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Baroreflex failure in a patient with central nervous system lesions involving the nucleus tractus solitariiAnimal studies have shown the importance of the nucleus tractus solitarii, a collection of neurons in the brain stem, in the acute regulation of blood pressure. Impulses arising from the carotid and aortic baroreceptors converge in this center, where the first synapse of the baroreflex is located. Stimulation of the nucleus tractus solitarii provides an inhibitory signal to other brain stem structures, particularly the rostral ventrolateral medulla, resulting in a reduction in sympathetic outflow and a decrease in blood pressure. Conversely, experimental lesions of the nucleus tractus solitarii lead to loss of baroreflex control of blood pressure, sympathetic activation, and severe hypertension in animals. In humans, baroreflex failure due to deafferentation of baroreceptors has been previously reported and is characterized by episodes of severe hypertension and tachycardia. We present a patient with an undetermined process of the central nervous system characterized pathologically by ubiquitous infarctions that were particularly prominent in the nucleus tractus solitarii bilaterally but spared the rostral ventrolateral medulla. Absence of a functioning baroreflex was evidenced by the lack of reflex tachycardia to the hypotensive effects of sodium nitroprusside, exaggerated pressor responses to handgrip and cold pressor test, and exaggerated depressor responses to meals and centrally acting alpha 2-agonists. This clinicopathological correlate suggests that the patient's baroreflex failure can be explained by the unique combination of the destruction of sympathetic inhibitory centers (ie, the nucleus tractus solitarii) and preservation of centers that exert a positive modulation on sympathetic tone (ie, the rostral ventrolateral medulla).
Document ID
20050000367
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Biaggioni, I.
(Clinical Research Center, Vanderbilt University Nashville, TN 37232)
Whetsell, W. O.
Jobe, J.
Nadeau, J. H.
Date Acquired
August 22, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Hypertension
Volume: 23
Issue: 4
ISSN: 0194-911X
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: RR-00095
CONTRACT_GRANT: HL-14192
CONTRACT_GRANT: HL-44589
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
Case Reports
NASA Discipline Regulatory Physiology

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