Semmes-Weinstein Monofilament Test

    In the last tweet, we introduced and interpreted "hand-brain perception and hand-brain movement". It can be seen that sensory recovery has a significance that cannot be underestimated in the rehabilitation treatment and recovery process of stroke patients. Before formulating a rehabilitation plan and carrying out rehabilitation treatment, accurate rehabilitation assessment is very critical and important. So, today we will introduce in detail a sensory assessment method that is widely used in clinical practice-the Semmes-Weinstein Monofilament test.

01What is S-W monofilament test?

    Semmes-Weinstein Monofilament (Semmes-Weinstein Aesthesiometer) is a nylon monofilament that tests the human body's sensory (tactile) threshold. It is a type of tactile measurement tool (Esthesiometer in American English and Aesthesiometer in British English). The principle is that according to the different diameter, length and material of the nylon monofilament, after special processing and calibration, the contact test part will be bent to 90° with force to produce different magnitudes of force (in grams-gm) to test the resistance of the specific part. The feeling of the force exerted to achieve the purpose of evaluation.


02Test tool composition

    Semmes-Weinstein Monofilament monofilament testing is internationally recognized as a very effective method for detecting touch pressure sensory disorders. The complete set of test kits has up to 20 specifications and strength levels to choose from. Different units can be selected according to specific clinical or scientific research applications. The silk is tested and can be determined to be normal (specification 1.65~2.83); loss of light touch (specification 3.22~3.61); loss of protective sensation (specification 3.84~4.31); loss of protective sensation (specification 4.56~6.65); complete loss of sensation (specification 4.56~6.65) Specification>6.65). Specifications and power levels are:

    Through sensory testing, we can objectively and quantitatively understand the specific situation of patients' sensory loss, assist clinical diagnosis to determine the degree of damage and functional limitation, and provide objective basis for formulating specific treatment plans.


03Indications

Central nervous system lesions, such as cerebrovascular lesions, spinal cord injuries, or peripheral neuropathy, such as brachial plexus palsy, sciatic nerve damage, etc.; Trauma, including cuts, lacerations, and burns; ischemic or nutritional metabolic disorders, such as Diabetes, Raynaud's disease, polyneuritis. This does not apply to those who have lost consciousness.


04Detailed operation methods

1) Instruct the patient to prepare for the test in a comfortable posture, and remove clothing, gloves, socks, glasses, jewelry and other objects that may hinder the test depending on the test site;

2) Determine the specific test site and select nylon monofilaments of different specifications according to the required strength;

3) Inform the patient that you will perform a monofilament sensory test on him or her, and cover the patient's eyes with a curtain or other object. Select a specific monofilament (the examiner holds the smallest monofilament to start the test) to conduct experience testing on a certain part, allowing the patient to experience the feeling;

4) Ask the patient to answer “yes” or “yes” when they feel stressed, and “no” or “no” when they do not feel stressed;

5) Keep the test monofilament perpendicular to the surface of the test site and contact the test site, and then apply pressure to bend the monofilament into a C shape. The force generated when the monofilament is bent is the test force of the monofilament of this specification. The monofilament bends and leaves the skin;

6) Record the relevant results. If there is feeling, it will be recorded as "+", if there is no feeling, it will be recorded as "-". If the patient can feel it just after bending the wire twice in a row, write down the number and look up the table to record the results.

Note: When using No. 1.65-4.08 wire, each size can be measured up to 3 times. The single wire is applied to the skin for 1-1.5 seconds at a time and lifted for 1.5 seconds each time. When using No. 4.17-6.65 silk, you only need to measure it once and grade it according to the feeling.



Finally, what other professional details do we need to pay attention to during the sensory evaluation process?

1) When checking sensory function, the patient must be conscious;

2) The examiner needs to be patient and meticulous, so that the patient understands the examination method and fully cooperates, and pays attention to adjusting the patient's attention;

3) The patient's posture should be appropriate and the examination site should be relaxed to improve examination accuracy;

4) Check the normal side first so that the patient knows what "normal" is. During the examination, pay attention to the symmetrical parts on both sides for comparison;

5) After the examination results are confirmed, attention should be paid to marking the type and scope of sensory impairment;

6) Adopt the principle of comparison between left and right, front and back, far and near ends, and repeat the inspection multiple times if necessary;

7) Avoid any suggestive questioning to obtain accurate clinical information.