Altered Spinal Excitability in Patients with Primary Fibromyalgia: A Case-Control Study

Abstract

Background and Purpose Abnormal excitability of the central nervous system, both spinal and supraspinal, has previously been described as a pathophysiological plastic mechanism for chronic pain syndromes. Primary fibromyalgia (FM) as one extreme of this spectrum of diseases. This case-control study aimed to determine the changes in the spinal excitability by investigating the Hoffman reflex (H-reflex) in patients with FM. Methods Thirty-eight patients with FM and 30 healthy controls participated in this case-control study. We measured the H-reflex bilaterally in the upper limbs (flexor carpi radialis) and the lower limbs (gastrocnemius and soleus). Moreover, pain-related variables were measured, including pain severity (using a visual analogue scale), pain duration, Widespread Pain Index, and the score on the Symptom Severity Scale. Various psychiatric comorbidities and quality-of-life parameters were measured for each patient, including scores on the Hamilton Depression Rating Scale, Taylor's Manifest Anxiety Scale, and the Revised Fibromyalgia Impact Questionnaire. Results A significant increase in the ratio of the maximum baseline-to-peak amplitudes of H and M waves (H max /M max ) but not in the H-wave minimum latency was found in patients with FM compared with healthy controls. There were no significant correlations between this ratio in both muscles and the various pain-related measures, psychiatric comorbidity, and quality of life in patients with FM. Patients with FM suffered more depression and anxiety than did the controls. Conclusions We found increased spinal excitability in patients with FM, which was not confined to the site of maximum pain. This information may help in the diagnosis of FM and supports the hypothesis of central sensitization.

Mechanisms of transcranial direct current stimulation (tDCS) for pain in patients with fibromyalgia syndrome

“…With aberrant central nervous system excitability ( Thabit et al, 2021 ), pain-processing brain regions in FMS sufferers are more hypersensitive to pressure stimuli than healthy people ( Truini et al, 2015 ).…”

Potential Significance of Altered Spinal Excitability in Patients With Primary Fibromyalgia

“…Elevation of this reflex may represent a more-comprehensive and insensitive pathology that is present in various neurological diseases. However, considering that no currently available laboratory data support a diagnosis of FM, 4 the results of this study 1 are certainly dramatic and show potential promise for clinical applications. Future studies focusing on the features of the H-reflex in FM subjects may contribute substantially to revealing unknown aspects of this mysterious disease.…”

“…I read with great interest the article by Thabit et al 1 reporting on their electrophysiology study showing increased spinal excitability in patients with fibromyalgia (FM). However, some points may need to be discussed further in order to obtain a better understanding of that report.…”