Systematic review of movement disorders mislabeled as functional: when incongruence misleads
Clinical Snapshot
PICO Framework
| P — Population | Adults diagnosed with functional movement disorders (FMD) who were subsequently reclassified as having another neurological or medical condition |
| I — Intervention | Application of diagnostic criteria including incongruence, inconsistency, and psychological factors |
| C — Comparator | Different combinations of diagnostic criteria (incongruence alone vs inconsistency alone vs neither vs both) |
| O — Outcomes | Rate of FMD misdiagnosis, phenomenology of misdiagnosed conditions, clinical features associated with misdiagnosis |
Bottom Line
This systematic review of 150 patients demonstrates that functional movement disorder misdiagnosis occurs most frequently when clinicians rely on 'incongruence with known diseases' rather than objective inconsistency signs. Gait disorders and dystonia were most commonly misdiagnosed. The key finding is that using incongruence alone led to 49% misdiagnosis rates, while focusing on inconsistency reduced this to 13.7%. For isolated movement disorders, absence of documented inconsistency increased misdiagnosis risk nearly four-fold. This evidence strongly supports the movement disorders community's shift toward positive neurological signs of inconsistency rather than subjective assessments of incongruence. Australian neurologists should prioritise documenting specific inconsistency features (entrainment, distractibility, variability with attention) over clinical impressions of 'bizarre' or 'non-organic' presentations when evaluating suspected functional movement disorders.
Key Findings
P Value: Not explicitly reported
Effect Size: OR 3.94 for isolated movement disorder misdiagnosis without documented inconsistency
Primary Outcome: Rate of FMD misdiagnosis by diagnostic approach
Nnt Or Sensitivity: Incongruence alone: 49% misdiagnosis rate; Inconsistency alone: 13.7% misdiagnosis rate
Confidence Interval: 95% CI 1.32-12.82
Clinical Application
Highly feasible - requires systematic application of inconsistency criteria rather than relying on incongruence Directly applicable to Australian neurology practice; aligns with RANZCP and RACP guidelines emphasising positive neurological signs in functional disorder diagnosis Movement disorder specialists, neurologists diagnosing functional neurological disorders
Abstract
BACKGROUND: Misdiagnosis of functional movement disorders (FMD) remains a concern for clinicians. We sought to review the phenomenology and clinical features associated with FMD misdiagnosis. METHODS: We conducted a systematic review of case reports, case series, and observational studies of adults diagnosed with FMD and subsequently reclassified as having another neurological or medical condition. PubMed was searched from inception to September 13, 2025, focusing on reported features of inconsistency, incongruence with known diseases, and low-validity features. Isolated (iMD) and mixed (mMD) movement disorders were analyzed separately. RESULTS: Forty-two included studies comprised 150 patients, of which 73 cases underwent detailed analysis. Gait disturbance (35%) and dystonia (27.5%) were the most common iMD phenomenologies (n = 40), while jerks and rigidity (24%) were the most common mMD phenomenology (n = 33). Incongruence with known diseases (50.7%), psychological factors (34.2%), and symptom variability (31.5%) were the main factors associated with misdiagnosis. Application of incongruence alone was associated with the highest rate of FMD misdiagnosis, similar to that of applying neither incongruence nor inconsistency (49% in both cases). Conversely, reliance on inconsistency alone was least associated with an FMD misdiagnosis (13.7%). Misdiagnoses of iMD were more likely in the absence of documented inconsistency (OR 3.94, 95% CI 1.32-12.82). CONCLUSIONS: FMD misdiagnoses, particularly of gait disorders and dystonia, were most commonly associated with the application of incongruence as diagnostic criterion. The lowest rate of FMD misdiagnosis was associated with ascertaining at least two positive neurological signs of inconsistency.
References
- 1.Marín-Medina, D. S., Zambrano, J. M., Espay, A. J., & Merello, M. (2026). Systematic review of movement disorders mislabeled as functional: when incongruence misleads. Journal of Neurology. https://doi.org/10.1136/jnnp-2017-317378
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