REFERENCE · DIAGNOSIS

Functional Sensory Symptoms

Refers to:

numbness or reduced, absent or altered touch sensation;
tingling, burning, hypersensitivity or unusual bodily sensation; and
an assessed body part feeling different, distant or absent when this is a sensory presentation.

Scope boundary: Visual and other special-sense symptoms need their own assessment, and dissociative disconnection is not automatically a sensory sign. This page’s examinations concern sensory modalities and should not be substituted for motor, seizure or cognitive assessment.

Featured technique: Systematic sensory history and examination across separate sensory modalities.
Diagnostic method: Map the pattern, repeat selected comparisons and interpret any inconsistency cautiously; traditional sensory signs are not reliable enough to stand alone.
Media needed: A clinician-led examination diagram that states the limitations as clearly as the technique.

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.

Sensory mapping

The clinician maps touch or other sensations and compares their distribution with nerves, roots and central pathways. An inconsistent pattern can inform assessment but is not sufficient on its own. A recent stroke-comparison study shows considerable overlap in sensory complaints. [1]

Sharply bounded or whole-limb sensory change

A clear boundary at a joint or a distribution unlike a single nerve can be a clinical clue. It is not inherently diagnostic: descriptions, attention, pain and other neurological disease can complicate the map. [1][3]

Midline splitting of light touch

The person reports a sharply divided sensation across the body’s midline. Historically considered a functional sign, it showed poor specificity in recent comparative research. Central neurological disease can produce similar findings; this should not independently rule in FND. [1][4]

Vibration splitting

The clinician compares vibration perception across a continuous bony surface. Reported differences have been used as a functional sign, but a recent study found poor diagnostic specificity. The test should not override the rest of the neurological examination. [1]

Consistency across sensory tasks

Repeated, clearly explained comparisons may reveal a specific internal inconsistency. Reliability depends on technique and comprehension; ordinary variability is not proof. A pilot bedside-sign study supports cautious combination with other findings. [3][4]

Quantitative sensory testing

Standardized equipment measures thresholds for sensory detection or pain. Recent comparative research found no clear added diagnostic value for identifying motor-FND sensory symptoms. It may characterize experience, but it is not a validated standalone FND test. [1]

Nerve conduction and evoked potentials

These assess selected peripheral or central pathways when indicated. They help investigate other or coexisting disease; normal results are not positive proof of FND and do not test every sensory pathway. [5]

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Functional sensory symptoms may include numbness, altered touch, tingling, burning or a sense that a body part is different. The clinician first works out which kind of sensation has changed and whether the pattern fits a nerve, nerve root, spinal cord, brain or another recognized condition.

Older teaching sometimes treated sharply split sensation at the body’s midline, or a difference when a vibrating tuning fork crossed a single bone, as strong proof of a functional symptom. Newer evidence shows that these findings also occur in people with other neurological diagnoses and have limited diagnostic value. A sensory diagnosis therefore needs more than one traditional bedside sign. [1][2]

Your examination may still help by documenting the symptom accurately and placing it beside the history, motor examination and necessary tests. The aim is not to catch you giving two different answers.

Sensory symptoms may come and go or remain

Functional numbness, tingling, altered sensation or hypersensitivity may be intermittent, fluctuate in location or intensity, occur during broader symptom flares, or persist for long periods. The pattern can change with activity, attention, pain, migraine, fatigue or sensory load in some people. Those changes are useful history but are not a diagnosis by themselves.

At the onset of familiar reduced or distorted sensation, protect the affected area from falls, burns, sharp objects and pressure injury. Use a previously taught sensory or attention strategy only if it is safe. Sudden new one-sided numbness, rapidly spreading symptoms or sensory change with weakness, speech difficulty or another acute neurological symptom needs medical assessment rather than being assumed to be FND.

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Do not use pins, heat, ice or repeated touching to map another person’s sensation at home. Reduced sensation can make injury easier, and interpretation requires anatomical knowledge and the rest of the examination. Help the person describe the location, timing and practical effect of the symptom instead.

