title: The corticomotor projection to liminally-contractable forearm muscles in chronic spinal cord injury: a transcranial magnetic stimulation study.
abstract: METHODS
  A cross-sectional study in chronic spinal cord injury with cervical lesions (cSCI).
  
  
  OBJECTIVE
  To determine the corticomotor projection and motor cortex organization of paralyzed forearm muscles that presented only liminal voluntary activation.
  
  
  METHODS
  Burke Medical Research Institute, White Plains, NY, USA.
  
  
  METHODS
  We identified ten people with chronic SCI who had a wrist flexor or extensor muscle with a motor power (MP) of 1 over 5. We recorded motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) over the primary motor cortex of the hemisphere contralateral to the target muscle. We measured resting motor threshold (RMT), corticomotor latency (LTY), MEP amplitude (AMP) and performed cortical motor mapping to determine the optimal site (OPT) and map area (AREA). Results were compared with the data from 18 controls.
  
  
  RESULTS
  A MEP in the target muscle was observed for all cSCI cases. LTY was normal, while corticomotor excitability (as determined by RMT and AMP) was reduced in about half of the group. The OPT site of the motor maps was within control range for all cSCI cases, while AREA was reduced in three cases.
  
  
  CONCLUSIONS
  Corticomotor conduction and cortical topography were appreciably normal despite only liminal activation of the target muscle with voluntary effort. Muscles with these characteristics may benefit from a targeted rehabilitation program even in the chronic phase after SCI.
authors.affiliation: Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Medical Research Institute, White Plains, NY, USA.|Department of Neurology, Cornell University, New York, NY, USA.|EMG and Motor Control Unit, Neurology Department, Hospital Clinic, Universitat de Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Cortes
authors.affiliation: Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Medical Research Institute, White Plains, NY, USA.|Department of Rehabilitation Medicine, Cornell University, New York, NY, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Thickbroom
authors.affiliation: Department of Epidemiology, Cornell University, New York, NY, USA.
authors.forename: J
authors.initials: J
authors.lastname: Elder
authors.affiliation: Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Medical Research Institute, White Plains, NY, USA.
authors.forename: A
authors.initials: A
authors.lastname: Rykman
authors.affiliation: EMG and Motor Control Unit, Neurology Department, Hospital Clinic, Universitat de Barcelona, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Valls-Sole
authors.affiliation: Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.|Institut Universitari de Neurorehabilitacio Guttmann, Department of Neurology, Universitat Autonoma, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pascual-Leone
authors.affiliation: Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Medical Research Institute, White Plains, NY, USA.|Department of Neurology, Cornell University, New York, NY, USA.|Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Edwards
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D005542:Forearm / Q000294:innervation / Q000503:physiopathology*; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009431:Neural Conduction; D009434:Neural Pathways / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult