Summary The aim of the study is to improve diagnosis of spinal disorders in patients with cervical spondylogenic myelopathy (CSM) using complex neurophysiological (NPh) methods of diagnostics, development of Nph criteria for estimation of neurosurgical treatment.

Materials and methods Comparison of clinical and NPh methods of diagnosis was made in 40 patients with CMS aged from 31 to 81 (average 53.6±0.95 years), 60% male and 40% female. Compression of the spinal cord at the cervical level was confirmed by MRI. Clinical assessment of motor and sensory disorders, disorders of pelvic organs according to modified Japanese Orthopedic Association Scoring Scale (JOA) and recovery rate (RR) analyzed surgical treatment outcome. NPh studies have been conducted with the help of electromyography (EMG), transcranial magnetic stimulation (TMS) and median somatosensory evoked potentials (SSEPs).

NPh research conducted using the Neuro–MEP–4 (Neurosoft, Russia) using a magnetic stimulator Neuro–MS (Neurosoft, Russia).

Results Results of surgical treatment were determined based on an assessment of neurological status of the patient on JOA scale at all stages: pre–operative (I1), and 6 and 12 months after surgery (I2). Our patients showed a significant difference between the clinical assessment of JOA score before surgery (I1) and after surgery (I2) (p<0,005): the average values of I1 was 9.1±1.4 points (6 to 13), I2–13.5±1.2 points (12 to 15). The average value of RR was 53.4±16.3 (from 20.5 to 86.7). There were no patients after surgery with the clinical evaluation score I2 MEP deviations were recorded in 36 (90%) patients, prolongation of MEP cortical latency–34 (86%), increased central motor conduction time (CMCT)–32 (80%), reduced amplitude–28 (70%), cortical MEP polyphasy recorded from muscles of upper extremities–26 (65%). A direct correlation between MEP date (especially recording from the muscles of upper extremities) and RR (r=0,42–0,93, p<0,01).

SSEP deviations were detected in 23 (63.8%) patients. Initial clinical evaluation in patients with deviations from median SSEP being worse, than in patients with normal SSEP (p<0,05). SSEP deviation before surgery: delay in interpeak intervals N9–N13, N9–N20 and N20 changes associated with worse recovery of neurological function after surgery, p<0,05. The most significant was the correlation N9–N20 with RR (r=–2.83, p<0.01).

Conclusions Use of SSEP and MEP provides functional diagnosis of conductive structures of the cervical spinal cord in patients with CSM at all stages of surgical treatment. Several SSEP and MEP indicators may have prognostic significance of the results of CSM surgical treatment. Median SSEP recording can be recommended as a very sensitive test in the CSM diagnosis.It can be independent predictor of a good clinical outcome after surgery.