HISTOLOGY AND INTRAMUSCULAR PRESSURE IN SPASTIC MUSCLE

A prospective study was performed to delineate the pathologic processe s occurring in the degradation of muscle function with the onset of sp asticity. Sixteen adult patients with spasticity secondary to traumati c brain injury (TBI) were evaluated clinically and histologically. Sho rt-term patients showed even distribution of mild, moderate, and sever e spasticity, while moderate spasticity predominated in the chronic gr oup. Motor control was predominately selective with pattern overlay in both groups. Muscles with spasticity of less than 6 months duration s howed nonspecific histologic changes. Muscles with spasticity of durat ion longer than 1 year demonstrated neurogenic atrophy, some also show ed signs of denervation followed by reinnervation. No evidence of comp artment syndrome was found in the spastic muscles studied. Transient h igh elevation of intramuscular pressure was noted in some patients dur ing muscle stretch or activity. Muscles that become spastic following TBI demonstrate neurogenic degeneration, generally apparent greater th an 1 year after the injury. Prior to this, spastic muscles demonstrate nonspecific atrophic changes.