FND Education Project

REFERENCE · DIAGNOSIS

Functional Paralysis

Refers to:

  • complete or near-complete loss of voluntary movement in one or more limbs;
  • functional hemiplegia or paraplegia diagnosed from positive clinical evidence; and
  • persistent or episodic severe limb immobility outside, or continuing beyond, a functional-seizure event.

Scope boundary: This page treats paralysis as the severe end of a functional limb-weakness presentation, not as a separate proven mechanism. Facial weakness belongs on the facial symptoms page. Immobility that occurs only within a stereotyped functional seizure belongs on the functional-seizures page. Sleep paralysis, cataplexy, postictal weakness and structural neurological causes are different presentations requiring appropriate assessment.

Primary techniques: Phenotype-specific comparison of attempted movement with automatic or synergistic movement—for example Hoover’s or the hip-abductor sign for unilateral leg paralysis, and the finger-abduction sign for unilateral arm paralysis.
Diagnostic method: Demonstrate a reproducible difference between voluntary access and movement recruited in another task, interpreted with the history, complete examination and appropriate investigation. No one sign covers bilateral or widespread paralysis.
Media needed: Clinician-led video with separate upper- and lower-limb examples plus a diagram explaining why the selected sign applies only to that movement pattern.

Diagnostic techniques at a glance

Diagnostic techniques at a glance

These brief entries describe signs, observations, criteria and investigations clinicians may consider. They are not a checklist of tests everyone needs. Evidence and limitations differ for each entry; a positive sign must fit the whole clinical picture, including possible coexisting disease.

The longer explanations already on this page remain below. Individual technique pages will be developed and reviewed separately.

Hoover’s sign in suitable unilateral paralysis

Automatic heel pressure may be preserved during movement of the other leg despite absent requested movement. This comparison can support functional weakness when the opposite leg is sufficiently strong. It cannot be assumed valid in severe bilateral paralysis. [2]

Hip-abductor sign

The clinician compares sideways leg force during paired and separate tasks. Preserved associated force may support a functional component in a suitable asymmetric presentation. The primary study was small and unblinded; pain and limitations in the comparison leg matter. [4]

Abduction-finger sign

Resisted spreading of fingers in the less affected hand may produce associated spreading in the paralysed hand. The original severe-unilateral-paralysis study supports this sign. Extrapolation to partial weakness is unsafe because associated movements also occur without functional paralysis. [3]

Spinal Injuries Center test

A severely weak leg may maintain a bent-knee position after being placed there, despite inability to lift voluntarily. A primary comparative study supports this restricted use. Milder neurological weakness can also maintain the position, and mechanical support must be considered. [5]

Elbow flex-ex comparison

Opposite-direction force may emerge in the weak arm during resisted movement of the other arm. The original unilateral-weakness study supports a possible functional contrast, but evidence is small and does not establish a universal test for complete bilateral paralysis. [6]

Preserved automatic or task-linked movement

A clinician may observe movement during a comfortable repositioning or another spontaneous action that is unavailable on request. This can provide positive evidence only when the comparison truly tests the same capacity and excludes compensation or reflex movement. [7][8]

Tone, reflexes and plantar responses

These help localize disease and interpret the paralysis. An older comparative series described preserved findings, but normal tone or reflexes alone do not establish FND and may occur in other disorders. Historical psychiatric or compensation-based assumptions are not diagnostic signs. [9]

Motor and sensory pathway investigations

Selected nerve-conduction, EMG, evoked-potential or imaging studies investigate competing and coexisting disease. They are not positive FND tests. Normal findings do not establish the cause of paralysis or rule out every neurological condition. [10]

Tests that require residual voluntary movement

Drift without pronation, collapsing weakness and paradoxical wrist flexion require movement or force that may be absent in complete paralysis. Inability to perform them is not a positive result. Use the limb-weakness page only when the phenotype fits. [11][12]

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Functional paralysis means that a person cannot access some voluntary limb movement even though the movement system is not damaged in the way seen after a spinal-cord injury, stroke or nerve injury. It is real and can be profoundly disabling. Clinically it is usually considered a severe presentation of functional weakness; this separate page exists because complete movement loss creates different safety, care and rehabilitation questions.

