Carpal Tunnel Syndrome

(Braunwald, 15/e, pp 1984–1986.) Carpal tunnel syndrome results from median nerve entrapment and is usually due to excessive use of the wrist. The process has been associated with thickening of connective tissue as in acromegaly, or with deposition of amyloid. It also occurs in hypothyroidism, rheumatoid arthritis, and diabetes  mellitus. As in this patient, numbness occurs  in  the  distribution  of  the  median  nerve. Later  in  the  process,  atrophy  of  the  abductor pollicis brevis becomes apparent. The Tinel sign (parasthesia induced in the median nerve distribution by a reflex hammer hitting on the volar aspect of the wrist) is very characteristic. De Quervain’s tenosynovitis causes focal wrist pain on the radial aspect of the hand and is due to inflammation of the tendon sheath of the abductor pollicis longus.  It  should  not  produce a  postive Tinel sign. Amylotrophic lateral sclerosis may present with distal muscle weakness that is diffuse and not focal. Diffuse atrophy and muscle fasiculations would be prominent. Rheumatoid arthritis would not produce these symptoms unless inflammation  of  the  wrist  was  causing  median nerve entrapment in the carpal tunnel.

Tuberculosis REF: Apley’s system of orthopedics & fracture 8′ edition page 247-248

Carpal tunnel syndrome is produced by entrapment of median nerve beneath the flexor retinaculum. Associated conditions that can leads to carpal tunnel syndrome are:

1. Idiopathic (most common)
2. Pregnancy
3. Endocrine disorders

• Hypothyroidism
• Diabetes mellitus
• Myxedema
• Acromegaly
• Hyperparathyroidism

4. Deposition disorders

• Rheumatoid disorder
• Gout
• Rheumatic disorder
• Amyloidosis
• Sarcoidosis
• Leukemia
• Chronic renal failure

Many systemic conditions are strongly associated with carpal tunnel syndrome (CTS).

These conditions may directly or indirectly affect microcirculation, pressure thresholds for nerve conduction, nerve cell body synthesis, and axon transport or interstitial fluid pressures.

Perturbations in the endocrine system, as observed in individuals withdiabetes, acromegaly and hypothyroidism and in women who are pregnant, are linked to CTS.

Conditions affecting metabolism (eg, alcoholism, renal failure with hemodialysis, mucopolysaccharidoses) also are associated with CTS.

Carpal tunnel syndrome is caused by the compression of the median nerve at wrist and is most common type of nerve entrapment syndrome.

 This is usually due to excessive use of the hands and occupational exposure to repeated trauma.

Infiltration of the transverse carpal ligament with amyloid (as occur in multiple myeloma) or thickening of connective tissue in rheumatoid arthritis, acromegaly, amyloidosis, mucopolysaccharidosis and hypothyroidism are less common cause of the syndrome.

It is not uncommon for the condition to make its appearance during pregnancy.

The tendon of flexor carpi radialis lies within a split in the flexor retinaculum i.e. between the retinaculum and its deep slip. It thus lies in a separate tunnel or compartment formed between two slips of flexor retinaculum and not within the true carpal tunnel. The true carpal tunnel lies deep to the flexor retinaculum including its deep slip radially.

The patient’s symptoms are classic for carpal tunnel syndrome. Carpal tunnel syndrome is the most common compressive neuropathy in the upper extremity. It is caused by compression of the median nerve in the carpal tunnel. The median nerve provides sensation to the palmar side of the thumb, index finger, long finger and radial half of the ring finger. The floor of the tunnel is formed by the carpal bones; the roof is formed by the transverse carpal ligament.

• A patient with a C5 nerve cervical nerve root compression would have weakness in their deltoids and biceps with sensory changes in the lateral arm.
• Cubital tunnel syndrome is compression of the ulnar nerve at the elbow. Symptoms include pain and paresthesias over the medial forearm and hand as well as weakness in the ulnar nerve distribution.
• Radial tunnel syndrome is compression of a branch of the radial nerve at the forearm. It is a pain-only problem without motor or sensory changes. 

D i.e. Oppose the thumb

Ans. is ‘d’ i.e., Beta2 microglobulin

o Patient on long-term hemodialysis for renal failure develop amyloidosis as a result of deposition of beta2 microglobulin.

Ans. is ‘c’ i.e., Addisons disease 

Answer is D (Addison’s disease):

Addison’s disease is not associated with carpal tunnel syndrome

Endocrinal Causes of Carpal Tunnel Syndrome

• Acromegaly (CMDT)
• Hypothyroidism (Myxoedema) (Harrison’s)
• Hyperparathyroidism (CMDT)
• Diabetes Mellitus (Harrison’s)

Ans. A: Hyperparathyroidism

Carpal tunnel syndrome (CTS) is a compressive neuropathy of the median nerve at the wrist.

The carpal tunnel is located at the base of the palm and is bounded on 3 sides by carpal bones and anteriorly by the transverse carpal ligament.

Inside run the median nerve, flexor tendons, and their synovial sheaths.

Following may be the factors for CTS:

• Inflammation of the flexor tendon sheath caused by activities involving repetitive wrist flexion (e.g., assembly packing, computer keyboard work, playing a musical instrument, craftwork)
• Edema from trauma of any type (e.g., fractures), which can compress the median nerve
• Compression of the median nerve from pregnancy or oral contraceptive-related edema
• Strong association between being overweight or obese and the presence of CTS
• Acromegaly
• Rheumatoid arthritis
• Gout/ pseudogout
• TB
• Renal failure and hemodialysis
• Hypothyroidism
• Amyloidosis
• Wrist osteoarthritis

Ans. B: Median Nerve

Ans. is ‘c’ i.e., Leprosy

Carpal tunnel syndrome

• Carpal tunnel syndrome is the most common and widely known entrapment neuropathy in which the body’s peripheral nerve is compressed or traumatized. Carpal tunnel syndrome occurs when the median nerve is compressed in the carpal tunnel below flexor retinaculum. The carpal tunnel is a narrow rigid passage way of ligament and bones at the base of hand, in front of distal part of wrist. Carpal tunnel houses the median nerve and 9 tendons (4 FDS, 4 FDP & FPL).

