CARPAL TUNNEL
SYNDROME
Carpal
tunnel syndrome is the most common compression neuropathy in the upper
extremity. The median nerve becomes compressed beneath the transverse carpal
ligament, which is the roof of the carpal tunnel. The carpal tunnel itself
contains nine flexor tendons, their associated synovium, and the median nerve.
The patient most often complains
that the hand “goes to sleep.” Activities such as driving the car, holding a
book, or blow drying the hair will often exacerbate these symptoms. Night-time
wakening is nearly universal as the wrist is pulled into a flexed position
during sleep by the strong wrist flexors, and this is often the symptom that
encourages the patient to seek medical advice.
The diagnosis of carpal tunnel
syndrome is made by a careful clinical history combined with a focused physical
examination. Associated conditions including diabetes mellitus, rheumatoid
arthritis, gout, hypothyroidism, and pregnancy must be discussed. Physical
examination first excludes more proximal nerve compression (cervical, brachial
plexopathy, pronator syndrome). The Phalen test and percussion of the median
nerve at the carpal tunnel can reproduce paresthesias into the radial three
digits. Direct compression over the median nerve (Durkan test) has been shown
to be both sensitive and specific for diagnosing carpal tunnel syndrome.
Sensory testing should also be performed, as well as evaluation for thenar
atrophy signs of more advanced/prolonged median nerve
compression. Electrodiagnostic testing is frequently obtained to confirm the diagnosis,
grade the severity of median nerve compression/injury, and provide prognostic
nformation for recovery after surgical decompression.
Initial treatment consists of night
splinting with the wrist in neutral, use of anti-inflammatory medications when
appropriate, and modification of activities. The next step in treatment employs
injection of corticosteroid into the carpal canal. Eighty percent of patients
report symptom improvement after injection lasting on average 3 to 9 months. Failure
of conservative measures or patients presenting initially with severe
compression/thenar atrophy/dense numbness are considered for surgical
release of the carpal tunnel. Surgery can be performed either open or
endoscopically with the shared goal of complete release of the transverse
carpal ligament and distal antebrachial fascia. Complete relief of night
symptoms occurs quickly, while sensory improvement takes longer to recover.
Residual numbness is not uncommon in severe cases, and patients must be educated
prior to surgical release about this occurrence.
