Pathophysiology: Carpal Tunnel Syndrome (CTS) is a common condition, especially amongst office workers and those whose work tasks involve repetitive movements of the wrist. It is characterised by pain, numbness, and tingling (a sensation of pins and needles) in the hand but may also affect the arm. It is caused by a compression of one of the 3 nerves that pass through the wrist (most commonly the median nerve). In most cases, carpal tunnel syndrome is progressive with early diagnosis and treatment essential. If left untreated CTS can worsen, which can lead to nerve damage and a severity of symptoms that effects daily functioning.
Anatomy: The carpal tunnel is an inch wide narrow passageway located at the wrist along the base of the palm. It protects the median nerve along with the nine flexor tendons (which each have a skin of synovial sheath surrounding them) that bend the fingers and thumb. The floor and sides of the carpal tunnel are formed by the small bones that make up the wrist with the roof being a strong band of connective tissue called the transverse carpal ligament. These boundaries are very rigid with little capacity to stretch so when the synovial sheaths of the flexor tendons become inflamed there is compression on the soft tissues within the carpal tunnel. The median nerve which runs down the forearm and passes through the carpal tunnel provides feeling and motor control to the thumb, index, middle and ring fingers.
Epidemiology: CTS is the most frequently encountered peripheral nerve compression pathology with a prevalence estimated at 3.7%. It is more prevalent in females than in males and most commonly seen in the middle age population which may be attributed to lifestyle and work situations. Causes may include activities involving repetitive wrist flexion, oedema (swelling) from trauma, compression from pregnancy and obesity and other health conditions (diabetes, rheumatoid arthritis and thyroid issues). Diagnosis is based on a clinical history of repetitive movements, as well as findings of muscle weakness and carpal tunnel sensation testing. Corroborating electrodiagnostic studies can also be obtained.
Symptoms: CTS has a gradual onset often with an unknown origin or cause. Initially symptoms may be intermittent but as the condition worsens symptoms may occur more frequently or may persist for longer periods of time and can include:
- Numbness, tingling or a burning pain primarily in the thumb, index, middle and ring fingers
- Occasional shock-like sensations that radiate to the fingers and thumb
- Pain or tingling in the elbow and shoulder
- Weakness and clumsiness in the hand making activities of daily living difficult
- Loss of proprioception (a feeling of awareness of where your hand is without looking at it)
Treatment: If identified and treated early, neurologic findings are reversible. If left untreated, CTS can cause muscle atrophy, chronic hand weakness, and permanent numbness in the hand. Physical therapy is recommended for early intervention and typically consists of activity modification (ergonomics), patient education, carpal bone and nerve mobilisation along with soft tissue manipulation. Late stage treatment can involve using a splint in an attempt to offload the carpal tunnel region. In some cases surgery may be required to take pressure off the median nerve and prevent permanent damage.