[Functional studies of the spinal cord in chronic stenosing diseases of the cervical spine using somatosensory evoked potentials].

Report about 35 persons with chronic stenosing diseases of cervical spine which was investigated through somatosensory evoked potentials (SSEP) after stimulation of the median (M-SSEP), ulnar (U-SSEP) and tibial (T-SSEP) nerve. The examinations were always performed in extreme possible cervical ante and retroflexion. The majority of patients (n = 17) presented with a bony spinal stenosis. Less often were cervical disc prolaps (n = 8) or a atlanto-axial dislocation in primary chronic polyarthritis (n = 7) the cause of the illness. The rest of the patients (n = 3) had still different sources of stenoses of the spine. In 23 of 35 patients a change of the SSEP occurred during measurement while in this extreme cervical ante-and retroflexion. In 15 of these cases the initially pathological SSEP deteriorated, while in 8 patients an initially normal SSEP turned pathological in the functional position. Most often changes of the so-called "Functional SSEP" occurred in multisegmental bony cervical stenosis. In most cases a change in the T-SSEP obtained, independently of the main localisation of the radiologically verified spinal stenosis. The SSEP changes are illustrated through typical examples. The determination of SSEP in extreme positions of the cervical spine appears, therefore, as a suitable method to discover transient dysfunctions or the increase of dysfunctions of the cervical spinal cord. They can also serve as a preoperative screening method of dysfunctions of the cervical spinal cord in operations of planned long duration with unfavourable positioning of the cervical spine (extreme antiflexion, twisting, or retroflexion).(ABSTRACT TRUNCATED AT 250 WORDS)