Carpal Tunnel Injection

Carpal Tunnel Injection

As the median nerve travels through the carpal tunnel, it may become compressed. Carpal tunnel syndrome is the condition of pressure being placed on the median nerve. The transverse carpal ligament is usually thickened at the wrist and this causes the compression of the nerve. The condition usually occurs due to an overuse injury such as repetitive hand grip movements. The predisposing factors for carpal tunnel syndrome include trauma, fractures, pregnancy, diabetes, rheumatoid arthritis, ganglion cyst, smoking, alcoholism, advanced age, and obesity. As a result of this compression, the patient may experience pain and paresthesia in the median nerve distribution as well as weakness in the hand. The median nerve is inside the carpal canal. The transverse carpal ligament covers the median nerve and if this ligament is thickened, it can compress the median nerve. It is almost like a narrow tunnel, and the median nerve is much like a truck passing through the narrow tunnel. ^o angle to the skin of the wrist. Next, direct the needle towards the base of the thumb and advance the needle distally and slowly. You should mark the site 4-5 cm proximal to the distal palmar crease between the palmaris longus and the flexor carpi radialis tendons. For the proximal approach, you should advance the needle distally towards the wrist at about a 20^o angle to the skin, keep the needle between the two tendons, be aware that the nerve is in between the two tendons (the nerve is really superficial) and adjust the needle as needed, and then inject the desired fluid.

We try to make room for the nerve to past through. The tunnel is widened by doing carpal tunnel surgery. Cutting the transverse carpal ligament, as seen in this example. We can possibly make room for the median nerve with steroid injection, because injection will decrease the inflammation. The typical patient with carpal tunnel syndrome will have hand pain, numbness and tingling in the radial 3 ½ fingers (median nerve distribution). These symptoms may wake the patient up at night. Treatment is usually a night splint or anti-inflammatory medication. Sometimes we give some patients a steroid injection which can be helpful. In general, you will know which patients will have a good prognosis from the treatment of carpal tunnel, and these are the patients who will have night symptoms. Another indication for a good prognosis is the response to steroid injection. If the steroid injection helps the symptoms, then the patient will do well from the carpal tunnel surgery. Failure to improve after steroid injection indicates a less favorable outcome from the surgery. The injection is usually helpful when it is not clear to the clinician where the symptoms are coming from. If you inject the carpal tunnel and the patient improves, then you know the predominant problem is the carpal tunnel, because all of the three conditions can give the same symptoms. This is especially important in double crush syndrome where the median nerve can be compressed at two different places along its course, and one of these places can be the carpal tunnel. Injection also has therapeutic value. Injection allows a period of relief in patients with mild or moderate carpal tunnel symptoms. 80% of the patients will have some transient improvement with injection and 20% of the patients will improve up to 1 year. The median nerve is located between the palmaris longus and flexor carpi radialis tendons. You can give the injection by ultrasound or you can do it blindly. When you do blind injection, you can do it by the usual approach or by the proximal approach. With the usual approach, you should mark the intersection of the palmaris longus tendon and the distal palmar crease. Next, go 1 cm proximal and 1 cm ulnar to that site, this will be the point of the injection.

Use a 25 gauge needle with the preferred brand and amount of steroids and 1 mL of 1% lidocaine. The physician should warn the patient before the injection that if any feeling of numbness, paresthesia, or sever pain exists to let the physician know about it. If the symptoms exist, the doctor should withdraw the needle or adjust it before injection. You may use local anesthesia or a spray. You should use a sterile field, make sure that you have a consent, make sure that you have a time-out sheet, and mark the site before injection. To administer a usual approach injection, you should put the needle at a 45