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Carpal Tunnel Syndrome

(Also known as Median Nerve Entrapment at the Wrist)

MPC 00662

ICD-9 354.0

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Definition

Carpal Tunnel Syndrome (CTS) is an entrapment neuropathy of the median nerve at the wrist which produces paresthesia and weakness of the muscles of the hand.

General terms such as "cumulative trauma disorder" and "repetitive strain injury of the wrist" need to be avoided. Further, "wrist tendinitis" is a separate and distinct entity.

Where a neuropathy such as CTS is part of the symptomatology of another disease entity, it is included in the assessment of that disease entity.

Please note: Entitlement should be granted for a chronic condition only. For VAC purposes, "chronic" means that the condition has existed for at least 6 months. Signs and symptoms are generally expected to persist despite medical attention, although they may wax and wane over the 6 month period and thereafter.

Diagnostic Standard

Diagnosis by a qualified medical practitioner is required. It is to include positive findings on nerve conduction (EMG) testing, which is generally regarded as the standard test for diagnosis of CTS, and evidence of relevant symptoms of CTS.

Care should be taken to ensure an accurate diagnosis is made. The diagnostic positive finding for CTS is decreased median nerve conduction at the wrist. This finding may be demonstrated in individuals who are asymptomatic.

Clinical examination should rule out the possibility of alternate diagnoses such as cervical radiculopathy, peripheral neuropathy, and hand/arm vibration syndrome.

Evidence of duration of a disability existing for at least 6 months should be provided.

Anatomy and Physiology

CTS is caused by pressure on the median nerve where it passes in company with the flexor tendons of the fingers through the tunnel formed by carpal bones and the transverse carpal ligament at the wrist.

The classically described physical tests for CTS include:

  1. Phelan's test, in which paresthesia is reproduced after 60 seconds of wrist flexion, and
  2. Tinel's sign in which paresthesia/electrical sensations occur in the affected fingers after tapping over the carpal tunnel at the wrist.

CTS is classified as follows:

  1. intrinsic, i.e. secondary to another underlying disease or condition
  2. use-related, e.g. from manual work, sports, hobbies
  3. injury-related

Clinical Features

The first symptoms of CTS include paresthesia in the distribution of the median nerve of the hand affecting one or more of the thumb, index finger, third (middle) finger and the radial side of the fourth (ring) finger. Symptoms may also include hand weakness and pain.

The presence of thenar muscle atrophy is often indicative of advanced CTS.

Conservative treatment is generally used for less severe cases, and surgery is reserved for serious and prolonged cases. The success rate of surgery is high in the absence of aggravating factors; however, surgical intervention in individuals who return to occupations involving repetitive movement, assembly line work, typing or the use of vibration tools is associated with a higher risk of failure.

Pension Considerations

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  1. Causes And / Or Aggravation

    The timelines cited below are not binding. Each case should be adjudicated on the evidence provided and its own merits.

    1. Overuse prior to clinical onset or aggravation

      For overuse to cause or aggravate CTS, the following should be evident*:

      • The overuse activity should be performed for the specified number of hours per day; and
      • The overuse activity should be performed for at least 60 days out of 120 consecutive days; and
      • Signs/symptoms should begin during the overuse activity or within 30 days after the overuse activity ceases; and
      • Signs/symptoms should be ongoing or recurrent for at least 6 months to be considered chronic for pension purposes.

      * The definitions and criteria apply to a normal joint. The total time per day or total number of days required to qualify as overuse may be less when the joint is abnormal or where other pertinent circumstances exist. To illustrate:

      1. A combination of relevant factors (where only 1 factor is required for overuse) may reduce the total time per day required to qualify as overuse, e.g. activity involving both high repetition and extreme posture as defined may require performance of the overuse activity less than 2 hours per day, OR activity involving extreme posture as defined and a level of high repetition which is in excess of the definition (e.g. 10 times per minute) may require performance of the overuse activity less than 2 hours per day.
      2. A combination of one or more relevant factors performed to excess for more than 2 hours per day may reduce the total number of days required to qualify as overuse, e.g. activity of high repetition in the order of 10 times per minute performed 4 hours per day may require performance of the overuse activity for less than 60 out of 120 consecutive days.

