NEUROPATHOPHYSIOLOGY OF MOVEMENT-DISORDERS IN CEREBRAL-PALSY

Recent developments in understanding the pathophysiology of disordered motor control in cerebral palsy are reviewed. In spastic cerebral pal sy, evidence for abnormal segmental as well as supraspinal control of motor neuron output exists. Impaired Ia inhibition of antagonist muscl es has been suggested but recently contested. Evidence also supports t he role of decreased presynaptic inhibition of Ia afferents and decrea sed nonreciprocal Ib inhibition. Furthermore, early cerebral injury re sults in reorganization of supraspinal (corticospinal) inputs to motor neuron pools. In extrapyramidal cerebral palsy, injury of basal gangl ia or thalamus has been demonstrated. A scheme for understanding the n eurochemical circuitry of the extrapyramidal system is discussed. Anim al models and certain specific human diseases provide examples of how this circuitry may be disturbed, thereby resulting in an imbalance bet ween the direct and indirect striatal output systems and in impaired m otor control. Future studies employing postmortem neurochemical analys is, functional magnetic resonance imaging, and positron emission tomog raphic scanning may foster progress in this area.