Carpal Tunnel Injection
Limited evidence that corticosteroid injections are better than placebo for short term (<1 month) relief of symptoms.
There are many approaches to this injection. We will review a traditional method here.
Obtain informed consent from the patient.
Gather appropriate materials needed for the procedure.
First draw up 2-3cc of 1 or 2% lidocaine into a 5cc syringe.
Then draw up steroid into the same syringe in order to intermix the two together. You may use this list of four commonly used steroids as a reference.
Think about your anatomy. Where is the carpal tunnel located? What structures run through it?
The "tunnel" is created by the flexor retinaculum that overlies the radial artery, flexor tendons, median nerve, and ulnar artery and nerve.
The distal border of the retinaculum is just beneath the crease of the wrist.
In this image: The carpal tunnel has been identified.
Position the patient with their forearm extended and their palm facing upwards. Have the patient bring their pinky finger and thumb together to isolate the palmaris longus tendon.
See if you can locate these landmarks on yourself. Do you have a palmaris longus tendon?
Although rare, some people do not have a palmaris longus tendon. In this case, direct the needle just ulnar to the midline of the wrist (in line with the ring finger).
Cleanse the skin with povidone-iodine or an alcohol swab.
In this image: Bringing the pinky finger and thumb together help to isolate the palmaris longus tendon.
Using a 25-gauge, 1.5-inch needle, insert the needle just ulnar to the palmaris longus tendon (or towards the ring finger) and at the level of the crease of the wrist.
Direct the needle dorsally and distally at about 30 degrees from the skin surface.
In this image: The physician injects the medication into the carpal tunnel.
Inject the medication.
Is there resistance? Is the patient complaining of paresthesias? If yes, then STOP. Withdraw the needle a little and redirect it more ulnar. The medication should flow freely and with minimal discomfort to the patient.
Accidental intraneural injection may leave the patient with significant discomfort afterwards and may require surgical decompression.
To complete the procedure:
Withdraw the needle and apply pressure for a few seconds.
Cover the puncture site with a sterile bandage.