      Overuse means high repetition and/or extreme posture and/or high force and/or vibration in the soft tissues around the wrist joint prior to clinical onset or aggravation.

      High repetition means actions performed more than 2 to 4 times a minute, or cycles less than 30 seconds for a substantial part of the day.

      Extreme posture of the wrist is a flexion/extension angle greater than 45 degrees, and ulnar deviation greater than 20 degrees for a substantial part of the day. (A neutral flexion/extension angle is 0 to 25 degrees, and a non-neutral angle is 25 to 45 degrees. A neutral ulnar deviation is less than 10 degrees, and a non-neutral deviation is 10 to 20 degrees).

      Holding an object in grip or pinch position with extreme posture is an exception to "extreme posture of the wrist", and requires that the position be held for most of the day.

      High force means hand weights of more than 3 kg. for a substantial part of the day.

      Vibration means direct vibration of the affected hand or forearm for a substantial part of the day.

      Substantial part of the day means for a total of 2 hours or more per working day.

      Most of the day means for a total of 4 hours or more per working day.

      Determination of a service-relationship for an overuse syndrome will generally depend on whether the overuse factors can be seen to have arisen out of or to be directly connected with the performance of military duties.

      Repetitive activities which have been implicated in the development of CTS include those which involve repetitive and forceful gripping, those which involve low force wrist movements with fine finger movements, and those which involve repeated use of the palm of the hand. Examples of such activities are as follows:

      • Squash
      • Golf
      • Data entry and typing
      • Permanent use of a manual wheelchair - this excludes temporary use of a manual wheelchair such as when recovering from an ankle sprain, or when the manual wheelchair is pushed primarily by a person other than the person affected by the permanent medical condition.

      Occupations involving repetitive work that are closely associated with CTS include:

      • Radio Operator
      • Teletype Operator
      • Postal Clerk
      • Data Entry Clerk

      In repetitive activities, the initial manifestation is aching of the affected part which occurs at work and disappears at rest. In the early stages there is no interference with work. Continued exposure without treatment results in recurrent pain occurring throughout the work day and persisting after ceasing work. The condition may take weeks or months to resolve even with treatment and cessation of work. The chronic stage brings pain at work and at rest, aggravated even by non-repetitive movements.

      Examples of occupations involving vibration include Aviation Technician, Aero Engine Technician and Airframe Technician, all of which may involve pneumatic drilling.

    2. Suffering an injury to the affected wrist, other than a wrist fracture, prior to clinical onset or aggravation

      The injury would alter the normal contour of the carpal tunnel, or damage the median nerve or flexor tendons within the carpal tunnel, or damage the forearm muscles forming the flexor tendons within the carpal tunnel.

      For the injury to cause or aggravate CTS, the symptoms of CTS must commence within several months of the injury.

    3. Suffering a fracture to the affected wrist prior to clinical onset or aggravation

      The injury would alter the normal contour of the carpal tunnel, or damage the median nerve or flexor tendons within the carpal tunnel.

      For the wrist fracture to cause or aggravate CTS, the symptoms must commence within several months of the fracture.

    4. Surgery to the affected wrist prior to clinical onset or aggravation

      The surgery would alter the normal contour of the carpal tunnel, or damage the median nerve or flexor tendons within the carpal tunnel.

      For the surgery to cause or aggravate CTS, symptoms must commence within several months of the surgery.

    5. Obesity prior to clinical onset or aggravation

      For obesity to cause or aggravate CTS, it must result in a significant weight gain (of the order of a 20% increase in baseline weight) and occur in association with a body mass index (BMI) of 30 or greater.

    6. Hemodialysis (renal dialysis) treatment prior to clinical onset or aggravation

      For hemodialysis treatment to cause or aggravate CTS, it must take place for a period of at least 1 year immediately before clinical onset or aggravation of CTS.

