Weber Two-Point Discrimination Test: Difference between revisions
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== Introduction == | == Introduction == | ||
'''Two point discrimination''' is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. It is often tested with two sharp points during a [https://www.physio-pedia.com/Neurological_Assessment neurological] examination <ref name=":0">Blumenfeld, Hal (2010). Neuroanatomy through Clinical Cases. Sunderland, MA: Sinauer Associates, Inc. pp. 71–72. ISBN .</ref><ref name=":1">Bickley, Lynn; Szilagui, Peter (2007). Bates' Guide to Physical Examination and History Taking (9th ed.). Lippincott Williams & Wilkins. ISBN . ASIN B0028IKRYG</ref> and is assumed to reflect how finely innervated an area of [https://www.physio-pedia.com/Skin skin] is. In clinical settings, two-point discrimination is a widely used technique for assessing tactile perception.<ref>Shooter | '''Two point discrimination''' is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. It is often tested with two sharp points during a [https://www.physio-pedia.com/Neurological_Assessment neurological] examination <ref name=":0">Blumenfeld, Hal (2010). Neuroanatomy through Clinical Cases. Sunderland, MA: Sinauer Associates, Inc. pp. 71–72. ISBN .</ref><ref name=":1">Bickley, Lynn; Szilagui, Peter (2007). Bates' Guide to Physical Examination and History Taking (9th ed.). Lippincott Williams & Wilkins. ISBN . ASIN B0028IKRYG</ref> and is assumed to reflect how finely innervated an area of [https://www.physio-pedia.com/Skin skin] is. In clinical settings, two-point discrimination is a widely used technique for assessing tactile perception.<ref>Shooter D. [https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1445-2197.2005.03557.x Use of two‐point discrimination as a nerve repair assessment tool: preliminary report.] ANZ journal of surgery. 2005 Oct;75(10):866-8.</ref> It relies on the ability and/or willingness of the patient to subjectively report what they are feeling and should be completed with the patient’s eyes closed.<ref name=":0" /> | ||
== Method == | == Method == | ||
The examiner uses a '''paper clip, two point discriminator, or calipers'''<ref>Finnell, | The examiner uses a '''paper clip, two point discriminator, or calipers'''<ref>Finnell JT, Knopp R, Johnson P, Holland PC, Schubert W. [https://onlinelibrary.wiley.com/doi/abs/10.1197/j.aem.2003.11.022 A Calibrated Paper Clip Is a Reliable Measure of Two‐point Discrimination.] Academic emergency medicine. 2004 Jun;11(6):710-4.</ref> to apply pressure on two adjacent points in longitudinal direction or perpendicular to the long axis of the finger.<ref>Two point discrimination. Science direct. Available from https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/two-point-discrimination#:~:text=Two%E2%80%90point%20discrimination%20is%20a,pain%20fibers%20rather%20than%20touch. [last accessed 25/01/2021]</ref> The minimal distance with which the patient can distinguish between two stimuli is found by moving from proximal to distal. This distance is called '''threshold for discrimination'''. The area being tested must not be seen by the patient and the patient must concentrate on feeling the points. For accurate results, the hand must be immobile on a hard surface and it must be ensured that the two points are simultaneously touching the skin. The patient is asked to report whether one or two points was felt. The smallest distance between two points that still results in the perception of two distinct stimuli is recorded as the patient's two-point threshold.<ref name=":2">O'Sullivan, Susan (2007). Physical Rehabilitation Fifth Edition. Philadelphia: F.A. Davis Company. pp. 136–146. ISBN .</ref> Performance on the two extremities can be compared for discrepancies. Although the test is still commonly used clinically, it has been roundly criticized by many researchers as providing an invalid measure of tactile spatial acuity, and several highly regarded alternative tests have been proposed to replace it. | ||
There must be no skin blanching as it indicates too much pressure being applied. There may be increase or decrease in the distance between the points depending on the patient's response. Starting distance between the points can be easily distinguished. If the | There must be no skin blanching as it indicates too much pressure being applied. There may be an increase or decrease in the distance between the points depending on the patient's response. Starting distance between the points can be easily distinguished. If the patient is hesitant to respond or becomes inaccurate, the patient is required to respond accurately on several trials before the test can be repeated. | ||
Normal discrimination distance recognition is less than 6mm, but it varies from person to person. This test is best for hand sensation involving static holding of object between the finger and thumb requiring pinch strength.<ref>G.Lundborg, Birgitta Rosen. [https://www.researchgate.net/publication/8375190_The_Two-Point_Discrimination_Test_-_Time_For_a_Re-Appraisal The two point discrimination test], The Journal of Hand Surgery British & European Volume 29(5):418-22 </ref><ref>Boldt, R., Gogulski, J., Gúzman-Lopéz, J. ''et al.'' [https://link.springer.com/article/10.1007/s00221-014-3908-y#citeas Two-point tactile discrimination ability is influenced by temporal features of stimulation]. ''Exp Brain Res'' 232, 2179–2185 (2014). </ref> | Normal discrimination distance recognition is less than 6mm, but it varies from person to person. This test is best for hand sensation involving the static holding of an object between the finger and thumb requiring pinch strength.<ref>G.Lundborg, Birgitta Rosen. [https://www.researchgate.net/publication/8375190_The_Two-Point_Discrimination_Test_-_Time_For_a_Re-Appraisal The two point discrimination test], The Journal of Hand Surgery British & European Volume 29(5):418-22 </ref><ref>Boldt, R., Gogulski, J., Gúzman-Lopéz, J. ''et al.'' [https://link.springer.com/article/10.1007/s00221-014-3908-y#citeas Two-point tactile discrimination ability is influenced by temporal features of stimulation]. ''Exp Brain Res'' 232, 2179–2185 (2014). </ref> | ||
