Intrathecal baclofen increases corticospinal output to hand muscles in multiple sclerosis
Abstract
Continuous intrathecal baclofen infusion (CIBI) is a highly effective treatment for severe spasticity, especially of spinal origin.1-2 The beneficial effect of CIBI on spasticity is related to its gamma-aminobutyric acid (GABA)B-ergic action on spinal interneurons, resulting in a profound depression of disinhibited mono- and polysynaptic spinal reflexes.1-3 Although the effects on spinal reflexes have been studied in detail,2-4 the effects of CIBI on the corticofugal projections to the spinal motor neurons have not been characterized. This study used transcranial magnetic stimulation (TMS) to assess the effects of CIBI on corticospinal projections to the intrinsic hand muscles in patients with severe spastic quadriparesis due to MS. Eleven patients (age 31 to 57 years, 10 women and 1 man) with advanced MS with severe spastic quadriparesis (Expanded Disability Status Scale score >7) were studied. Because of resistance to oral antispastic medication, a programmable infusion pump (Medtronic Inc., Minneapolis, MN) was implanted for CIBI. Daily …