CARPAL TUNNEL SYNDROME

Name: HLL

Age: 45 yrs

Sex: Female

Race: Chinese

R/N: 02/1016

Sarawak General Hospital

Case Report

45 year old Chinese housewife presented with the chief complaint of progressive pain

and numbness over the left wrist for more than 5 years. She clearly states that her left

hand has the tendency to drop objects and also has severe nocturnal parasthesia. Her

pain in the left hand most often disturbs her sleep. She has no known medical illness.

On examination noted patient to have Tinel sign and Phalen test positive. The Phalen

test positive was elicited withen 15 seconds. There was no significant thenar muscle

wasting but mild weakness was noted. Her abductor pollicis brevis muscle power was

grade 4. Two point discrimination test over her index and middle finger showed more

than 10mm. Careful examination of the cervical spine and L shoulder revealed no

abnormalities. Semmes Weinstein Monofilament test showed diminished light touch

and protective sensation of the L thumb, index and middle finger.

She was diagnosed to have L carpal tunnel syndrome.

Patient was initially subjected conservative management by using a splint and tablet

neurobion. After 3 months patient was reviewed and she complained of pain with no

improvement in her symptoms. She was subjected for an open carpal tunnel release on

27/2/03 under general anaesthesia. The median nerve was found to be flattened due

adhesion of surrounding tissues. The carpal transverse ligament was divided under

direct vision and neurolysis was done. Next light dressing applied, followed by

splinting of the L hand. After 3weeks post operative patient claimed to have reduced

night pain and Semmes Weinstein Monofilament showed minimal improvement. At 6

weeks patient claimed to be symptom free and the Semmes Weinstein Monofilament

was normal.

DISSCUSSION

Carpal tunnel syndrome is increasingly recognized as one manifestation of overuse

syndrome resulting in compression of median nerve at the wrist. In 1880 James

Putnam, a Boston neurologist published a report on a previously un-described

condition of pain and paraesthesia in the median nerve distribution of the hand

attributing it aetiology to vasomotor in origin. (A Thurston, 2000)

Hunt stressed that the numbness and paraesthesia according to their distribution is

more attributed to the compression of the thenar branch of the median nerve as it

passes beneath the transverse carpal ligament as a result of occupational overuse

(A Thurston, 2000)

In 1913 Marie and Foix reported that the thenar atrophy was due to the median nerve

compression and by early transaction of the transverse carpal ligament the progression

of the disease can be arrested. However Learmonth preformed the first surgical release

of the transverse carpal ligament in 1933.

In order to understand the treatment of this problem, we will discuss the anatomy,

etiology, pathophysiology, diagnosis and treatment option of carpal tunnel syndrome.

ANATOMY

Carpal tunnel is a fibro-osseous tunnel present at the wrist. Flexor retinaculum forms

the roof of this tunnel. Medially attached to hook of hamate and pisiform. Laterally

attached to trapezium and scaphoid tubercle. The floor formed by carpal bones. Ten

structures pass thro this tunnel.

1) flexor pollicis longus

2) four superficial flexor digitorum to the finger

3) four deep flexor digitorum to the fingers

4) median nerve

All structures are surrounded by thick synovial lining of radial and ulna bursae. (2)

The recurrent motor branch of median nerve has three common variants;

extraligamentous (46%), subligamentous (31%), transligamentous (23%).The latter

two are at risk for injury during carpal tunnel release.The communicating median and

ulnar nerve is present in 80% to 90% of cases and may lie in close proximity to the

distal edge of the transverse carpal ligament. The injuries can result in a postoperative

parasthesia to the long and ring finger.The palmar cutaneous branch originates from

the median nerve in the forearm, approximately 8cm proximal to the wrist crease an

continues distally between the flexor carpi radialis and palmaris longus tendons.

It becomes superficial at the wrist and is vulnerable to both transverse and oblique

wrist incisions.

PATHOPHYSIOLOGY AND ETIOLOGY

Any condition that leads to the swelling of the synovial tissue or increase in the

volume of structures inside the carpal tunnel will cause compression of the median

nerve.

