Beyond movement: Headache in patients with functional movement disorders.

Objective: To evaluate headache comorbidity in a cohort of patients with functional movement disorders by assessing the prevalence, clinical characteristics, and temporal relationship of headache with the onset of functional symptoms.

Background: Functional movement disorders are common and potentially treatable. Although headache is frequent in these patients, few studies have evaluated their headache features.

Methods: This observational cohort study included consecutive patients with functional movement disorders evaluated in our Functional Movement Disorders Unit between October 2021 and November 2022. Clinical and demographic features from clinical charts were reviewed, and patients completed a self-administered questionnaire designed by the authors that included headache characteristics, disease duration, treatments received, and the Headache Impact Test-6. Headache type was classified as per the Classification of Headache Disorders, third edition (ICHD-3).

Results: A total of 51 patients with functional movement disorders were included. Of those, 40 (78%) reported having recurrent headache. Headache intensity was moderate-severe in 33/40 (83%), and about two-thirds experienced headache >9 days/month. Disability secondary to headache was high (median [interquartile range] Headache Impact Test-6 score 62 [49-66]). Based on the ICHD-3, 23/40 (58%) of patients with headache met the criteria for migraine or probable migraine, 11/40 (27%) for tension-type headache, two of 40 (5%) for new daily persistent headache, and one of 40 (3%) for primary exercise headache, while three of 40 (7%) were unclassifiable. The onset of headache occurred before the functional movement disorder in 28/40 (70%), after the functional movement disorder in five of 40 (12%), and simultaneously in six of 40 (15%). In this last group, four of the six (67%) patients described a daily headache from the onset, and two met the criteria for new daily persistent headache.

Conclusions: Headache is a frequent condition in patients with functional movement disorders and an additional burden of disability beyond their motor symptoms. We found that, besides migraine and tension-type headache, new daily persistent headache may be a comorbid phenotype in patients with functional movement disorders and should be further studied in larger prospective studies.