Carpal Tunnel Syndrome (CTS) is a common nerve compression disorder affecting the hand and wrist. It occurs when the median nerve, a major nerve supplying the hand, becomes squeezed within a narrow passage in the wrist. This compression leads to symptoms that interfere with daily activities and sleep quality.
Understanding the Anatomy of Carpal Tunnel Syndrome
The carpal tunnel is a tight, unyielding passageway on the palm side of the wrist, about one inch wide. Its floor and sides are formed by the small carpal bones, and its roof is the thick transverse carpal ligament.
The tunnel contains nine flexor tendons, which control finger movement, and the median nerve. Swelling or inflammation of the synovium, the tissues surrounding the tendons, takes up space within the tunnel. Since the bones and ligament cannot stretch, this increased pressure compresses the median nerve.
Compression interferes with the median nerve’s ability to transmit signals, often by restricting its blood flow. This dysfunction causes the characteristic numbness, tingling, and eventual weakness associated with the syndrome.
Identifying the Key Symptoms
The most recognizable symptoms of CTS involve sensory changes within the median nerve’s distribution. Patients experience numbness, tingling, and a burning sensation, primarily in the thumb, index finger, middle finger, and the thumb-side half of the ring finger. The pinky finger and the outside of the hand are unaffected, which helps distinguish CTS from other nerve problems.
Symptoms are often most intense at night, frequently waking people from sleep. This nocturnal aggravation occurs because sleeping with bent wrists increases pressure within the carpal tunnel. Patients often shake or rub their hands to temporarily restore sensation.
If nerve compression continues, the condition progresses to include motor symptoms. The muscles at the base of the thumb, known as the thenar muscles, may become weak or shrink (atrophy). This leads to difficulty with fine motor tasks, such as gripping small objects, buttoning clothes, or an increased tendency to drop items.
Common Triggers and Risk Factors
CTS development is attributed to mechanical and physiological factors that decrease space within the tunnel. Mechanically, activities requiring repetitive wrist movements, forceful gripping, or prolonged vibration can cause irritation. Examples include assembly line work, using power tools, or tasks involving repeated wrist flexion and extension.
Many cases are linked to systemic health conditions causing fluid retention or inflammation. Recognized risk factors include diabetes, rheumatoid arthritis, and thyroid dysfunction. Hormonal changes, particularly during pregnancy, can also lead to temporary swelling that precipitates the syndrome.
Being female and having a smaller wrist anatomy increases the likelihood of developing CTS, as the tunnel space is more restricted. Genetic predisposition also plays a role, as does age, with the condition being more prevalent in middle-aged and older adults.
Diagnosis and Management Approaches
Diagnosis begins with a detailed medical history and a physical examination focused on the hand and wrist. Healthcare providers perform specific physical tests, known as provocative maneuvers, to reproduce symptoms.
Diagnostic Tests
Phalen’s maneuver involves holding the backs of the hands together with wrists fully flexed for 30 to 60 seconds; numbness or tingling in the median nerve distribution indicates a positive result. Another test is Tinel’s sign, where lightly tapping over the median nerve at the wrist causes a shock-like or tingling sensation, indicating nerve irritation. To confirm the diagnosis and determine severity, a nerve conduction study (NCS) is ordered. The NCS measures the speed and strength of electrical signals along the median nerve, revealing any slowing of conduction velocity across the carpal tunnel.
Conservative Management
Initial management focuses on non-surgical treatments to reduce pressure and inflammation. Wearing a rigid wrist splint, especially at night, keeps the wrist in a neutral position to alleviate compression. Nonsteroidal anti-inflammatory drugs (NSAIDs) manage pain, and corticosteroid injections into the carpal tunnel can provide temporary relief by reducing swelling.
Surgical Intervention
When conservative treatments fail or nerve compression is severe, surgical intervention is recommended. The procedure, known as carpal tunnel release, is usually performed on an outpatient basis. The surgeon cuts the transverse carpal ligament, the tunnel’s roof, to permanently increase space and relieve pressure on the median nerve. Surgery can be performed using a standard open incision or an endoscopic technique involving smaller cuts and a camera.