Functional Movement Disorders
Functional movement disorder (FMD) is one of the most common conditions in neurologic practice, falling under the umbrella of functional neurologic disorder (FND). FMD is defined as a disorder of voluntary movement or motor agency manifest by impaired voluntary movement in the presence of normal automatic movement. Subtypes include functional tremor, functional dystonia, functional limb weakness, functional jerky movements (myoclonus), and functional gait disorder. This article provides a practical overview of diagnosis and multidisciplinary treatment, drawn primarily from the Continuum Movement Disorders issue (August 2025).
Bottom Line
- Diagnosis: FMD is a "rule-in" diagnosis based on positive clinical signs (Hoover sign, tremor entrainment, distractibility) — not a diagnosis of exclusion
- Explanation: Treatment is unlikely to help unless the patient is confident of the diagnosis and motivated to improve; show the patient their positive signs as evidence of reversibility
- Comorbidities: Chronic pain (>50%), fatigue, anxiety, depression, PTSD, OCD are common; adverse experiences and neurodevelopmental differences (ADHD, ASD) are overrepresented
- Treatment: Multidisciplinary rehabilitation (FND-specific physiotherapy, CBT, occupational therapy, speech therapy); requires active patient participation
- Overlap with PD: Some patients develop FMD in the prodrome of Parkinson disease; follow up patients with late-onset functional tremor
- Hypnotherapy has surprisingly good evidence and should be used more often
Epidemiology
- One of the most common conditions seen in neurology clinics (second only to headache in some series)
- Incidence: 4–12 per 100,000/year; prevalence: 50–100 per 100,000
- Women are 2–3x more likely to be affected than men (systematic meta-analysis of 4,905 cases)
- Onset at any age, but peak in 30s–40s
- About 1 in 6 patients with FMD also has a functional speech disorder
Diagnosis: The "Rule-In" Approach
FMD should be diagnosed based on demonstrating typical positive clinical features, not by excluding other conditions. The neurologic examination is both diagnostic and therapeutic — it can demonstrate to the patient that normal automatic movement is preserved.
Positive Diagnostic Signs by Phenotype
| Phenotype | Positive Signs | DSM-5 / Clinical Criteria |
|---|---|---|
| Functional tremor | Entrainment: Tremor frequency changes to match contralateral rhythmic movement. Distractibility: Tremor stops or changes during distraction tasks. Variability: Frequency and amplitude change spontaneously | Clinically definite if entrainment or pause present on contralateral ballistic movement |
| Functional limb weakness | Hoover sign: Involuntary hip extension when flexing contralateral hip is normal, but voluntary extension is weak. Hip abductor sign: Similar principle. Give-way weakness: Initial resistance followed by collapse. Drift without pronation (arm without pronator drift) | Internal inconsistency between voluntary and automatic movement |
| Functional dystonia | Fixed posture: Inverted ankle, clenched fist, or fixed neck posture present from onset (unlike organic dystonia which develops gradually). Pain at onset. Resistance to passive movement: Increases with attention. Absence of overflow | Fixed dystonia from onset is highly suggestive; mobile dystonia harder to distinguish |
| Functional gait | Dragging gait: Trailing non-physiologic leg drag. Excessive slowness without other explanation. Ability to correct balance: Apparent instability with remarkable ability to recover (chair sign). Gait improves with distraction, backward walking, or running | Pattern inconsistent with any known neurologic gait disorder |
| Functional jerks / myoclonus | Pre-movement Bereitschaftspotential on EEG back-averaging (absent in organic myoclonus). Variable amplitude and frequency. Stimulus-dependent latency | Electrophysiologic testing can confirm cortical pre-movement potential |
Important Diagnostic Cautions
- FMD can coexist with organic neurologic disease — MS, Parkinson disease, and epilepsy are risk factors for developing FND
- Late-onset functional tremor: Follow up carefully for the possibility of evolving Parkinson disease (FMD may develop in the PD prodrome)
- Investigations are usually necessary to look for comorbidities, not to make the diagnosis
