Characterisation of Chronic Pain Syndrome in Patients With Functional Neurological Disorder

Abstract

Background: Functional neurological disorders (FNDs) are characterised by the presence of motor, sensory, or cognitive neurological symptoms not explained by a recognised neurological disorder. Chronic pain is not part of the diagnostic criteria for FND, but these two conditions frequently coexist. Our objective was to evaluate the frequency and mechanism-based characteristics of chronic pain symptoms in a single-center cohort of patients with FND.

Methods: Data were collected prospectively using a standardised questionnaire and a face-to-face interview.

Results: In this study, 63 consecutive patients with FND were interviewed, 54 (86%) of whom reported chronic pain. The onset of pain was associated with a traumatic event in 41% of patients. Pain was described as permanent in 65% of patients, primarily localised to the lower limbs (83%), but actually affecting several other body regions in the vast majority of cases (89%). Pain intensity averaged 5 to 6 out of 10, and its impact on daily activities was rated at 5.5 out of 10 on the Brief Pain Inventory. The description of pain symptoms was more consistent with neuropathic pain or cognitive symptoms of central sensitization than with nociceptive pain or emotional symptoms of central sensitization.

Conclusion: Chronic pain is the most frequently reported symptom by patients, even more than other clinical symptoms specific to FND. This pain has a significant impact on the daily lives of patients.

Significance: Chronic pain is very common in patients with functional neurological disorders and is characterised by highly varied pathophysiological mechanisms. Given its frequency, heterogeneity, and potential impact on other aspects of the functional neurological disorder and on its prognosis, improved management of chronic pain is needed in these patients, particularly through the optimisation of symptomatic treatment strategies.

Keywords: chronic pain; descriptors; functional neurological disorder; mechanisms; treatment.