Functional Dystonia: Diagnostic Technique Inventory

The pattern-based assessment is the expanded clinical page. Several entries contribute to it; others describe differential assessment or research methods. This is not a checklist of procedures everyone needs.

Original ten entries

Onset and fixed-posture pattern

The clinician documents how rapidly a posture developed, whether it became fixed early and its relationship to injury. Cohort research identifies patterns associated with functional dystonia, but sudden onset, trauma or a fixed posture alone does not diagnose it. [3][4]

Inconsistency across tasks

The same body region is observed at rest and during suitable activities. A reproducible mismatch may contribute to diagnosis. Fixed functional dystonia may not change with distraction, so the absence of change does not exclude it. [1]

Distractibility in mobile dystonia

Some moving postures lessen or change during another task. This is supportive only in context because other dystonias also depend on task and attention. Do not force a fixed or painful joint to seek the sign. [1]

Pattern incongruity

A movement-disorders specialist compares posture, spread and task dependence with recognized dystonia syndromes. An anatomically or physiologically meaningful inconsistency may support FND. An unfamiliar or unusual posture is insufficient; rare genetic and acquired dystonias remain possible. [1][3]

Sensory tricks and sensory examination

The clinician asks whether a light touch or other cue changes posture and assesses accompanying sensory findings. Response or non-response can inform the differential but does not distinguish functional from other dystonia on its own. [1]

Coexisting positive functional signs

Matching weakness, tremor or gait signs can strengthen a combined formulation. Each still needs its own validated interpretation; a functional symptom elsewhere does not establish that every posture is functional. [1][5]

Pain, CRPS and contracture assessment

Pain, swelling, skin changes and passive movement limits help identify associated conditions and safe examination boundaries. These are assessment findings rather than positive FND signs. Neither pain nor a CRPS label settles the cause of dystonia. [1][3]

Cortical and reciprocal inhibition studies

TMS and reflex studies have found overlapping abnormalities in functional and other dystonia. These are research approaches, not validated clinical discriminators. A shared abnormal result cannot diagnose either cause in an individual. [6]

Tactile temporal discrimination

Specialist testing measures the ability to distinguish closely timed touches. Similar abnormalities were found in functional and primary dystonia. It therefore does not provide a specific diagnostic test for functional dystonia. [7]

Sensorimotor plasticity testing

Paired-stimulation research examines how motor responses change after repeated sensory–motor pairing. Group differences have been investigated, but no sufficiently validated individual diagnostic threshold is established for routine practice. [5][8]

Research addition — September 29, 2026

Polyelectromyography during propofol sedation

A pilot study compared muscle recordings during sedation and recovery in 10 people with established functional dystonia and 17 with idiopathic dystonia. Different activity patterns were observed, but this is preliminary evidence from selected groups. The technique involves an anaesthetic service and specialist monitoring; it is not a routine confirmatory test or a demonstration to arrange outside that setting. See the evidence discussion. [9]

Research and Sources

The original citation numbers 1–8 are retained, with the pilot study added as citation 9. A fresh full-text review of every inherited experimental paper remains pending. The broader evidence and access record is on the detailed assessment page.

Citation	Figure	Full citation
[1]	—	Frucht L, Perez DL, Callahan J, et al. Functional dystonia: differentiation from primary dystonia and multidisciplinary treatments. Frontiers in Neurology. 2021;11:605262. FND-CIT-0021. https://doi.org/10.3389/fneur.2020.605262
[2]	—	Bennett K, Diamond C, Hoeritzauer I, Gardiner P, McWhirter L, Carson A, Stone J. A practical review of functional neurological disorder (FND) for the general physician. Clinical Medicine. 2021;21(1):28–36. FND-CIT-0001. https://doi.org/10.7861/clinmed.2020-0987
[3]	—	Schrag A, Trimble M, Quinn N, Bhatia K. The syndrome of fixed dystonia: an evaluation of 103 patients. Brain : a journal of neurology. 2004;127(Pt 10):2360-2372. DOI. PMID: 15342362. FND-CIT-0142.
[4]	—	Ercoli T, Defazio G, Geroin C, et al. Sudden Onset, Fixed Dystonia and Acute Peripheral Trauma as Diagnostic Clues for Functional Dystonia. Movement disorders clinical practice. 2021;8(7):1107-1111. DOI. PMID: 34631946. FND-CIT-0136.
[5]	—	Edwards MJ, Koens LH, Liepert J, et al. Clinical neurophysiology of functional motor disorders: IFCN Handbook Chapter. Clinical neurophysiology practice. 2024;9:69-77. DOI. PMID: 38352251. FND-CIT-0022.
[6]	—	Espay AJ, Morgante F, Purzner J, et al. Cortical and spinal abnormalities in psychogenic dystonia. Annals of neurology. 2006;59(5):825-834. DOI. PMID: 16634038. FND-CIT-0149.
[7]	—	Morgante F, Tinazzi M, Squintani G, et al. Abnormal tactile temporal discrimination in psychogenic dystonia. Neurology. 2011;77(12):1191-1197. DOI. PMID: 21900627. FND-CIT-0171.
[8]	—	Morgante F, Naro A, Terranova C, et al. Normal sensorimotor plasticity in complex regional pain syndrome with fixed posture of the hand. Movement disorders : official journal of the Movement Disorder Society. 2017;32(1):149-157. DOI. PMID: 28124436. FND-CIT-0158.
[9]	—	Eleopra R, Paio F, Rinaldo S, et al. Polyelectromyography Under Propofol to Differentiate Functional from Idiopathic Dystonia: A Pilot Study. Movement Disorders. 2026;41(2):395–405. Published online November 12, 2025. DOI/full text. FND-CIT-0229.

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