      Amyloid deposits (insoluble fibrillar proteins) have been found in the carpal tunnel tissues in more than 70% of dialysis patients operated on for CTS.

      Arterial venous shunts commonly used for dialysis can result in a vascular steal syndrome at the wrist, increasing the risk of CTS or its aggravation.

      There is no direct evidence that peritoneal dialysis promotes CTS.

    7. Double crush syndrome prior to clinical onset or aggravation

      "Double crush syndrome" is the occurrence of an injury to a nerve that is previously diseased or injured.

      When the nerve is previously diseased from another cause, such as nerve fiber compression more proximally (at the cervical spine, thoracic outlet, or elbow), less pressure is required at the wrist to produce or aggravate CTS.

    8. Myxedema at time of clinical onset or aggravation

      Myxedema is a condition characterized by dry, waxy swelling of the skin and other tissues and associated with primary hypothyroidism.

    9. Acromegaly prior to clinical onset or aggravation

      Acromegaly is a chronic disease of adults due to hyper-secretion of the pituitary growth hormone and characterized by enlargement of many parts of the skeleton, especially the distal portions of the nose, ears, jaws, fingers and toes.

    10. Amyloidosis prior to clinical onset or aggravation

      Amyloidosis is a group of conditions of diverse causes characterized by the accumulation of amyloid in various organs and tissues of the body such that vital function is compromised.

    11. Rheumatoid Arthritis of the wrist prior to clinical onset or aggravation
    12. Gout of the affected wrist prior to clinical onset or aggravation

    13. A space occupying lesion of the carpal tunnel prior to clinical onset or aggravation

      "Space occupying lesion" of the affected carpal tunnel is a lesion which is situated within the carpal tunnel, such as:

      • hemangioma
      • neuroma of the median nerve
      • aneurysm of the median artery
      • calcification
      • synovial sarcoma
      • tendon sheath fibroma
      • lipoma and ganglion

    14. Peripheral neuropathy prior to clinical onset or aggravation

      "Peripheral neuropathy" is a neuropathy associated with Diabetes Mellitus and alcohol-abuse disorders.

      For Diabetes Mellitus to cause or aggravate CTS, it must have existed for approximately 5 years immediately before the clinical onset or aggravation of CTS.

      There is epidemiological evidence that long-standing Diabetes Mellitus increases the risk of suffering CTS, and that the risk of developing the syndrome increases with the duration of the diabetes.

    15. Pregnancy prior to clinical onset or aggravation

      While pregnancy may cause or aggravate CTS, CTS caused solely from a pregnancy is generally considered reversible within a few months of the completion of the pregnancy.

    16. Hyperthyroidism or treated hyperthyroidism at time of clinical onset or prior to aggravation.
    17. Inability to obtain appropriate clinical management

