title: Giant SEPs and SEP-recovery function in Unverricht-Lundborg disease.
abstract: OBJECTIVE
  To evaluate the relationship between sensory hyperexcitability as revealed by giant SEPs and the SEP recovery function (SEP-R) in a series of patient with progressive myoclonic epilepsy of Unverricht-Lundborg type, identified as epilepsy, progressive myoclonic 1A (EPM1A), MIM #254800.
  
  
  METHODS
  We evaluated SEPs by applying median nerve stimuli and SEP-R using paired stimuli at inter-stimulus intervals (ISIs) of between 20 and 600 ms in 25 patients and 20 controls. The SEPs were considered "giant" if the N20P25 and P25N33 amplitudes exceeded normal mean values by +3SD.
  
  
  RESULTS
  During the paired-stimulus protocol, the SEPs elicited by the second stimulus (S2) were detectable at all ISIs but consistently suppressed in the 13 patients with giant SEPs reflecting a significantly delayed SEP-R. Maximal suppression roughly corresponded to the plateau of a broad middle latency (>100 ms) wave pertaining to the S1 response.
  
  
  CONCLUSIONS
  The cortical processing dysfunction generating giant SEPs in EPM1A patients consistently combines with a long-lasting suppression of hyperexcitability that leads to a delayed giant SEP-R without obstructing the response to incoming stimuli.
  
  
  CONCLUSIONS
  The delayed SEP-R is not due to true inhibition but the suppression of aberrant hyper-synchronisation sustaining giant SEPs. A broad middle latency SEP component adds a significantly suppressive effect. This suggests that cortico-subcortical circuitries contribute to both the gigantism and the delayed SEP-R.
authors.affiliation: Department of Neurophysiology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Visani
authors.forename: L
authors.initials: L
authors.lastname: Canafoglia
authors.forename: D
authors.initials: D
authors.lastname: Rossi Sebastiano
authors.forename: P
authors.initials: P
authors.lastname: Agazzi
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: Ciano
authors.forename: S
authors.initials: S
authors.lastname: Franceschetti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D020194:Unverricht-Lundborg Syndrome / Q000503:physiopathology*; D055815:Young Adult