{{#ev:youtube | _f488-BNid8 | 300}}<ref>Example vedios. Two point discrimination tests. Available from https://www.youtube.com/watch?v=_f488-BNid8 [last accessed 25/01/2021] </ref> | {{#ev:youtube | _f488-BNid8 | 300}}<ref>Example vedios. Two point discrimination tests. Available from https://www.youtube.com/watch?v=_f488-BNid8 [last accessed 25/01/2021] </ref> | ||
{{#ev:youtube | dB4gCv42ETw | 300}}<ref>kuhealthproffesions. 2 point discrimination. Available from https://www.youtube.com/watch?v=dB4gCv42ETw [last accessed 25/01/2021] </ref> | {{#ev:youtube | dB4gCv42ETw | 300}}<ref>kuhealthproffesions. 2 point discrimination. Available from https://www.youtube.com/watch?v=dB4gCv42ETw [last accessed 25/01/2021] </ref> | ||
=== Normal and impaired performance === | === Normal and impaired performance === | ||
Body areas differ both in tactile receptor density and somatosensory cortical representation. Normally, a person should be able to recognize two points separated by 2 to 8 mm on fingertips. On the lips, it is 2 to 4 mm, and on the palms, it is 8 to 12 mm and 30–40 mm on the shins or back.<ref>Vriens JP, Glas HW | Body areas differ both in tactile receptor density and somatosensory cortical representation. Normally, a person should be able to recognize two points separated by 2 to 8 mm on fingertips. On the lips, it is 2 to 4 mm, and on the palms, it is 8 to 12 mm and 30–40 mm on the shins or back.<ref>Vriens JP, Van der Glas HW. [https://www.sciencedirect.com/science/article/pii/S0901502709009461 Extension of normal values on sensory function for facial areas using clinical tests on touch and two-point discrimination.] International journal of oral and maxillofacial surgery. 2009 Nov 1;38(11):1154-8.</ref><ref>Weinstein S. Intensive and extensive aspects of tactile sensitivity as a fuction of body part, sex and laterality. In: Kenshalo DR, ed. The skin senses. Springfield: Charles C.Thomas; 1968. p. 195-222.</ref> The posterior column-medial lemniscus pathway is responsible for carrying information involving fine, discriminative touch. Therefore, two-point discrimination can be impaired by damage to this pathway or to a peripheral nerve.<ref name=":2" /><ref name=":1" /> | ||
==== Two Point Discrimination Value ==== | ==== Two Point Discrimination Value ==== | ||
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* Poor 11-15mm | * Poor 11-15mm | ||
* Protective where only one point is perceived. | * Protective where only one point is perceived. | ||
* Anesthetic where points are not perceived.<ref>Dellon AL, Mackinnon SE, Crosby PM. Reliability of two-point discrimination measurements. | * Anesthetic where points are not perceived.<ref>Dellon AL, Mackinnon SE, Crosby PM. [https://www.sciencedirect.com/science/article/pii/S0363502387800497 Reliability of two-point discrimination measurements.] The Journal of hand surgery. 1987 Sep 1;12(5):693-6.</ref> | ||
== References == | == References == | ||
Revision as of 14:19, 25 January 2021
Original Editor - Chelsea Mclene
Top Contributors - Chelsea Mclene, Kim Jackson and Aminat Abolade
Introduction[edit | edit source]
Two point discrimination is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. It is often tested with two sharp points during a neurological examination [1][2] and is assumed to reflect how finely innervated an area of skin is. In clinical settings, two-point discrimination is a widely used technique for assessing tactile perception.[3] It relies on the ability and/or willingness of the patient to subjectively report what they are feeling and should be completed with the patient’s eyes closed.[1]
Method[edit | edit source]
The examiner uses a paper clip, two point discriminator, or calipers[4] to apply pressure on two adjacent points in longitudinal direction or perpendicular to the long axis of the finger.[5] The minimal distance with which the patient can distinguish between two stimuli is found by moving from proximal to distal. This distance is called threshold for discrimination. The area being tested must not be seen by the patient and the patient must concentrate on feeling the points. For accurate results, the hand must be immobile on a hard surface and it must be ensured that the two points are simultaneously touching the skin. The patient is asked to report whether one or two points was felt. The smallest distance between two points that still results in the perception of two distinct stimuli is recorded as the patient's two-point threshold.[6] Performance on the two extremities can be compared for discrepancies. Although the test is still commonly used clinically, it has been roundly criticized by many researchers as providing an invalid measure of tactile spatial acuity, and several highly regarded alternative tests have been proposed to replace it.
