title: 18F-fluorodeoxyglucose hypometabolism in cerebellar tonsil and flocculus in downbeat nystagmus.
abstract: A patient with downbeat nystagmus was examined by F-fluorodeoxyglucose-positron emission tomography once while off and twice while on successful treatment with 4-aminopyridine. All positron emission tomography scans of the patient showed a reduced cerebral glucose metabolism bilaterally in the region of the cerebellar tonsil and flocculus/paraflocculus when compared with a normal database of the whole brain. An additional region-of-interest analysis revealed that 4-aminopyridine treatment lessened the hypometabolism. This finding supports the hypothesis that the cerebellar tonsil and (para-) flocculus play a crucial role in downbeat nystagmus. The hypometabolism might reflect reduced inhibition or even disinhibition of the circuits to the vestibular nuclei, thus causing downbeat nystagmus. The reduced hypometabolism during treatment probably indicates an improvement of the cerebellar inhibition.
authors.affiliation: Department of Neurology, Johannes-Gutenberg University, Mainz, Germany. bense@neurologie.klinik.uni-mainz.de
authors.forename: Sandra
authors.initials: S
authors.lastname: Bense
authors.forename: Christoph
authors.initials: C
authors.lastname: Best
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Buchholz
authors.forename: Valerie
authors.initials: V
authors.lastname: Wiener
authors.forename: Mathias
authors.initials: M
authors.lastname: Schreckenberger
authors.forename: Peter
authors.initials: P
authors.lastname: Bartenstein
authors.forename: Marianne
authors.initials: M
authors.lastname: Dieterich
mesh_terms: D015761:4-Aminopyridine / Q000627:therapeutic use; D000368:Aged; D002531:Cerebellum / Q000378:metabolism* / Q000473:pathology*; D005133:Eye Movements / Q000502:physiology; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009759:Nystagmus, Pathologic / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D049268:Positron-Emission Tomography / Q000379:methods; D026902:Potassium Channel Blockers / Q000627:therapeutic use
chemical_list: D026902:Potassium Channel Blockers; D019788:Fluorodeoxyglucose F18; D015761:4-Aminopyridine