Factors causing carpal tunnel syndrome

1) Anatomy

a) decrease in the size of the carpal tunnel

bony abnormalities of the carpal bones

acromegaly

flexion and extension of the wrist

b) increase in contents of the canal

forearm and wrist fractures (e.g. Colles and scaphoid fractures)

dislocation and sublaxation of the carpal bones (e.g. Scaphoid rotatory

sublaxation, lunate volar dislocation)

post traumatic arthritis (e.g. Osteophytes)

musculotendinous variants

aberrant muscles (e.g. lumbricals , palmaris longus)

local tumours (e.g. Neuroma, lipoma, multiple myeloma)

persistent medial artery (thrombosed/ patent)

hyperthrophic synovium

hematoma (e.g. hemophilia, anticoagulant therapy, trauma)

2) Physiology

a) neuropathic conditions b) inflammatory conditions

diabetes mellitus non specific synovitis

alcoholism gout

double crush syndrome rheumatoid arthritis

c) alteration in fluid balance

d) external forces

pregnancy vibration

menopause direct pressure

eclampsia

hypothyroidism

renal failure

long term dialysis

raynaud disease

Paget disease

Scleroderma

obesity

amyloidosis

Rojviroj et al (1992) reported that he pressure of the carpal tunnel in patients with an

idiopathic carpal tunnel syndrome, was significantly higher than normal and the mean

pressure was highest in 90 degrees of wrist dorsiflexion and lowest in the neutral

position. Szabo (1982) reported similar findings but showed that after repeated

extending and flexing the wrist, recovery to resting pressure took longer than in

patients without carpal tunnel syndrome.

Changes in the nerve following compression are complex and multifactorial including

nerve ischemia and changes in axoplasmic transport. As paranodal swelling occurs,

internodal myelin thins leading to segmental demyelination.

Prolong and repeated damage to the myelin alters the axon distal to the point of

compression. If compression persist all modalities – motor, sensory and autonomic can

be affected. [5]

CLINICAL MANISFESTATION AND DIAGNOSIS

Commonest symptoms are sensory in nature with the patient reporting the hand ‘going

to sleep’. Numbness mostly confined to the median nerve distribution with index and

middle finger involved. (initially intermittent but may become persistent and

aggravated with wrist flexion)

Sympathetic disturbances such as excessive sweating and mild edema. As carpal

tunnel syndrome worsens nocturnal pain and tingling sensation may wake the patient.

Shaking or rubbing the hand relieves the pain temporarily.

Motor involvement may present as clumsiness due to weakness intrinsic thenar

musculature supplied by median nerve. Patient develops tendency to drop things and

difficulty in unscrewing bottle caps.

Based o pattern of involvement carpal tunnel syndrome can be divided into three

stages; early, progressive and late. In early the symptoms only arise when provoked. In

progressive the sensory symptoms are always there with mild motor symptoms. In late

both sensory and motor involvement are quite advanced and thenar wasting is usually

noted.

DIAGNOSTIC TEST

a) abductor pollicis brevis power test – compare the strength on the normal and affected side.

b) two point discrimination which is mapped out on the finger –tips

c) tinsel’s test

d) phalen’s test

e) reverse phalen’s test

Songcharoen et al (1988) evaluated the usefulness of the above test where tinnel’s was

95% specific, Phalen’s was 76.1% specific where else reverse phalen’s was less

specific.

INVESTIGATION

a) Nerve conduction studies can be used to confirm the diagnosis and maybe useful in

deciding whether surgery is needed. It must be kept in mind that false negative

results could occur. Grundberg (1983) reported 8% of symptomatic patients with

normal electrical studies.

b) Radiographs – carpal tunnel syndrome following traumatic events or associated

with osteoarthritis a normal AP x-ray will be needed to rule out any bony

pathology.

DIFFERENTIAL DIAGNOSIS

1) cervical radiculopathy

2) thoracic outlet compression

3) anterior interosseous nerve entrapment

4) double crush syndrome

5) polymyalgia rheumatica

TREATMENT

A) Conservative

this mode of treatment is usually offered to early stages of carpal

tunnel syndrome. It compromises of night splints, NSAID, change in daily

activities/occupation causing the symptoms, physiotherapy, steroidal

injections. (Gelberman RH, 1992

Splinting- a regimen of day and night splinting is believed to reduce median nerve

irritation due to excessive extension.

if symptoms improve by 3 months then only continue night splinting.

if no improvement noted then add NSAID/ steroidal injections for 3 months.

Despite the above treatment if severity still increases to opt for surgical release.

Physiotherapy and occupational therapy that is aimed to evaluate static and dynamic

postures that increases the overuse of certain group o muscles.

