A Cross-Sectional Study on Central Sensitization and Autonomic Changes in Fibromyalgia

Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret near-infrared spectroscopy signals. Changes in CBF and total hemoglobin (tHb) were in parallel, although tHb showed no change when changes in CBF were small (< or =10%). Increasing CBF caused an increase in oxygenated hemoglobin (HbO(2)) and a decrease in deoxygenated hemoglobin (deoxy-Hb). Decreasing CBF was accompanied by a decrease in HbO(2), whereas changes in direction of deoxy-Hb were various. Cerebral blood congestion caused increases in HbO(2), deoxy-Hb, and tHb. Administration of pentylenetetrazole without increasing the flow rate caused increases in HbO(2) and tHb with a decrease in deoxy-Hb. There were no significant differences in venous oxygen saturation before vs. during seizure. These results suggest that, in activation studies with near-infrared spectroscopy, HbO(2) is the most sensitive indicator of changes in CBF, and the direction of changes in deoxy-Hb is determined by the degree of changes in venous blood oxygenation and volume.

To discuss the current terminologies used for fibromyalgia syndrome (FMS) and related overlapping conditions, to examine if central sensitivity syndromes (CSS) is the appropriate nosology for these disorders, and to explore the issue of disease versus illness. A literature search was performed through PubMed, Web of Science, and ScienceDirect using a number of keywords, eg, functional somatic syndromes, somatoform disorders, medically unexplained symptoms, organic and nonorganic, and diseases and illness. Relevant articles were then reviewed and representative ones cited. Terminologies currently used for CSS conditions predominantly represent a psychosocial construct and are inappropriate. On the other hand, CSS seems to be the logical nosology based on a biopsychosocial model. Such terms as "medically unexplained symptoms," "somatization," "somatization disorder," and "functional somatic syndromes" in the context of CSS should be abandoned. Given current scientific knowledge, the concept of disease-illness dualism has no rational basis and impedes proper patient-physician communication, resulting in poor patient care. The concept of CSS is likely to promote research, education, and proper patient management. CSS seems to be a useful paradigm and an appropriate terminology for FMS and related conditions. The disease-illness, as well as organic/non-organic dichotomy, should be rejected.

Slow breathing practices have been adopted in the modern world across the globe due to their claimed health benefits. This has piqued the interest of researchers and clinicians who have initiated investigations into the physiological (and psychological) effects of slow breathing techniques and attempted to uncover the underlying mechanisms. The aim of this article is to provide a comprehensive overview of normal respiratory physiology and the documented physiological effects of slow breathing techniques according to research in healthy humans. The review focuses on the physiological implications to the respiratory, cardiovascular, cardiorespiratory and autonomic nervous systems, with particular focus on diaphragm activity, ventilation efficiency, haemodynamics, heart rate variability, cardiorespiratory coupling, respiratory sinus arrhythmia and sympathovagal balance. The review ends with a brief discussion of the potential clinical implications of slow breathing techniques. This is a topic that warrants further research, understanding and discussion. Key points Slow breathing practices have gained popularity in the western world due to their claimed health benefits, yet remain relatively untouched by the medical community. Investigations into the physiological effects of slow breathing have uncovered significant effects on the respiratory, cardiovascular, cardiorespiratory and autonomic nervous systems. Key findings include effects on respiratory muscle activity, ventilation efficiency, chemoreflex and baroreflex sensitivity, heart rate variability, blood flow dynamics, respiratory sinus arrhythmia, cardiorespiratory coupling, and sympathovagal balance. There appears to be potential for use of controlled slow breathing techniques as a means of optimising physiological parameters that appear to be associated with health and longevity, and that may extend to disease states; however, there is a dire need for further research into the area. Educational aims To provide a comprehensive overview of normal human respiratory physiology and the documented effects of slow breathing in healthy humans. To review and discuss the evidence and hypotheses regarding the mechanisms underlying slow breathing physiological effects in humans. To provide a definition of slow breathing and what may constitute “autonomically optimised respiration”. To open discussion on the potential clinical implications of slow breathing techniques and the need for further research.