title: Sensorimotor cortex excitability in Unverricht-Lundborg disease and Lafora body disease.
abstract: OBJECTIVE
  To investigate whether Unverricht-Lundborg disease (ULD) and Lafora body disease (LBD) can be differentiated on the basis of their neurophysiologic profiles.
  
  
  METHODS
  Somatosensory evoked potentials (SSEPs), long-loop reflexes (LLRs), and the influence of conditioning nerve stimulation on the motor potentials evoked by transcranial stimulation in 8 patients with LBD and 10 patients with ULD were investigated.
  
  
  RESULTS
  Both groups showed sensorimotor cortex hyperexcitability, but their electrophysiologic profiles were different. Enlarged P25 to N33 SSEP components and enhanced LLRs were common in the ULD patients, whereas medium-latency "giant" SSEP components and less consistently enhanced LLRs were more frequently found in the patients with LBD. Cortical relay time was extremely brief in ULD but varied in LBD. Conditioning somatosensory stimuli differently affected motor cortex excitability, leading to early facilitation in ULD and delayed and prolonged facilitation in LBD.
  
  
  CONCLUSIONS
  Patients with Unverricht-Lundborg disease (ULD) and Lafora body disease (LBD) have different electrophysiologic profiles. The ULD findings point to an aberrant subcortical or cortical loop (possibly short-cutting the somatosensory cortex) that is involved in generating the prominent action myoclonus characterizing the disorder. The LBD findings highlight sustained hyperexcitability of the sensorimotor cortex in response to afferent stimuli, which fit with a more severe impairment of inhibitory mechanisms.
authors.affiliation: Department of Clinical Neurophysiology, IRCCS National Neurological Institute C. Besta, Milano, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Canafoglia
authors.forename: C
authors.initials: C
authors.lastname: Ciano
authors.forename: F
authors.initials: F
authors.lastname: Panzica
authors.forename: V
authors.initials: V
authors.lastname: Scaioli
authors.forename: C
authors.initials: C
authors.lastname: Zucca
authors.forename: P
authors.initials: P
authors.lastname: Agazzi
authors.forename: E
authors.initials: E
authors.lastname: Visani
authors.forename: G
authors.initials: G
authors.lastname: Avanzini
authors.forename: S
authors.initials: S
authors.lastname: Franceschetti
mesh_terms: D000293:Adolescent; D000328:Adult; D004558:Electric Stimulation; D004569:Electroencephalography; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D020192:Lafora Disease / Q000175:diagnosis / Q000503:physiopathology*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D012021:Reflex, Abnormal; D013003:Somatosensory Cortex / Q000503:physiopathology*; D020194:Unverricht-Lundborg Syndrome / Q000175:diagnosis / Q000503:physiopathology*