Carpal Tunnel Surgery


Anatomy of the Carpal Tunnel

The Carpal Tunnel

Figure #1 – Anatomy of the Carpal Tunnel

The median nerve is an extension of the complex neural network in the arm beginning in the armpit, This network is called the brachial plexus. The nerves extend from the brachial plexus into the arm, and several of these nerves come together in the forearm to form the median nerve. The median nerve then runs through the forearm into the wrist where it passes through the Carpal Tunnel. The carpal tunnel is a narrow passageway measuring about an inch in width. The floor and sides of the tunnel are formed by small bones called carpal bones, and the roof of the tunnel is created by a strong ligament called the transverse carpal ligament. Ten structures including the median nerve and the flexor tendons of the hand all pass through this small canal. Because the boundaries of the carpal tunnel are rigid, there is minimal ability for the tunnel to “stretch” or increase in size if necessary.

The Median Nerve

Figure #2 – Anatomy of the Median Nerve

The median nerve exits from the carpal tunnel and travels into the hand. It provides feeling to the front (palmar) side of the thumb, index finger, and middle fingers, as well as the half of the ring finger that is adjacent to the middle finger. The median nerve provides some additional feeling to the back (dorsal) side of the fingertips as well. In addition to sensation, the median nerve provides motor control for some of the small thumb muscles called thenar muscles. For a video review of the thenar muscles visit https://www.youtube.com/watch?v=asim2dTD8aI

What is Carpal Tunnel Syndrome?

There are many different syndromes that develop when nerves in the body become entrapped within a tunnel or similar structure, and these are referred to as entrapment syndromes. Carpal tunnel syndrome is the most common and widely known entrapment syndrome.

Any time the space within the carpal tunnel is reduced, the pressure on the contents inside of the tunnel increases. If this pressure is significant enough, it will begin to affect the median nerve within the canal and cause it to begin to function improperly. When this happens, Carpal tunnel syndrome (CTS) exists.

Compression of the median nerve within the carpal tunnel may result in numbness, weakness, pain in the hand and wrist, and sometimes weakness of the hand.

Statistics of Carpal Tunnel Syndrome

According to the Journal of the American Medical Association (https://jamanetwork.com/journals/jama), the prevalence of carpal tunnel syndrome in the general adult population ranges from 2.7% to 5.8%. (reference 1&2)

According to the Journal of Neurology, Neurosurgery, and Psychiatry (reference 3) (https://jnnp.bmj.com/), in over 50% of patients with CTS, symptoms are reported to be present in both hands

What are the Symptoms of Carpal Tunnel Syndrome?

Usually, the symptoms of carpal tunnel syndrome begin subtly and progress slowly over a period of time. The dominant hand is usually the first hand affected. The first symptoms typically appear in one or both hands while sleeping. It is common for people to sleep with flexed wrists, even though they may not be aware they are doing so. The initial symptoms usually begin with a feeling that they need to “shake out” the hands or wrists.

As CTS progresses, a tingling in the affected hand may be felt during the day. The tingling occurs in the areas of the median nerve illustrated in figure 2. When the motor function of the median nerve becomes affected, decreased functioning of the thenar muscles in the thumb may occur. Decreased functioning of the thumb muscles typically leads to a reduction in grip strength making it difficult to make a fist, hold small objects, and/or perform daily tasks. If this continues to go untreated, the muscles at the base of the thumb (thenar muscles) can begin to decrease in size, a condition referred to as thenar atrophy.

Classic Symptoms of CTS:

  • Numbness, tingling, burning, and pain in the sensory locations of the median nerve (figure 2)
  • Shock-like sensations within the distribution of the median nerve
  • Pain or tingling sensations traveling up the forearm and upper arm to the shoulder
  • Weakness and clumsiness of the affected hand resulting in difficulty performing fine movements such as buttoning clothes.
  • Dropping things as a result of altered muscle function

How Did I Get Carpal Tunnel Syndrome?

