Absence of transcallosal inhibition in adolescents with diplegic cerebral palsy.

The role of intracortical organization in the pathophysiology of cerebral palsy (CP) is not clear. We used transcranial magnetic stimulation to investigate the paradigm of transcallosal inhibition (TI) in a group of adolescent patients with diplegic CP (n = 4), hereditary spastic paraplegia (n = 2), and healthy control adolescents (n = 4). None of the patients with CP showed TI, whereas all other subjects had normal TI. These findings indicate a lack of inhibitory control of the motor cortex in CP.