NEURORADIOLOGIC AND ELECTROPHYSIOLOGIC ASSESSMENT OF CERVICAL SPONDYLOTIC AMYOTROPHY

Dissociated motor loss due to cervical spondylosis and disc herniation was evaluated in 10 patients who presented with left deltoid paresis in the absence of sensory deficits or myelopathy. All of these cases u nderwent cervical anterior decompression. Based on magnetic resonance imaging, computed tomography myelography, and computed tomography disc ography, patients were divided into two pathologic types: The first sh owed focal bony spur and disc herniation with axial cord rotation and nerve root compression, and the second demonstrated ventral cord flatt ening. Electrophysiologic studies included evoked muscle action potent ials. Motor evoked potentials, recorded epidurally from the ventral as pect of the thecal sac and the nerve root within the anterior discecto my or vertebrectomy sites, proved clinically most useful. Combining th e latest available neuroradiologic and electrophysiologic information, 4 types of neural injury associated with deltoid pareses were identif ied in the 10 patients. The first included isolated C5 nerve root lesi ons; the second, C6 nerve root lesions; the third, both C5 and C6 nerv e root lesions, and finally, intrinsic cord pathology.