Carpal tunnel syndrome is the result of any action or event that compresses the median nerve within the carpal tunnel. There are many factors that may cause swelling or reduced space within the carpal tunnel. Common contributing factors include:

  • Trauma such as a sprain or fracture
  • Hyperpituitarism (overactive pituitary gland)
  • Hypothyroidism (underactive thyroid gland)
  • Rheumatoid arthritis or other types of arthritis
  • Work stress from repeated activities like typing
  • Repeated use of vibrating hand tools
  • Fluid retention during pregnancy or menopause
  • Cysts or tumors in the tunnel

Who is at Risk of Developing Carpal Tunnel Syndrome?

Women are actually three times more likely to develop carpal tunnel syndrome than men are. The reasons for this disparity are not completely clear, but some experts point to the fact that the carpal tunnel itself is smaller in females than it is in men. Individuals with systemic diseases that affect the nervous system such as diabetes may have nerves that are more susceptible to pressure. Carpal tunnel syndrome rarely occurs in children; it is almost always found in adults.

Carpal tunnel syndrome may develop as a result of many different types of repetitive workplace related tasks. The more common professions associated with carpal tunnel syndrome are:

  • Assembly line work
  • Paving services (use of a jack hammer)
  • Sewing or knitting
  • Surgeons
  • Bakers
  • Cashiers
  • Hair Stylists
  • Musicians

How is Carpal Tunnel Syndrome Diagnosed?

The earlier the diagnosis is made, the higher the rate of success for the treatment. If CTS is ignored, it may lead to permanent damage of the medial nerve.

History

A thorough review of the patient’s medical history and history of the symptoms must be performed in order to make sure that there are no other issues causing the symptoms. Pain and numbness of the hands can sometimes be radiating from the arms, shoulders, or neck. It is important to determine whether any of these other areas are a source of the hand or wrist pain. Additionally, there may be issues within the hand itself that are not related to the carpal tunnel. A complete history of the symptoms will help to locate the source of pain, and a history of daily and work activities may identify a cause.

Evaluation

Physical Exam

The wrist is examined for tenderness, swelling, masses, and warmth.  Each finger is tested for sensation on all surfaces. The thenar muscles at the base of the hand are also examined for strength and signs of atrophy.

Clinical Tests

Specific clinical tests that induce pressure within the carpal tunnel may reproduce the symptoms of CTS.

Tinel’s Test- The doctor taps on the median nerve in the person’s wrist.  The test is positive when tingling occurs in the affected fingers.

Figure #3 – Tinel’s Sign

Phalen’s maneuver (or the Wrist-flexion Test) – involves the person pressing the backs of the hands and fingers together with their wrists flexed as far as possible.  This test is positive if tingling or numbness occur in the affected fingers within 1-2 minutes.

Figure #4 – Phalen’s Maneuver

Electrodiagnostic Testing

Nerve conduction velocity studies (NCV study) – can measure the electrical conduction of the median nerve. To perform an NCV study, several electrodes are attached to the skin on the affected arm, a shock-emitting electrode is placed directly over the median nerve, and a recording electrode is placed over the thenar muscles of the thumb. Several quick electrical pulses are transmitted to the nerve, and the time it takes for the muscle to contract in response to the pulses is recorded. This speed is referred to as the conduction velocity of the nerve. The median nerve on the opposite arm may be studied for comparison. A slow conduction velocity could indicate a compression of the median nerve within the carpal tunnel.

Electromyogram (EMG) – examines the electrical activity generated by the contraction of a particular muscle. It is performed by inserting small needles into the muscles being tested and recording the electrical activity produced by the contraction of the muscle. The electrical activity in the muscle is first recorded while at rest. It is then recorded while the muscle is contracted slowly and steadily. The electrode may be relocated and the test repeated to record the activity in different areas of the muscle.

