Carpal tunnel syndrome is a common disorder
characterized by pain, burning , and tingling of the
palmar surface of the hand, resulting from compression
of the median nerve between the carpal ligament and
other structures within the carpal tunnel (entrapment
neuropathy) The volume of the contents of the tunnel can
be increased by organic lesions such as synovitis of the
tendon sheaths or carpal joints, recent or malhealed
fractures, tumors, and occasionally congenital
anomalies. Even though no anatomic lesion is apparent,
flattening or even circumferential constriction of the
median nerve may be observed during operative section of
the ligament. The disorder may occur in pregnancy, is
seen in individuals with a history of repetitive use of
the hands, and may follow injuries of the wrists.
A familial type of carpal tunnel syndrome has been
reported in which no etiologic factor can be identified.
Carpal tunnel syndrome can also be a feature of many
systemic diseases: rheumatoid arthritis and other
rheumatic disorders (inflammatory tenosynovitis);
myxedema, amyloidosis, sarcoidosis, and leukemia (tissue
infiltration); acromegaly; hyperparathyroidism,
hypocalcemia, and diabetes mellitus.
Clinical Findings
Pain in the distribution of the median nerve, which may
be burning and tingling (acroparesthesia), is the
initial symptom. Aching pain may radiate proximally into
the forearm and occasionally proximally to the shoulder,
neck, and chest. Pain is exacerbated by manual activity,
particularly by extremes of volar flexion or
dorsiflexion of the wrist. It may be most bothersome at
night.
Impairment of sensation in the median nerve distribution
may not be apparent. Subtle disparity between the
affected and opposite sides can be demonstrated by
testing for two-point discrimination or by requiring the
patient to identify different textures of cloth by
rubbing them between the tips of the thumb and the index
finger. Tinel's or Phalen's sign may be positive.
(Tinel's sign is tingling or shock-like pain on volar
wrist percussion; Phalen's sign, pain or paresthesia in
the distribution of the median nerve when the patient
flexes both wrists to 90 degrees with the dorsal aspects
of the hands held in apposition for 60 seconds.) The
carpal compression test, performed by applying direct
pressure on the carpal tunnel, may be more sensitive and
specific than the Tinel and Phalen tests. Muscle
weakness or atrophy, especially of the abductor pollicis
brevis, appears later than sensory disturbances. Useful
special examinations include electromyography and
determinations of segmental sensory and motor conduction
delay.
Distal median sensory conduction delay may be evident
before motor delay.
Differential Diagnosis
This syndrome should be differentiated from other
cervicobrachial pain syndromes, from compression
syndromes of the median nerve in the forearm or arm, and
from mononeuritis multiplex. When left-sided, it may be
confused with angina pectoris.
Treatment
Treatment is directed toward relief of pressure on the
median nerve. When a primary lesion is discovered,
specific treatment should be given. When soft tissue
swelling is a cause, elevation of the extremity may
relieve symptoms. Splinting of the hand and forearm at
night may be beneficial.
Injection of corticosteroid into the carpal tunnel can
alleviate symptoms in some patients, particularly those
with synovitis of the wrist. To reduce the chance of
nerve injury, this injection should be performed by a
physician thoroughly familiar with the anatomy of the
carpal tunnel.
Operative division of the volar carpal ligament gives
lasting relief from pain, which usually subsides within
a few days. Muscle strength returns gradually, but
complete recovery cannot be expected when atrophy is
pronounced.
