Q000503:physiopathology
chemical_list: D011950:Receptors, Cholinergic; D011963:Receptors, GABA-A; D001712:Biperiden; D010830:Physostigmine; D001418:Baclofen