Carpal tunnel syndrome (also known as median nerve compression) is a common cause of pain tingling or numbness in the hand and wrist.
In carpal tunnel syndrome, the median nerve that runs through the carpal tunnel in your wrist is squashed. This nerve leads to the ball of the thumb and other parts of the hand. Injecting corticosteroids is one of the most effective treatments available.
Ultrasound is used to take pictures or images of the wrist to confirm or exclude if carpal tunnel syndrome is present. Ultrasound is good at assessing if there is swelling of the median nerve and also assessing the adjacent structures (such as joints and tendons), which might be irritating or compressing the nerve.
What happens during a carpal tunnel ultrasound and injection?
You will be taken into the scanning room by the sonographer (ultrasound technician). You will either be lying on a scanning bed or sitting down with your hand on a table or bed in a comfortable position. The sonographer will apply gel over your wrist and take images using ultrasound. These images will then be shown to the radiologist (specialist doctor) who will discuss them with you and might take some further images.
If carpal tunnel syndrome is confirmed, and the radiologist recommends an injection, the procedure will be explained to you. You will be able to ask any questions at this time. The skin over your wrist is cleaned with antiseptic liquid. A small needle is passed through your skin directly into the carpal tunnel using ultrasound images to guide the placement of the needle. A small amount of corticosteroid and local anesthetic is then injected, and the needle removed.
After the injection, the wrist and hand should generally be rested completely for 6 hours, followed by minimal use for between one and three days.
Are there any after effects of a carpal tunnel ultrasound and injection?
Immediately after the injection, you might have numbness in your hand from the local anesthetic. It is recommended that you do not drive until the numbness has settled or have someone drive you home after the procedure.
The most common after effect is a temporary increase of your symptoms over one, two, or even three days. The corticosteroid does not start working for at least 24 hours and sometimes up to seven days.