title: Generators and temporal succession of giant somatosensory evoked potentials in cortical reflex myoclonus: epicortical recording from sensorimotor cortex.
abstract: OBJECTIVE
  To clarify the generator mechanism of giant somatosensory evoked potentials (giant SEPs) and the hyperexcitability of primary somatosensory and motor cortices (SI and MI).
  
  
  METHODS
  In a patient with intractable focal seizures manifesting cortical reflex myoclonus of the left foot, giant SEPs to left tibial nerve stimulation were epicortically recorded as a part of presurgical evaluation with subdural electrodes.
  
  
  RESULTS
  In the single pulse SEPs, enlarged P1-N1 components were observed at the foot area of the SI and MI (86.5-258.8 microV, respectively), and the peak latencies were always shorter at SI than at MI by 6 ms. Similar findings were obtained for peroneal and sural nerve stimulation. In the paired pulse SEPs, the second response was less suppressed, as compared to other interstimulus intervals (ISIs), with ISIs of 40 and 200 ms both at SI and MI.
  
  
  CONCLUSIONS
  In this particular patient, cortical hyperexcitability to somatosensory stimuli seems to originate from SI but subsequently both SI and MI are responsible for the generation of giant SEPs and cortical reflex myoclonus.
  
  
  CONCLUSIONS
  Somatosensory and primary motor cortices both generated enhanced early cortical components of SEPs, most likely by enhancing the latter by the former.
authors.affiliation: Department of Neurology, Kyoto University Graduate School of Medicine, and Takeda General Hospital, Kyoto, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Hitomi
authors.forename: Akio
authors.initials: A
authors.lastname: Ikeda
authors.forename: Riki
authors.initials: R
authors.lastname: Matsumoto
authors.forename: Masako
authors.initials: M
authors.lastname: Kinoshita
authors.forename: Junya
authors.initials: J
authors.lastname: Taki
authors.forename: Keiko
authors.initials: K
authors.lastname: Usui
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Mikuni
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagamine
authors.forename: Nobuo
authors.initials: N
authors.lastname: Hashimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shibasaki
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology; D009207:Myoclonus / Q000503:physiopathology*; D010543:Peroneal Nerve / Q000503:physiopathology / Q000528:radiation effects; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D013003:Somatosensory Cortex / Q000503:physiopathology*; D013979:Tibial Nerve / Q000503:physiopathology / Q000528:radiation effects