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Meta-Analysis
. 2024 Aug 16;95(9):874-885.
doi: 10.1136/jnnp-2023-332810.

Pain and functional neurological disorder: a systematic review and meta-analysis

Moritz Steinruecke  1 , Isabel Mason  2 , Mairi Keen  2 , Laura McWhirter  2   3 , Alan J Carson  2   3 , Jon Stone  2   3 , Ingrid Hoeritzauer  2   3
Affiliations
Meta-Analysis

Pain and functional neurological disorder: a systematic review and meta-analysis

Moritz Steinruecke et al. J Neurol Neurosurg Psychiatry. .

Abstract

Background: Functional neurological disorder (FND) is characterised by neurological symptoms, such as seizures and abnormal movements. Despite its significance to patients, the clinical features of chronic pain in people with FND, and of FND in people with chronic pain, have not been comprehensively studied.

Methods: We systematically reviewed PubMed, Embase and PsycINFO for studies of chronic pain in adults with FND and FND in patients with chronic pain. We described the proportions of patients reporting pain, pain rating and timing, pain-related diagnoses and responsiveness to treatment. We performed random effects meta-analyses of the proportions of patients with FND who reported pain or were diagnosed with pain-related disorders.

Results: Seven hundred and fifteen articles were screened and 64 were included in the analysis. Eight case-control studies of 3476 patients described pain symptoms in a higher proportion of patients with FND than controls with other neurological disorders. A random effects model of 30 cohorts found that an estimated 55% (95% CI 46% to 64%) of 4272 patients with FND reported pain. Random effects models estimated diagnoses of complex regional pain syndrome in 22% (95% CI 6% to 39%) of patients, irritable bowel syndrome in 16% (95% CI 9% to 24%) and fibromyalgia in 10% (95% CI 8% to 13%). Five studies of FND diagnoses among 361 patients with chronic pain were identified. Most interventions for FND did not ameliorate pain, even when other symptoms improved.

Conclusions: Pain symptoms and pain-related diagnoses are common in FND. Classification systems and treatments should routinely consider pain as a comorbidity in patients with FND.

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Conflict of interest statement

Competing interests: LM has received funding from the Scottish government to undertake long COVID research and undertakes expert witness work in court cases concerning neuropsychiatric disorders, including FND. AJC gives expert testimony in court on a range of neuropsychiatric topics, including pain disorders. He is President of the FND Society and Associate Editor of JNNP. JS reports honoraria from UptoDate, personal fees from expert witness work, grants from National Research Scotland and runs a free self-help website, www.neurosymptoms.org, for patients with FND. IH reports fees from expert witness work.

Figures

Figure 1
Figure 1
Flow diagram of study selection.
Figure 2
Figure 2
Proportion of patients with FND reporting chronic pain compared with patients with other neurological conditions. FND, functional neurological disorder.
Figure 3
Figure 3
Pain reporting among patients with FND. (A) Random effects meta-analysis of the proportion of patients with FND reporting pain. (B) Random effects meta-analyses of the proportions of patients with different FND subtypes reporting pain. Small points represent individual studies. Large points represent subgroup meta-analyses by FND subtype. FMD, functional movement disorder; FND, functional neurological disorder; FS, functional seizures.
Figure 4
Figure 4
Pain scoring by patients with FND. Pain scores were transformed to 0–10 (10=worst). All studies using the SF-36 specifically reported pain subdomain scores. Error bars denote combined SD across studies. BPI, Brief Pain Inventory; FND, functional neurological disorder; PCS, Pain Catastrophising Scale; SF-36, 36 Item Short Form Survey; TWSTRS, Toronto Western Spasmodic Torticollis Rating Scale; VAS, Visual Analogue Scale.
Figure 5
Figure 5
Meta-analyses of comorbid complex regional pain syndrome (CRPS), irritable bowel syndrome (IBS) and fibromyalgia diagnoses among patients with FND. Error bars denote 95% CIs. FND, functional neurological disorder.
See this image and copyright information in PMC

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