The carpal tunnel is a narrow (about an inch wide) passageway in the wrist.
The tunnel’s floor and sides are formed by small bones wrist bones known as the carpal bones.
The tunnel’s roof is the transverse carpal ligament—a robust band of connective tissue.
Since the boundaries are very rigid, there is little capacity for the carpal tunnel to increase in size or “stretch.”
One of the primary nerves in the hand is called the median nerve.
It goes down the forearm and the arm, passes through the carpal tunnel and into the hand.
The median nerve not only controls the muscles situated around the base of the thumb, it also provides the feeling in the middle, ring, and index fingers as well as the thumb.
Nine tendons that bend the thumb and the fingers also pass through the carpal tunnel.
These tendons are known as flexor tendons.
When the tunnel narrows down or when the tissues that surround the flexor tendons swell, pressure is placed on the median nerve.
When the median nerve is compressed or squeezed, carpal tunnel syndrome occurs.
Many carpal tunnel syndrome cases are attributed to a combination of factors.
Studies indicate that older people and women are more prone to developing the condition.
Risk factors for carpal tunnel syndrome include:
- Repetitive use of the hand – repetition of wrist and hand activities or motions for prolonged periods may irritate the tendons in the wrist. The irritation may cause it to swell and put pressure on the median nerve.
- Heredity – there might be anatomic differences that can affect the amount of space for the nerve and these are often genetic.
- Wrist and hand position – activities that involve extreme flexion or extension of the wrist and hand for prolonged periods may cause nerve pressure.
- Pregnancy – hormonal changes that occur during pregnancy may cause swelling.
- Health conditions – conditions that are often associated with carpal tunnel syndrome can include thyroid gland imbalance, rheumatoid arthritis, and diabetes.
Telltale symptoms that point to carpal tunnel syndrome can include:
- Pain, tingling, burning, and numbness in the thumb and the middle, index, and ring fingers
- Tingling or pain that travels to the forearm and extends to the shoulder
- Occasional shock-like sensations that are felt in the middle, index, and ring fingers as well as the thumb
- Hand clumsiness and weakness
- Loss of proprioception (awareness of where the hand is in space)
Symptoms of carpal tunnel syndrome often manifest gradually.
Many patients report the symptoms come and go at first.
However, symptoms have been observed to occur more often and linger for longer periods as the condition worsens.
Experiencing symptoms during night time is often very common and may sometimes wake patients up from sleep.
During the day, symptoms become more evident when the wrist is bent backwards or forward (i.e. when driving, holding a book, using the phone, etc.) for long periods.
Many patients find relief from the symptoms when moving or shaking their hands.
Aside from asking about the patient’s symptoms, medical history, and general health, the doctor will also perform hand and wrist tests to accurately diagnose the condition.
During the physical examination, the doctor will likely perform the following:
- Tap along (or press down) the median nerve to check for tingling or numbness. This test is called the Tinel’s sign.
- Hold and bend the wrist in a flexed position. This is done to test for numbness and hand tingling.
- Check for muscle weakness around the thumb’s base.
- Test for hand and fingertip sensitivity by lightly touching them while the patient’s eyes are closed.
- Look for signs of muscle atrophy around the thumb’s base.
Electrophysiological tests – determines how well the median nerve is working and whether there is too much pressure placed. The tests can also help assess if the patient is suffering from other nerve conditions such as neuropathy. Electrophysiological tests can include electromyogram (EMG) and nerve conduction studies.
Ultrasound – ultrasound of the wrist may be recommended to check for signs of median nerve compression.
X-rays – this is often recommended when the doctor wants to rule out other conditions (ligament injury, fracture, and arthritis) that may exhibit the same symptoms.
Magnetic resonance imaging (MRI) scans – this may be requested to check for other possible causes for the symptoms or to look for abnormal tissues that may have caused median nerve compression.
While the development of the condition is often gradual, left untreated, the condition can worsen over time.
That being said, it is of prime importance that the condition is diagnosed and evaluated in its early stages.
When diagnosed and treated early, it is often easier to slow down or stop the progression of the condition altogether.
Splinting or bracing – wearing a splint or brace at night can help ensure the wrist is not bent while sleeping. Keeping the wrist in a neutral or straight position can help minimize the pressure on the median nerve. Wearing a splint during the day can also help guarantee some of the symptoms will not worsen.
Nonsteroidal anti-inflammatory drugs (NSAIDs) – medications like naproxen and ibuprofen has been known to help effectively relieve inflammation and pain.
Nerve gliding exercises – some patients can benefit from exercises designed to help the median nerve move freely within the carpal tunnel. These specific exercises may be taught by a doctor or a physical therapist.
Steroid injections – Corticosteroid (or cortisone) is injected into the carpal tunnel to minimize the inflammation. However, while the injection can minimize symptom flare-ups and relieve pain, the effect is sometimes only temporary.
If nonsurgical treatment alternatives will not relieve the symptoms, carpal tunnel syndrome surgery will most likely be recommended.
Surgery recommendation will also depend on the severity of the symptoms.
In cases where patient experiences constant numbness and wasting of the thumb muscles, surgery might be considered to prevent irreversible damage.
Open carpal tunnel release – in this procedure, the doctor will divide the roof of the carpal tunnel (transverse carpal ligament) to increase the size of the tunnel and minimize median nerve pressure.
Endoscopic carpal tunnel release – in this procedure, the doctor will make two very small incisions (also called portals) and uses an endoscope to view the inside of the wrist and hand. A special knife will be used to divide the transverse carpal ligament.