There must be no skin blanching as it indicates too much pressure being applied. There may be an increase or decrease in the distance between the points depending on the patient's response. Starting distance between the points can be easily distinguished. If the patient is hesitant to respond or becomes inaccurate, the patient is required to respond accurately on several trials before the test can be repeated.
Normal discrimination distance recognition is less than 6mm, but it varies from person to person. This test is best for hand sensation involving the static holding of an object between the finger and thumb requiring pinch strength.[7][8]
Normal and impaired performance[edit | edit source]
Body areas differ both in tactile receptor density and somatosensory cortical representation. Normally, a person should be able to recognize two points separated by 2 to 8 mm on fingertips. On the lips, it is 2 to 4 mm, and on the palms, it is 8 to 12 mm and 30–40 mm on the shins or back.[11][12] The posterior column-medial lemniscus pathway is responsible for carrying information involving fine, discriminative touch. Therefore, two-point discrimination can be impaired by damage to this pathway or to a peripheral nerve.[6][2]
Two Point Discrimination Value[edit | edit source]
- Normal <6mm
- Fair 6-10mm
- Poor 11-15mm
- Protective where only one point is perceived.
- Anesthetic where points are not perceived.[13]
References[edit | edit source]
- ↑ 1.0 1.1 Blumenfeld, Hal (2010). Neuroanatomy through Clinical Cases. Sunderland, MA: Sinauer Associates, Inc. pp. 71–72. ISBN .
- ↑ 2.0 2.1 Bickley, Lynn; Szilagui, Peter (2007). Bates' Guide to Physical Examination and History Taking (9th ed.). Lippincott Williams & Wilkins. ISBN . ASIN B0028IKRYG
- ↑ Shooter D. Use of two‐point discrimination as a nerve repair assessment tool: preliminary report. ANZ journal of surgery. 2005 Oct;75(10):866-8.
- ↑ Finnell JT, Knopp R, Johnson P, Holland PC, Schubert W. A Calibrated Paper Clip Is a Reliable Measure of Two‐point Discrimination. Academic emergency medicine. 2004 Jun;11(6):710-4.
- ↑ Two point discrimination. Science direct. Available from https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/two-point-discrimination#:~:text=Two%E2%80%90point%20discrimination%20is%20a,pain%20fibers%20rather%20than%20touch. [last accessed 25/01/2021]
- ↑ 6.0 6.1 O'Sullivan, Susan (2007). Physical Rehabilitation Fifth Edition. Philadelphia: F.A. Davis Company. pp. 136–146. ISBN .
- ↑ G.Lundborg, Birgitta Rosen. The two point discrimination test, The Journal of Hand Surgery British & European Volume 29(5):418-22
- ↑ Boldt, R., Gogulski, J., Gúzman-Lopéz, J. et al. Two-point tactile discrimination ability is influenced by temporal features of stimulation. Exp Brain Res 232, 2179–2185 (2014).
- ↑ Example vedios. Two point discrimination tests. Available from https://www.youtube.com/watch?v=_f488-BNid8 [last accessed 25/01/2021]
- ↑ kuhealthproffesions. 2 point discrimination. Available from https://www.youtube.com/watch?v=dB4gCv42ETw [last accessed 25/01/2021]
- ↑ Vriens JP, Van der Glas HW. Extension of normal values on sensory function for facial areas using clinical tests on touch and two-point discrimination. International journal of oral and maxillofacial surgery. 2009 Nov 1;38(11):1154-8.
- ↑ Weinstein S. Intensive and extensive aspects of tactile sensitivity as a fuction of body part, sex and laterality. In: Kenshalo DR, ed. The skin senses. Springfield: Charles C.Thomas; 1968. p. 195-222.
- ↑ Dellon AL, Mackinnon SE, Crosby PM. Reliability of two-point discrimination measurements. The Journal of hand surgery. 1987 Sep 1;12(5):693-6.
