Functional Sensory Symptoms: Diagnostic Technique Inventory

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Detailed mapping · Splitting-sign limitations

Diagnostic techniques at a glance

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]

Research and Sources

The inherited descriptions retain their original citations. The IFCN chapter concerns functional motor neurophysiology; it is background rather than a validation of normal sensory studies as an FND test. Individual investigation protocols remain outside this initial expansion.

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.