  2. Medical Conditions Which Are To Be Included In Entitlement / Assessment

  3. Common Medical Conditions Which May Result In Whole Or In Part From Carpal Tunnel Syndrome and/its Treatment

References for Carpal Tunnel Syndrome

  1. Australia. Department of Veterans Affairs: medical research in relation to the Statement of Principles concerning Carpal Tunnel Syndrome, which cites the following as references:
    1. Al Qattan MM, Manktelow RT and Bowen CVA (1994) Pregnancy-induced carpal tunnel syndrome requiring surgical release longer than 2 years after delivery. Obstetrics and Gynecology. August Vol 84 No 2 pp 249-251.
    2. Bardin T, Kuntz D, Zingraff J, Voisin M-C, Zelmar A and Lansaman J (1985) Synovial Amyloidosis in patients undergoing long-term hemodialysis. Arthritis and Rheumatism. September Vol 28 No 9 p 1057.
    3. Barnhart S, Demers PA, Miller M, Longstreth WT and Rosenstock L (1991) Carpal tunnel syndrome among ski manufacturing workers. Scandinavian Journal of Work and Environmental Health. Vol 17 pp 46-52.
    4. Carroll LL, Tzamaloukas AH, Scremin AE and Eisenberg B (1993) Hand dysfunction in patients on chronic hemodialysis. The International Journal of Artificial Organs. Vol 16 No 10 p 698.
    5. Chammas M, Bousquet P, Ranard E, Poirier J-L, Jaffiol C and Allieu Y (1995) Dupuytren's disease, carpal tunnel syndrome, trigger finger and diabetes mellitus. The Journal of Hand Surgery. Jan Vol 20A No 1 p113.
    6. Cullum DE and Molloy CJ. (1994) Occupation and the carpal tunnel syndrome. The Medical Journal of Australia. November Vol 161 p 553.
    7. de Krom MCTFM, Knipschild PG, Dester ADM, Thijs CT, Boekkooi PF and Spaan F (1992) Carpal tunnel syndrome: Prevalence in the general population. Journal of Clinical Epidemiology. Vol 45 No 4 p 373.
    8. de Krom MCTFM, Kester ADM, Knipschild PG and Spaans F (1990) Risk factors for carpal tunnel syndrome. American Journal of Epidemiology. Vol 132 No 6 p1104-1105.
    9. Dieck GS and Kelsy JL (1985) An epidemiologic study of the carpal tunnel syndrome in an adult female population. Preventive Medicine. Vol 14 pp 67-8.
    10. Florack TM, Miller RJ, Pellegrini VD, Burton RI and Dunn MG (1992) The prevalence of carpal tunnel syndrome in patients with basal joint arthritis of the thumb. The Journal of Hand Surgery. July Vol 17A No 4 p 626.
    11. Franklin GM, Haug J, Heyer N, Checkoway H and Peck N. (1991) Occupational carpal tunnel syndrome in Washington State 1984-1988. American Journal of Public Health. June Vol 81 No 6 pp 741-746.
    12. Gamstedt A, Holm-Glad J, Ohlson C-G and Sundstrom M (1993) Hand abnormalities are strongly associated with the duration of diabetes mellitus. Journal of Internal Medicine. Vol 234 p 192.
    13. Hagberg M, Nystrom A and Zetterlund B (1991) Recovery from symptoms after carpal tunnel syndrome surgery in males in relation to vibration exposure. The Journal of Hand Surgery. Jan Vol 16A No 1 p 70.
    14. Hagberg M, Morgenstern H and Kelsh M (1992) Impact of occupations and job tasks on the prevalence of carpal tunnel syndrome. Scandinavian Journal of Work Environment and Health. Vol 18 p 344.
    15. Gilliland BC (1994) Relapsing Polychondritis and Miscellaneous Arthritides. Harrison's Principles of Internal Medicine. 13th Edition. Isselbacher KJ, Braunwald E, Wilson JD, Martin JB, Fauci AS & Kasper DL (Eds) McGraw-Hill New York Chapter 299 p 1707.
    16. Katz JN, Larson MG, Fossel AH and Liang MH (1991) Validation of a surveillance case definition of Carpal Tunnel Syndrome. American Journal of Public Health. Vol 81 No 2 p 191.
    17. McCarty DJ (1985) Arthritis and Allied conditions: A Textbook of Rheumatology 10th Edition. Lea and Febiger Philadelphia (First Pub. 1940).
    18. Miyasaka N, Sato K, Kitano Y, Higaki M, Nishioka K and Ohta K (1992) Aberrant cytokine production from tenosynovium in dialysis associated amyloidosis. Annals of the Rheumatic Diseases. Vol 51 p 797-800.
