Overview of Carpal Tunnel Injection
Carpal tunnel syndrome (CTS) is a common health issue that affects a lot of people. It’s the leading cause of peripheral nerve compression, which is when pressure is applied to a nerve, causing pain or discomfort. About 99 out of 100,000 people experience this condition. CTS is most common in people over the age of 40 and it’s more often seen in women, who make up between 65% and 75% of reported cases.
CTS occurs when the median nerve, located in a tunnel-like structure in your wrist known as the carpal tunnel, is squeezed or compressed. Normally, the pressure in this area is between 2 to 31 mm Hg (millimeters of mercury, a measurement of pressure). However, in patients with CTS, the pressure can increase to between 32 to 110 mm Hg.
When the median nerve is compressed, it can cause pain or a tingling sensation (paresthesias) in the areas of the hand that this nerve controls. This includes the underside (palm side) of the thumb, index finger, middle finger, and half of the ring finger on the thumb side.
People may be at a higher risk of developing CTS if they are overweight, pregnant (especially late in the pregnancy), older in age, have experienced an injury to their wrist, or have an autoimmune disease that causes inflammation and soreness (rheumatic disorder). However, it’s still not clear if repetitive activities like typing are a risk factor for CTS.
There are various ways that CTS can be treated, including using a wrist brace to keep the wrist still, physical therapy, and pain relief medicines that can be either applied directly on the skin or taken by mouth. More intensive treatments may involve injecting steroid (a type of medicine that reduces inflammation) into the carpal tunnel, or performing surgery to relieve the pressure in this area.
The exact causes of CTS are not fully understood, but it’s generally thought to not have a single cause or could be due to a combination of factors. Some potential risk factors could be type 1 or 2 diabetes, an underactive thyroid (hypothyroidism), going through menopause, being overweight, arthritis, and being older in age.
People with diabetes seem to have a higher chance of developing CTS, with a 30% occurrence in patients with diabetic neuropathy (nerve damage due to high blood sugar levels), and 14% in patients without symptoms of nerve damage. Hormonal changes that happen during pregnancy, menopause, and with hypothyroidism might also contribute to CTS.
Certain physical conditions, such as inflammation, thickening, arthritis, and irregular shape or position of bones, can contribute to the compression of the median nerve.
Anatomy and Physiology of Carpal Tunnel Injection
The carpal tunnel is a narrow passageway located on the palm side of your wrist. This tunnel, bordered by small wrist bones and a tight band of tissues, houses the median nerve along with nine tendons that help bend your fingers. Sometimes, increased pressure in this tunnel leads to pain in your hand along the path of the median nerve.
The median nerve starts from a network of nerves in the arm, called the brachial plexus. This nerve provides movement to the thumb muscle and sensation to the first three and a half fingers on the thumb side of your hand. On the other hand, the ulnar nerve provides sensation to the rest half of your fourth finger (the ring finger) and the little finger.
Why do People Need Carpal Tunnel Injection
If treatments like wearing a wrist brace, doing physical therapy, or taking pain relief medicine do not alleviate your symptoms, you may need to have a medical procedure called a carpal tunnel injection. This procedure can also be used if tests that check the speed and strength of your nerves (this is called electromyography or nerve conduction velocity) don’t provide a clear answer. In these cases, a carpal tunnel injection can help confirm whether you have carpal tunnel syndrome before considering surgery.
When a Person Should Avoid Carpal Tunnel Injection
There are certain situations when a doctor may advise against giving a carpal tunnel injection. This could be due to the patient refusing the treatment, or if there’s an infection or swelling at the spot where the injection would be given. If a patient is on blood thinners, they could potentially receive a carpal tunnel injection. However, the doctor would need to closely assess for any signs of bleeding.
How is Carpal Tunnel Injection performed
If other treatments for Carpal Tunnel Syndrome (CTS) don’t work, some patients might try injections. Mostly, these injections contain a type of medicine called corticosteroids. Doctors don’t all agree on the best place to give these injections. However, a study compared different places and found that the safest might be within a tendon in your wrist, just before the carpal tunnel.
