Autonomic changes in fibromyalgia: Clinical and electrophysiological study

Background: Autonomic nervous system (ANS) dysfunction is one of the suggested pathophysiological mechanisms of fibromyalgia (FM). Its dysfunction may contribute to enhanced pain and other clinical problems associated with FM. Previous studies showed conflicting results regarding ANS function in FM. Some studies showed increased while other showed decreased ANS activity in FM patients. Thus, the autonomic responses in FM patients need further elaboration. Aim of the work: The aim of this work was to evaluate the autonomic dysfunction in FM patients clinically and electrophysiologically. Subjects and methods: Twenty-five patients (23 females and 2 males) diagnosed as FM and 15 apparently healthy individuals served as a control group were included in this study. Patients were subjected to thorough clinical examination and assessment of 1 – pain by McGill pain questionnaire (MPQ), 2 – sleep by Visual Analogue Scale (VAS), 3 – depression by Hamilton Rating Scale for Depression(HRSD) and 4 – functional status by Fibromyalgia impact questionnaire (FIQ). Assessment of ANS function was carried out by tilt table test, measuring supine and standing blood pressure (BP) and heart rate (HR) and sympathetic skin response (SSR) of the hands. Results: Compared to controls, there was a statistically significant decrease of standing systolic BP standing, diastolic BP and standing HR as well as a statistically significant increase in latency and decrease in amplitude of SSR of the hands of the FM patients. HRSD was correlated positively with supine systolic BP and standing diastolic BP whileMcGill pain questionnaire was correlated positively with supine systolicBP.Moreover,VAS falling asleepwas correlated positivelywith standing systolicBP. Conclusion: The studied FM patients showed ANS dysfunction in the form of abnormal responses to active and passive changes in posture as well as abnormal SSR.