Intrathecal baclofen in hereditary spastic paraparesis.

Intrathecal baclofen has not been previously evaluated for the treatment of the disabling hypertonia associated with hereditary spastic paraparesis. Muscle tone and deep-tendon reflexes were evaluated in three patients with hereditary spastic paraparesis after a double-blind, cross-over bolus injection of intrathecal baclofen. Patients underwent placement of a subcutaneous pump for continuous infusion of intrathecal baclofen. Three months after implantation the muscle tone decreased 2.04 points (p less than .0001) and the reflex score decreased 2.25 points (p less than .001). Patients initially reported subjective weakness, but muscle testing revealed either an increase or no change in voluntary motor function. Baclofen doses of 60 to 264 micrograms per day were required for effective control of muscle tone and spasticity. Much of the disability in familial spastic paraparesis may be related to the loss of suprasegmental inhibition of spinal reflexes overwhelming the residual voluntary motor function.