Dissociated motor loss in the upper extremities. Clinical features and pathophysiology.

Dissociated motor loss occurring in the upper extremities with and without lower extremity myelopathy was evaluated in patients with cervical spondylosis. The presence of dissociated motor loss without attendant myelopathy was correlated with selected compression of the anterior nerve root in the lateral spinal canal, close to the intervertebral foramen. The clinical and radiologic feature differentiating these two dissociative syndromes were reviewed.