Study of dynamic somatosensory evoked potentials in patients with asymptomatic central cervical spinal stenosis

Objective. To perform comparative analysis of the components of dynamic somatosensory evoked potentials (DSSEP) from the upper and lower extremities with varying grades of central cervical spinal stenosis (CSS) in patients with mildly symptomatic and asymptomatic course of the disease.

Material and Methods. The retrospective monocentric study included 56 patients (29 men and 27 women; age 54.8 ± 9.6 years) with CSS examined in 2019–2024. In accordance with the grading system of Kang et al., patients were divided into three groups: Group 1 included 25 patients with grade 1, Group 2 – 23 people with grade 2, and Group 3 – 8 patients with grade 3. All patients underwent DSSEP examination from the upper and lower extremities in the neutral position and in flexion and extension positions of the neck at an angle of 45 Changes in the amplitude of the cortical peak N20, the spinal peak N13 and the interpeak interval N9–N20 were assessed when recording dynamic DSSEPs from the upper extremities. The changes in the amplitude of the cortical peak P38 were assessed when recording DSSEPs from the lower extremities. In addition to assessing the absolute values of the indicators, the index of change in the indicators was calculated.

Results. In the neutral position, statistically significant differences were found between groups 1 and 3 in the amplitude of the N20, N13 and P38 components and the N9–N20 interpeak interval. Statistically significant differences were also found between groups 2 and 3 in N20, N13, P38 peaks and the N9–N20 interval. At the same time, statistically significant differences were not found between Groups 1 and 2. When assessing the dynamic SSEPs, patients in Group 1 showed a statistically significant decrease in the N20 amplitude in the extension position and an increase in the N9–N20 latency in the flexion position. In Group 2, in addition to a statistically significant decrease in the N20 amplitude in the extension position and an increase in N9–N20 latency in the flexion position, a statistically significant decrease in the N13 amplitude was noted both in the flexion position and during extension. In Group 3, a statistically significant decrease in the amplitude of N13 during extension and of P38 during flexion was revealed. When analyzing the index of change in the indicators, no significant differences were found between the groups, however, statistically significant differences were recorded for the N9–N20 interval between Group 1 and Group 3, as well as between Group 2 and Group 3 without statistically significant differences between Group 1 and Group 2.

Conclusion. The use of dynamic SSEPs allows for an objective assessment of the degree of damage to the cervical spinal cord in patients with asymptomatic central stenosis of the cervical spinal canal of varying grades. Further multicenter studies are needed to clarify the reference values of dynamic SSEP parameters and, taking them into account, to develop clear criteria for selecting candidates for surgical treatment.

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