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Special Test

Semmes Weinstein Monofilament Test

Semmes Weinstein Monofilament Test is a neurological test that is used in sensory loss of the skin.

In Semmes Weinstein Monofilament Test, the palm of the hand is divided into several areas, and only one point (usually in the center) is tested in each area:

  1. Between the fingertip and DIP joint.
  2. Between the DIP joint and PIP joint.
  3. Between the PIP joint and finger web.
  4. Between the finger web and the distal anterior (palmar) crease.
  5. Between the distal anterior (palmar) crease and the central palm.
  6. Base of palm and wrist.
  7. Superficial radial nerve distribution.

The clinician applies a monofilament perpendicular to the surface, and the pressure is increased until the monofilament begins to bend. Filament 2.83 MN is considered the “Normal” filament and indicates normal light touch perception. A positive test for CTS is when the patient with eyes closed cannot report which digit is receiving pressure at 2.83 mg.

See Also: Carpal Tunnel Syndrome

Light Touch Testing Scale and Filament Forces Using Semmes Weinstein Monofilament Test

ColorPressure (mg)Monofilament (MN)
Diagonal redlineNo response0

Diagnostic Usefulness of the Semmes Weinstein Monofilament Test in one study by Koris et al found that this test has a Sensitivity of 82% and a Specificity of 86%.

Another study by Pagel et al. found the Sensitivity of 98% and a Specificity of 15% for the Semmes Weinstein Monofilament Test.

In a study on 36 hands with carpal tunnel syndrome, the Interexaminer Reliability was κ = .22 (.26, .42).

Semmes Weinstein Monofilaments
Semmes Weinstein Monofilaments

Weber Two Point Discrimination Test

The Weber Two Point Discrimination Test were first introduced by Weber in1953 using calipers and by Moberg in 1958 using a paper clip.

Today it is recommended that a two-point aesthesiometer tool such as a Disk Criminator be used. The instrument is explained and demonstrated to the patient until an appreciation can be made between one and two points in an area of normal sensibility.

The instrument is applied, in a perpendicular fashion, to all of the fingertips in a mixed series of two and one points for five consecutive applications. The patient should be able to recognize at least four out of the five or seven out of ten. The clinician repeats the tests in an attempt to find the minimal distance at which the patient can distinguish between the two stimuli, decreasing or increasing the distance between the points depending on the response by the patient.

This distance is called the threshold for discrimination: Normal discrimination distance is less than 6 mm, although this can vary between individuals, and in the area of the hand, with normal fingertip scores between 2 and 5 mm and finger surface scores between 3 and 7 mm.

Studies investigating the sensitivity and the specificity of the Weber Two Point Discrimination Test indicate that the test has a high specificity but low sensitivity.

Buch-Jaeger and Foucher found the test to have a sensitivity of 6 % and a specificity of 99 %. Another study by Gellman and colleagues found the sensitivity to be 33 % and the specificity to be 100 %. These findings suggest that the Weber Two Point Discrimination Test is useful for ruling in CTS.

Disk Criminator
Disk Criminator


  1. Koris M, Gelberman RH, Duncan K, Boublick M, Smith B. Carpal tunnel syndrome. Evaluation of a quantitative provocational diagnostic test. Clin Orthop Relat Res. 1990 Feb;(251):157-61. PMID: 2295167.
  2. Moberg E: Objective methods for determining the functional value of sensibility in the hand. J Bone Joint Surg Br 40A:454–476, 1958.
  3. Tubiana R, Thomine J-M, Mackin E: Examination of the Hand and Wrist. London: Mosby, 1996.
  4. Omer GE: Report of committee for evaluation of the clinical result in peripheral nerve injury. J Hand Surg 8:754–759, 1983.
  5. Buch-Jaeger N, Foucher G: Correlation of clinical signs with nerve conduction tests in the diagnosis of carpal tunnel syndrome. J Hand Surg Br 19:720–724, 1994
  6. Gellman H, Gelberman RH, Tan AM, et al: Carpal tunnel syndrome. An evaluation of the provocative diagnostic tests. J Bone Joint Surg Am 68A:735–737, 1986.
  7. MacDermid JC, Kramer JF, Woodbury MG, McFarlane RM, Roth JH. Interrater reliability of pinch and grip strength measurements in patients with cumulative trauma disorders. J Hand Ther. 1994 Jan-Mar;7(1):10-4. doi: 10.1016/s0894-1130(12)80035-4. PMID: 8012479.
  8. Netter’s Orthopaedic Clinical Examination An Evidence-Based Approach 3rd Edition Book.
  9. Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.
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