Do you recall patients complaining of hypersensitivity to light, sound, cold, stress or mechanical pressure (e.g. jewellery on the neck)? This often relates to hypersensitivity of the central nervous system, a mechanism referred to as central sensitization. Brain orchestrated inhibitory mechanisms no longer work properly, while the brain activates descending fascilatory pathways. It’s like driving a Ferrari without brakes.
Central sensitization is frequently present in a variety of chronic disorders like fibromyalgia, chronic whiplash associated disorders, osteoarthritis, irritable bowel syndrome and some cases of chronic low back pain. In the late nineties, it was first hypothesized that chronic fatigue syndrome (CFS) is characterized by central sensitization as well.
Many people with CFS feel most comfortable attributing their illness to a disorder of the central nervous system, and this seems to be rational given the cluster of symptoms that occur in the illness. Symptoms like fatigue, non-refreshing sleep, concentration difficulties, impairments in short-term memory, sensitivity to variable stimuli like bright light and chemicals, a decreased load tolerance and widespread pain are suggestive of central nervous system involvement.
In the past ten years, several studies have examined central sensitization in patients with CFS. When all data are studied together, it becomes clear that CFS is characterised by central sensitization [1]. Patients with CFS are hypersensitive for a variety of sensory stimuli, including electrical stimulation, mechanical pressure, heat and histamine. Various tissues respond hypersensitive: the skin, muscle tissue, and the lungs. Central sensitization accounts in part for exercise intolerance in these patients as well.
Thanks to this BiM blog you already know 75% of what is written in the paper. So you can skip the first part of the paper and go directly to the subheading ‘How does central sensitization fit into our overall understanding of CFS?’. Here the fun part begins. That section explains that the presence of central sensitization in CFS is in line with our current understanding of this illness. Central sensitization in CFS corroborates with the presence of several psychological influences on the illness, the presence of infectious agents and immune dysfunctions, and the dysfunctional hypothalamus pituitary adrenal-axis as seen in these severely debilitated patients. This is important for an illness with a long history of disagreement between scientists. A change in thinking towards studying and treating CFS as a central sensitization disorder appears warranted.
About Jo
Jo Nijs holds a PhD in rehabilitation science and physiotherapy. He is a researcher and assistant professor at the Vrije Universiteit Brussel (Brussels, Belgium) and the Artesis University College Antwerp (Belgium), and he is a physiotherapist at the University Hospital Brussels. His research and clinical interests are patients with chronic unexplained pain/fatigue. He has (co-)authored more than 100 peer reviewed publications and served over 40 times as an invited speaker at national and international meetings.
References
[1] Nijs J, Meeus M, Van Oosterwijck J, Ickmans K, Moorkens G, Hans G, & De Clerck LS (2011). In the mind or in the brain? Scientific evidence for central sensitisation in chronic fatigue syndrome. European journal of clinical investigation PMID: 21793823