Carpal Tunnel Syndrome Injection

Edward A. Jackson, MD, DABFM, FABFM

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Subject: Carpal Tunnel Syndrome Injection

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Carpal tunnel syndrome is among the most frequent clinically presenting nerve entrapments. It is caused by the compression of the median nerve within the carpal canal. This canal is a space that is created by the carpal bones below and the transverse carpal ligament above. Any condition that either enlarges structures within the canal or decreases the size of the canal can produce compression on the median nerve. Things such as tumors, ganglia, or tenosynovitis of the flexor tendons of the wrist will reduce the canal space. Conditions such as pregnancy, amyloidosis, or thyroid dysfunctions may create edema that also can compress the canal. 
Carpal tunnel is more common in women (3:1 female-to-male ratio). Underlying causes for tenosynovitis such as repetitive injuries due to work activities such as typing or overuse should be corrected first. Control of illnesses such as thyroid conditions and diabetes should also be beneficial in the treatment. 
Patients will usually complain of paresthesias (numbness) and pain in the median nerve distribution. The median nerve supplies sensation to the first three digits and the radial half of the fourth digit. Most patients complain of increased problems at nighttime, especially when they sleep on the wrist or maintain the wrist in a flexed position. As the syndrome persists, there may be pain radiating to the wrist and forearm with atrophy of the thenar muscles, especially the thumb abductors. 
Testing for this syndrome often involves the Tinel and Phalen tests. The Tinel test creates a paresthesia by tapping upon the median nerve at the wrist (01412520). The Phalen test is performed by having the patient flex the wrists together for 30 to 60 seconds to reproduce paresthesias and numbness (01412520). 
Both of these tests are poorly sensitive (20% and 46% respectively). Nerve conduction studies may provide more objective data and reveal a delay in the conduction of an electrical impulse across the carpal canal. 
Figure 1
Figure 1
Figure 2
Figure 2
Figure 3
Figure 3
Conservative treatment may include rest, ice, the use of wrist splinting to limit flexion, and the use of nonsteroidal anti-inflammatory drugs (NSAIDS). Use of injected corticosteroids has been shown to improve the condition. Most studies can document at least a 70% short-term benefit with an injection of steroids. A repeat injection may be performed if symptoms recur but should be limited to two or three injections to limit crystalline deposition into the canal. If repeated injections fail, surgery should be considered. 



  • Signs and symptoms suggesting median nerve compression in the carpal canal with the absence of severe symptoms or pain and absence of severe signs such as thenar muscle wasting


  • Usually not done in pediatric populations

  • Avoid during third trimester of pregnancy

  • Overlying skin with signs and symptoms of cellulitis or infection

  • A mass in the canal

  • History of bleeding disorders or coagulopathy

  • Uncooperative patient (relative)

The Procedure

Step 1

Place patient supine with affected arm fully extended. Face the patient’s feet alongside the affected arm. 

Step 2

Have the patient make a fist against some resistance to locate the palmaris longus tendon. The needle can be inserted on either side of the palmaris longus tendon. 

Step 3

Locate the second wrist crease on the volar side of the wrist. 

Step 4

Prepare a syringe with 0.5 cc of steroid and 1 to 2 cc of lidocaine 1% without epinephrine. Prep the wrist with the antiseptic, and allow it to dry (See Appendix E: Skin Preparation Recommendations). Lay the syringe almost flat against the forearm, and aim the needle directed to the tip of the third digit, angling slightly downward. 

Step 5

Advance the tip of the needle about 1 cm below the surface of the hand into the carpal tunnel space. Some advocate only advancing to the beginning of the canal (1 to 1.5 cm). Alternatively, you can advance it to within the canal (2 to 2.5 cm). Inject the steroid and lidocaine mixture. The patent should note numbness in the median nerve distribution with relief of pain. 

Step 6

The needle is withdrawn, and an adhesive bandage is placed over the injection site. Consider using a splint and NSAIDs after the injection, and have the patient rest the wrist. 
  • PITFALL: The needle should pass easily into the canal. With resistance, withdraw and redirect the needle, still aiming for the tip of the third digit.

  • PITFALL: If the needle touches or penetrates the nerve itself, the patient may experience pain and numbness in the median nerve distribution. Ask the patient to report if this happens. If the needle tip touches the nerve, withdraw and redirect the needle slightly upward but still aiming for the tip of the third digit.


  • Increased pain after steroid injection (temporary and usually resolves in 48 hours)

  • Accidental injection into the median nerve

  • Bruising of the skin

Pediatric Considerations

This syndrome is rarely found in children, and the procedure is usually not performed in this population. 

Postprocedure Instructions

Advise the patient to rest the wrist after the procedure. Encourage the patient to wear the splint if prescribed, which may improve the outcome. Also advise the patient to use ice and/or NSAIDS for pain relief if needed. 

Coding Information and Supply Sources

Consult the ordering information that appears in Appendix G. Needles, syringes, and splints are available from local surgical supply houses. A suggested tray for performing soft tissue aspirations and injections is listed in Appendix I. Skin preparation recommendations appear in Appendix E


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