title: Posture-Dependent Corticomotor Excitability Differs Between the Transferred Biceps in Individuals With Tetraplegia and the Biceps of Nonimpaired Individuals.
abstract: Following biceps transfer to enable elbow extension in individuals with tetraplegia, motor re-education may be facilitated by greater corticomotor excitability. Arm posture modulates corticomotor excitability of the nonimpaired biceps. If arm posture also modulates excitability of the transferred biceps, posture may aid in motor re-education.
  
  
  
  Our objective was to determine whether multi-joint arm posture affects corticomotor excitability of the transferred biceps similar to the nonimpaired biceps. We also aimed to determine whether corticomotor excitability of the transferred biceps is related to elbow extension strength and muscle length.
  
  
  
  Corticomotor excitability was assessed in 7 arms of individuals with tetraplegia and biceps transfer using transcranial magnetic stimulation and compared to biceps excitability of nonimpaired individuals. Single-pulse transcranial magnetic stimulation was delivered to the motor cortex with the arm in functional postures at rest. Motor-evoked potential amplitude was recorded via surface electromyography. Elbow moment was recorded during maximum isometric extension trials, and muscle length was estimated using a biomechanical model.
  
  
  
  Arm posture modulated corticomotor excitability of the transferred biceps differently than the nonimpaired biceps. Elbow extension strength was positively related and muscle length was unrelated, respectively, to motor-evoked potential amplitude across the arms with biceps transfer.
  
  
  
  Corticomotor excitability of the transferred biceps is modulated by arm posture and may contribute to strength outcomes after tendon transfer. Future work should determine whether modulating corticomotor excitability via posture promotes motor re-education during the rehabilitative period following surgery.
authors.affiliation: 1 Edward Hines, Jr. VA Hospital, Hines, IL, USA.|2 Rehabilitation Institute of Chicago, Chicago, IL, USA.|3 Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Peterson
authors.affiliation: 2 Rehabilitation Institute of Chicago, Chicago, IL, USA.|3 Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Rogers
authors.affiliation: 1 Edward Hines, Jr. VA Hospital, Hines, IL, USA.|4 Loyola University-Chicago, Maywood, IL, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Bednar
authors.affiliation: 5 The Cleveland FES Center at MetroHealth, Cleveland, OH, USA.|6 Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Bryden
authors.affiliation: 5 The Cleveland FES Center at MetroHealth, Cleveland, OH, USA.|6 Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Keith
authors.affiliation: 2 Rehabilitation Institute of Chicago, Chicago, IL, USA.|3 Northwestern University Feinberg School of Medicine, Chicago, IL, USA.|7 Northwestern University, Evanston, IL, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Perreault
authors.affiliation: 1 Edward Hines, Jr. VA Hospital, Hines, IL, USA.|2 Rehabilitation Institute of Chicago, Chicago, IL, USA.|3 Northwestern University Feinberg School of Medicine, Chicago, IL, USA.|7 Northwestern University, Evanston, IL, USA.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Murray
mesh_terms: D000328:Adult; D001132:Arm / Q000473:pathology / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008954:Models, Biological; D009044:Motor Cortex / Q000503:physiopathology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009929:Organ Size; D011187:Posture / Q000502:physiology*; D011782:Quadriplegia / Q000473:pathology / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: corticospinal tracts; muscle length; muscle strength; spinal cord injuries; transcranial magnetic stimulation; upper extremity