Physiological assessment of aspects of autonomic function in patients with secondary progressive multiple sclerosis

Abstract

A detailed non-invasive study of systemic and regional haemodynamic responses to a range of autonomic tests which assess sympathetic and parasympathetic pathways (mental arithmetic, cutaneous cold, isometric exercise, deep breathing, Valsalva manoeuvre and head-up tilt) were performed in ten patients with secondary progressive multiple sclerosis and ten age- and sex-matched healthy normal subjects (controls). Blood pressure rose in controls during the pressor tests and was maintained during tilt. In six out of ten patients with multiple sclerosis blood pressure was unchanged during one or more of the three pressor tests, but was maintained in all during tilt. In the controls, superior mesenteric artery blood flow fell during pressor tests and head-up tilt. In multiple sclerosis patients, superior mesenteric artery blood flow did not change during pressor tests but fell during tilt. Cardiac index rose during isometric exercise and fell during head-up tilt in controls. Forearm blood flow rose during mental arithmetic in the controls only, but fell during tilt in both groups. Individual analysis indicated that of the ten multiple sclerosis patients, four had responses during the pressor tests similar to controls. Responses to deep breathing and to the Valsalva manoeuvre in controls and multiple sclerosis patients were similar. We conclude that some patients with an aggressive and disabling form of multiple sclerosis have selective autonomic dysfunction, in particular involving pressor responses, despite the lack of postural hypotension. The autonomic abnormality is likely to involve central autonomic interconnections rather than afferent or sympathetic efferent pathways. Further clarification of the nature, site and progression of these lesions is needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular autonomic dysfunction in multiple sclerosis: correlation with orthostatic intolerance

“…The proportion of patients with two or more abnormal test results (which is generally taken to establish significant autonomic dysfunction [21]) ranged from 10% [38] to 50% [34]. The majority of studies revealed an involvement of both sympathetic and parasympathetic pathways, with the heart rate response to deep breathing [2,23,32,38] and the blood pressure response to sustained HG [27,32,36,38] being most frequently impaired. However, no group differences in the deep breathing test were found by other authors [8,11,22] or in the present study.…”

“…A number of investigations have focused on cardiovascular reflex tests [2,11,12,16,17,23,24,26,36,38], but these have provided conflicting data about the frequency and distribution of cardiovascular autonomic dysfunction in MS. More than 50% of the patients observed by Pentland et al [26], Nordenbo et al [24], Gallai et al [12], and Anema et al [2] showed abnormal responses on one or more tests, while much lower frequencies were found by Linden et al [16,17], Ferini-Strambi et al [8], Frontoni et al [11] and Nasseri et al [23]. The proportion of patients with two or more abnormal test results (which is generally taken to establish significant autonomic dysfunction [21]) ranged from 10% [38] to 50% [34].…”

“…Other manifestations of autonomic dysfunction may include sweating, gastrointestinal, and cardiovascular disturbances. In this regard, orthostatic dizziness (OD) has been found in up to 49% of patients [2,16,38], and abnormal responses to cardiovascular reflex tests are reported with varying frequencies [2,11,12,17,24,26,36,38]. However, the mechanisms leading to OD are poorly understood, and the correlation with autonomic function tests (AT) has not been systematically studied before.…”

Impaired carotid baroreflex control of arterial blood pressure in multiple sclerosis

“…It is therefore reasonable to suspect that the autonomic neural regulation of beat-to-beat fluctuations in blood pressure by the arterial baroreflex is altered in individuals with MS. Prior investigations on cardiovascular autonomic dysfunction in MS have mostly been descriptive in nature, failing to provide mechanistic insight (Acevedo et al 2000;Anema et al 1991;Flachenecker and Reiners 2005;Flachenecker et al 1999;Frontoni et al 1997;Nasseri et al 1998;Pentland and Ewing 1987;Racosta et al 2015;Senaratne et al 1984;Thomaides et al 1993). To our knowledge, there has been only one attempt to assess baroreflex control in individuals with MS. Utilizing dynamic sinusoidal neck suction to induce carotid hypertension, Sanya et al (2005) demonstrated baroreflex impairments in persons with MS.…”

“…Arterial baroreflex control of blood pressure is essential for short-term (i.e., beat-to-beat) regulation of blood pressure (Smit et al 2002;Timmers et al 2003). The arterial baroreceptor reflex prevents large fluctuations of arterial blood pressure by providing the central nervous system with continuous information from stretch-sensitive baroreceptors originating at the carotid sinus and aortic arch.…”