Abnormalities of cardiovascular neural control and reduced orthostatic tolerance in patients with primary fibromyalgia.
OBJECTIVE
Fibromyalgia (FM) is a syndrome characterized by widespread musculoskeletal pain. Symptoms of orthostatic intolerance may also be present, suggesting underlying abnormalities of cardiovascular neural regulation. We tested the hypothesis that FM is characterized by sympathetic overactivity and alterations in cardiovascular autonomic response to gravitational stimulus.


METHODS
Sixteen patients with primary FM and 16 healthy controls underwent electrocardiography examination, finger blood pressure, respiration, and muscle sympathetic nerve activity (MSNA) recordings at rest and during stepwise tilt test, up to 75 degrees . The autonomic profile was assessed by MSNA, plasma catecholamine, and spectral indices of cardiac sympathetic (LFRR in normalized units, NU) and vagal (HFRR both in absolute and NU) modulation and of sympathetic vasomotor control (LFSAP) computed by spectrum analysis of RR and systolic arterial pressure (SAP) variability. Arterial baroreflex function was evaluated by the SAP/RR spontaneous-sequences technique, the index a, and the gain of MSNA/diastolic pressure relationship during stepwise tilt test.


RESULTS
At rest, patients showed higher values of heart rate, MSNA, LFRR NU, LF/HF, LFSAP, and reduced HFRR than controls. During tilt test, lack of increase of MSNA, less decrease of HFRR, and excessive rate (44%) of syncope were found in patients, suggesting reduced capability to enhance the sympathetic activity to vessels and withdraw the vagal modulation to sino-atrial node. Baroreflex function was similar in both groups.


CONCLUSIONS
Patients with FM have an overall enhancement of cardiovascular sympathetic activity while recumbent. Lack of increased sympathetic discharge to vessels and decreased cardiac vagal activity characterize their autonomic profile during tilt test, and might account for the excessive rate of syncope.
Furlan
Raffaello
R
Department of Internal Medicine II, Ospedale L. Sacco, Università degli Studi di Milano, Milano, Italy. raffaellof@fisiopat.sacco.unimi.it
Colombo
Simona
S
Perego
Francesca
F
Atzeni
Fabiola
F
Diana
Alessandro
A
Barbic
Franca
F
Porta
Alberto
A
Pace
Fabio
F
Malliani
Alberto
A
Sarzi-Puttini
Piercarlo
P
D000328:Adult; D001795:Blood Pressure Determination; D002320:Cardiovascular Physiological Phenomena; D016022:Case-Control Studies; D004562:Electrocardiography; D005260:Female; D005356:Fibromyalgia / Q000150:complications* / Q000175:diagnosis; D005500:Follow-Up Studies; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011311:Pressoreceptors / Q000502:physiology; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013575:Syncope / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D018667:Tilt-Table Test