Characteristic Features of Dysautonomia Distinguishing Chronic Fatigue Syndrome from Fibromyalgia – One Clinic's Experience pp. 103-124
Authors: Itzhak Rosner, Jochanan E. Naschitz, Bnai-Zion Medical Center and Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
Abstract: Substantial clinical overlap may exist amongst functional somatic syndromes, in general, and chronic fatigue syndrome (CFS) and fibromyalgia (FM), in particular. The underlying pathophysiology of these disorders is unclear. In this article we review studies performed at our institution, exploring similarities and dissimilarities between CFS and FM based on autonomic nervous functioning and electrocardiographic QT. Two methods were recently developed to assess autonomic nervous functioning via cardiovascular reactivity in response to a standardized postural challenge. The 'hemodynamic instability score' (HIS) computes blood pressure and heart rate changes along the tilt test and the resulting measurements are processed by image analysis techniques. Three studies assessed the HIS in CFS patients. Group averages of HIS were CFS = +3.72 (SD 5.02) vs. healthy = -4.62 (SD 2.26) and FM -3.25 (SD 2.63) (p <0.0001). An other technique is based on beat-to-beat heart rate and pulse transit time recordings during the tilt test, data processing by fractal and recurrence plot analysis and computing a ‗Fractal & Recurrence Analysis-based Score‘ (FRAS). FRAS values >0.22 were specific for CFS vs. healthy subjects and FM (2 studies). A different approach, measurement of the QT interval on the surface electrocardiogram found that the corrected QT in CFS patients is relatively shortened and thereby differs from QT in FM (p <0.0001). Jointly, these records show characteristic features to the CFS dysautonomia phenotype, supporting the distinction between CFS and FM. This data may be relevant in providing objective criteria for CFS diagnosis and distinction from other functional somatic syndromes.