title: Decreased cortical excitability in Unverricht-Lundborg disease in the long-term follow-up: a consecutive SEP study.
abstract: OBJECTIVE
  To delineate long-term change of cortical excitability by measuring somatosensory evoked potentials (SEPs) in patients with Unverricht-Lundborg disease (ULD).
  
  
  METHODS
  SEPs to median nerve stimulation were repeatedly examined in two genetically proven ULD patients manifesting stable condition over 16 years, namely disabling but non-progressive myoclonus and cessation of generalised tonic-clonic seizures.
  
  
  RESULTS
  In both patients, five sets of early cortical components were identified 16 years ago: two tangential components of N20-P20 and P30-N30 and three radial components of P25, N35 and N40. Cortical SEPs were regarded as abnormally enhanced 'giant' based on the N35 amplitude (>mean+3 SD of normal controls). The bimodal negative peaks of N35 and N40 showed different spatial distribution: N35 maximum in the central area and N40 in the centro-parietal area. At present, N35 remained giant while N40 disappeared in both patients.
  
  
  CONCLUSIONS
  It is possible that currently preserved giant SEPs at least at N35 reflect disabling cortical myoclonus and that disappearance of N40 might reflect a lesser degree of increased cortico-cortical connectivity and/or decreased cortical hyperexcitability in the association cortices. It might possibly have resulted in the disappearance of GTCSs.
  
  
  CONCLUSIONS
  We delineated long-term change of giant SEP in ULD.
authors.affiliation: Department of Neurology, Kyoto University School of Medicine, Kyoto, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Riki
authors.initials: R
authors.lastname: Matsumoto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kondo
authors.forename: Jun
authors.initials: J
authors.lastname: Kawamata
authors.forename: Takefumi
authors.initials: T
authors.lastname: Hitomi
authors.forename: Morito
authors.initials: M
authors.lastname: Inouchi
authors.forename: Masao
authors.initials: M
authors.lastname: Matsuhashi
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Takahashi
authors.forename: Akio
authors.initials: A
authors.lastname: Ikeda
mesh_terms: D002540:Cerebral Cortex / Q000503:physiopathology*; D055313:Cystatin B / Q000235:genetics; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D020194:Unverricht-Lundborg Syndrome / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology
chemical_list: D055313:Cystatin B