- The Bereitschaftspotential that precedes voluntary movements does NOT precede tics, supporting the distinction between tics and volitional movement
Assessment of Comorbidities
A full assessment of comorbidities is critical for formulation and treatment triage:
| Comorbidity | Prevalence / Relevance |
|---|---|
| Chronic pain (nociplastic) | >50% of FND patients; typically fibromyalgia-type pain; often develops as involuntary adaptive response to pain (brain "dissociates" from limb) |
| Fatigue | Common; significantly impacts QoL; drives "boom-and-bust" activity patterns |
| Functional dizziness | Persistent postural perceptual dizziness (PPPD); look for dissociation if dizziness reported |
| Anxiety, depression, PTSD, OCD | Common psychiatric comorbidities; PTSD and OCD often hidden and need specific questioning |
| Adverse experiences | Abuse and neglect (childhood or adult) are risk factors; may sensitize the threat response system leading to dissociation |
| Neurodevelopmental differences | ADHD and ASD probably overrepresented; ASD may alter interoception and sensory adaptation |
| Personality traits | Borderline/emotionally unstable traits overrepresented; obsessive personality most common subtype (25% meet OCD criteria) |
| Other FND symptoms | Functional seizures, altered sensation, vision/hearing problems, functional cognitive disorder |
Diagnostic Explanation
FND therapy is unlikely to help unless the patient is confident of the explanation and motivated to improve. All team members should explain FND consistently.
Communication Framework
- Name the condition clearly: "You have functional limb weakness / functional dystonia / FND"
- General analogy: "A problem with the software rather than the hardware" or "like a piano that is out of tune — nothing is broken, but the system is not working"
- Show the evidence: "Did you see how your leg briefly returned to normal when I did that test (Hoover sign)? That shows the automatic movements are still OK — there is a problem with voluntary movement"
- Tremor: "Your tremor just temporarily stopped or changed rhythm there — that is a typical feature of functional tremor"
- Reversibility: "This is not an easy condition to improve, but it does have the potential to improve, and many people make a good recovery"
- Overcoming dualism: Patient: "Is it in my mind or brain?" → "That question does not make sense because FND shows the mind and brain are the same thing"
Formulation
Beyond diagnosis, formulation examines the individual's personal risk factors to understand how the FND symptoms arose. This is an important next step that a neurologist can start and a psychiatrist, psychologist, or therapist can continue. Formulation may include:
- Predisposing factors: Childhood adversity, neurodevelopmental traits, personality factors
- Precipitating factors: Injury, pain, illness, surgery, stressful life events
- Perpetuating factors: Avoidance, attention to symptoms, pain, deconditioning, illness beliefs
- Protective factors: Social support, insight, motivation, prior successful treatment
Triage for Treatment
Treatment triage should come before initiating treatment and is often neglected. Key questions:
- Is there diagnostic agreement? If the patient believes their symptoms are due to MS or Lyme disease, therapy is likely futile. Full agreement is not necessary — "Do we have anything to lose by trying an FND-focused approach?" can be useful.
- Is there readiness for change? Rehabilitation is like learning a difficult skill (playing a musical instrument) — a "slow fix," not a "quick fix." Specific, realistic goals are important.
- Symptom severity: Mild/intermittent symptoms may need only education and self-management; overwhelming mental health concerns, pain, or fatigue may need to be addressed before FND-focused therapy.
- Therapist expertise: Therapy from an untrained therapist can be counterproductive.
Multidisciplinary Treatment
Generic Elements Across All Therapies
- Managing "boom-and-bust" patterns: Patients overdo activities when feeling better, then experience severe fatigue, pain, or FND symptom exacerbation. Finding a sustainable baseline is the starting point.
- Overcoming avoidance: Patients avoid activity due to fear of worsening, falling, or embarrassment. Graded exposure helps.
- Pain management: Integrate nociplastic pain treatment when present (nociplastic pain = nervous system dysfunction, not structural damage).
