REFERENCE · DIAGNOSTIC TECHNIQUE

Sensory Mapping and Comparison

Clinician-focused educational reference; assessment requires suitable training and consent.

Purpose and Suitability
Anatomy and Physiology
Preparation and Safety
Performing the Assessment
Interpreting Findings
Explaining the Result
Evidence and Limitations
Media and Accessibility
Research and Sources

Purpose and Suitability

Use this assessment to describe the symptom accurately and investigate its anatomical pattern. Mapping can guide a differential diagnosis; it is not a standalone FND test. Acute symptoms require the appropriate urgent pathway before elective comparisons.

Sensory modality: One kind of feeling, such as touch, temperature or awareness of joint position.

Ask what “numbness” means to this person. Loss of feeling, inability to move and a strange bodily sensation may need different examinations.

Anatomy and Physiology

Signals from the body pass through peripheral nerves and spinal pathways to the brain. Pain and temperature chiefly use the spinothalamic system; vibration and position sense chiefly use the dorsal-column–medial-lemniscus system. Light touch alone gives limited localization information. [4]

Localization: Working out which part of the nervous system could explain the pattern. Proprioception: Awareness of body position and movement.

A clinical map describes responses; it does not directly measure an FND brain-network mechanism.

Preparation and Safety

Explain the purpose and obtain permission before contact. Agree a stop signal, breaks and comfortable positioning. Ask about painful skin, wounds and sensitivity. Support a limb that cannot be positioned safely. These are practical teaching safeguards, not a validated diagnostic protocol.

Use appropriate clinical equipment and infection-control procedures. Avoid excessive or injurious stimulation, repeated symptom provocation and concealed “surprise” tests. Stop if the person withdraws consent or cannot comfortably continue. Record an omitted comparison as untested.

Performing the Assessment

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.

This preserves the earlier clinical outline. It is an educational sequence, not a validated seven-item score. [1][2]

For joint position, small supported finger or toe movements can be assessed without visual cues if appropriate. For vibration, use the clinician’s standard tuning-fork method at bony landmarks. Map each relevant modality separately and record the stimulus and site. [4]

Interpreting Findings

Potentially supportive: Describe the actual reproducible discrepancy and why competing explanations do not adequately explain it. A boundary alone does not settle the diagnosis.

No discrepancy found: This does not exclude functional sensory symptoms.

Indeterminate: Pain, fatigue, comprehension, changing stimulus pressure or another neurological condition may prevent a meaningful comparison. Do not translate this into a judgment about effort or honesty.

A sharp joint boundary, whole-limb change or variable response needs contextual interpretation. See splitting-sign limitations. The map must be considered alongside the history, motor findings, reflexes and indicated investigations. [1][2]

One detected touch does not demonstrate safe cooking, walking, repeated hand use or low support needs. Ask about the relevant everyday activity; fuller context belongs on the symptom page.

Explaining the Result

An authored explanation example, not a research or patient quotation:

“Your answers help us understand which kinds of feeling have changed and where. I will explain how this pattern fits the rest of your examination, what it supports and what still needs checking.”

If a comparison supports FND, describe that comparison in ordinary words. Give the person a written account when helpful.

Evidence and Limitations

Sensory mapping is a clinical examination method, not a validated numerical discriminator for FND. The overview’s evidence notes distinguish the current motor-FND cohort from isolated sensory presentations. No sensitivity or specificity is assigned to this educational sequence.

The general examination reference supports modality selection and localization; it is not an FND validation study. The older pilot study remains relevant background, with fresh full-text reappraisal pending. [3][4]

Media and Accessibility

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.

Provide captions, a transcript and a written description. No media has been added.

Research and Sources

Local citation numbers match the symptom overview so the relocated outline remains traceable. Each source is included below; shared IDs remain stable.

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]	Newman G. How to assess sensation. MSD Manual Professional Edition. Reviewed August 2025. Clinical examination reference. Accessed October 1, 2026. FND-CIT-0245.