Fibromyalgia and Neuropathic Pain Have Both Differences and Similarities in Sensory Profiles

Fibromyalgia and Neuropathic Pain Have Both Differences and Similarities in Sensory Profiles

FMRalf Baron from the Klinik für Neurologie, Universitätsklinikum Schleswig-Holstein in Germany and colleagues, compared co-morbities and sensory perceptions in patients with Painful Diabetic Neuropathy and Fibromyalgia.

The study entitled “Fibromyalgia and neuropathic pain – differences and similarities. A comparison of 3057 patients with diabetic painful neuropathy and fibromyalgia,” was recently published in the journal BMC Neurology.

Painful diabetic neuropathy (DPN) is a chronic neuropathic pain syndrome caused by a metabolic damage of primary afferent neurons. The sensory symptoms include numbness, prickling, burning or electric shocks.

Fibromyalgia (FM) is a chronic pain condition characterized by widespread pain mainly perceived in deep somatic tissues, i.e., in muscles and joints. Moreover, the patients have abnormal pain sensitivity and frequent additional comorbidities like sleep disturbances and affective disorders.

Patients with diabetic neuropathy (DPN) and fibromyalgia (FM) differ substantially in pathogenetic factors and the spatial distribution of the perceived pain. However, similar abnormal sensory complaints and pain exists in both conditions.

In this regard, the team of researchers conducted a multicenter trial in 450 outpatient centers, involving 1434 fibromyalgia patients and 1623 patients with painful diabetic neuropathy, and compared the two conditions epidemiological features and co-morbidities. Moreover, they examined similarities and differences of sensory symptoms between the two conditions. All the participants were asked to fill a battery of self-report questionnaires assessing sleep disturbances, depression, pain and sensory perceptions.

Data analysis revealed differences between the two groups of patients (DPN vs. FM), in depression and sleep disturbances. However, patients with DPN and FM reported similar designations for their sensory perceptions. These included burning pain, prickling and touch-evoked allodynia. The analysis of the results identified five different groups according to sensory profiles (combination of sensory symptoms), with two of subgroups being specific for fibromyalgia whereas one profile occurred predominantly in DPN patients. Two sensory profiles were found frequently in patients of both entities (20-35%).

Based on these findings, the team of researchers suggest that patients can be classified on the basis of their sensory symptoms, by the use of self-report questionnaires. Results revealed that DPN and FM patients experience very similar sensory phenomena. The combination of sensory symptoms was found to be unique for each condition, suggesting that are distinct aetiologies in the symptoms generation. With regards to sensory profiles, found to be overlapped in 20-35% of patients in both aetiologies, the researchers suggest a potential association with similar mechanisms operating in certain subgroups of DPN and FM patients. The researchers mention that this questionnaire approach to sensory symptoms can open potential treatment strategies for the symptoms the patients suffer from most.