Peripheral and central nervous system correlates in fibromyalgia

Area of Science:

• Neurology
• Pain Medicine
• Clinical Research

Background:

• Fibromyalgia (FM) involves complex pain processing alterations.
• Pathophysiology of FM remains incompletely understood.
• Investigating peripheral and central nervous system changes in FM is crucial.

Purpose of the Study:

• To examine structural changes in peripheral nociceptors via skin biopsy.
• To assess functional changes in central pain pathways using laser-evoked potentials (LEP).
• To correlate these findings with clinical features and comorbidities in FM patients.

Main Methods:

• Skin biopsies for intraepidermal nerve fibre density (IENFD) quantification.
• LEP recordings from hand, thigh, and foot stimulation.
• Recording of clinical data, comorbidities (migraine, mood disorders), and nerve conduction studies.

Main Results:

• Reduced IENFD observed in 85% of patients at the thigh.
• Altered N2P2 habituation index in 97.5% of patients, correlating with thigh IENFD.
• No significant differences in LEP latencies/amplitudes; no association found between IENFD, LEP, and clinical features/comorbidities.

Conclusions:

• Fibromyalgia commonly presents with mild proximal small fibre pathology, not distal neuropathy.
• Altered habituation index supports central sensitization's role in FM pathogenesis.
• Central pain processing impairment, with associated mild proximal small fibre pathology, likely underlies FM.