carpal tunnel overview

 

What is a carpal tunnel syndrome?

carpal tunel syndrom is a compression damage (an entrapement) of an important hand nerv. (median neve)

carpal tunnel and median nerv
carpal tunnel and median nerv

Affected by this pressure damage is the Nervus medianus (in the Illustration marked yellow below and located between the two black arrows)

Near the wrist, a wide torn tensions between the thumb ball and the small finger ball. (Arrows)

This torn is the roof of the canal. This canal is calles carpal canal or carpal tunnel.

The carpal tunnel contains an important nerve of the hand – the Nervus medianus. (Marked yellow in the graphic, between the black arrows)

With a carpal tunnel syndrome (CTS), the canal is too narrow and pressure is applied on the nerve (Nervus medianus = centre hand nerve).

What is the carpal tunnel ?

The carpal tunnel is a tunnel-like tube, which is located in the recess between the thum ball musculature and the small finger ball musculature.

Roof of carpal tunnel
Roof of carpal tunnel

The illustration shows how the the roof of the carpal tunnel is seen during a surgery. The clamp is located in the carpal canal, straight under the roof.

What happens through the nerve pressure?

The clamped nerve hurts. Typical for this symptom is, that the pain is severe, especially during night. As the disease pattern proceeds, a numb feeling occurs, which is affecting expecially the thumb, index finger and middle finger.

If the disease is existing for several years, the thenar muscle often decrease. The thumb can not strongly opposite to the fingers.

carpal-tunnel-advanced
advanced compression of the median nerv

The illustration shows a surgery photography of an advanced carpal tunnel syndrome. The intense change of the median nerv can be recognized with the naked eye.

The blue arrows show the nerve (centre hand nerve) with normal diameter. The red arrow show the hourglass shaped narrowing at the Nervus medianus.

What is the origin of the carpal tunnel syndrome?

There are basically two causes to be distinguished:

  1. Narrowing of the carpal canal (e.g. as a result of a bone fracture)
  2. Abnormal increased volume within the carpal canal: e.g. caused by tumors as a result of  kidney disease (Amyloid with Dialysis patients).

However, those known causes represent only the smaller part of all occuring cases.

Mostly the cause for the disease can not be determined!

What is the trigger for this disease?

The trigger for the pain and the numb feeling is an in crease of volume within the carpal canal.

The increased requirement for space in the carpal tunnel is mostly caused by the proliferation of tendon sheaths in the carpal tunnel. (The bending tendons, located in the carpal tunnel, have a fine coating which are colloquially called tendon sheaths. Those tendon sheaths can remarkably profilerate and cause thereby an increased pressure within the carpal canal)

Who is mainly affected by a carpal tunnel syndrome?

Women around and after the menopause are particularly frequent affected. The carpal tunnel syndrome is, with a frequency of occurence (incidence) of 1%, the most frequent nerve-entrapment disorder.

Men can also be affected. The ration of affected women vs men is 5 : 1 in most hand surgical departments. With children the occurence of the disease is quite rare.

What is a CTS?

Doctors and persons affected often use the abbreviation CTS for Carpal Tunnel Syndrome.

Can both hands be affected by the carpal tunnel syndrome?

Yes. This is more of a rule than an exception. The frequency of a carpal tunnel syndrome on both sides is aroung 80%. Out of this, about 50% are in need of a surgery!

Information about the carpal tunnel syndromes anatomy:

For person with a particular interest, The illustration shows a  section of the carpal tunnel.

thenar_eminence and carpal tunnel
transverse carpal Ligament

next    (diagnosis of carpal tunnel syndrom)

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