FND Education Project

REFERENCE · DIAGNOSIS

Functional Limb Weakness

Refers to:

  • partial loss of voluntary movement or power in an arm, hand, leg or foot;
  • heaviness, reduced grip, dropping objects, foot drag or a limb giving way when weakness is the main problem; and
  • fluctuating, episodic or persistent limb weakness that does not amount to complete or near-complete paralysis.

Scope boundary: Use the functional paralysis page for complete or near-complete voluntary movement loss, the facial symptoms page for facial droop or weakness, and the drop-attacks page for sudden falls. A walking manifestation may also belong on the gait page; the examination must follow the actual presentation.

Quick Reference

Presentation: Partial, episodic or persistent difficulty producing voluntary power in an arm or leg. Establish the distribution, time course and relevant neurological findings before selecting a sign.

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For the Person With FND

The thought is there, but the movement does not come—or it comes with much less power than expected. Functional limb weakness is a real, involuntary difficulty accessing movement. It can affect an arm, hand, leg or foot. This page covers partial weakness; complete or near-complete loss of voluntary movement has its own functional paralysis page, and apparent facial weakness has its own functional facial symptoms page.

Functional weakness does not have to look the same all day. It may persist, fluctuate in severity or appear mainly in episodes. The limb involved can sometimes vary. A person may notice a relationship with a particular task, fatigue, pain, competing attention, sensory or cognitive load, or another FND symptom. These are possible patterns to describe—not required causes or proof that the person should be able to prevent the symptom.

“For me, my legs respond less and less when I become distracted or overwhelmed by too many things happening around me. It also happens around one of my functional seizures.”

— Project-lead lived experience. This is one person’s pattern, not a rule about what causes functional weakness.

A symptom that is absent or milder during an appointment is no less real. The clinician should listen to the history and look for positive features that fit the person’s actual presentation, while also assessing other possible or coexisting causes.

What the examination can explain

The clinician looks for findings that fit your particular weakness. A leg comparison cannot simply be applied to an arm, and a single variable movement is not enough to explain every presentation. A positive finding is most useful when the clinician shows what changed, explains why it matters and discusses the rest of the assessment. [1]

Hoover’s sign is one example: the affected leg may press down more strongly during the other leg’s movement than when asked to press down directly. The separate Hoover’s-sign page explains the anatomy, examination and limits. It supports a diagnosis in the right context; it does not measure your whole ability to walk or manage a day. [2]

“In my own case, the neurologist adapted Hoover’s Sign to show that the weakness of my arms appeared to be restored under a certain distraction. That became like evidence to me that this was not an injury preventing use of my arms.”

— Project-lead lived experience. In clinical terminology, Hoover’s sign refers specifically to a leg comparison. An upper-limb examination may use the same broader idea—comparing deliberate movement with movement that becomes more available during another action—but the clinician should name and explain the actual arm sign or task rather than call it Hoover’s sign.

What else can cause weakness?

Weakness can arise from problems affecting the brain, spinal cord, nerves or muscles. Pain and joint problems may also limit movement. The clinician considers the onset, distribution, sensation, reflexes and other findings when deciding which explanations need investigation. FND and another condition may coexist. [1]

Depending on the clinical question, an assessment may involve imaging, blood tests or nerve and muscle studies. These are not a standard list that everyone needs. Ask what a proposed test is looking for and how its result will change the plan. A scan and a positive movement comparison answer different questions. See what investigations can tell us. [1]

Understanding possible mechanisms

An examination can show that movement becomes more available under one condition than another. That observation does not identify the original cause of the symptom. Research considers how attention, prediction, sensation and movement control interact; no single model explains every person. A history of stress or trauma is not required to take the weakness seriously or make an appropriate assessment. [1]

What weakness means for your day

Explain what happens outside the appointment as well as what happens during it. An example might be being able to hold an object briefly but struggling to use the hand repeatedly while preparing a meal. What help makes an activity possible? Is it safe? What happens afterwards? These are questions to explore, not assumptions about your abilities.

