eMedicine Specialties > Physical Medicine and Rehabilitation > Upper Limb Musculoskeletal Conditions

Carpal Tunnel Syndrome

Author: Nigel L Ashworth, MB, ChB, MSc, FRCPC, Professor and Chief, Division of Physical Medicine and Rehabilitation, Glenrose Rehabilitation Hospital, University of Alberta
Contributor Information and Disclosures

Updated: Dec 4, 2008

Introduction

Background

Carpal tunnel syndrome (CTS) is a collection of characteristic symptoms and signs that occurs following entrapment of the median nerve within the carpal tunnel. Usual symptoms include numbness, paresthesias, and pain in the median nerve distribution. These symptoms may or may not be accompanied by objective changes in sensation and strength of median-innervated structures in the hand.

Related eMedicine topics:
Carpal Tunnel Syndrome [Emergency Medicine]
Carpal Tunnel Syndrome [Orthopedic Surgery]
Carpal Tunnel Syndrome [Radiology]

Pathophysiology

Until the advent of electrophysiologic testing in the 1940s, carpal tunnel syndrome (CTS) commonly was thought to be the result of compression of the brachial plexus by cervical ribs and other structures in the anterior neck region. It is now known that the median nerve is damaged within the rigid confines of the carpal tunnel, initially undergoing demyelination followed by axonal degeneration. Sensory fibers often are affected first, followed by motor fibers. Autonomic nerve fibers carried in the median nerve also may be affected.

The cause of the damage is subject to some debate; however, it seems likely that abnormally high carpal tunnel pressures exist in patients with CTS. This pressure causes obstruction to venous outflow, back pressure, edema formation, and ultimately, ischemia in the nerve.

The risk of development of CTS appears to be associated, at least in part, with a number of different epidemiologic factors, including genetic, medical, social, vocational, avocational, and demographic.1 A complex interaction probably exists between some or all these factors, eventually leading to the development of CTS. Definite causative factors, however, are far from clear.

Frequency

United States

The incidence of carpal tunnel syndrome is 1-3 cases per 1000 subjects per year; prevalence is approximately 50 cases per 1000 subjects in the general population. Incidence may rise as high as 150 cases per 1000 subjects per year, with prevalence rates greater than 500 cases per 1000 subjects in certain high-risk groups.

International

A paucity of population-based studies of carpal tunnel syndrome (CTS) exists; however, the incidence and prevalence in developed countries seems similar to the United States (eg, incidence in the Netherlands is approximately 2.5 cases per 1000 subjects per year; prevalence in the United Kingdom is 70-160 cases per 1000 subjects).2,3,4 CTS is almost unheard of in some developing countries (eg, among nonwhite South Africans).

Mortality/Morbidity

Carpal tunnel syndrome is not fatal, but it can lead to complete, irreversible median nerve damage, with consequent severe loss of hand function, if left untreated.

Race

Whites are probably at highest risk of developing carpal tunnel syndrome (CTS). The syndrome appears to be very rare in some racial groups (eg, nonwhite South Africans).4 In North America, white US Navy personnel have CTS at a rate 2-3 times that of black personnel.5

Sex

The female-to-male ratio for carpal tunnel syndrome is 3-10:1.

Age

The peak age range for development of carpal tunnel syndrome (CTS) is 45-60 years. Only 10% of patients with CTS are younger than 31 years.

Clinical

History

The patient's history often is more important than the physical examination in making the diagnosis of carpal tunnel syndrome (CTS).

  • Numbness and tingling
    • Among the most common complaints, patients will reveal that their hands fall asleep or that things slip from their fingers without their noticing (loss of grip, dropping things); numbness and tingling also are commonly described.
    • Symptoms are usually intermittent and are associated with certain activities (eg, driving, reading the newspaper, crocheting, painting). Nighttime symptoms that wake the individual are more specific to CTS, especially if the patient relieves symptoms by shaking the hand/wrist. Bilateral CTS is common, although the dominant hand is usually affected first and more severely than the other hand.
    • Complaints should be localized to the palmar aspect of the first to the fourth fingers and the distal palm (ie, the sensory distribution of the median nerve at the wrist). Numbness existing predominantly in the fifth finger or extending to the thenar eminence or dorsum of the hand should suggest other diagnoses. A surprising number of CTS patients are unable to localize their symptoms further (eg, whole hand/arm feeling dead). This generalized numbness may indicate autonomic fiber involvement and does not exclude CTS from the diagnosis.
  • Pain
    • The sensory symptoms above commonly are accompanied by an aching sensation over the ventral aspect of the wrist. This pain can radiate distally to the palm and fingers or, more commonly, extend proximally along the ventral forearm.
    • Pain in the epicondylar region of the elbow, upper arm, shoulder, or neck is more likely to be due to other musculoskeletal diagnoses (eg, epicondylitis) with which CTS commonly is associated. This more proximal pain also should prompt a careful search for other neurologic diagnoses (eg, cervical radiculopathy).
  • Autonomic symptoms
    • Not infrequently, patients report symptoms in the whole hand. Many patients with CTS also complain of a tight or swollen feeling in the hands and/or temperature changes (eg, hands being cold/hot all the time).
    • Many patients also report sensitivity to changes in temperature (particularly cold) and a difference in skin color. In rare cases, there are complaints of changes in sweating. In all likelihood, these symptoms are due to autonomic nerve fiber involvement (the median nerve carries most autonomic fibers to the whole hand).
  • Weakness/clumsiness - Loss of power in the hand (particularly for precision grips involving the thumb) does occur; in practice, however, loss of sensory feedback and pain is often a more important cause of weakness and clumsiness than is loss of motor power per se.

Physical

Clinical examination is important to rule out other neurologic and musculoskeletal diagnoses; however, the examination often contributes little to the confirmation of the diagnosis of carpal tunnel syndrome (CTS).

  • Sensory examination
    • Abnormalities in sensory modalities may be present on the palmar aspect of the first 3 digits and radial one half of the fourth digit. Semmes-Weinstein monofilament testing or 2-point discrimination may be more sensitive in picking this up; however, in the author's experience, pinprick sensation is as good as any test.
    • Sensory examination is most useful in confirming that areas outside the distal median nerve territory are normal (eg, thenar eminence, hypothenar eminence, dorsum of first web space).
  • Motor examination - Wasting and weakness of the median-innervated hand muscles (LOAF muscles) may be detectable.
    • L - First and second lumbricals
    • O - Opponens pollicis
    • A - Abductor pollicis brevis
    • F - Flexor pollicis brevis
  • Special tests - No good clinical test exists to support the diagnosis of CTS.
    • Hoffmann-Tinel sign
      • Gentle tapping over the median nerve in the carpal tunnel region elicits tingling in the nerve's distribution.
      • This sign still is commonly looked for, despite the low sensitivity and specificity.
    • Phalen sign
      • Tingling in the median nerve distribution is induced by full flexion (or full extension for reverse Phalen) of the wrists for up to 60 seconds
      • This test has 80% specificity but lower sensitivity.
    • The carpal compression test6
      • This test involves applying firm pressure directly over the carpal tunnel, usually with the thumbs, for up to 30 seconds to reproduce symptoms.
      • Reports indicate that this test has a sensitivity of up to 89% and a specificity of 96%.
    • Palpatory diagnosis
      • This test involves examining the soft tissues directly overlying the median nerve at the wrist for mechanical restriction.
      • This palpatory test has been noted to have a sensitivity of over 90% and a specificity of 75% or greater.
    • The square wrist sign
      • The ratio of the wrist thickness to the wrist width is greater than 0.7.
      • This test has a modest sensitivity/specificity of 70%.
  • Several other tests have been advocated, but they rarely provide additional information beyond that which the Phalen and square wrist signs provide.

Causes

Note that carpal tunnel syndrome (CTS) is associated with many different factors.7 In particular, the more the hand and wrist are used, the greater the symptoms. This observation does not necessarily mean that using the hand and wrist causes the syndrome or that more median nerve damage ensues. Association should not be assumed to signify causation.

  • Demographics
    • Increasing age
    • Female sex
    • Increased body mass index (BMI), especially a recent increase
    • Square-shaped wrist
    • Short stature
    • Dominant hand
    • Race (white)
  • Genetics
    • A strong family susceptibility exists and is probably related to multiple inherited characteristics (eg, square wrist, thickened transverse ligament, stature).
    • A number of inherited medical conditions also are associated with CTS (eg, diabetes, thyroid disease, hereditary neuropathy with liability to pressure palsies).
  • Medical conditions
    • Wrist fracture (Colles)
    • Acute, severe flexion/extension injury of wrist
    • Space-occupying lesions within the carpal tunnel (eg, flexor tenosynovitis, ganglions, hemorrhage, aneurysms, anomalous muscles, various tumors, edema)
    • Diabetes
    • Thyroid disorders (usually myxedema)
    • Rheumatoid arthritis and other inflammatory arthritides of the wrist
    • Recent menopause (including post-oophorectomy)1
    • Renal dialysis
    • Acromegaly
    • Amyloidosis
  • Vocational/avocational7,8,9 - Activities that may be associated with CTS (particularly in combination) involve the following:
    • Prolonged, severe force through the wrist
    • Prolonged, extreme posture of the wrist
    • High amounts of repetitive movements
    • Exposure to vibration and/or cold
  • Other factors
    • Lack of aerobic exercise
    • Pregnancy and breastfeeding
    • Use of wheelchairs and/or walking aids

More on Carpal Tunnel Syndrome

Overview: Carpal Tunnel Syndrome
Differential Diagnoses & Workup: Carpal Tunnel Syndrome
Treatment & Medication: Carpal Tunnel Syndrome
Follow-up: Carpal Tunnel Syndrome
Multimedia: Carpal Tunnel Syndrome
References
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References

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Further Reading

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Keywords

carpal tunnel syndrome, carpal tunnel, carpal tunnel treatment, carpal tunnel symptoms, carpal syndrome, carpal tunnel surgery, carpal tunnel syndrome treatment, carpal wrist, wrist braces, carpal tunnel wrist brace, symptoms of carpal tunnel, CTS, median neuropathy at the wrist, median nerve entrapment at the wrist, cumulative trauma disorder, repetitive strain injury

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Contributor Information and Disclosures

Author

Nigel L Ashworth, MB, ChB, MSc, FRCPC, Professor and Chief, Division of Physical Medicine and Rehabilitation, Glenrose Rehabilitation Hospital, University of Alberta
Nigel L Ashworth, MB, ChB, MSc, FRCPC is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, Association of Academic Physiatrists, Australian & New Zealand Association of Neurologists, British Medical Association, Canadian Association of Physical Medicine and Rehabilitation, Canadian Medical Association, Canadian Society of Clinical Neurophysiologists, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.

Medical Editor

Benjamin M Sucher, DO, FAAPMR, FAOCPMR, Medical Director, EMG Center of Arizona and Electrodiagnostic Medical Group
Benjamin M Sucher, DO, FAAPMR, FAOCPMR is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, American Osteopathic Association, and American Osteopathic College of Physical Medicine and Rehabilitation
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Patrick M Foye, MD, FAAPMR, FAAEM, Associate Professor of Physical Medicine and Rehabilitation, Co-Director of Musculoskeletal Fellowship, Co-Director of Back Pain Clinic, Director of Coccyx Pain (Tailbone Pain, Coccydynia) Service, University of Medicine and Dentistry of New Jersey, New Jersey Medical School
Patrick M Foye, MD, FAAPMR, FAAEM is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, Association of Academic Physiatrists, and International Spine Intervention Society
Disclosure: Nothing to disclose.

CME Editor

Kelly L Allen, MD, Regional Medical Director, IMX-Medical Management Services
Disclosure: Nothing to disclose.

Chief Editor

Robert H Meier III, MD, Director, Amputee Services of America; Active Medical Staff, Presbyterian/St Luke's Hospital, Spalding Rehabilitation Hospital, Select Specialty Hospital; Consulting Staff, Kindred Hospital
Robert H Meier III, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation and Association of Academic Physiatrists
Disclosure: Nothing to disclose.

 
 
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