What is Carpal Tunnel Syndrome?

First described by Paget in 1854 [1], Carpal Tunnel
Syndrome (CTS) remains a puzzling and disabling condition
commonly presented to Rheumatologists and Orthopaedic
Hand clinicians. It is a compressive neuropathy, which is
defined as a mononeuropathy or radiculopathy caused by
mechanical distortion produced by a compressive force [2].
The American Academy of Orthopaedic Surgeons (AAOS)
Clinical Guidelines on the Diagnosis of CTS defines it as a
symptomatic compression neuropathy of the median nerve at
the level of the wrist [3].
 CTS is the most well-known and frequent form of
median nerve entrapment [3-8], and accounts for 90% of all
entrapment neuropathies [9]. An entrapment neuropathy is a
chronic focal compressive neuropathy caused by a pressure
increase inside non-flexible anatomical structures [10]. CTS
is a neuropathy caused by entrapment of the median nerve at
the level of the carpal tunnel, delimitated by the carpal bones
and by the transverse carpal ligament [2]. Physiological
evidence indicates increased pressure within the carpal
tunnel, and therefore decreased function of the median nerve
at that level [3].
 Other forms of median nerve entrapment neuropathies
include pronator syndrome and anterior interosseous nerve
syndrome. Pronator syndrome is defined as compression of the
median nerve in the forearm that results in sensory alteration in
the median nerve distribution of the hand and the palmar
cutaneous distribution of the thenar eminence [11, 12].
Anterior interosseous nerve syndrome [13] is characterised by
complete or partial loss of motor function of the muscles
innervated by the anterior interosseous nerve (AIN), a motor
branch of the median nerve in the forearm [4].