FND-Specific Physiotherapy
Physiotherapy builds on the differences between abnormal voluntary movement (the FMD symptom) and normal automatic movements (revealed by examination maneuvers like Hoover sign, tremor entrainment, or improved gait when running/walking backward). Key elements:
- Observation: Video recording and full-length mirrors help patients see their movements objectively
- Addressing maladaptive resting postures: e.g., resting weak arm in lap, sitting with dystonic foot curled
- Movement retraining: Focus on activity (standing) rather than impairment (leg weakness); gait retraining with treadmill, weight shifting, sliding movements
- Treatment adjuncts: Functional electrical stimulation, TENS, EMG biofeedback
Psychological Therapy
- CBT model (loosely based on panic disorder models): Addresses avoidance of prodromal symptoms (autonomic arousal, dissociation, fear); patient learns to use distraction or sensory grounding to persist with unpleasant symptoms rather than succumb to the event
- Interpersonal/psychodynamic approaches: Especially helpful for those with trauma history or disturbed relationships
- Acceptance and commitment therapy (ACT): Third-wave CBT encouraging mindful acceptance of negative emotions and bodily feelings
- Evidence is stronger for functional seizures than FMD specifically, but clinical experience supports value across FND
Other Therapies
| Therapy | Evidence / Notes |
|---|---|
| Occupational therapy | Combines physical and mental health; graded exposure to triggering activities; judicious provision of aids (minimize in improving patients; provide for disabled/refractory) |
| Speech therapy | FND-focused: uses distraction to regain automatic speech; starting with yawning, coughing, humming to trigger vocalization |
| Hypnotherapy | Surprisingly good evidence; should be used more often or integrated with other therapies |
| TMS | Suprathreshold or subthreshold stimulation; may work by demonstrating normal movement; no difference between cranial and spinal stimulation (suggesting demonstration of improvement is the key ingredient) |
| Botulinum toxin | RCT showed no benefit over placebo for functional dystonia, but both groups improved; may be helpful as adjunct with physiotherapy |
| Therapeutic sedation | Older technique; useful for functional quadriplegia, fixed dystonia, or functional coma where reversibility is hard to demonstrate |
| Pharmacotherapy | No RCTs for medications in chronic FMD; treat psychiatric comorbidities (SSRIs, clomipramine for OCD); tricyclics may help in functional somatic disorders |
Relapse Planning
Functional movement disorders commonly relapse. Planning is essential:
- Create a written relapse plan with the patient and therapist about what treatments work best
- Help patients and families recognize early warning signs and "overdoing it" patterns
- Patients should understand that relapse does not mean failure — the condition has potential for re-improvement
When Treatment Has Failed
- Ensure all diagnostic, formulation, explanation, and therapy steps have been thoroughly addressed before concluding the condition is refractory
- Accept that some patients will have a disability that cannot be greatly modified; optimize quality of life and manage comorbidities
- The patient should not be blamed and should be reminded that improvement remains possible in the future
Developing an FND Service: Practical Advice
- Find at least one collaborator from psychiatry or psychology — this is a feature of successful FND services
- Triage: Work on patients who agree with the diagnosis and are ready for therapy; recognize those who are not
- Therapists need FND expertise — therapy from untrained therapists can be counterproductive
- Time-limited treatment with goal-determined start/stop points is more effective than open-ended therapy
- Education alone probably does not improve outcomes but is an essential base for treatment
- Community resources for pain, fatigue, and mental health are especially important
Useful Resources
- Neurosymptoms.org: Free website and app for patients and families; includes formulation tool
- FND Society (fndsociety.org): Virtual continuing education courses for clinicians
- FND Hope (fndhope.org): Patient-led organization with peer support and provider directory
References
- Continuum (Minneap Minn). August 2025; 31(4 Movement Disorders). Multidisciplinary Treatment for Functional Movement Disorder (pp 1182–1199).
- Lidstone SC, Costa-Parke M, Robinson EJ, et al. Functional movement disorder gender, age and phenotype study: a systematic review and individual patient meta-analysis of 4,905 cases. J Neurol Neurosurg Psychiatry. 2022;93(6):609–616.
- Hallett M, Aybek S, Dworetzky BA, et al. Functional neurological disorder: new subtypes and shared mechanisms. Lancet Neurol. 2022;21(6):537–550.
- Aybek S, Perez DL. Diagnosis and management of functional neurological disorder. BMJ. 2022;376:o64.