During the injection, you could be sitting down or lying down. Your affected wrist would be facing upwards and slightly bent back, with a towel rolled up underneath for support. The doctor may also tape your fingers down. An ultrasound scanner could be used to check your wrist for any unusual features like cysts, inflammation, or tumors. With the ultrasound scanner positioned across your wrist at the point where it bends, the doctor can view the bone called the pisiform, the ulnar nerve and artery (which run down the side of your wrist), and the median nerve (which might be swollen). Doppler imaging (a type of ultrasound) can help identify which structures shown on the ultrasound are blood vessels. The doctor’s aim is to guide the injection so that it surrounds the median nerve. The medicine might also be injected into the tissue beneath the synovium, a membrane around certain joints, which recent research has suggested could be the cause of some cases of CTS.
After making sure everything is sterile, the doctor inserts the needle on the side of your wrist where your pinky finger is. This needle placement should be shallow and above the ulnar nerve or artery, reaching a band of tissue called the flexor retinaculum that’s over the carpal tunnel. First, the doctor injects the medicine at the front part of the median nerve. This causes the nerve to move away from the flexor retinaculum, which could help to ease any pressure that might be trapping the nerve. Then, the doctor directs the needle deeper to inject the back part of the nerve. The idea is for the nerve to be completely surrounded by the injected medicine and ‘floating’ in it.
According to one study, 75% of corticosteroid injections into the wrist were accurately targeted by just using landmarks (specific points on the body), while 8.7% accidentally damaged the median nerve. Using ultrasound to guide the injection has been proven to greatly lower the number of bad outcomes. A review of multiple studies also showed that more people see improvement in CTS if their doctor uses ultrasound for guidance, compared to injecting by using landmarks. This improvement is seen after about 3 months.
Lately, there’s been interest in using injections of platelet-rich plasma (PRP) to help with long-term pain relief. PRP has a high number of platelets and growth factors, which can help to reduce symptoms of CTS. It supports the repair of the outside coating of the median nerve, helping to return its function to normal. A review that included five previous research papers — three of these were randomized controlled trials, one was a case-control study, and the other was a case report — showed that PRP can be effective for people with mild CTS. We still need bigger studies to prove how helpful PRP injections can be for CTS.
Possible Complications of Carpal Tunnel Injection
There may be some complications that can occur during a carpal tunnel injection, which is a treatment procedure for the wrist condition known as carpal tunnel syndrome. These potential issues include:
* Bleeding: This is when blood seeps out at the site where the injection was administered.
* Elevated blood glucose levels: This means having a higher than normal amount of sugar in the bloodstream, which might need to be monitored, especially for people with diabetes.
* Infection: This happens when bacteria get into the body through the injection site, causing redness, swelling, or heat.
* Median nerve injury: This takes place if the needle accidentally damages the median nerve, which runs down your arm and through your wrist – particularly in the carpal tunnel region.
* Pain: This refers to discomfort felt at the injection site or the area around it.
* Paresthesias: This is a medical term for unusual sensations like tingling, prickling or burning, often felt in the hands or fingers.
What Else Should I Know About Carpal Tunnel Injection?
Carpal Tunnel Syndrome (CTS) is a condition that usually develops slowly over months, years, or even decades. A common symptom is a feeling of “pins and needles” in your thumb, index and middle fingers, as well as pain in the hand that often worsens at night. As the condition keeps developing, you might start feeling pain and numbness in the affected region during daily activities like driving, lifting things, or using the computer. Eventually, the pain might become constant and your hand might even swell and lose muscle in the thumb area (this is known as thenar atrophy). A doctor can notice thenar atrophy during a physical examination.
When you visit a doctor, they might ask you to perform Tinel’s and Phalen’s tests in the office. These are simple exercises that put stress on the median nerve in your wrist. During Tinel’s test, your doctor will tap on your wrist and if it causes your symptoms, it indicates you might have CTS. Phalen’s test involves bending your wrist for about a minute to check if it causes your symptoms.
Though CTS can usually be diagnosed based on these physical signs and symptoms, nerve conduction tests are considered the most accurate method of diagnosis. However, one downside of nerve conduction testing is that it can cause discomfort and stress for the patient.