When sensation changes suddenly

An episode may last briefly or become part of a much longer flare. Help protect numb or poorly controlled areas from heat, pressure, cuts and falls. Ask before touching a hypersensitive area, and use only the sensory or grounding method already agreed with the person. Do not repeatedly test whether they can feel an object.

Once safe, note location, quality, onset, duration, associated symptoms and recovery. A familiar intermittent pattern and a new acute neurological pattern should not automatically be treated as the same thing.

Sudden one-sided numbness, a rapidly changing pattern or sensory loss with other urgent symptoms needs appropriate medical assessment even when the person already has FND.

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Episodic and prolonged presentations

Document temporal pattern as carefully as anatomical distribution: continuous versus episodic symptoms, duration, frequency, migration, warning, activity or environmental context, associated motor/migraine/seizure-like symptoms and recovery. A sensory symptom that is absent during examination can still be clinically important, but fluctuation alone is weak evidence for a functional diagnosis.

For an established episodic functional pattern, provide an onset plan that emphasizes injury prevention and a limited, previously trained sensory-discrimination, functional-task or attention strategy. New or substantially changed sensory episodes still require appropriate anatomical and medical reassessment.

Technique outline: careful sensory mapping

Clarify the symptom in the patient’s words: onset, exact distribution, time course, associated pain or weakness, functional effect and factors that change it.
Form an anatomical differential before testing. Examine touch, pin sensation, temperature, vibration, joint position and cortical sensory function only as indicated, rather than collapsing them into “sensation.”
Explain each stimulus and demonstrate it on an unaffected area. Ask for simple comparisons such as “same or different,” avoiding leading questions.
Map relevant boundaries using a consistent stimulus and pressure. Repeat or vary selected trials when needed, but avoid excessive testing and avoid painful stimulation for the sake of demonstrating inconsistency.
Interpret midline splitting, vibration splitting and sharply bounded patterns cautiously. None is sufficiently specific to establish functional sensory symptoms alone.
Integrate the result with motor and reflex findings and assess appropriate alternatives, including central and peripheral neurological disease, migraine, pain disorders, complex regional pain syndrome and medication or metabolic causes.
If the positive evidence remains weak, say so. A descriptive sensory examination plus follow-up may be more accurate than an overconfident label.

Media contributor brief

Use an actor or healthy volunteer to show the method, not a staged abnormal response:

A body diagram identifying the symptom area described in the history.
A clinician demonstrating light touch, vibration and position sense as separate modalities.
A brief repeated comparison using the same stimulus and neutral wording.
A full-screen evidence note: “Traditional midline and vibration-splitting signs have limited specificity and cannot diagnose FND alone.”

Do not use needles, painful pressure, extreme temperature or concealed startling stimuli. Keep the participant’s answers out of the title and thumbnail; the important teaching point is disciplined mapping and cautious interpretation.

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Research and Sources

Evidence notes

A 2026 case-control study of 102 patients with functional sensory symptoms found limited diagnostic utility for several classic sensory signs, including midline and vibration splitting. [1]
The broader diagnostic review supports diagnosis from positive clinical features while warning against weakly supported or isolated findings. [2]

Citation table

Citation	Full citation
[1]	Nielsen G, Higgins R, Stone J, Coebergh J, Edwards MJ. Functional sensory symptoms and signs: a case-control study of 102 patients. Brain Communications. 2026;8(1):fcag031. FND-CIT-0023. https://doi.org/10.1093/braincomms/fcag031
[2]	Espay AJ, Aybek S, Carson A, et al. Current concepts in diagnosis and treatment of functional neurological disorders. JAMA Neurology. 2018;75(9):1132–1141. FND-CIT-0002. https://doi.org/10.1001/jamaneurol.2018.1264

[3]	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.
[4]	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.
[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.

Technique outline created: August 24, 2026 · Neurology and sensory-testing review pending

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