Pain, edema and weakness can be treated with fluid therapy and TENS (transcutaneous

electrical nerve stimulation)

Pyridoxine administered in deficiency states causing carpal tunnel syndrome

Steroid (hydrocortisone) injection into carpal tunnel to reduce swelling due to flexor

Tenosynovitis has published reports to suggest up to 80% improvement initially in

patients with early carpal tunnel syndrome and only about 10% of these patients have

permanent relief. (Gelberman RH, 1992)

B) Surgery

Indication: - failed conservative management in patients with early carpal tunnel

syndrome.

:-patients who present with progressive and late carpal tunnel syndrome

:-acute presentation of carpal tunnel syndrome.

Principal of the surgery would be to decompress the median nerve by releasing the

transverse carpal ligament.

Techniques a) open carpal tunnel release

b) double incision of ‘Wilson’

c) minimal incision of ‘Bromley’ – endoscopic technique

In open carpal tunnel release generally a longitudinal curved incision is made over the

palm region parallel to the thenar crease. The incision can be in a form of a lazy “S”

thus avoid crossing the flexor crease at right angle to avoid painful scar post operatively

On reaching the transverse carpal ligament, place a blunt dissector beneath

the fascia and then incise the whole breath of the ligament (avoid injury to the

superficial palmar arterial arch about 5-8mm distal to the transverse carpal ligament. If

synovitis is present then tenosynovectomy may be indicated. After the surgery

compression dressing and volar splinting must be carried out.

In the past few years, endoscopic techniques have been used more widely to decrease

the incidence of post operative pain and painful scar from and open operative

procedure

Advantages of endoscopic surgery are

-less palmar scarring

-less ulnar pillar pain

-rapid return to work and complete return of hand strength.

Disadvantages of endoscopic surgery

-technically demanding procedure

-limited visual field

-increase chances to injure median nerve flexor tendons and superficial palmar artery

arch

-inability to control bleeding

-limitation caused by mechanical failures.

Contraindication of endoscopic release are

-patients who require neurolysis, tenosynovectomy or decompression of guyon’s

canal.

-presence of space occupying lesions and muscle, tendon or vessel abnormalities.

-patients with localized infection.

-patients who have undergone previous surgeries and currently requires revision surgery

-presence of anatomical variants of median nerve.

Orthopedic surgeons are working to improve endoscopic carpal tunnel release by

modifying techniques or instrumentation. Chow (1993) has refined his two portals

approach by replacing an extrabursal approach for the original transbursal technique,

with fewer post operative complications.

Recently, Mirza et al 1996 introduced a distal (palmar) uniportal endoscopic carpal

tunnel release .Mirza and King belief that a distal (palmar) uniportal endoscopic carpal

tunnel release has it benefits since it is a single incision in the palm which excludes the

need for a second incision in the wrist and avoids injury to the palmar cutaneous

branch of the median nerve. However all endoscopic wrist surgery has a large learning

curve and needs to be performed by experienced hands.

REFERENCES

1. A. Thurston: Aetiology of the so called ‘idiopathic’ carpal tunnel syndrome.

Current Orthopaedics NOV 2000.

2. Carpal Tunnel and ulnar Tunnel Syndromes and Stenosing Tenosynovitis:

Campbell Operative Orthopaedic Volume 4; 3638

3. Gelberman RH, Aronson D, Weisman MH; Carpal Tunnel Syndrome, result of

a prospective trial of steroid injection and splinting. J Hand Surg

1992; 17A:1003-1008.

4. Grundberg AB: Carpal tunnel decompression in spite of a normal

electromyography. J Hand Surg 1983; 348-349.

5. Mirza MA, King ET, Newer techniques of carpal tunnel release. Ortho Clin.

North Am. 1996; 27:355-371.

6. Rojviroj S, Sirichativapee N, Kowsuwon W, Wongwiwattananon J, Tamnan

thong N, Jeeravipoolvam P: Pressures in the carpal tunnel. A comparison ofpatients

with carpal tunnel syndrome and normal subjects. J Bone and Joint Surg 1990; 72B 516-518.

7. Szabo RM, Gelberman RH, Williamson RV, et al: Vibratory sensory testing in

acute peripheral nerve compression. J Hand Surg 1984; 9A 104-109.

8. Topics in upper extremity care published jointly by the Christine M. Kleinert Institute for

Hand and Microsurgery and Louisville Hand Surgery.