Migraine and Fibromyalgia: Central Sensitization as a Shared Mechanism

Migraine and fibromyalgia are two of the most commonly co-occurring chronic pain conditions in clinical practice. Research has consistently found that people with migraine have elevated rates of fibromyalgia compared to headache-free populations, and that people with fibromyalgia have substantially higher rates of migraine than the general population. The co-occurrence rates are high enough to suggest that the two conditions share fundamental neurobiological mechanisms rather than simply co-existing by chance.

The concept that provides the most useful framework for understanding the migraine-fibromyalgia relationship is central sensitization — a state of amplified sensory processing in the central nervous system that lowers the threshold for pain and other sensory experiences across the body.

What Central Sensitization Is

Central sensitization refers to an increase in the excitability of neurons in the spinal cord and brain that process sensory information, particularly pain. When central sensitization is present, the pain system responds to stimuli that would not normally be painful, responds more intensely to stimuli that are mildly painful, and generates pain that extends beyond the site of original tissue injury or activation.

In migraine, central sensitization develops during attacks as the neuroinflammatory process spreads from peripheral trigeminal nerve fibers to the trigeminal nucleus caudalis and thalamus. Allodynia — the scalp tenderness and sensitivity to light touch that develops during migraine attacks — is a clinical manifestation of central sensitization in migraine.

In fibromyalgia, central sensitization is considered the primary mechanism underlying widespread musculoskeletal pain, fatigue, sleep disturbance, and cognitive symptoms. The pain of fibromyalgia is not driven by peripheral tissue injury but by amplification of sensory signals within the central nervous system.

Shared Neurobiological Features

Both migraine and fibromyalgia are associated with reduced activity of descending pain inhibitory pathways that normally suppress pain transmission. In healthy individuals, these pathways originate in the periaqueductal gray matter and rostral ventromedial medulla, reducing pain perception through endogenous opioid and monoaminergic mechanisms. In people with migraine or fibromyalgia, conditioned pain modulation is reduced compared to healthy controls.

Serotonin and norepinephrine are the primary neurotransmitters of the descending pain inhibitory system, and dysfunction in these systems is implicated in both conditions. The effectiveness of serotonin-norepinephrine reuptake inhibitors including duloxetine and milnacipran in fibromyalgia, and of tricyclic antidepressants in migraine, reflects this shared pharmacological target.

Clinical Implications of Co-occurrence

People with both migraine and fibromyalgia have higher levels of pain-related disability, greater psychological distress, and worse health-related quality of life than people with either condition alone. The conditions appear to compound each other's severity, possibly through the mutual amplification of central sensitization.

Treatment Overlap

Treatment of one condition may partially benefit the other through shared mechanisms. Medications that target central sensitization and descending pain modulation, including tricyclic antidepressants and serotonin-norepinephrine reuptake inhibitors, have evidence for both conditions. Behavioral approaches including cognitive behavioral therapy and mindfulness-based stress reduction that address pain catastrophizing and central pain amplification may similarly benefit both.

Communicating Both Diagnoses to Healthcare Providers

People with both migraine and fibromyalgia benefit from ensuring that all treating providers are aware of both diagnoses. Treatments appropriate for one condition may be contraindicated or suboptimal in the context of the other, and the combined burden of both conditions warrants a more aggressive approach to preventive management than either condition alone might justify. A single provider who manages both conditions, or close coordination between a headache specialist and a rheumatologist or pain specialist, produces more coherent care than siloed management.