Effect of Myoarchitectonic Spinolaminoplasty on Concurrent Hypertension in Patients With Cervical Spondylotic Myelopathy

OBJECTIVE: When treating patients with cervical spondylotic myelopathy (CSM), we often note amelioration in concomitant hypertension after surgery. To assess the effects of surgery and the mechanisms thereof, blood pressure (BP) and parasympathetic nervous activity were monitored prospectively in CSM patients undergoing surgery. METHODS: Sixty-eight consecutive CSM patients who underwent surgery with myoarchitectonic spinolaminoplasty were enrolled. BP and electrocardiography were recorded preoperatively and at 1, 3, and 6 months postoperatively. Forty-six patients completed the scheduled follow-ups and were analyzed. Preoperatively, 17 had a mean BP higher than 100 mmHg (the HT group) and 12 had hypertension despite taking medication (the HT-refractory group). To evaluate alterations in parasympathetic function, the coefficient of variation of the RR interval (CVRR) was evaluated. RESULTS: A significant BP reduction was observed in the HT group 6 months after surgery, but not in the normotensive group (n=29). The effect was more remarkable in the HT-refractory group. A transient BP increase at 1 and 3 months after surgery was observed in all groups. Comparisons were made between groups classified by age (over 65 years or younger than 60 years) and the presence or absence of an intramedullary hyperintense T2 signal on magnetic resonance imaging, but no significant differences were detected. Measurements of CVRR did not significantly differ between the groups over the course of follow-up. CONCLUSION: Hypertension coexisting with CSM can be ameliorated after surgical treatment. The effect is likely to be mediated by moderation of sympathetic activity, rather than parasympathetic activation. We believe that a combination of adequate decompression of the spinal cord and relief from musculoskeletal stresses effectuate this moderation.