If both tests are being performed, nerve conduction studies are done before an EMG. The tests may take anywhere from 15 minutes to an hour or more.

Radiology and Imaging

X-rays – may be performed to rule out fractures, arthritis, and any other potential causes.

Ultrasound – can evaluate certain characteristics of the median nerve which may be indicative of CTS. Swelling of the nerve, as well as flattening or notching of the nerve, can indicate CTS.

MRI’s – can give doctors a look at the soft tissues in the area. It may be ordered when looking for other causes for the symptoms or to look for abnormal tissues that could be compressing the median nerve. An MRI may also help to determine if there are issues with the nerve itself, such as scarring from a previous injury.

How is Carpal Tunnel Syndrome Treated?

Once carpal tunnel syndrome is diagnosed and alternatives causes for the pain and discomfort have been ruled out, treatment should begin as soon as possible. (Note: Before treating CPS, contributing causes such as arthritis and diabetes should be controlled first. Speak with your doctor to determine your best course of treatment.)

Non-Surgical Treatments

If diagnosed early, carpal tunnel syndrome may be treated without surgery in a variety of ways:

How is Bracing or splinting used to treat Carpal Tunnel Syndrome?

Wearing a wrist brace or splint at night will prevent the wrist from bending while sleeping. Keeping the wrist in a neutral position reduces pressure on the median nerve within the carpal tunnel. In addition, the splint may also be worn during the day when performing activities that trigger the symptoms.

Nonsteroidal Anti-Iinflammatory Drugs (NSAIDs)

Medications such as ibuprofen and naproxen not only relieve pain but also work to reduce inflammation. This combination of benefits may help to temporarily relieve the pain while reducing the inflammation to correct the problem over the long term.

Lifestyle Modification

 It is important to identify all triggering activities that lead to pain or discomfort, particularly those that force the wrist to be flexed or extended for prolonged periods of time. Once identified, it is best to avoid these movements altogether. If they cannot be avoided, then modifying your work process or your work site might help. Frequent breaks and the use of a brace when performing these activities may also help.

Steroid Injections

Steroids such as cortisone help to reduce inflammation and swelling. A steroid injection into the carpal tunnel may help to reduce swelling and provide relief. This relief is usually only temporary. Sometimes, the injection is used for diagnostic purposes. If the pain is relieved after the injection, then it is most likely CTS.

Exercises

Some patients may benefit from exercises that help the median nerve move more freely within the confines of the carpal tunnel. Specific exercises may be recommended by your doctor or therapist.

Surgical Treatments

According to the National Institute of Neurological Disorders and Stroke, (https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Carpal-Tunnel-Syndrome-Fact-Sheet) Carpal tunnel release is one of the most common surgical procedures performed in the United States.  The procedure can be performed while the patient is awake with just local anesthesia or a regional anesthesia block. Mild sedation can be added if necessary. The procedure typically takes less than an hour, and patients go home the same day. The procedure is performed by incising the carpal ligament and releasing it (figure #6). By releasing the ligament, the carpal tunnel is un-roofed, and the carpal tunnel is no longer in a confined space. The pressure on the median nerve is then removed.

There are two surgical methods to perform a release of the carpal ligament:

Carpal Tunnel Release Surgery

Open release surgery is the traditional procedure used to correct carpal tunnel syndrome, consists of making an incision up to 2 inches in the base of the hand, then releasing  the carpal ligament to enlarge the carpal tunnel. 

Figure #5 – Carpal Tunnel Release Surgery- Incision
Figure #6 – Carpal Tunnel Release Surgery – Releasing the carpal ligament
Endoscopic Release Surgery

Endoscopic release surgery is a newer technique which may allow a somewhat faster functional recovery time and less postoperative discomfort than the open release procedure.  However, the procedure may take longer to perform, and it may also have a higher risk of complications and the need for additional surgical procedures in the future.  As opposed to the larger incision of the open technique, the surgeon makes one or two small incisions (about ½ inch each) in the wrist and palm and then inserts a tube with a camera. The camera is attached to a monitor, giving the surgeon a view inside of the wrist and hand. Once the camera is used to identify the nerve, ligament, and tendons, the transverse carpal ligament is then released.

