Pulsatile Compression of the Rostral Ventrolateral Medulla in Hypertension

Abstract

The rostra1 ventrolateral medulla (RVLM) has been known to be a major regulating center of sympathetic and cardrovascular acttvtttes An assoctatton between essential hypertension and neurovascular compressron of the RVLM has been reported m clmrcal observattons, mcludmg magnetic resonance tmagmg (MRI) studies To reconfirm this relattonshtp, we performed MRI usmg a high-resolutton 5 12X512 matrix m pattents wtth essential and secondary hypertenston and m normotensrve SubJeCtS The duratton of hypertension and the degree of organ damage by hypertension were not srgmficantly drfferent between the two hypertension groups Neurovascular compressron of the RVLM was observed m 74% of the essential hypertension group, and the incidence of compresston was srgmficantly higher than m the secondary hypertension group (11%) or m the normotenstve group (13%) (P< 01) These results from the clmrcal studies suggest that neurovascular compressron of the RVLM ts, at least m part, causally related to essential hypertension Although blood pressure elevation by pulsatrle compressron of the RVLM m an experimental baboon model has already been reported, tts un-T he rostra1 ventrolateral medulla (RVLM) contams neurons that are considered to be an orlgin of tome sympathetic discharge and a maJor center regulating sympathetic and cardiovascular actrvities 132 Chemical or electrrcal sttmulatron of the RVLM increases sympathetic nerve activities to elevate blood pressure, whrle its destruction causes hypotensron.s-6Since the report by Jannetta and Gendell,T it has been shown that posterior inferior cerebellar artery, anterior inferior cerebellar artery, and vertebral artery occasionally compress the medulla oblongata and that patients with essential hypertension are associated with neurovascular compresston of the ventrolateral medulla at the root-entry zone of glossopharyngeal and vagus nerves (ie, the RVLM) m clnucal observations mcludmg magnetic resonance imagmg (MRI) studtes.a-16 To reconfirm this relationship, we performed MRI using a high-resolution 5 12x5 12 matrix, a newly developed magnetic device, in patients with essential and secondary hypertension and in normotensive SubJects. Jannetta et a110 also reported blood pressure elevation by pulsatile compression of the RVLM m an experimental baboon model However, the mechanism of the development ofFrom the Second Department of Medicine and Department of Radiology (S N , T M ), Kyoto Prefectural Umversny of Medlcme, Kawaramacht-HnokoJt, Kanngyo-ku, Kyoto City, Japan Reprint requests to Dr Satoshr Morrmoto, Second Department of Medicine, Kyoto Prefectural Umversrty of Medtcme, KawaramachtHirokojr, Kamtgyo-ku, Kyoto city 602, Japan 0 1997 American Heart Assocratron, Inc -hypertension was not mvesttgated precisely. Therefore, we performed experimental studies to mvesttgate whether pulsatile compression of the RVLM would increase arterial pressure and to determine the underlying mechanism of the pressor response m rats Clinical Studies MethodsNineteen patients with essential hypert...

Efficacy of an L- and N-type calcium channel blocker in hypertensive patients with neurovascular compression of the rostral ventrolateral medulla

“…[4][5][6][7][8][9][10] Using MRI, we found that the incidence of NVC of the RVLM in patients with EH was significantly higher than that in patients with secondary hypertension or in normotensive subjects, although the stage of hypertension did not differ significantly between the two hypertension groups. 11,12 We and others have reported that hypertensive patients show increased plasma levels of NE. 15,16 Therefore, it is assumed that NVC of the RVLM may be, at least in part, causally related to EH.…”

“…[4][5][6][7][8][9][10] We have reported that magnetic resonance imaging (MRI) with a high-resolution matrix revealed a significantly higher incidence of NVC of the RVLM in EH patients as compared with those with secondary hypertension or normotensive patients, although the degree of organ damage from hypertension was not significantly different between the two groups of hypertensive patients. 11,12 Jannetta et al 13,14 and we 15 have reported that microvascular decompression (MVD) of the RVLM decreases blood pressure (BP) in hypertensive patients with NVC of the RVLM. Therefore, it is assumed that MVD of the RVLM could be a useful therapeutic strategy to reduce BP in these patients.…”

Efficacy of clonidine in patients with essential hypertension with neurovascular contact of the rostral ventrolateral medulla

“…However, our previous study in rats revealed that BP elevation by pulsatile compression of RVLM becomes more marked in a pressure-dependent manner. 15 Therefore, we cannot rule out the possibility that a decrease in arterial stimulation of RVLM by BP reduction led to a further reduction of BP. At present, there is an ongoing clinical study designed to compare the pressure-lowering effects of L-type calcium antagonists, which do not have sympatholytic effects, in NVC+ and NVC-patients.…”

“…5,6 After the initial report by Jannetta and Gendell in 1978, 7 several clinical studies have suggested an association between neurovascular contact (NVC) of RVLM and essential hypertension (EH). [8][9][10][11][12][13][14][15] Jannetta et al 16,17 have reported that MVD of RVLM decreases blood pressure (BP) in hypertensive patients with NVC of RVLM. MVD of RVLM could be a useful therapeutic strategy to reduce BP in these patients.…”

Blood pressure lowering effects of non-surgical procedures for vascular decompression: good news to be taken with caution

“…1 A further support to the so-called 'neurogenic hypothesis' of hypertension comes from the evidence of a close link between some hypertensive states and neurovascular compression of the rostral ventrolateral medulla, that is, an area of the central nervous system with an important efferent pathway of the sympathetic nervous system. [2][3][4][5] This association is strengthened by the evidence that in different experimental animal models electrical, chemical or mechanical stimulation of the ventricular medulla triggers a transient pressor response. [6][7] It is also strengthened by the finding that in subgroups of patients with severe and/or resistant hypertension microsurgical decompression at the level of the rostral ventrolateral medulla substantially improves blood pressure control, leading to a long-term blood pressure normalization in a not negligible number of patients.…”