Extensor Tendon Injury
An Occupational Therapy Perspective
The Nerves of the Hand
The hand is innervated by three main nerves. These nerves consist of the median, ulnar and radial nerve (Wilhelmi, 2013) These nerves are in charge of the sensation of the hand and movement of the muscles in the hand. Each one of these hands gives off sensation to different parts of the hand (Wilhelmi, 2013).
Looking at the palmer side of the hand (the side where your palm is on), the hand is mainly innervated by the ulnar and median nerves. On the dorsal side of the hand (the back of your hand), the hand is innervated by the ulnar nerve, radial nerve and median nerve (Wilhelmi, 2013).
Given that the injury on Felix’s hand is in zone 5 of the dorsal hand. The nerves of concern are the ulnar nerve, more specifically the dorsal branch of the ulnar nerve, and the radial nerve, more specifically the superficial branch of the radial nerve (Washington University School of Medicine, 2010). It is important to ensure that Felix does not have any nerve damage in this section from the injury and that all sensation is still intact.
Testing for Sensation in the Hand
There are many tests that an occupational therapist can use to identify sensation issues in the hand. The video below shows a few different sensation tests an occupational therapist can potentially do on Felix:
A very common sensory test done is called the two-point discrimination test. This test allows the occupational therapist to measure if the individual is able to perceive two points of stimuli that is presented at the same time. The goal is to identify the smallest distance between the two points that can still be identified by client being test (Wayne State University Department of Health Care Sciences, n.d.).
The device used for this test is called a disk-criminator, as seen in the image below:
Static Discrimination Test
The occupational therapist will ask the client to close their eyes for this test. The occupational therapist will randomly place either one point or two points on random parts of the skin around zone 5 and along the finger tips and ask the client if they feel one point or two points. As you can see from the disk-criminator image above, there are different distances between each two pointers. The occupational therapist will start with the widest distance between points and work their way closer till the client can no longer feel the difference between the two points. They will do the test 10 times with each set of point distances, randomly going between one and two points. If the client can answer correctly 7 or more times, the occupational therapist will move to a closer set of points. They will continue this until the client gets less than 7 correct responses (Mobilis Rolyan Workshop, n.d.).
Dynamic Discrimination Test
This test is very similar to a static test, however the difference between this is that the one point or two points are moving while they maintain contact with the skin. The occupational therapist will apply light pressure on the skin while they move the points. A guide is that the skin should blanch while applying the pressure (Mobilis Rolyan Workshop, n.d.).
Scoring Interpretation of Two Point Discrimination Test
(Mobilis Rolyan Workshop, n.d).
Recently, studies have shown that two point orientation discrimination testing has a higher validity level of determining spatial acuity over the traditional two point discrimination test (Tong, Mao, and Goldreich, 2013). This test is very similar to a traditional two point discrimination test, however the client needs to identify if the orientation of the points are vertical or horizontal along with if they’re one point or two points (Tong, Mao, and Goldreich, 2013). This is still a very new test and has not been done extensively so there are no exact thresholds for this test yet, however it can be considered in Felix’s case as well.
Relevance To Felix
It would be necessary to conduct a two-point discrimination test for Felix to determine if any sensory issues exist. If issues do exist, the OT would help educate Felix on a hand desensitization program that could help reduce the uncomfortable feeling in his hand (London Health Sciences Centre, n.d.).
The program would consist of:
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Massage: Massaging the sensitive area of the hand with skin lotion in a circular motion. It is recommended that Felix increases the amount of pressure gradually that he applies to the sensitive area (London Health Sciences Centre, n.d.).
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Tapping: Felix will be instructed to tap around the sensitive skin of his hand, and slowly work in towards the most sensitive area of his hand. He can also tap certain objects on his skin such as a cotton ball, sponge, eraser, or the end of a pencil (London Health Sciences Centre, n.d.).
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Textures: Felix will be instructed to rub the sensitive area with different textures. He should start off with fine, soft fabrics and then he can progress to harder and coarser fabrics. Examples of fabrics consist of satin, fur, terry cloth, flannel, cotton, denim, canvas and velcro (London Health Sciences Centre, n.d.).
Through the healing process, the OT would continue to do the two-point discrimination test to continue to track Felix’s progress and improvements (London Health Sciences Centre, n.d.).
References:
Griffin, M., Hindocha, S., Jordan, D., Saleh, M. & Khan, W. (2012). Management of extensor tendon injuries. The Open Orthopaedics Journal. 6, 36-42.
London Health Sciences Centre (n.d.). Hand Desensitization Program. London, Ontario.
Mobilis Rolyan Workshop. (n.d.). Two-Point Discrimination. Retrieved from http://www.htherapy.co.za/user_images/splinting/Two_Point_Discrimination_2009.pdf
Tong, J., Mao, O., & Goldreich, D. (2013). Two-point orientation discrimination versus the traditional two-point test for tactile spatial acuity assessment.Frontiers in Human Neuroscience, 7, 1-11.
Tucker, S. (2013, April, 23). Sensory OT Assessment- Semmes- Weinstein, two-point discrimination, tuning forks [Video file]. Retrieved from https://www.youtube.com/watch?v=-VIVsLXAiDk
Washington University School of Medicine. (2010). Peripheral Nerve Surgery: A Resource for Surgeons. Retrieved from http://nervesurgery.wustl.edu/ev/sensation/Hand/Radial%20Nerve/Pages/default.aspx
Wayne State University Department of Health Care Sciences, (n.d.). Somatosensory Examination and Evaluation Study Guide: Two Point Discrimination. Retrieved from http://healthcaresciencesocw.wayne.edu/sensory/6_1.htm
Wilhelmi, B.J. (2013). Hand Anatomy. Retrieved from http://emedicine.medscape.com/article/1285060-overview#a6