CFS & Fibromyalgia Related Conditions An Overview of Central Sensitivity Syndromes A category that includes fibromyalgia, chronic fatigue, and other conditions By Adrienne Dellwo Adrienne Dellwo LinkedIn Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic. Learn about our editorial process Updated on August 07, 2022 Medically reviewed by Anita C. Chandrasekaran, MD, MPH Medically reviewed by Anita C. Chandrasekaran, MD, MPH LinkedIn Anita Chandrasekaran, MD, MPH, is board-certified in internal medicine and rheumatology and currently works as a rheumatologist at Hartford Healthcare Medical Group in Connecticut. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Definition Types Symptoms Treatment Frequently Asked Questions Central sensitization syndromes (CSS) are a collection of disorders where the central nervous system misfires and amplifies sensory input resulting in pain, fatigue, brain fog, and sleep problems. Fibromyalgia (FMS), chronic fatigue syndrome (ME/CFS), and other chronic pain conditions fall under the CSS umbrella. Central sensitization syndromes are sometimes known as functional somatic syndrome, medically unexplained syndrome, and somatoform disorders. Fibromyalgia, chronic fatigue, and other central sensitization syndromes have a broad range of physical and psychological symptoms that span multiple systems and can be hard to classify. This article discusses central sensitization syndromes, the underlying mechanisms behind CSS, and available treatment options. Westend61 / Getty Images What Is a Central Sensitization Syndrome? An illness described as a CSS involves something called central sensitization. "Central" means the central nervous system, which is made up of your brain and spinal cord. "Sensitization" is the end result of something that has made you sensitive. Allergies are the type of sensitization people are generally the most familiar with. In allergies, your body has an inappropriate physical reaction to something that doesn't bother other people at all. In fact, while the sensitivities of a CSS aren't exactly allergies, they do involve an inappropriate physical reaction. In CSS, the body becomes sensitive to things that are processed by the central nervous system, which can include bright lights, loud noises, strong smells, rough textures, and pressure on the body. It may also involve certain foods or chemicals. Especially in FMS, the body is sensitized to anything unpleasant, i.e., cold, heat, a tickle or an itch. Types of Central Sensitization Syndrome Aside from FMS and ME/CFS, the following conditions have been proposed to be part of the CSS family: Chronic pelvic pain, including vulvodynia Headache and migraine Idiopathic low back pain Interstitial cystitis (painful bladder) Irritable bowel syndrome Multiple chemical sensitivity Myofascial pain syndrome Primary dysmenorrhea (painful period) Restless legs syndrome Temporomandibular joint disorder (TMJ) Psychiatric disorders are common in CSS as well. Research suggests that's because they all involve dysregulation of the same neurotransmitters, with the dysregulation in CSS in different regions of the brain than in psychiatric disorders. Psychiatric conditions that commonly overlap with CSS include: Major depressionObsessive-compulsive disorderBipolar disorderPost-traumatic stress disorderGeneralized anxiety disorderPanic attack Symptoms of Central Sensitization Syndrome Neurotransmitters that are involved in at least some of the CSS include: SerotoninNorepinephrineDopamineGABA & glutamate The pain of CSS comes from a couple of different abnormal pain types: hyperalgesia and allodynia. Hyperalgesia takes normal pain from things that everyone considers painful (a broken limb, an infected tooth, etc.) and makes it worse. It's often referred to as "turning up the volume" of pain. This makes things like injuries, surgeries, and chronic sources of pain especially debilitating. Allodynia makes you feel pain from things that shouldn't hurt, such as the brush of fabric against your skin, or your arm resting against your side when you sleep. Allodynia can make your clothes painful even when they're not too tight, or make you unable to enjoy a hug. It turns all manner of ordinary experiences into painful ones, which often means making significant changes to your life to minimize it. Other proposed mechanisms of CSS include: Inflammation in or originating in the nervous system Autonomic nervous system dysfunction Dysfunction of the HPA axis, which is part of the body's stress-response system Treating Central Sensitivity Syndromes The different individual symptoms and mechanisms of each CSS require a customized treatment approach, but in general, most CSS tend to respond to some of the same types of treatment, especially antidepressants (which help correct neurotransmitter dysregulation), exercise, and cognitive-behavioral therapy (CBT). However, it should be noted that people with ME/CFS have special considerations when it comes to exercise, and CBT is a highly controversial treatment for this illness, especially when it's paired with graded exercise. While these conditions are believed to be related, it's important to get each one diagnosed and treated properly. Be sure to talk to your healthcare provider about any symptoms that don't seem to be related to your current diagnoses. A Word From Verywell The CSS classification is good news for all of us with these conditions. It signifies a positive change in how these illnesses are understood and viewed by the medical community. That's what we need when it comes to getting research attention, which leads to better diagnostics and treatments. Frequently Asked Questions How common are central sensitization syndromes? Central sensitization syndromes affect millions of Americans, but the exact number is unclear. While people can have overlapping disorders, estimates for some CSS conditions in the United States include:Fibromyalgia: 2% of adultsChronic fatigue syndrome: 0.25% to 0.75% of adultsTMJ: 5% to 12% of adults What are usually the first signs of fibromyalgia? Fibromyalgia can present differently in individuals. Pain, fatigue, and brain fog are the most common first signs of fibromyalgia. Other common symptoms include insomnia, headaches, depression, and digestive issues. Learn More: Symptoms of Fibromyalgia What is peripheral sensitization? Peripheral sensitization refers to an oversized response from pain receptors in the peripheral nervous system. This can occur from nerve damage from an injury or illness. The pain of peripheral sensitivity corresponds to the site of the injury. 8 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Fleming KC, Volcheck MM. Central sensitization syndrome and the initial evaluation of a patient with fibromyalgia: a review. Rambam Maimonides Med J. 2015;6(2):e0020. doi:10.5041/RMMJ.10204 Mayer TG, Neblett R, Cohen H, et al. The development and psychometric validation of the central sensitization inventory. Pain Pract. 2012;12(4):276-285. doi:10.1111/j.1533-2500.2011.00493.x Yunus MB. The prevalence of fibromyalgia in other chronic pain conditions. Pain Res Treat. 2012;584573. doi:10.1155/2012/584573 Adams LM, Turk DC. Psychosocial factors and central sensitivity syndromes. Curr Rheumatol Rev. 2015;11(2):96-108. Nijs J, Malfliet A, Ickmans K, Baert I, Meeus M. Treatment of central sensitization in patients with 'unexplained' chronic pain: an update. Expert Opin Pharmacother. 2014;15(12):1671-83. doi:10.1517/14656566.2014.925446 Centers for Disease Control and Prevention. Fibromyalgia. Institute of Medicine. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) key facts. Spiegel DR, Pattison A, Lyons A, et al. The role and treatment implications of peripheral and central processing of pain, pruritus, and nausea in heightened somatic awareness: a review. Innov Clin Neurosci. 2017;14(5-6):11-20. By Adrienne Dellwo Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit