The carpal tunnel, located in the wrist joint is a narrow passageway which is made up by the carpal bones and a transverse carpal ligament (flexor retinaculum). The median nerve, which controls sensation and movement in the thumb, index, middle and one-half of the ring finger and nine flexor tendons, runs through this passageway.
One half of the carpal tunnel is formed by the eight rigid carpal bones on the posterior (back) of the wrist, while the transverse carpal ligament being located on the anterior (front) side of the wrist, forms the remaining half. The size of the carpal tunnel is about the size of the index finger in diameter, and the flexor tendons and median nerve glide past each other with ease within the carpal tunnel when it is of sufficient size.
Carpal Tunnel Syndrome
Carpal tunnel syndrome is caused by inappropriate usage of the hands and wrists for a long period. A pressure can be caused on the median nerve, if the tendons increase in size due to inflammation or hypertrophy, or if the carpal tunnel size decreases due to laxity in the joint. This may lead to swelling of the tissues surrounding the carpal tunnel resulting in carpal tunnel syndrome. This syndrome develops gradually causing symptoms of numbness and tingling in your thumb, index and middle fingers, weakness, or pain in the hand.
Pregnancy, diabetes, obesity, hypothyroidism and arthritis are common risk factors for carpal tunnel syndrome. It also occurs as a result of wrist injuries, such as fractures.
Pins and needles/ Paraesthesia: Carpal tunnel syndrome can cause a feeling of tingling or burning in part or all of the shaded area shown below. This is similar to the "pins-and-needles" sensation you get when your hand falls asleep. This is typically the first symptome to develop affecting the index and middle fingers first noticed at night or first wake up in the morning. During the day, pain or tingling when holding things, like a phone or a book, or when driving may be noticed wherein shaking or moving your fingers usually helps.
Numbness of the same finger(s) or in part of the palm, may develop if the condition becomes worse. A feeling of swelling in fingers may exist, even though no swelling is present, or they may have trouble distinguishing between hot and cold. As the disorder progresses, the numb feeling may become constant.
Dryness of the skin may develop in the same fingers.
Weakness of some muscles in the fingers and/or thumb occurs in severe cases. This may cause poor grip and a tendency to drop objects and eventually lead to muscle wasting at the base of the thumb.
Additional side-effects of carpal tunnel syndrome may include generalized aching, swelling, and diminished coordination of the fingers, especially when performing fine motor movements required for picking up small objects.