Fibromyalgia: a Pain Medicine perspective

What fibromyalgia really is

Fibromyalgia is a syndrome of chronic widespread pain accompanied by fatigue, sleep disturbances and cognitive difficulties. It is not an inflammatory disease, it is not psychological, and it is certainly not "nothing." It is a real condition, with clear neurobiological underpinnings, that affects between 2% and 4% of the adult population.

For decades it was considered a "muscle" disease. Today we know the problem lies mainly in how the central nervous system processes pain signals. People with fibromyalgia perceive as painful what would not be painful to someone else. That is not "imagination": it is a real functional alteration of the body's pain-modulation system.

The pain in fibromyalgia is widespread: it affects several regions of the body, tends to be symmetrical, waxes and wanes in intensity, and comes with a deep sense of exhaustion that rest never quite relieves. A helpful way to understand it is to think of the body's alarm system as being overly sensitized: signals that would normally be ignored are now felt as pain.

A technical nuance I consider key: fibromyalgia is not diagnosed with tests. There is no blood work, MRI or electromyogram that confirms it. Tests serve to rule out other treatable causes — hypothyroidism, severe vitamin D deficiency, rheumatologic diseases, sleep apnea — but the diagnosis is clinical, based on current criteria that assess widespread pain, fatigue, sleep disturbances and cognitive symptoms. When a patient brings me 50 normal test results and still has years of diffuse pain, the problem is not that a test is missing: it is that, most likely, nobody applied the correct diagnostic criteria.

How it is diagnosed today

Fibromyalgia is diagnosed clinically. There is no MRI, blood test or X-ray that confirms it. The current American College of Rheumatology criteria (2016) define it by:

• Widespread pain in several regions of the body, present for at least three months.
• Associated symptoms: fatigue, non-restorative sleep, cognitive difficulties (so-called "brain fog").
• No other condition that better explains the symptoms.

Tests are used to rule out other causes (rheumatoid arthritis, hypothyroidism, polymyalgia rheumatica, severe vitamin D deficiency, myopathies, lupus). If those tests are normal and the clinical picture fits, the diagnosis is fibromyalgia — with no need to keep searching for lesions that are not going to appear.

Why the whole body hurts: central sensitization

The main mechanism in fibromyalgia is what we call central sensitization: the central nervous system amplifies pain signals. Functional MRI studies show that in patients with fibromyalgia, the brain areas that process pain activate more intensely — and in response to stimuli that would not trigger a response in other people.

There are also alterations in the neurotransmitters that modulate pain: increased substance P, and decreased serotonin, norepinephrine and dopamine. These changes explain why medications that act on those systems (certain antidepressants, gabapentinoids) tend to be effective, while common anti-inflammatories and opioids are of little use — and even counterproductive in the long run.

Deep sleep is almost always disrupted. Patients describe sleeping many hours yet waking up as if they had not slept at all. That lack of restorative sleep worsens pain and fatigue, creating a cycle that is hard to break.

Treatments that are working

Treatment for fibromyalgia is multimodal. No single intervention produces major results on its own, but combining them well does change a patient's quality of life. What is best supported by evidence today:

• Pain neuroscience education: understanding what is happening in your body is, in itself, a therapeutic intervention. It reduces anxiety and the endless search for diagnoses, and improves adherence to treatment.
• Graded, progressive aerobic exercise: walking, swimming, cycling. Start very slowly and build up gradually. It is the non-drug intervention with the strongest evidence. Pain may increase at first, but sustained over weeks it brings significant improvement.
• Specific medication: pregabalin, duloxetine and low-dose amitriptyline have the best evidence. They are not "antidepressants for depressed people" — they are pain-system modulators that act precisely on the neurotransmitters altered in fibromyalgia.
• Cognitive behavioral therapy: helps manage anxiety, catastrophizing and the sense of losing control. It does not "cure" fibromyalgia, but it makes living with it considerably easier.
• Rigorous sleep hygiene: working specifically on sleep quality is central. Without restorative sleep, nothing else works.

What does not work, or backfires: opioids as long-term treatment (they worsen sensitization), chronic high-dose NSAIDs (they do not act on the underlying mechanism), and prolonged rest (it deconditions the body and worsens the condition).

My approach to treating fibromyalgia is always multimodal, and I make that clear from the very first visit. No single drug resolves the condition: the combination of central pain-modulating medication, low-intensity aerobic activity started very gradually, dedicated work on sleep and — when appropriate — psychological support is what shows the best sustained results. When a patient asks me for "the fibromyalgia pill," I explain that no such pill exists, but that there is a concrete path which, walked with patience, usually improves quality of life a great deal. Consistency matters more than dose.

Living with it and getting better: what to realistically expect

Fibromyalgia, as things stand today, cannot be "cured." But most patients who commit to a comprehensive treatment plan see a significant improvement in their quality of life. That means: fewer flares, better sleep, better day-to-day function, less rescue medication, fewer trips to the emergency department.

Improvement is usually gradual, not immediate. The first months are the hardest, because new habits need to take hold (exercise, sleep, medication that takes time to stabilize). But after 4-6 months of well-conducted treatment, the great majority of patients notice an important change.

The role of the Pain Medicine specialist in fibromyalgia is to coordinate the treatment, adjust the specific medication, rule out and treat painful comorbidities (because many patients with fibromyalgia also have a facet syndrome, a localized myofascial pain or a headache that can be treated specifically), and accompany the patient through a process that takes time and consistency.

For me, success in treating fibromyalgia is not measured by making the pain disappear — that rarely happens completely — but by giving the patient back functional capacity and predictability. When someone who spent years unable to plan anything because they "never knew how they would wake up" starts having stable weeks, going back to their walks, sleeping better and feeling they have tools to manage the flares when they come, that is successful treatment. The goal is not a cure: it is for fibromyalgia to stop running the patient's life, and for the patient to take the wheel again.

Dr. Mauricio Casarsa

Anesthesiologist, specialist in Pain Medicine and Interventional Pain Management. Postgraduate training at UBA (Fundación Dolor) and UNLP (CAIDBA). Staff physician at Hospital Alemán, Buenos Aires.

MN 137756 · San Isidro · Villa Urquiza