The diagnosis should be supported by positive features in the person’s own movement pattern. A clinician may compare movement produced while directly trying with movement recruited automatically during a different task. The relevant comparison depends on which limb and movement are affected. Hoover’s sign and the hip-abductor sign concern selected unilateral leg presentations; a finger-abduction sign has been described for unilateral arm paralysis. These signs are not tests of honesty, and none is a universal test for paralysis. [1][2][3][4]

Do not ask somebody at home to force a limb or repeatedly reproduce these signs. Pain, injury, comprehension, severe bilateral symptoms, neglect and coexisting neurological or musculoskeletal conditions may make a comparison unsafe or uninterpretable.

Persistent, episodic and seizure-associated immobility

Paralysis may be persistent, fluctuate or occur in episodes. The word alone does not establish the category. An isolated limb that remains unable to move between events is assessed as a motor presentation. Whole-body or limb immobility confined to a familiar seizure-like event is assessed as part of that event. If both occur, each appearance needs its own plan.

Some people report marked weakness or paralysis around functional seizures or periods of severe fatigue. Timing is useful context, but it does not decide the category or mechanism. Seizure-confined immobility follows the seizure-event pathway; limb paralysis outside the event follows the motor pathway; and severe fatigue needs assessment of fatigue, load and other contributors rather than being treated as proof of either diagnosis.

When familiar paralysis begins or worsens, stop driving, standing, transferring, carrying dangerous objects or using machinery; get into a safe position; and use the support or mobility plan already agreed. New paralysis, a sudden changed pattern or paralysis with facial droop, new speech or understanding difficulty, severe headache, new bladder or bowel change, saddle numbness, fever, injury or altered consciousness needs urgent assessment rather than automatic attribution to FND.

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For Family, Friends, and Other Supporters

Complete movement loss can vary without being voluntary. Do not pull the person upright, force a limb, remove an aid or demand that they demonstrate a previously observed movement. Ask what help is wanted, use trained transfer methods and bring the person’s usual aid or communication device.

If the established episode plan identifies an automatic movement cue, offer it once and only when the person is safe. When the person cannot use a cue, practical care—safe positioning, pressure relief, warmth, toileting access, hydration and a way to call for help—may matter more than active retraining. Record duration, distribution, associated symptoms and recovery if the person wants this information kept.

A previous functional diagnosis does not determine the cause of every new paralysis episode. Follow the person’s emergency plan and seek reassessment for a new, markedly changed, prolonged or injured presentation.

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Match the sign to the phenotype

  1. Define whether the presentation is unilateral or bilateral, upper- or lower-limb, focal or widespread, persistent or episodic, and isolated or part of a larger event.
  2. Establish safety, pain, passive range, musculoskeletal limitations, sensory findings, cognition and competing or coexisting neurological disease.
  3. Select a validated or described comparison only when its movement and laterality match. Hoover’s sign compares voluntary and synergistic hip extension; the hip-abductor sign compares voluntary and contralaterally recruited abduction; the finger-abduction sign was described for unilateral upper-limb paralysis.
  4. Reproduce the contrast carefully and interpret it with the entire examination. Do not generalize a positive sign in one movement to all limbs or all tasks.
  5. Explain the result as evidence that an automatic movement pathway remains accessible, not as evidence that the patient could move normally by choosing to try harder.

No validated single bedside sign was located for bilateral or widespread functional paralysis. In those presentations, document the complete pattern, positive evidence actually observed, limitations of the examination and the work-up of plausible alternatives. Normal investigations alone do not make the diagnosis.

Media contributor brief

People and setup: A neurologist or suitably trained clinician, a separately consented patient or actor/volunteer, an examination bed, and cameras that keep both sides and the examiner’s contacts visible.

Essential sequence:

  1. State which paralysis phenotype the example represents and what the sign cannot assess.
  2. Show the direct voluntary task without editing out unsuccessful attempts.
  3. Show the automatic or synergistic comparison in the same continuous sequence.
  4. Label the movement, side, examiner hand position and expected comparison.
  5. End with the explanation that the finding is interpreted with the whole assessment and cannot be used for self-diagnosis.

Do not combine footage from different people or attempts to manufacture a contrast. Do not force range, provoke collapse or film an acute undiagnosed episode.

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Research and Sources

Evidence notes

  • Functional paralysis is treated here as a severe presentation of functional limb weakness. A separate reference page improves findability and permits phenotype-specific safety and rehabilitation guidance; it does not assert a distinct mechanism. [1]
  • Hoover’s sign has moderate sensitivity and high specificity in one prospective suspected-stroke cohort, but only eight participants had functional weakness. The upper-limb finger-abduction and lower-limb hip-abductor publications concern unilateral presentations and do not establish a universal sign. [2][3][4]

Citation table

Citation Full citation
[1] 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
[2] McWhirter L, Stone J, Sandercock P, Whiteley W. Hoover’s sign for the diagnosis of functional weakness: a prospective unblinded cohort study in patients with suspected stroke. Journal of Psychosomatic Research. 2011;71(6):384–386. FND-CIT-0018. https://doi.org/10.1016/j.jpsychores.2011.09.003
[3] Tinazzi M, Simonetto S, Franco L, et al. Abduction finger sign: a new sign to detect unilateral functional paralysis of the upper limb. Movement Disorders. 2008;23(16):2415–2419. FND-CIT-0057. https://doi.org/10.1002/mds.22268
[4] Sonoo M. Abductor sign: a reliable new sign to detect unilateral non-organic paresis of the lower limb. Journal of Neurology, Neurosurgery & Psychiatry. 2004;75(1):121–125. Historical terminology retained in the article title. FND-CIT-0058. https://pmc.ncbi.nlm.nih.gov/articles/PMC1757483/
[5] Yugué I, Shiba K, Ueta T, Iwamoto Y. A new clinical evaluation for hysterical paralysis. Spine. 2004;29(17):1910-3; discussion 1913. DOI. PMID: 15534415. FND-CIT-0166.
[6] Lombardi TL, Barton E, Wang J, et al. The elbow flex-ex: a new sign to detect unilateral upper extremity non-organic paresis. Journal of neurology, neurosurgery, and psychiatry. 2014;85(2):165-167. DOI. PMID: 23695497. FND-CIT-0134.
[7] Stone J, Warlow C, Sharpe M. The symptom of functional weakness: a controlled study of 107 patients. Brain : a journal of neurology. 2010;133(Pt 5):1537-1551. DOI. PMID: 20395262. FND-CIT-0047.
[8] Daum C, Gheorghita F, Spatola M, et al. Interobserver agreement and validity of bedside ‘positive signs’ for functional weakness, sensory and gait disorders in conversion disorder: a pilot study. Journal of neurology, neurosurgery, and psychiatry. 2015;86(4):425-430. DOI. PMID: 24994927. FND-CIT-0130.
[9] Baker JH, Silver JR. Hysterical paraplegia. Journal of neurology, neurosurgery, and psychiatry. 1987;50(4):375-382. DOI. PMID: 3585346. FND-CIT-0120.
[10] 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.
[11] Daum C, Aybek S. Validity of the “Drift without pronation” sign in conversion disorder. BMC neurology. 2013;13:31. DOI. PMID: 23548051. FND-CIT-0131.
[12] Sonoo M. Paradoxical wrist flexion: A new test to detect functional weakness of the upper limb. eNeurologicalSci. 2021;22:100302. DOI. PMID: 33344786. FND-CIT-0185.

Technique outline created: September 2, 2026 · Neurology, rehabilitation, lived-experience and accessibility review pending

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