Choosing upper limb muscles for focal intervention after traumatic brain injury

The upper motoneuron syndrome (UMNS) resulting from lesions of corticospinal pathways is an important source of disability after traumatic brain injury (TBI). Classic expressions of motor behavior in UMNS are of 2 kinds: (1) manifestation of muscle underactivity, termed negative signs, and (2) manifestation of a variety of forms of muscle overactivity, termed positive signs. Combinations of negative and positive signs give rise to clinical patterns of movement dysfunction such as the flexed elbow, the clenched fist, and the thumb-in-palm deformity. These clinical patterns can be viewed as reflecting a net balance of muscle forces acting across the joints of a limb. Individual muscles are amenable to a variety of focal interventions such as neurolysis, chemodenervation, or surgery. Since more than one muscle acts across most joints, choices among muscles for focal intervention are many. This article will focus on focal interventions of upper limb muscles of patients with TBI who have UMNS and will explore the theme of choosing upper limb muscles for focal interventions after TBI.