Figure #7 – Endoscopic Carpal Tunnel Release Surgery

Which Technique is Better?

According to a meta-analysis published in Clinical Orthopaedics and Related Research in 2015 (https://journals.lww.com/clinorthop/pages/default.aspx):

  • Endoscopic release allows earlier return to work and improved strength during the early postoperative period.
  • Results at 6 months or later are similar.
  • Patients undergoing endoscopic release have a greater risk of nerve injury and a lower risk of scar tenderness compared with open release.
  • Additional research is required to define the learning curve of endoscopic release and clarify the influence of surgeon volume on its safety.

Recovery from Carpal Tunnel Surgery

Although symptoms may be relieved immediately after surgery, full recovery from carpal tunnel surgery can take several months. Usually, there is a decrease in

Complications from Carpal Tunnel Surgery

Complications are rare but may include infections, nerve damage, stiffness, and pain at the scar.  Work activity typically needs to be modified for several weeks after the surgery is performed. Sometimes it is necessary to adjust job activities or even change jobs after recovery.

Recurrence of Carpal Tunnel Syndrome after Surgery:

Recurrence of carpal tunnel syndrome following treatment is rare. It is worth noting that less than 50% of individuals report their hand or hands feeling completely normal after surgery. Residual numbness and weakness is common.

What Research on Carpal Tunnel Syndrome is Currently Being Performed?

According to the National Institute of Neurological Disorders and Stroke (NINDS) (https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Carpal-Tunnel-Syndrome-Fact-Sheet) the NINDS is evaluating the following:

  • Factors that lead to progressive nerve injury and how damage to nerves is related to symptoms of pain, numbness, and loss of function.
  • Biomechanical stresses that contribute to the nerve injury responsible for the symptoms of carpal tunnel syndrome in order to better understand, treat, and prevent this ailment.

The NIH’s National Center for Complementary and Integrative Health (https://nccih.nih.gov/) is investigating:

  • The effects of acupuncture on pain, loss of median nerve function, and changes in the brain associated with CTS.
  • The effectiveness of osteopathic manipulative treatment in conjunction with standard medical treatment for CTS.

The National Institute of Arthritis and Musculoskeletal and Skin Disorders (NIAMS) (www.niams.nih.gov) is evaluating:

  • Research on tissue damage associated with repetitive motion disorders, including CTS using animal models to help doctors understand and characterize connective tissue in hopes of reducing tissue buildup and identifying new treatments.
  • More information about carpal tunnel syndrome research supported by NINDS and other NIH Institutes and Centers can be found using the NIH reporter (projectreporter.nih.gov).

Where Can I Find Additional Information?

BRAIN
P.O. Box 5801
Bethesda, MD 20824
301-496-5751
800-352-9424
www.ninds.nih.gov

National Institute of Arthritis and Musculoskeletal and Skin Diseases
National Institutes of Health, DHHS
31 Center Dr., Rm. 4C02 MSC 2350
Bethesda, MD 20892-2350
301-496-8190
877-226-4267
www.niams.nih.gov

Centers for Disease Control and Prevention (CDC)
U.S. Department of Health and Human Services
1600 Clifton Road
Atlanta, GA 30333
404-639-3311 or 404-639-3543
800-311-3435
https://www.cdc.gov/

Occupational Safety & Health Administration
U.S. Department of Labor
200 Constitution Avenue, N.W.
800-321-6742
Washington, DC 20210
www.osha.gov

U.S. National Library of Medicine
National Institutes of Health/DHHS
Bethesda, MD 20894
8600 Rockville Pike
301-594-5983
888-346-3656
https://www.nlm.nih.gov/