The relationship of corticospinal excitability with pain, motor performance and disability in subjects with chronic wrist/hand pain.

There is a growing body of evidence of changes in corticospinal excitability associated with musculoskeletal disorders, however there is a lack of knowledge of how these changes relate to measures of pain, motor performance and disability. An exploratory study was performed utilizing Transcranial Magnetic Stimulation to investigate differences in corticospinal excitability in the Abductor Pollicis Brevis (APB) between 15 pain-free subjects and 15 subjects with chronic wrist/hand pain and to determine how corticospinal excitability was associated with measures of pain (visual analog scale, AUSCAN™), hand motor performance (isometric and key pinch strength, Purdue Pegboard Test), disability (AUSCAN™), and spinal motoneuronal excitability. Input-output curves demonstrated increased corticospinal excitability of the APB in the affected hand of subjects with chronic pain (p<0.01). Changes in corticospinal excitability were significantly correlated with pain intensity (r=0.77), disability (r=0.58), and negatively correlated with motoneuronal excitability (r=-0.57). Corticospinal excitability in subjects with heterogeneous injuries of the wrist/hand was associated with disability and pain.