Results from a recent study published in the journal European Neurology, indicate thermal and discomfort thresholds are lower in patients with Multiple Sclerosis and comorbid Fibromyalgia in comparison to healthy individuals.

Multiple sclerosis (MS) is a disabling neurological disease with pain being reported as one of the most common and disabling symptoms, with a prevalence range between 29 and 82%. From the forms of chronic pain in MS, fibromyalgia (FM) comorbidity has been reported in the latest stage of MS, and resulting similar to those reported in rheumatic diseases like SLE and RA. MS patients have lower thermal and discomfort thresholds , but those thresholds have not been evaluated in MS patients with FM comorbidity.

To examine the thermal and discomfort thresholds in the assessment of pain intensity between MS patients with FM (PFM+) and MS patients with pain not associated to FM (PFM-), in their study entitled “Chronic Pain in Multiple Sclerosis Patients: Utility of Sensory Quantitative Testing in Patients with Fibromyalgia Comorbidity,” Maria Grazia Grasso from the IRCCS Fondazione ‘Santa Lucia and colleagues at the ‘Sapienza’ University of Rome, in Italy evaluated chronic pain in 133 patients with definite MS, according to the McDonald criteria. FM was measured according to the 1990 ACR diagnostic criteria. To measure the thresholds in the patients and in 60 matched controls, the researchers used an algometer.

Results revealed that 88 patients had chronic pain; from these, the researchers found that 12 had neuropathic pain, 22 patients were PFM+ and 65 patients were PFM-. Patients with PFM+ were mainly female and had a greater disability in comparison to patients with no pain. Statistical analysis also revealed that the thresholds were lower in patients with MS patients in comparison to the controls, especially in those in the PFM+. The severity of FM impacted the thermal threshold, while the female gender impacted the discomfort threshold.

The results are conclusive regarding the fact that thermal and discomfort thresholds were lower in patients than controls and were the lowest in PFM+. Their more severely impaired thermal threshold supports a neurophysiological basis of such association. However, larger studies, including patients with lower disability scores, might shed more light on the utility of quantitative sensory testing in detecting the patients at higher risk of FM comorbidity, even in the early stage of disease, according to the researchers.