Electrodiagnostic Evaluation of Carpal Tunnel Syndrome

Excerpt

Carpal tunnel syndrome (CTS) accounts for approximately 90% of all focal entrapment neuropathy, making it a frequent electrodiagnostic consultation. It is present in about 3.8% of the general population. It is more common in women than in men, and while it occurs in all age groups, incidence generally reaches a peak within the age of 40 to 60 years. Hypothyroidism, diabetes mellitus, rheumatoid arthritis, gout, peripheral edema, acromegaly, tumors, trauma, and pregnancy are risk factors that predispose patients to develop CTS. Furthermore, patients whose occupations rely on the hands' repetitive movements and those with forceful hand movements are also prone to developing CTS.

The clinical presentation typically reveals numbness, weakness, and paresthesias within the thumb, index, middle, and radial side of the ring finger. The thenar area has normal sensation as the palmar cutaneous sensory branch innervates it, which does not pass through the carpal tunnel. However, the recurrent thenar motor branch does pass through the carpal tunnel and gives innervation to the opponens pollicis, abductor pollicis brevis, and superficial head of the flexor pollicis brevis. Patients' symptoms tend to worsen at night or during the hand's repetitive movements, especially those requiring prolonged wrist flexion.

Depending on the severity of the patient's symptoms, they can categorize into three stages. Stage 1 presents with frequent awakenings at night due to tingling in their hands and fingers, which may last through the morning with associated stiffness. Stage 2 shows symptoms that are also present during the day. Motor deficits may also be apparent with patients reporting dropping objects from their hands. Stage 3, the final stage, demonstrates atrophy of the thenar muscles and may respond poorly to surgical decompression.