The spectrum of magnetic resonance imaging findings in hypertension-related neurovascular compression.

Hypertension (HTN) has been controversially related to neurovascular compression (NVC) at the rostral ventrolateral (RVL) medulla in anatomical, surgical, and radiological reports. Our objective was to investigate the association between primary HTN and signs of NVC at the medulla oblongata on magnetic resonance imaging (MRI) and to explore a new classification based on image criteria. Subjects with (n=64) and without (n=29) HTN were studied. Three-millimeter slices, with 1-mm intervals in between, were performed on T2-weighted images in axial and coronal views. Attention was focused on the relationship between the upper medulla and the surrounding arteries. The findings were divided into three categories: 1) non-NVC: absence of signs of NVC, 2) NVC type I: an artery in contact with the RVL medulla but not compressing it, and 3) NVC type II: evident compression of the RVL medulla by an artery. Signs of NVC were observed in 65.7% (42/64) of the HTN group (type I: 39.1%, 25/42 patients; type II: 26.6%, 17/42 patients). Among the normotensive subjects, 27.6% (8/29) had signs of NVC; only one (3.3%) of these had NVC type II (evident compression), and the rest were NVC type I. We conclude that the presence of NVC at the RVL medulla on MRI is related to HTN. More importantly, the finding of frank compression (NVC type II) is present almost exclusively in hypertensive subjects; only one individual (3.3% of our normotensive population) had NVC type II.

Atividade simpática na hipertensão arterial associada à compressão neurovascular do bulbo rostral ventro-lateral em humanos / Sympathetic activity in hypertension related to neurovascular compression

A microneurografia foi usada para investigar a atividade simpática periférica (ASP) em 25 indivíduos hipertensos, investigados quanto à presença de compressão neurovascular (CNV) no bulbo com a técnica de ressonância magnética (RM). De acordo com a RM, foram formados três grupos: CNV-, sem sinais de CNV (n=9); CNV Tipo I, com imagem vascular junto ao bulbo mas sem deformação anatômica (n=8); e CNV Tipo II, com imagem vascular causando compressão no bulbo (N=8). O grupo CNV Tipo II apresentou ASP mais elevada que os grupos CNV Tipo I e CNV-, tanto no repouso, quanto após estímulos hipotérmico e exercício isométrico. A demonstração de ASP diferenciada dependendo do tipo de CNV é um fato importante, pois pode identificar um subgrupo de hipertensos nos quais a CNV possa ter alguma implicação fisiopatológica.Sympathetic activity in hypertension with neurovascular compression in humans. /Microneurography was used to measure peripheral muscle sympathetic nerve activity (MSNA) in 25 subjects with hypertension, who were submitted to magnetic resonance imaging (MRI) to detect neurovascular compression (NVC) at the medulla. Three groups were formed according to MRI: NVC-, without signs of NVC (N=9); NVC Type I, with a vessel nearby medulla but not compressing it (N=8); NVC Type II, with a vessel compressing the medulla (N=8). Group NVC Type II had higher MSNA than other groups during rest period and after stimuli with cold and isometric exercise. These results show different values of PSA in subjects with different findings of NVC, and are important to the identification of subgroups whose image of NVC really have clinical relevance...