In a study of 107 people with functional weakness and 46 neurological-disease controls, disability was similar between groups, while being out of work because of symptoms was more common in the functional-weakness group. The study also identified mental-health needs in some participants. It does not show that psychological difficulties caused their weakness or tell us any one person’s level of disability. [3]

An occupational therapist can help explore daily activities and their demands; physiotherapy can assess movement and mobility; your GP and neurology team can coordinate assessment of other health concerns. Psychological care can address distress and adjustment where needed. See assessment and everyday function. [19]

Episodic, fluctuating and longer-lasting weakness

If familiar weakness begins suddenly, make the immediate situation safe first: stop driving, walking without adequate support, carrying something dangerous or using machinery; sit or lie down if needed; use the aid or safety plan already recommended. The recovery overview retains the existing guidance about agreed rehabilitation cues.

New weakness, a substantially different pattern, or weakness with new facial droop, speech change, severe headache, altered awareness, loss of bladder or bowel control, saddle numbness, fever or another urgent feature needs medical assessment rather than automatic attribution to FND. Sudden stroke-like symptoms require emergency help, even if they improve. [20]

Do not repeatedly perform Hoover’s sign on yourself or ask someone at home to interpret it. A useful question for the clinician is: “Which positive sign supported my diagnosis, and what did it show in my examination?”

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For Family, Friends, and Other Supporters

Help with safety first. If the person cannot safely remain standing, bring their usual walking aid or help them reach a stable seat without pulling on the weak arm or forcing a joint.

Before an appointment, ask whether they want help remembering examples or preparing questions. Useful observations include what the person was doing when the change began, which limb was affected, how long it lasted, whether another symptom occurred with it, and what recovery looked like. These details can help the clinical team without turning family life into constant monitoring.

During assessment, help communicate access needs with permission: a quieter explanation, time to process a question, a supported position or a break. The person should remain part of the discussion. Do not secretly repeat a manoeuvre or provoke symptoms to make them visible.

A moment of stronger automatic movement does not mean the person can reproduce it on command. Do not use a positive sign as a challenge—“You moved then, so do it now”—or secretly repeat the test. If the person wants help, record the clinician’s explanation and the movement cue that was agreed for rehabilitation.

Afterwards, check that the person knows who to contact about unanswered questions or a changed symptom. Longer-term practice and episode support belong in the paired recovery guidance.

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For Clinicians and the Care Team

Define the phenotype before choosing a sign

Document the distribution and severity of weakness, baseline function, onset and course, episode or flare duration, frequency, warning symptoms, task and environmental context, relationship to other FND symptoms, falls or injuries, pain and recovery. Examine for competing and coexisting central nervous system, peripheral nerve, neuromuscular, musculoskeletal and systemic causes as indicated. Fluctuation, distractibility or a normal investigation is not sufficient by itself; use a positive sign that matches the observed phenotype. [1]

If weakness is not present during the appointment, a credible history, a safely obtained recording and positive findings documented at another examination may remain useful. Do not deliberately induce a hazardous episode.

Interpret the finding and its scope

The Hoover’s-sign page now owns the examination outline, anatomy, explanation and evidence limits. Record which comparison was performed and any confounders. The prospective study involved only eight functional cases; its accuracy estimates should not be treated as universal. [2]

Upper-limb comparisons

For arm or hand weakness, document the actual positive feature used—for example inconsistency between formal power testing and a spontaneous, synergistic or task-linked movement—along with its anatomical and functional context. Do not relabel an arm comparison as Hoover’s sign. Avoid relying on collapsing weakness alone, because pain, comprehension and other neurological disorders can also affect performance. The observed inconsistency should be clear, reproducible enough to explain and interpreted with the rest of the examination. [1]

Report the diagnostic finding separately from observed task performance, sustained function and support needs. For OT and physiotherapy handover, include the context and assistance under which a task was completed, and what remains unknown about repetition, safety, sensory/cognitive demands and recovery cost. General practice can coordinate follow-up and coexisting-condition review. Mental-health assessment should address the person’s needs without being treated as confirmation of the functional diagnosis. [3][19]

Diagnostic techniques at a glance

The full sixteen-entry inventory is preserved separately. The links below retain earlier incoming anchors; the inventory distinguishes detailed evidence-reviewed content from summaries awaiting expansion.

