Carpal tunnel syndrome
(CTS) is a common problem affecting the hand and wrist. Symptoms begin when the median nerve gets squeezed inside the carpal tunnel of the wrist, a medical condition known as nerve entrapment
or compressive neuropathy. Any condition that decreases the size of the carpal tunnel or enlarges the tissues inside the tunnel can produce the symptoms of CTS. This syndrome has received a lot of attention in recent years because of suggestions that it may be linked with occupations that require repeated use of the hands, such as typing on a computer keyboard or doing assembly work. Actually, many people develop this condition regardless of the type of work they do.
This guide will help you understand
- where the carpal tunnel is located
- how CTS develops
- what can be done for the condition
Where is the carpal tunnel, and what does it do?
The carpal tunnel is an opening through the wrist to the hand that is formed by the bones of the wrist on one side and the transverse carpal ligament on the other. (Ligaments connect bones together.) This opening forms the carpal tunnel.
The median nerve passes through the carpal tunnel into the hand. It gives sensation to the thumb, index finger, long finger, and half of the ring finger.
It also sends a nerve branch to control the thenar muscles of the thumb. The thenar muscles help move the thumb and let you touch the pad of the thumb to the tips of each finger on the same hand, a motion called opposition.
The median nerve and flexor tendons pass through the carpal tunnel.
The median nerve rests on top of the tendons, just below the transverse carpal ligament. The flexor tendons are important because they allow movement of the fingers, thumb, and hand, such as when grasping. A material called tenosynovium covers the tendons. The tenosynovium is a slippery covering that allows the tendons to glide next to each other as they contract and relax to move the hand and fingers.
What causes CTS?
Any condition that makes the area inside the carpal tunnel smaller or increases the size of the tissues within the tunnel can lead to symptoms of CTS. The carpal tunnel cannot expand so any condition that causes abnormal pressure in the tunnel can produce symptoms of CTS. And any increase in pressure within the carpal tunnel can reduce blood flow to the nerve, leading to loss of nerve function.
Various types of arthritis can cause swelling and pressure in the carpal tunnel. The way people do their tasks can put them at risk for problems of CTS. Some of these risks include
• Wrist alignment
One of these risks alone may not cause a problem. But doing a task that involves several factors may pose a greater risk. And the longer a person is exposed to one or more risks, the greater the possibility of having a problem with CTS. In other instances, CTS can start when the tenosynovium thickens from irritation or inflammation. This thickening causes pressure to build inside the carpal tunnel. But the tunnel can’t stretch any larger in response to the added swelling, so the median nerve starts to squeeze against the transverse carpal ligament. If the pressure continues to build up, the nerve is eventually unable to function normally. When pressure builds on the median nerve, the blood supply to the outer covering of the nerve slows down and may even be cut off. The medical term for this is ischemia. At first, only the outside covering of the nerve is affected. But if the pressure keeps building up, the inside of the nerve will start to become thickened. New cells (called fibroblasts)form within the nerve and create scar tissue.
This is thought to produce the feelings of pain and numbness in the hand. If pressure is taken off right away, the symptoms will go away quickly. Pressure that isn’t eased right away can slow or even stop the chances for recovery. Other conditions in the body can produce symptoms of CTS. Pregnancy can cause fluid to be retained, leading to extra pressure in the carpal tunnel.
What does CTS feel like?
- Worse at night initially; Later during day dull ache also
- Location: Arm, forearm, wrist, hand & fingers
- Repetitive or sustained activity: Exacerbates pain
- The hand may begin to feel like it’s asleep, especially in the early morning hours after a night’s rest.
- Touching the pad of the thumb to the tips of the other fingers becomes difficult, making it hard to grasp items such as a steering wheel, newspaper, or telephone.
How do doctors identify the condition?
At the Centre for Musculoskeletal Medicine we begin the evaluation by obtaining a history of the problem, followed by a thorough physical examination. Your description of the symptoms and the physical examination are the most important parts in the diagnosis of CTS.
- Commonly, patients will complain first of waking in the middle of the night with pain and a feeling that the whole hand is asleep.
- Careful investigation usually shows that the little finger is unaffected. This can be a key piece of information to make the diagnosis. Other complaints include numbness while using the hand for gripping activities, such as sweeping, hammering, or driving.
- If your symptoms started after a traumatic wrist injury, X-rays may be needed to check for a fractured bone or a fracture with dislocation. If more information is needed to make the diagnosis, electrical studies of the nerves in the wrist or diagnostic ultrasound may be requested. Several tests are available to see how well the median nerve is functioning, including the nerve conduction velocity (NCV) test. This test measures how fast nerve impulses move through the nerve.
What can be done for CTS?
At the Centre for Musculoskeletal Medicine we consider the following options.
- Activities that are causing your symptoms need to be changed or stopped if at all possible.
- Avoid repetitive hand motions, heavy grasping, holding onto vibrating tools, and positioning or working with your wrist bent down and out.
- Ultrasound, soft tissue and mobilisation of the wrist to decrease swelling, inflammation and to encourage normal gliding of the tendons and median nerve within the carpal tunnel.
- A wrist brace will sometimes decrease the symptoms in the early stages of CTS. A brace keeps the wrist in a resting position, not bent back or bent down too far. When the wrist is in this position, the carpal tunnel is as big as it can be, so the nerve has as much room as possible inside the carpal tunnel. A brace can be especially helpful for easing the numbness and pain felt at night because it can keep your hand from curling under as you sleep. The wrist brace can also be worn during the day to calm symptoms and rest the tissues in the carpal tunnel.
- Medications such as anti-inflammatories may also help control the swelling and reduce symptoms of CTS.
- Cortisone injection into the carpal tunnel may be suggested. This medication is used to reduce the swelling in the tunnel and may give temporary relief of symptoms. A cortisone injection may help ease symptoms and can aid your doctor in making a diagnosis. If you don’t get even temporary relief from the injection, it could indicate that some other problem is causing your symptoms. When your symptoms do go away after the injection, it’s likely they are coming from a problem within the carpal tunnel.