Article

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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Langue : ANGLAIS