The media brief and image review are now on the technique page.

For the Person With FND
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Research and Sources

Evidence notes

This expansion separates diagnostic reasoning from examination technique and daily-life impact. The two first-person passages remain project-lead lived experience, with their wording and qualifications preserved. They are not diagnostic evidence.

The clinical review supplies context, the Hoover cohort supplies a narrow validation result, the functional-weakness study supplies group-level disability and mental-health information, and OT guidance supplies an assessment framework. None defines an individual’s severity or prognosis. The remaining inventory entries retain their original sources and await individual re-review.

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] 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.
[4] Sonoo M. Abductor sign: a reliable new sign to detect unilateral non-organic paresis of the lower limb. Journal of neurology, neurosurgery, and psychiatry. 2004;75(1):121-125. PMID: 14707320. FND-CIT-0058.
[5] 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.
[6] 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.
[7] 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.
[8] 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.
[9] Chabrol H, Peresson G, Clanet M. Lack of specificity of the traditional criteria for conversion disorders. European psychiatry : the journal of the Association of European Psychiatrists. 1995;10(6):317-319. DOI. PMID: 19698360. FND-CIT-0126.
[10] van der Ploeg RJ, Oosterhuis HJ. The “make/break test” as a diagnostic tool in functional weakness. Journal of neurology, neurosurgery, and psychiatry. 1991;54(3):248-251. DOI. PMID: 2030354. FND-CIT-0152.
[11] Ziv I, Djaldetti R, Zoldan Y, et al. Diagnosis of “non-organic” limb paresis by a novel objective motor assessment: the quantitative Hoover’s test. Journal of neurology. 1998;245(12):797-802. DOI. PMID: 9840352. FND-CIT-0162.
[12] Knutsson E, Mårtensson A. Isokinetic measurements of muscle strength in hysterical paresis. Electroencephalography and clinical neurophysiology. 1985;61(5):370-374. DOI. PMID: 2412788. FND-CIT-0150.
[13] Horn D, Galli S, Berney A, et al. Testing Head Rotation and Flexion Is Useful in Functional Limb Weakness. Movement disorders clinical practice. 2017;4(4):597-602. DOI. PMID: 30363481. FND-CIT-0155.
[14] 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 : official journal of the Movement Disorder Society. 2008;23(16):2415-2419. DOI. PMID: 18951441. FND-CIT-0057.
[15] 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.
[16] Marcus H, Aldam P, Lennox G, Laing R. Medically unexplained neurological symptoms. JRSM short reports. 2010;1(3):25. DOI. PMID: 21103117. FND-CIT-0153.
[17] Bacchi S, Slee M. Physical examination in functional unresponsiveness. Practical neurology. 2023;23(1):54-56. DOI. PMID: 36717206. FND-CIT-0119.
[18] Dolbow J, El-Azzouni S, Zhang Y, Geiger C. A practical guide to assessing functional motor weakness: a review of validated techniques. Journal of neurology. 2025;272(6):427. DOI. PMID: 40423819. FND-CIT-0183.
[19] Nicholson C, Edwards MJ, Carson AJ, et al. Occupational therapy consensus recommendations for functional neurological disorder. Journal of Neurology, Neurosurgery & Psychiatry. 2020;91(10):1037–1045. https://doi.org/10.1136/jnnp-2019-322281 Includes the authors’ assessment supplement. Professional consensus, not a validation study of every assessment tool. FND-CIT-0011.
[20] NHS. Symptoms of a stroke. Reviewed September 12, 2024; accessed September 17, 2026. Source. FND-CIT-0108.

Sources 4–18 remain for the preserved inventory links and their historical anchors; see the inventory for the associated claims.

Expanded September 26, 2026, preserving project-lead material from the September 10 draft. Clinical, lived-experience and accessibility review pending.

For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources