Carpal Tunnel Syndrome: A Compressive Neuropathy

US Pharm. 2015;40(1):HS-23-HS-28.

Carpal tunnel syndrome (CTS) is a painful and progressive condition caused by compression of the median nerve, a key nerve in the wrist. The median nerve runs between the transverse carpal ligament and the carpal bones into the palm of the hand, and it can become pressed or squeezed at the wrist. This nerve controls sensations to the palm side of the thumb and fingers (not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move.¹

The carpal tunnel is a narrow, rigid passageway of ligament and bones at the base of the hand that houses the median nerve and tendons. At certain times, the tunnel narrows because of thickening from irritated tendons and causes the median nerve to be compressed. This results in pain, weakness, or numbness in the hand and wrist, radiating up to the arm. Carpal tunnel syndrome is one of the most common and widely known examples of neuropathy, a disease in which the body’s peripheral nerves are traumatized.¹

The incidence of CTS is on the rise, in particular among teenagers as a result of high-volume texting and other repetitive work. In this article, we will review the causes, symptoms, risks, diagnosis, and treatment of this fast-growing peripheral neuropathy.

In recent years, CTS has been found to be a leading cause of work-related disability, resulting in a median 27 days off work and a significant cost to employers. The medical cost of this condition in the United States has been estimated to exceed $2 billion per year. It is reported that about 3.7% of the general U.S. population suffered from CTS in 2003.²

SYMPTOMS

Symptoms start slowly, with frequent tingling, burning, itching, or numbness in the palm of the hand and the fingers. These are caused by interruption of conduction within the large myelinated nerve fibers. The effect is predominant in the thumb and the index and middle fingers. Many people with CTS say their fingers are useless and swollen, even though little or no swelling is apparent. Pain commonly occurs at night in one or both hands, leading to insomnia. A person with CTS may wake up feeling the need to shake the hands  or wrists. Shaking the hands diminishes symptoms.³

More severe symptoms include decreased grip strength and difficulty grasping small objects or performing other manual tasks. In untreated and chronic cases, the muscles at the base of the thumb may gradually become wasted. In certain cases, people have difficulty distinguishing between hot and cold by touch.^2,3

CAUSES

The pressure on the median nerve and the tendons in the carpal tunnel is often the result of a combination of factors, rather than a problem with the nerve itself. A major cause of CTS is that the carpal tunnel is simply smaller in some people than in others (a congenital predisposition).⁴

Other contributing factors include trauma or injury to the wrist that causes swelling; overactivity of the pituitary gland; hypothyroidism; rheumatoid arthritis; mechanical problems in the wrist joint; work stress; repeated use of vibrating hand tools; fluid retention during pregnancy or menopause; and the development of a cyst or tumor in the canal. People with certain types of jobs are likely to have CTS; e.g., assembly-line workers, grocery store cashiers, violinists, carpenters, golfers, knitters, and gardeners. Regardless of all the above, in some cases no cause can be identified.⁴

Although there are not enough clinical data to prove whether repetitive and forceful movements of the hand and wrist during work or other activities can cause CTS, certain disorders such as bursitis and tendinitis with repeated motions have been reported to cause this problem. Writer’s cramp, a dystonic disorder, may also cause wrist pain.

RISK FACTORS

CTS usually occurs only in adults. Women are three times more likely than men to develop CTS, perhaps because the carpal tunnel itself may be smaller in women than in men. The dominant hand is usually affected first and produces the most severe pain. Patients with diabetes or other metabolic disorders that increase the risk of neuropathy are more susceptible to compression.⁵

The risk of developing CTS is especially common among people who perform assembly-line work, such as manufacturing, sewing, finishing, and cleaning, as well meat, poultry, or fish packing. Interestingly, CTS is three times more common among assemblers than among data-entry personnel.⁵

DIAGNOSIS

As with all other disorders, early diagnosis and treatment of CTS are important to avoid permanent damage to the median nerve. At this stage, clinicians start with a physical examination of the person’s hands, arms, shoulders, and neck to determine if the patient’s complaints are related to daily activities or to an underlying disorder; this will help rule out other painful conditions that mimic CTS. First, the wrist is examined for tenderness, swelling, warmth, and discoloration; then each finger is tested for sensation, and the muscles at the base of the hand are examined for strength and signs of atrophy. Routine laboratory tests and x-rays can reveal diabetes, arthritis, and fractures.⁶

Clinicians use the tests shown in TABLE 1 to try to produce the symptoms of CTS.⁷

^​

TREATMENT

Treatments for CTS should begin as early as possible. Underlying causes such as diabetes or arthritis should be treated first.

Initial treatment of CTS includes splinting of the wrist at a neutral angle. The splint should be worn at night and also during the day based on the patient’s activities. Immobilizing the wrist in a splint avoids damage from twisting or bending.

Early treatment also involves resting the affected hand and wrist for at least 2 weeks and avoiding activities that may worsen symptoms. If there is inflammation, applying cool packs can help reduce swelling.

Nonsurgical Treatments

Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, and other nonprescription pain relievers may ease symptoms that have been present for a short time or have been caused by strenuous activity. Therefore, many clinicians initiate an NSAID to alleviate symptoms; however, these drugs do not provide relief for many patients. Improvement usually will not happen before 2 weeks and may be short-lived.⁸

Orally administered diuretics can decrease swelling based on the principle that an increase in fluid in the carpal tunnel leads to an increase in pressure, thereby causing symptoms. Diuretics are an option for initial treatment; however, studies show little, if any improvement.⁸

Corticosteroids can be taken by mouth or injected directly into the wrist with a local anesthetic such as lidocaine to relieve pressure on the median nerve and provide immediate, temporary relief to persons with mild or intermittent symptoms. Oral steroids have been found to be more effective than NSAIDs and other drugs, but they are not as effective as local steroid injection, which are far superior both in efficacy and duration. The initial response to steroid injection in CTS is about 70%. The number of steroid injections should be limited to no more than two to avoid injury to the tendons and median nerve.⁹

Alternative Therapies and Exercise: Acupuncture and chiropractic care have benefited some patients, but their effectiveness remains unproven due to the lack of comprehensive studies. An exception is yoga, which has been shown to reduce pain and improve grip strength among patients with CTS.

Stretching and strengthening exercises supervised by a physical therapist who is trained to use exercises to treat physical impairments can be helpful. Also, working with occupational therapists who are trained in evaluating people with physical impairments will build skills to improve the health and well-being of people who have CTS.

Topical safflower plant extract ointment (Zolacet) has been noted to exhibit anti-inflammatory and immunomodulating properties, which may make it beneficial in CTS. The plant has several flavonoids that may have analgesic effects. Patients who used the product four times a day on their wrist claimed relief of pain by the end of a 4-week period. Information on the product is limited, and the only side effect reported was a mild rash.¹⁰

Surgical Treatment

For most patients with continued CTS pain despite treatment with splinting, oral medications and steroid injection, surgery is the only option for relief. In the U.S., if symptoms last more than 6 months, surgery for release of pressure around the wrist and median nerve is recommended. Surgery is done under local anesthesia and is performed on an outpatient basis. Many patients require surgery on both hands. The following are types of carpal tunnel release surgery¹¹:

Open-Release Surgery: The traditional procedure used to correct CTS requires an incision up to 2 inches in the wrist and cutting of the carpal ligament (the tissue that holds the joints together) to enlarge the carpal tunnel.

Endoscopic Surgery: This procedure may allow faster functional recovery and less postoperative discomfort than traditional open-release surgery. The surgeon makes two incisions (about ½ inch each) in the wrist and palm, inserts a camera attached to a tube, observes the tissue on a screen, and cuts the carpal ligament. This two-portal endoscopic surgery, generally performed under local anesthesia, is effective and minimizes scarring and any scar tenderness. It is possible that the patient may not experience relief from the procedure if the original condition was misdiagnosed or if the surgery was conducted after the median nerve was permanently damaged.¹¹

Postsurgery Care: Although symptoms may be relieved immediately after surgery, full recovery from carpal tunnel surgery can take months. Some patients may have infection, nerve damage, stiffness, and pain at the scar. Occasionally, the wrist loses strength because the carpal ligament is cut. Patients should undergo physical therapy after surgery to restore wrist strength. Some patients may need to adjust job duties or even change jobs after recovery from surgery.¹²

Recurrence of CTS following treatment is rare. The majority of patients recover completely.

PREVENTION

To take precautionary measures at work, people can do on-the-job conditioning, take frequent rest breaks, wear splints to keep wrists straight, perform stretching exercises, and use correct posture and wrist position. Workstations, tools, and tasks can be redesigned to help one maintain a more natural position during work. Employers can help with ergonomics, improving workplace conditions and job demands based on the capabilities of workers. Regardless of all of these measures, research has not conclusively shown that such workplace changes prevent the occurrence of CTS.¹²

TARSAL TUNNEL SYNDROME

Anatomy similar to that of the wrist and hand exists in the ankle and foot. Tarsal means “ankle,” and when the sensory nerve that passes through the tarsal tunnel is irritated by pressure in the tunnel, numbness and tingling of the foot and toes can be felt. Although the condition is similar to CTS, it is far less common yet is treated similarly.

REFERENCES

1. Bland JD. Carpal tunnel syndrome. BMJ. 2007;335:343-346.
2. Kao SY. Carpal tunnel syndrome as an occupational disease. J Am Board Fam Pract. 2003;16:533-542.
3. American Academy of Orthopaedic Surgeons. Guideline on the treatment of carpal tunnel syndrome. www.aaos.org/Research/ guidelines/CTStreatmentguide. asp. Accessed October 12, 2014.
4. Page MJ, Massy-Westropp N, O’Connor D, et al. Splinting for carpal tunnel syndrome. Cochrane Database Syst Rev. 2012;(7):CD010003.
5. Armstrong T, Dale AM, Franzblau A, et al. Risk factors for carpal tunnel syndrome and median neuropathy in a working population. J Occup Environ Med. 2008;50:1355-1364.
6. Viera AJ. Management of carpal tunnel syndrome. Am Fam Phys. 2003;68:265-272.
7.Vasiiadis HS, Georgoulas P, Shrier I, et al. Endoscopic release for CTS. Cochrane Database Syst. Rev. 2014(1):CD008265.
8. Wong SM, Hui AC, Tang A, et al. Local vs systemic corticosteroids in the treatment of carpal tunnel syndrome. Neurology. 2001;56:1565-1567.
9. Lee JH, An JH, Lee SH, et al. Effectiveness of steroid injection in treating patients with moderate and severe degree of carpal tunnel syndrome measured by clinical and electrodiagnostic assessment. Clin J Pain. 2009;25:111-115.
10. Hanania M, Duarte R, Livingstone D, et al. Topical safflower plant extract  for chronic pain: a prospective, open-label study. Integr Med. 2005;4:16-20.
11. Jones, MC. Management of carpal tzunnel syndrome. US Pharm. 2010;35(1):30-32.
12. Web Med. Carpal tunnel syndrome surgery. www.webmd.com/pain-management/carpal-tunnel/open-carpal-tunnel-release-surgery.

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