[Changes in the motor units in patients with traumatic paraplegia]

Neuromuscular biopsies were obtained in 10 patients with traumatic spinal cord lesions at various levels and in one patient with cerebral lesions due to a long lasting coma. In all cases, there was a rapid onset of both fibers types atrophy, with numerous transitional type III and intermediate fibers. Only the two patients with cervical lesions had an increased terminal innervation ratio suggesting denervation. Our observations do not support the hypothesis of a transneuronal degeneration. These changes cannot be related to disuse only as the atrophy does not preferentially involve type II fibers. The underlying neural mechanism of spasticity in muscle of patients with cortico-spinal lesions could explain the change of the histochemical pattern of the muscle fibers.