What causes carpal tunnel syndrome?
Do you think you are suffering from carpal tunnel syndrome?
a. This disease affects not only healthy people but also people with risk factors that predispose them to carpal tunnel syndrome such as:
- excess weight
- wrist fracture
b. Occupational factors such as the repetition of certain strong gripping movements or flexing and extension of the wrist or exposure to vibrating tools are sometimes mentioned as risk factors.
c. Most often, no predisposing factor is found. This is called idiopathic carpal tunnel syndrome.
d. The carpal tunnel is an anatomical zone of the wrist that is located at the junction between the hand and the forearm. It contains the nine flexor tendons that serve to bend the fingers of the hand and an important nerve, which runs through the extent of the canal, called the median nerve. This important nerve gives sensitivity (the sense of touch or tact) to the thumb, forefinger, middle finger and half of the ring finger. The small finger is usually spared in carpal tunnel syndrome because it is not innervated by the median nerve but by the ulnar nerve. Numbness of the little finger (fifth finger or little finger) therefore suggests another disease. The median nerve also stimulates and innervates the muscles at the base of the thumb in the palm of the hand.
e. The floor of the canal is formed by the bones of the wrist and its roof by a very solid and thick ligament called the transverse ligament or the annular ligament of the wrist. In some situations, and often because of the swelling and inflammation that may occur in the tendons, the pressure in the canal, and therefore the median nerve, increases. This increase in intra-ductal pressure compromises blood circulation and oxygenation of the nerve cells that make up the nerve. These nerve fibers can no longer function normally and conduction velocity of the electrical signals in the nerve slows down, causing numbness. In advanced cases, nerve conduction stops completely (nerve conduction block). Nerve fibers and their cells, called the axons, can then be irretrievably damaged. This results in a loss of perception of touch or tact in the thumb, index, middle and ring finger that compromises the function of the hand. The hand becomes awkward. Muscular atrophy may also occur due to the weakening of the muscles innervated by the median nerve. These consequences can become irreversible without prompt treatment. This is the danger of neglecting this pathology or of waiting too long before acting.