    19. Nathan PA, Keniston RC, Myers LD and Meadows KD (1992) Obesity as a risk factor for slowing of sensory conduction of the median nerve in industry: a cross-sectional and longitudinal study involving 429 workers. Journal of Medicine. April Vol 34 No 4 p 381.
    20. Phalen GS (1966) Seventeen years' experience in diagnosis and treatment of six hundred fifty-four hands. The Journal of Bone and Joint Surgery. March Vol 48-a No 2 p 219.
    21. Radecki P (1994) The familial occurrence of carpal tunnel syndrome. Muscle and Nerve. March Vol 17 p 329.
    22. Roquer J and Cano JF (1993) Carpal tunnel syndrome and hyuperthyroidism. Acta Neurological Scandinavia. Vol 88 pp 149-152.
    23. Schwarz A, Keller F, Seyfert S, Poll W, Molzahn M and Distler A (1984) Carpal tunnel syndrome: a major complication in long-term hemodialysis patients. Clinical Nephrology. Vol 22 No 3 p 135.
    24. Sivri A, Celiker R, Sungur C and Gokce Kutsal V (1994) Carpal tunnel syndrome: A major complication in hemodialysis patients. Scandinavian Journal of Rheumatology. Vol 23 p 289.
    25. Stock SR (1991) Workplace ergonomic factors and the development of musculoskeletal disorders of the neck and upper limbs: A meta-analysis. American Journal of Industrial Medicine. Vol 19 p 88.
    26. Strasberg SR, Novak CB, Mckinnon SE and Murray JF (1994) Subjective and employment outcome following secondary carpal tunnel surgery. Annals of Plastic Surgery. May Vol 32 No 5 p 488.
    27. Takasu S, Takatsu S, Kunitomo K and Kokumai Y (1994) Serum Hyaluronic Acid and Interleukin-6 as possible markers of carpal tunnel syndrome in chronic hemodialysis patients. Artificial Organs. Vol 18 No 6 p 421.
    28. Tanaka S, Wild DK, Seligman PJ, Halperin WE, Behrens VJ and Putz-Anderson V (1995) Prevalence and work-relatedness of self-reported carpal tunnel syndrome among US workers: Analysis of the Occupational Health Supplement data of 1988 National Health Interview Survey. American Journal of Industrial Medicine. April Vol 27 No 4 p 466.
    29. Vessey MP, Villard-Mackintosh L and Yeates D (1990) Epidemiology of carpal tunnel syndrome in women of childbearing age. Findings in a large cohort study. International Journal of Epidemiology. Vol 19 No 3 pp 655-659.
    30. Werner RA, Albers JW, Franzblau A and Armstrong TJ (1994) The relationship between body mass index and the diagnosis of carpal tunnel syndrome. Muscle and Nerve. June Vol 17 p 636.
  2. Bernard, Bruce P., ed. Musculoskeletal Disorders (MSDs) and Workplace Factors. A Critical Review of Epidemiologic Evidence for Work-Related Musculoskeletal disorders of the Neck, Upper Extremity, and Low Back. NIOSH. Retrieved on Sept 5, 2001
  3. Canada. Department of Veterans Affairs. Medical Guidelines on Peripheral Neuropathies.
  4. Dee, Roger, et al. Principles of Orthopaedic Practice. 2nd ed. Montreal: McGraw-Hill, 1997.
  5. Fauci, Anthony S. and Eugene Braunwald, et al, eds. Harrison's Principles of Internal Medicine. 14th ed. Montreal: McGraw-Hill, 1998.
  6. Goldman, L., ed. Cecil Textbook of Medicine. 21st ed. New York: W.B. Saunders, 2000.
  7. Mahoney, James. 1995. Cumulative Trauma Disorders and Carpal Tunnel Syndrome: Sorting out the Confusion. Can J Plast Surg 3(4):185 - 189.
  8. Rosenstock, Linda and Mark R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Toronto: W.B. Saunders, 1994.
  9. Ruddy, Shaun, et al, eds. Kelley's Textbook of Rheumatology. 6th ed. Toronto: W.B. Saunders, 2001.
  10. Sluiter, J.K., K.M. Rest, et al. 2001. Criteria document for evaluating the work-relatedness of upper-extremity musculoskeletal disorders. Scandinavian Journal of Work, Environment and Health. Vol 27, supp 1.
  11. Weinstein, Stuart L. and Joseph A. Buckwalter. Turek's Orthopaedics Principles and Their Application. 5th ed. Philadelphia: J.B. Lippincott, 1994.
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