Functional neurological disorder is common in patients attending chronic pain clinics

Background and purpose: Chronic pain is a common comorbidity in those with functional neurological disorder (FND); however, the prevalence and characteristics of FND in those with chronic pain is unknown.Methods: A retrospective electronic records review was made of consecutive new patients attending a chronic pain clinic of a regional service. Clinical features, medication for and outcome of chronic pain, any lifetime diagnoses of functional disorders, FND, and psychiatric disorders, and undiagnosed neurological symptoms were recorded.Results: Of 190 patients attending the chronic pain clinic, 32 (17%) had a lifetime diagnosis of FND and an additional 11 (6%) had undiagnosed neurological symptoms. Pain patients with comorbid FND were more likely to have chronic primary pain (88% with FND, 44% without FND, p < 0.0001), widespread chronic primary pain (53%, 15%, p < 0.00001), and depression (84%, 52%, p < 0.005) and less likely to have a pain-precipitating event (19% vs. 56%, p < 0.001). However, there was no significant difference between these patients in opiate prescription, benzodiazepine prescription, or pain outcome.Conclusions: This first study of FND in a chronic pain patient population found a remarkably high prevalence of FND (17%) and is possibly an underestimation. The size of the overlap indicates that FND and chronic pain research fields are likely to have a lot to learn from each other.

Automated summary

This study aimed to investigate the prevalence and characteristics of functional neurological disorder (FND) in patients with chronic pain. The results showed that among 190 chronic pain patients, 32 (17%) had a diagnosis of FND and an additional 11 (6%) had undiagnosed neurological symptoms. Chronic pain patients with comorbid FND were more likely to have chronic primary pain, widespread chronic primary pain, and depression. However, there were no significant differences in medication prescription or pain outcome between patients with and without FND.