Object: Several studies have suggested that neurovascular compression (NVC) of the brainstem might be a cause of hypertension. Because this compression syndrome might be demonstrated by MR imaging studies, several authors have tried to assess its prevalence in small series of patients with hypertension. This article presents a meta-analysis of these studies.
Methods: The studies reviewed by the authors were based on MR imaging and included the presence of left-sided NVC of the left rostral ventrolateral medulla oblongata (RVLM) and/or the cranial nerves IX and X root entry zone in patients with apparent primary hypertension compared with normotensive patients. Several studies also included patients with secondary hypertension as an additional control group, which is analyzed separately.
Results: Meta-analysis included data from 14 studies (597 patients with primary hypertension and 609 controls). The effect size was OR 2.68 (95% CI 1.51-4.75, p = 0.001) (random effect), which is consistent with the hypothesis that NVC of the left RVLM is more frequent in patients with apparent primary hypertension compared with normotensive individuals. Stratification for the study design revealed an effect size for prospective studies of OR 1.97 (95% CI 0.74-5.30, p = 0.178) and for retrospective studies of OR 3.36 (95% CI 1.66-6.79, p = 0.001).
Conclusions: This meta-analysis indicates a statistically significant effect size for left-sided NVC in apparent primary hypertension. However, this effect is absent if subanalysis is confined to prospective studies.