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...
