A New Diagnostic Medium for Cervical Spondylotic Myelopathy: Dynamic Somatosensory Evoked Potentials

To identify and reveal the sensitivity and efficiency of dynamic somatosensory evoked potentials (DSSEPs) in the diagnosis of cervical spondylotic myelopathy (CSM).

This retrospective study included 31 CSM and 15 control patients. All patients received SSEP examination with stimulation of median and ulnar nerves at neutral, flexed, and extended cervical positions; latency and amplitude were recorded at the C₂ and C₅ spinous processes and in the scalp over the primary sensory area (C_3'/4'). The percentage changes in latency and amplitude with dynamic motion were examined for each lead and compared between groups; the diagnostic cutoff values were determined using receiver operating characteristic curve analysis.

All the patients with CSM received surgeries and were followed up for 1 year. Amplitude parameters varied with a dynamic position in both groups; all recorded dynamic SSEP indices except right median stimulus recorded at C5 spinous process, right ulnar stimulus recorded at scalp point C3, and right ulnar stimulus recorded at C2 spinous process were significantly different between groups (P < 0.05), but latency was not (P > 0.05). At the neutral position, the amplitude of left media stimulus recorded at C2 spinous process (LMC₂) was associated with CSM, but with low diagnostic accuracy (area under the curve = 0.199). At a dynamic position, the percentage change in amplitude of LMC₂ and of left ulnar stimulus recorded at C2 spinous process (LUC₂) were determined to be diagnostic of CSM (P < 0.05), with areas under the curve of 0.891 and 0.912, respectively. Both records had high sensitivity and specificity in the diagnosis of CSM; the diagnostic cutoff values of LMC₂ and LUC₂ were calculated as 10.2% and 19.25%, respectively.

The percentage change in amplitude was obvious during cervical dynamic motion, with records from LMC₂ and LUC₂ being predictive of CSM diagnosis; dynamic SSEPs provided a simple, accurate, and noninvasive supplementary test for the diagnosis of complicated CSM.