Carpal Tunnel Syndrome: Anatomy, Diagnosis, and Treatment

Carpal tunnel syndrome is a nerve entrapment condition caused by compression of the median nerve as it passes through the carpal tunnel in the wrist. The video explains the anatomy of the carpal tunnel, including the carpal arch, flexor retinaculum, nine flexor tendons, and the median nerve, and describes how inflammation and swelling can narrow the space leading to pain, numbness, and tingling in the thumb, index and middle fingers and part of the ring finger. It discusses common risk factors such as repetitive hand use, obesity, pregnancy and rheumatoid arthritis, and explains diagnostic maneuvers like Phalen's, Tinel's signs, and electrophysiological testing. Finally, it outlines treatment options from activity modification and wrist splints to corticosteroid injections and surgical release of the transverse carpal ligament.

Overview of Carpal Tunnel Syndrome

Carpal tunnel syndrome is a nerve entrapment disorder in which the median nerve is compressed as it passes through the carpal tunnel at the wrist. The video provides a detailed explanation of the condition, highlighting how repetitive hand use and inflammation can lead to swelling within a very narrow passage, resulting in characteristic symptoms such as numbness, tingling, and pain in the hand, especially in areas supplied by the median nerve. It notes that symptoms often worsen with night-time hand use, reflecting the mechanical factors that aggravate nerve compression during rest.

Anatomy of the Carpal Tunnel

The wrist forms a box-like tunnel with a bony arch on the dorsal side that acts as the floor, and the flexor retinaculum, or transverse carpal ligament, on the palmar side that forms the roof. Inside this tunnel lie nine flexor tendons and the median nerve, which travels down the forearm and passes through the tunnel to the hand. The skin areas innervated by the median nerve include the thumb, index finger, middle finger, and the thumb side of the ring finger. A superficial palmar branch supplies sensation to the central base of the palm and travels proximal to the tunnel, which explains why sensation in the central palm is typically preserved in carpal tunnel syndrome. The ulnar and radial nerves provide sensation to other parts of the hand and forearm, respectively.

Pathophysiology and Symptoms

Carpal tunnel syndrome arises when nearby tendons become inflamed, causing edema and swelling that narrow the already tight carpal tunnel. This swelling increases pressure on the median nerve, producing a dull ache at first, followed by sharp paresthesias described as pins and needles that can radiate up the forearm. As the condition progresses, patients may experience muscle weakness leading to clumsiness in handling small objects, turning keys or buttons, and performing precise hand tasks. In advanced cases, the thenar muscles at the base of the thumb may waste away because they are supplied by the recurrent branch of the median nerve after it passes through the tunnel. Importantly, the palmar branch of the median nerve branches upstream and is not affected, which explains why some palm sensation remains intact. The syndrome commonly affects both hands, often due to repetitive bilateral activities like typing, and symptoms commonly worsen at night after daytime use.

Diagnosis: Tests and Tests’ Rationale

Diagnosis relies on a combination of clinical symptoms and objective testing. Electrophysiological testing helps quantify nerve conduction across the carpal tunnel, while physical maneuvers assist in provoking and reproducing symptoms. Phalen's maneuver involves flexing the wrists as far as possible and holding the position for about a minute to elicit median-nerve–related numbness in affected individuals. Tinel's sign is performed by tapping over the transverse carpal ligament to reproduce tingling or paresthesias in the median-nerve distribution. Durkin's test uses manual compression of the carpal tunnel for 30 seconds to reproduce symptoms and aid in confirming compression. Together, these assessments build a picture of median nerve compression consistent with carpal tunnel syndrome.

Management and Treatment Options

Treatment begins with noninvasive strategies focused on reducing mechanical stress and inflammation. Behavior modification includes keeping the wrists in a neutral position during typing and daily tasks, positioning the hands parallel to the table, using a computer mouse instead of a trackpad, and employing wrist splints or supports during typing hours. Physical therapy with stretching and isometric exercises can relieve symptoms and improve hand function. In more serious cases, non-surgical approaches such as corticosteroid injections or splinting may be attempted to reduce inflammation and nerve compression. If conservative measures fail to provide lasting relief, surgical division of the transverse carpal ligament is performed to widen the carpal tunnel and relieve median nerve pressure. The video emphasizes that timely diagnosis and a combination of lifestyle modifications, therapy, and, if needed, surgical intervention can effectively manage the condition.

Takeaways

Carpal tunnel syndrome is typically a bilateral condition driven by repetitive stress and inflammation, leading to numbness and tingling in the median-nerve distribution. A structured approach combining posture adjustments, splinting, targeted exercises, and, when necessary, surgical release, provides an effective path to relief and restoration of hand function.