Electrophysiological assessment of the effect of intrathecal baclofen in spastic children

Objectives: To evaluate the effect of intrathecal baclofen in a group of spastic children using electrophysiological procedures described in adults. Methods: Six children (aged 1–14 years) with severe spasticity of various aetiologies underwent transcranial magnetic stimulation, H reflex and flexor reflex studies before and after intrathecal injection of baclofen. Ashworth scale was used for clinical evaluation of spasticity. Results: Motor evoked potentials, present in two patients before baclofen, were preserved after injection. Before baclofen, H reflex was present in 5 patients (Hmax/Mmax from 0.23 to 0.84) and absent in one who had infantile neuroaxonal dystrophy. After baclofen, it was absent in 4 patients and markedly reduced in one. Surface of flexor reflex significantly decreased after baclofen (P=0.01), while threshold significantly increased (P=0.003). Conclusions: In spastic children, the action of baclofen on spinal pathways may be quantified by the same electrophysiological procedures as in adults. This approach may contribute to select optimal dosage.