The carpal tunnel is a tunnel in the wrist formed of the carpal bones on which the ligament across the carpal is stretched, a fibrous band which constitutes the roof of the tunnel, entering the scaphoid and trapezium bones on the one side and the piriformis and uncinate (the carpal bones of the hand) on the other.
Nervous tissue (median nerve), vascular tissue and tendons (hand flexor muscle tendons) pass through this tunnel. The thenar is a projection of the thumb, formed mainly of adductor brevis and opponens pollicis. When the carpal tunnel syndrome reaches its maximum degree of severity, there is atrophy (disappearance) of the thenar.
What are the causes of the Carpal Tunnel Syndrome?
Occupational pathogenesis seems to be the most frequent cause for development of the Carpal Tunnel Syndrome. There seems to be an association between repetitive work activities, both in the presence (greater risk) or absence of great force. It has been proved that prolonged and/or repeated bending-extension movements (and bending of the fingers, to a lesser extent) cause increase in pressure inside the carpal tunnel, and repeated stretching of the nerves and tendons inside the carpal tunnel can lead to inflammation which reduces the size of the tunnel, thus leading to pinching of the median nerve. Systemic diseases can also be associated with the Carpal Tunnel Syndrome (for example diabetes mellitus, rheumatoid arthritis, myxedema, amyloidosis), apart from physiological conditions (such as pregnancy, use of oral contraceptives, menopause), trauma (repeated fractures of the wrist with articular deformities), arthritis and deforming arthrosis.
Which are the riskiest jobs that lead to the Carpal Tunnel Syndrome?
The carpal tunnel syndrome shows significant association with certain work activities. In fact, those in the manufacturing, electronics, textile, food, footwear, leather industry, as well as those involved in packaging goods, cooks, and public sector workers are at risk.
Why are the symptoms more pronounced at night and on waking up?
The opinions in this regard are not univocal. There are a large
number of causes: at night, the wrist may remain overflexed or hypertensive
for a long time, thus leading to increased pressure inside the carpal
tunnel, resulting in pinching of the median nerve; the prone position
will distribute body fluids with increased flow to the upper limbs and
thus also inside the carpal tunnel resulting in increased pressure; just
resting the hand will not allow drainage of liquids from inside the carpal
tunnel.
What is the frequency of the Carpal Tunnel Syndrome?
Studies aimed at this aspect do not give univocal results; this
is understandable in view of the variables involved (different selection
criteria, the job done, diagnosis criteria, etc.).
A study conducted from 1983 to 1985 in Holland shows a rate of 3.4% in
women and 0.6% in men; but it is estimated that CTS is present to a further
5.8% in undiagnosed women (De Krom et al. J Clin Epidemiol 1992; 45:373-6).
The average annual occurrence calculated during the period 1961-1980 in
Minnesota is 149 every 100,000 inhabitants/year for women and 52 for men,
rough rate 99/100,000/year (Stevens et al. Neurology 1988; 38:134-8).
A study carried out in the Sienese area from 1991 to 1997 (Mondelli M.
et al. Toscana Medica July/August 1999) gives a rough rate of incidence
of 326.2/100,000/year (135.1 for males and 506.9 for women), the standard
incidence being 276.6/100,000/year. The average F: M incidence ratio is
3.8:1.
The decade most represented for both sexes is that between 50 and 59 years.
Is diagnosis of Carpal Tunnel Syndrome easy?
When the patient complains of tingling (paresthesias) and/or pain,
often radiating to the forearm, mainly at night or early in the morning,
the condition is most probably due to CTS.
However, it is necessary to carry out an objective neurological test and
EMG/ENG (electromyography/electroneurography) tests.
The objective neurological test examines the strength, the osteotendonitic
reflexes, and sensitivity, and can involve clinical tests.
The most common tests are the Tinel and Phalen tests. In the first case,
the carpal tunnel is tapped with a reflex hammer and the patient must
feel a shock in the median nerve distribution area; the second test consists
in bending or stretching the hand over the forearm for one minute; the
patient must feel a tingling sensation or the tingling sensation must
worsen.
However the tests can often give negative false or positive false results;
it is therefore not advisable to rely too much on the results obtained.
Therefore an EMG/ENG test is recommended.
The ENG (electroneurographic) test involves the use of surface electrodes
for sending small electric shocks and makes it possible to test the sensation
speed (the first factor that is affected in the CTS) the motorial speed,
the latency and amplitude of sensory and motor responses of the nerve
elicitated by the electric shock. However, to estimate the severity of
the syndrome and exclude nervous problems at different levels (for example,
cervical compression), the tests must be completed with the EMG test,
using tiny needles to record the muscular activity.
Cervical radiculopathy, brachial plexus problems, and polyneuropathy in
general often give rise to symptoms that simulate the CTS, and only a
correct complete test will help detect the difference.
The latter also allows classification of the extent of damage (as shown
on the main page).
In some patients even the first stage of the problem, with negative EMG/ENG
result can still be very troublesome.
Diagnosis of CTS is therefore usually not very difficult if the diagnostic
procedure is complete.
Which is the evolution of the Carpal Tunnel Syndrome?
Usually in the absence of treatment or change in the work activity,
CTS tends to worsen over the years.
In some patients however, it may remain unchanged over time.
Clinical experience shows that the symptoms worsen in cold weather and
lessen in warm weather although the severity of the disease does not change.
What anaesthesia is used for the operation and what is the duration of the convalescence?
Anaesthesia may be local or in the brachial plexus (in the armpit). Convalescence depends on the operation (traditional or by endoscopy) and varies from two to four weeks.
A structure that anchors a muscle to the skeleton and transmits the muscular contraction to the bone.
What is tendonitis and tenosynovitis?
Tendonitis is an inflammation of a tendon while tenosynovitis is the inflammation of its covering sheath; both conditions normally occur simultaneously.
What are the causes of tendonitis and tenosynovitis?
The causes are not always clear. Repeated and/or excessive movements are generally considered to be responsible. More rarely, they may be secondary to systemic diseases such as goitre, kidney failure, etc.
What are the symptoms of tendonitis and tenosynovitis?
Pain during movement is the main symptom; if the sheath is filled with fluid, there is swelling and it becomes impossible to make any movements.
What are the most common forms of tendonitis and tenosynovitis?
The sites most affected are the articular capsule of the shoulder, the radial and ulnare flexor of the carpal, the flexor muscle in the finger, the adductor longus tendon and extensor pollicis brevis, the Achilles tendon.
Which are the work activities most risky for hand-wrist tendonitis?
Epidemiological studies have shown high risk in workers in the manufacturing industry, those in the meat sector, those who have been continuing with the activity for a long time, the force used, and repetitivity of movements. The dimensions of the groove through which the dorsal tendons of the hand and wrist run are reduced and the pressure resulting from repetitive work activity can lead to inflammation of the tendon.
What is the treatment for tendonitis and tenosynovitis?
Solving the problem will require a long time (months), and different treatments can be used: rest, staying still (splints, corsets) infiltrations, physiotherapy, and more rarely surgical exploration.