Monday, August 4, 2008

70 - carpal tunnel syndrome

This condition was previously most commonly found
in women, 30 to 60 years of age. With the
increasing use of computers, Carpal Tunnel syndrome
is now seen with increasED frequency in all ages,
both in men and women.

Compression of the median nerve as it passes
through the carpal tunnel under the transverse
carpal ligament leads to signs and symptoms in
the distribution of the median nerve. People in
occupations that require chronic repetitive wrist
motion in flexion, extension, and gripping are
prone to develop carpal tunnel syndrome. Common
occupations include typists, computer operators,
grocery checkers, dental hygienists, and packing
house workers. Another factor in the development
of carpal tunnel syndrome is any activity that
results in chronic trauma to the volar side of
the wrist.

Carpal tunnel syndrome that develops as a result
of repetitive vibrational injury may have a worse
prognosis as the nerve may be injured both by
compression as well as recurrent mechanical
trauma. Assembly line, construction workers
involved in repetitive hammering, carpenters, and
electrical workers are prone to develop carpal
tunnel syndrome. Many times it is helpful if
patients can perform different types of
activities during an 8-hour shift (part of time
assembly line, part of time another job within
same factory).

Not all cases of carpal tunnel syndrome are due
to repetitve trauma. Premenstrual fluid
retention, early rheumatoid arthritis with
synovial tendon sheath thickening, distal radius
or carpal fractures may be responsible as they
restrict the space left for the nerve in the
carpal tunnel. The condition is sometimes seen in
association with thyroid disease, acromegaly, and
pregnancy. Diabetic patients are at increased
risk. Often, however, no obvious cause can be
found. Patients complain of paresthesias in the
hand and clumsiness in handling objects. Often
they claim that all the fingers are involved and,
although theoretically the little finger should
be spared, approximately 30% of patients also
have paresthesias in the ulnar nerve
distribution. Pain may radiate proximally to the
elbow or shoulder. Weakness of grip is also
common. The symptoms may become most marked at
night, often awakening the patient (nocturnal
paresthesias) and causing the patient to shake
the hand or hang it over the side of the bed. In
many cases the history and clinical examination
are unequivocal. In others it may be difficult
to differentiate the patient's symptoms from
those produced by radiculitis of the sixth
cervical root, pronator syndrome, or diabetic
peripheral neuropathy; indeed both conditions may
be present at the same time as carpal tunnel

Two-point discrimination testing:

is useful when screening for any of the compression
neuropathies such as carpal tunnel syndrome. The
test is performed by either bending the prongs of
a small paper clip so that there is a 6 mm
distance between the tips or by using a
commercially available two-point discrimination
caliper. The tips are placed against the volar
pulp of the fingers until there is a slight
blanching of the skin under the prongs. The
patient is then asked if he/she is able to
discriminate between one or two points. Both
hands should always be tested as bilateral carpal
tunnel syndrome is common. Normal two-point
discrimination is 4-6 mm. On physical examination
two-point discrimination may be abnormal (greater
than 6 mm), grip strength diminished, and thenar
atrophy present.

Tinel Test:

This test is performed by having the examiner
gently tap the area over the median nerve at the
wrist palmarly. While this can be done with a
reflex hammer it is done better using the
examiner's long finger bent 90 degrees at the PIP
joint as this joint is more sensitive. The test
result is considered positive if this produces
tingling in the fingers.

Phalen's(Wrist-Flexion) Test: The
patient actively places the wrist in complete but
unforced flexion. If numbness and tingling are
produced or exaggerated in the median nerve
distribution of the hand within 60 seconds, the
test result is considered positive. In patients
with limited wrist motion gentle compression over
the median nerve may produce the same result


For patients seen early, before the development
of abnormal two-point discrimination or thenar
atrophy, splinting of the wrist with or without
injection of steroids into the carpal canal may
prove successful.

If conservative treatment does
not relieve the symptoms electrodiagnostic
testing (EMG, NCV) is useful
when contemplating surgery or trying to rule out
another etiology. If, at the time of
presentation, there is either thenar atrophy or
abnormal two-point discrimination in the
distribution of the median nerve then surgical
release of the transverse carpal ligament is the
best treatment.

Surgical options:

Carpal tunnel release can be performed either utilizing
and open (standard) approach or Endoscopically through a
small incision at the wrist. The open approach is safer
when performing a revision carpal tunnel release.

Postoperatively, patients are typically protected
in a removable volar resting wrist
splint for 2 to 3 weeks. During this time finger
motion is encouraged. After the splint is removed
wrist range of motion exercises and grip
strengthening are started. Most patients will
return to their preoperative level of grip
strength and wrist motion by 3 months. Not all
patients require therapy after surgery but if
progress appears slow, referral to an
occupational or hand therapist should be made.
Patients are usually ready to return to work
between 6 and l2 weeks postoperatively after open
Carpal Tunnel release and typicall after 3 to 6 weeks
after endoscopic Carpal Tunnel Release (ECTR).

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