Carpal tunnel syndrome: Occupational disease

• Carpal tunnel syndrome is classified as an occupational disease in some occupational activities.
• The diagnosis of carpal tunnel syndrome as an occupational disease must be made by specialists in occupational medicine.
• The only way to solve carpal tunnel syndrome is surgery.

Carpal tunnel syndrome is defined as the entrapment of the median nerve in the carpal tunnel, formed by the flexor retinaculum and the carpal bones. 

The carpal tunnel is an anatomical space located in both wrists and is bounded by the bones of the hand in its lowermost region (called carpal bones) and a fibrous band that covers the passage of tendons, nerves, arteries and veins that make up the nerve and vascular structure of the wrist and corresponding hand.

The fibrous band that covers the wrist and envelops and protects all of the above structures can become thickened, especially due to multiple repeated microtrauma. This inflammation causes the fibrous band to grow and thicken, leading to entrapment of the components it envelops. 

Generally, the structure that suffers the greatest compression is the median nerve, which is the cause of all the symptomatology that we will discuss below and which accompanies carpal tunnel syndrome as an occupational disease.

Carpal tunnel syndrome is a well-known and frequent injury in various fields of work, having been included among the most frequent occupational diseases, affecting a large number of patients who have a specific work activity, which we mention in later sections.

Carpal tunnel syndrome can be caused or aggravated by work, leading to an occupational disease. For the appearance of carpal tunnel syndrome as an occupational disease, there are a series of risk factors associated with certain work activities, such as repetitive movements with changes in the muscular strength of the wrist in flexion and extension movements.

Precision activities with hands and fingers over many years are another risk factor for the presence of carpal tunnel syndrome in the workplace, with the jobs most affected by carpal tunnel syndrome as an occupational disease:

• Secretary
• Typist
• Health care staff
• Nurses
• Industrial workers
• Labourers
• Household Service

Another movement that generates an increased risk of presenting carpal tunnel syndrome as an occupational disease is the position maintained in the form of flexion or extension and supporting vibratory forces associated with increased muscle tone in the region of the wrists, in this sense, the most affected professions would be:

• Drivers of heavy machinery
• Construction workers
• Transport workers
• Motorsport athletes

The diagnosis associated with carpal tunnel syndrome as a consequence of work activity is complex, although there are certain professions which, due to the idiosyncrasies of the work itself, carry a high risk of suffering from this type of musculoskeletal disorder.

In any case, it is for occupational medicine and public health specialists to determine the association of the occurrence of carpal tunnel syndrome as an occupational disease.

The diagnosis of carpal tunnel syndrome, whether or not it is an occupational disease, is based on clinical suspicion according to the manifestations or symptomatology suffered by each patient. 

The usual clinical manifestations of carpal tunnel syndrome are the presence of pain, tingling, numbness and/or diminished sensation with or without pain in at least two of the 1st, 2nd or 3rd fingers of the same hand or both hands.

Generally there are no symptoms in the palm or dorsum of the hand, except in the most severe cases in which a muscular alteration of the palmar muscles is possible. Symptoms may also be present in the fifth finger, wrist pain or radiation proximal to the wrist. Worsening pain or a tingling and burning sensation at night is very common and may cause the patient to wake up.

The pain usually improves after waking up as the day wears on, and then gets worse.

Following clinical suspicion, the doctor attending to patients with suspected carpal tunnel syndrome may perform two interventions or clinical examinations that generally serve to rule out the presence of the problem in suspected cases. These tests are: the Phallen test and the Tinel test. In suspected cases of carpal tunnel syndrome with both of the above tests positive, an electromyographic test will still be necessary to confirm the diagnosis.

Electroneuromyography is a test that checks the speed of transmission of the nerves under study and their ability to activate the regions that depend on the nervous system muscularly. 

In the context of carpal tunnel syndrome, as an occupational disease or not, 2 needles are inserted into the wrist regions and the conduction capacity of the median nerve through them and its muscular response is measured. 

A positive electromyographic test will definitively confirm or rule out the presence of carpal tunnel syndrome.

The definitive treatment for carpal tunnel syndrome as an occupational disease is surgery to remove the compression of the sheath covering the nerve and vascular endings in the wrist of the affected hand. 

This type of intervention takes very little time and is usually performed under local and/or regional anaesthesia. The subsequent recovery is usually very quick and the discomfort and pain caused by carpal tunnel syndrome disappears immediately after the operation.

The operation for the resolution of carpal tunnel syndrome is based on cutting the fibrous sheath by access through the skin, either by endoscopy or by making an incision through the skin itself. Subsequent sutures will depend on the type of entry into the carpal canal.

In milder or moderate to mild cases, it is possible to try to reduce the size of the fibrous sheath that causes carpal tunnel syndrome by taking anti-inflammatory or analgesic drugs such as paracetamol, lyrica or minor and major opioids. 

Reduced inflammation of the tendons and fibrous sheath may allow daily activities and pain control for a number of years. 

A work study of the patient and the improvement of certain wrist positions during daily work activities can help delay the onset of this type of disease and reduce the clinical symptoms of the worker once he/she is already affected by carpal tunnel syndrome.