Causes of carpal tunnel syndrome

There are many causes of carpal tunnel syndrome :

1)     Idiopathic : – This is the most common cause.

2)     Pregnancy and menopause

3)     Metabolic : – Gout, Diabetes mellitus

4)     Endocrine : – Hypothyroidism, Myxedema, Acromegaly, Hyperparathyroidism.

5)     Deposition disorder Amyloidosis, Sarcoidosis, Rheumatid arthritis, Leukemia, CRF, Mucopoly saccharoidosis.

6)     Alcoholism

7)     Local causes : – Malunited colle’s fracture, osteo-arthritis of the carpal bones, synovitits of flexor tendon sheath, hematoma.

Clinical features of carpal tunnel syndrome

Carpal tunnel syndrome is more common in women and occurs between 35-50 years.

Symptoms usually start gradually, with frequent burning, tingling, paresthesia and numbness in the distribution of median nerve, i.e., lateral three & half of fingers and lateral 2/3rd of palm.

The symptoms often first appear during night, since many people sleep with flexed wrists. (Flexion decreases the space in carpal tunnel which results in increased pressure over median nerve).

Sensory symptoms can often be reproduced by percussing over median nerve (Tinel’s sign) or by holding the wrist fully flexed for a minute (Phalen’s test).

As the disease progresses, clumsiness of hand and impairment of digital function develop.

Later in the disease, there is sensory loss in median nerve distribution and obvious wasting of thenar eminence. Clinical Tests for Carpal tunnel syndrome

There are some provocative tests which act as important screening methods : ‑

1) Wrist flexion (Phalen’s test) : – The patient is asked to actively place the wrist in complete flexion. If tingling and numbness develop in the distribution of median nerve, the test is positive. This is the most sensitive provocative test.

2) Tourniquet test : – A pneumatic BP cuff is applied proximal to the elbow and inflated higher than the patient’s systolic BP. The test is positive if there is paresthesia or numbness in the region of median nerve distribution in hand.

3) Median nerve percussion test (Tinel’s sign) : – The median nerve is gently tapped at the wrist. The test is positive if there is tingling sensation.

4) Median nerve compression test : – Direct pressure is exerted equally over both wrists by the examiner. If symptoms of carpal tunnel syndrome appear, the test is positive.

Ans. is ‘A’ i.e., Ulnar nerve

Ten structures pass through the carpal tunnel, most of them flexor tendons(not the muscles themselves):

• flexor digitorum profundus (four tendons)
• flexor digitorum superficialis (four tendons)
• flexor pollicis longus (one tendon)
• Median nerve between tendons of flexor digitorum profundus and flexor digitorum superficialis

Ans. is ‘b’ i.e., Ulnar nerve

Contents of carpal tunnel are 1 nerve and 9 tendons :-

i) Median nerve

ii) 4 tendons of flexor digitorum profunds.

iii) 4 tendons of flexor digitorum superficialis.

iv) 1 tendon of flexor pollicis longus.

Ans. is ‘a’ i.e., Median nerve

Ans. is ‘a’ i.e., Phalen’s test

Clinical tests for carpal tunnel syndrome

• There are some provocative tests which act as important screening methods : ‑

1. Wrist flexion (Phalen’s test) : – The patient is asked to actively place the wrist in complete flexion. If tingling and numbness develop in the distribution of median nerve, the test is positive. This is the most sensitive provocative test.
2. Tourniquet test : – A pneumatic BP cuff is applied proximal to the elbow and inflated higher than the patient’s systolic BP. The test is positive if there is paresthesia or numbness in the region of median nerve distribution in hand.
3. Median nerve percussion test (Tinel’s sign) : – The median nerve is gently tapped at the wrist. The test is positive if there is tingling sensation.
4. Median nerve compression test : – Direct pressure is exerted equally over both wrists by the examiner. If symptoms of carpal tunnel syndrome appear, the test is positive.

Ans. is ‘b’ i.e., Carpal tunnel syndrome

Clinical Tests for Carpal tunnel syndrome

• There are some provocative tests which act as important screening methods : ‑

1. Wrist flexion (Phalen’s test) : – The patient is asked to actively place the wrist in complete flexion. If tingling and numbness develop in the distribution of median nerve, the test is positive. This is the most sensitive provocative test.
2. Tourniquet test : – A pneumatic BP cuff is applied proximal to the elbow and inflated higher than the patient’s systolic BP. The test is positive if there is paresthesia or numbness in the region of median nerve distribution in hand.
3. Median nerve percussion test (Tiners sign) : – The median nerve is gently tapped at the wrist. The test is positive if there is tingling sensation.
4. Median nerve compression test : – Direct pressure is exerted equally over both wrists by the examiner. If symptoms of carpal tunnel syndrome appear, the test is positive.

Ans. is ‘d’ i.e., FCU tendon

• The carpal tunnel is a narrow rigid passage way of ligament and bones at the base of hand, in front of distal part of wrist.
• The carpal tunnel contains nine tendons and a nerve: the flexor pollicis longus, the four flexor digitorum superficialis, the four flexor digitorum profundus as well as the median nerve