CASE REPORTHyponatremia accompanying volatile hypertension caused by baroreflex failure after neck surgery: case report and literature reviewSarafidis, Pantelis A.a; Theodorakopoulou, Marietaa; Dipla, Konstantinab; Zafeiridis, Andreasb; Boutou, Afroditic; Loutradis, Charalamposa; Faitatzidou, Danaea; Papagianni, Aikaterinia; Parati, GianfrancodAuthor Information aDepartment of Nephrology, Hippokration Hospital, Aristotle University, Thessaloniki bExercise Physiology and Biochemistry Laboratory, Department of Sports Science, Aristotle University, Serres cDepartment of Respiratory Medicine, Papanikolaou Hospital, Thessaloniki, Greece dIstituto Auxologico Italiano, IRCCS, Department of Cardiovascular, Neural and Metabolic Sciences, S. Luca Hospital, Milan Correspondence to Pantelis A. Sarafidis, MD, MSc, PhD, Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Konstantinoupoleos 49, GR54642 Thessaloniki, Greece. Tel: +30 2313 312930; fax: +30 2313 312930; e-mail: email@example.com Abbreviations: ABPM, ambulatory blood pressure monitoring; ACTH, adrenocorticotropic hormone; ADH, antidiuretic hormone; BP, blood pressure; bpm, beats per minute; CNS, central nervous system; CT, computed tomography; HR, heart rate; ICA, inner carotid artery; KE, potassium exchangeable; MVC, maximal voluntary strength; NaE, sodium exchangeable; od, once daily; sBRS, spontaneous baroreflex sensitivity; SIADH, syndrome of inappropriate antidiuretic hormone secretion; TBW, total body water; VMA, vanillylmandelic acid Received 31 December, 2019 Revised 29 January, 2020 Accepted 25 February, 2020 Journal of Hypertension: August 2020 - Volume 38 - Issue 8 - p 1617-1624 doi: 10.1097/HJH.0000000000002436 Buy Metrics Abstract The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of euvolemic hyponatremia, and many disorders have been associated with it. Baroreflex failure is a rare disorder characterized by extreme blood pressure (BP) fluctuations, most frequently caused by neck or head trauma and irradiation. We report a case of a 48-year-old patient referred to our department for asymptomatic hyponatremia and volatile hypertension. His past medical history included nasopharyngeal carcinoma treated with surgery and bilateral neck radiation. Following the diagnostic algorithm for hyponatremia, the diagnosis of SIADH was made. Ambulatory BP monitoring revealed highly variable BP; extensive autonomic nervous system function testing suggested baroreflex-cardiovagal failure. We propose the hypothesis that not only labile hypertension because of baroreflex failure but also hyponatremia can develop as a late consequence of neck trauma and irradiation. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.