Median neuropathy is a term describing the injury to the median nerve along its path from the brachial plexus to the distal forearm. The nerve is most susceptible to injury within the carpal tunnel. The term carpal tunnel syndrome is used to describe median nerve injury at that site, but median neuropathy can occur through numerous other mechanisms, which is why a thorough diagnostic workup is necessary.
The clinical presentation of median neuropathy depends on the location where the median nerve is injured. In the vast majority of cases, however, the carpal tunnel is the site where the injury occurs, and the term "carpal tunnel syndrome" is used as a distinct clinical entity to describe the pathophysiological and clinical changes . Several risk factors have been established, such as diabetes mellitus (a significantly higher incidence rate is observed compared to the general population), genetic predisposition, female gender, and profound occupational wrist efforts  . Most important symptoms are a pain of the hand (the thumb and the first two and a half fingers are innervated by the median nerve) and the wrist that often wakes patients at night, and is accompanied by paresthesias. Additionally, sensory loss in the abovementioned fingers on the palmar side of the hand and weakness or wasting of the thenar muscles (opponens pollicis, flexor pollicis brevis and abductor pollicis brevis) are signs of severe median nerve injury   . The dominant hand is more frequently affected, but a bilateral presentation may be observed as well.  . Apart from the carpal tunnel, the antecubital fossa is also an important site where median neuropathy can originate from, with most common causes being the injury during intravenous injection or cannulation, and trauma .
The diagnosis of a median neuropathy can be made successfully if all steps during workup are conducted properly, including a detailed patient history, a careful physical examination, and laboratory or imaging studies in the diagnosis is unclear. Firstly, information regarding the onset and severity of symptoms, as well as their location and duration, is of essential importance to the physician. The physical examination must include two tests - flexion of the wrist to 90 degrees for 1 minute, which could result in paresthesia (known as the Phalen's sign) and percussion of the nerve at the carpal tunnel (the onset of paresthesia indicates a positive Tinel's sign)  . If these measures do not provide enough clinical evidence, additional investigations include electromyography, nerve conduction studies, magnetic resonance imaging (MRI) and high-resolution ultrasonography (HRUS), a useful adjunctive method for the diagnosis of median neuropathy, being inexpensive, non-invasive and readily available  . Because diabetes mellitus is an important risk factor for carpal tunnel syndrome, blood glucose levels should be evaluated in all patients who present with signs and symptoms suggestive of this condition  .