Daily activities can be significantly affected by hand pain and numbness. Nerves travel from the spinal cord to the tips of the fingers, supplying sensation and powering muscles along the way. Compression at any point along the length of these nerves can cause hand symptoms. Cervical radiculopathy and carpal tunnel syndrome are nerve conditions that affect the hands and share some similar symptoms. However, they are distinctly different conditions.
Cervical nerve roots originate at the spinal cord in the neck. There are 7 spinal bones called vertebrae in the neck and 8 cervical spinal nerves denoted C1 through C8. Pairs of nerves exit through holes in the sides of each vertebrae. Nerve roots exit above their corresponding vertebrae, with the exception of C8. This nerve exits above the first thoracic vertebra, T1. The lower cervical nerves, C5 through T1, travel along the neck, then through the armpit to the shoulder. There this network of nerves separates into 5 main branches: the axillary, musculocutaneous, radial, median and ulnar nerves. The median nerve continues along the front of the forearm to the carpal tunnel -- located in the base of the palm just above the wrist. Nine tendons and the median nerve travel through this tunnel.
Each cervical nerve root supplies sensation to a particular area of the arm or hand. C6 and C7 supply sensation to the thumb, the index and middle fingers and the thumb side of the ring finger. This is also the area supplied by the median nerve, as it branches from these nerve roots. For this reason, nerve compression in the neck -- cervical radiculopathy -- can cause pain, tingling and numbness in the same areas of the hand affected by carpal tunnel syndrome. A primary difference in these conditions is the site of nerve compression. Cervical radiculopathy involves nerve compression in the neck, whereas carpal tunnel syndrome involves compression at the wrist.
Strength testing helps differentiate cervical radiculopathy from carpal tunnel syndrome. Prolonged nerve compression can lead to weakness in muscles supplied by these nerves. Myotomes are groups of muscles supplied by a particular nerve root. Muscle testing is used to help determine if a nerve root is compressed. The doctor or therapist applies manual pressure to the arm in a specific position to check for muscle weakness. To test the C6 nerve root, resistance is applied by the tester in the opposite direction as the elbow is held in a bent position -- or against the wrist held in a backward bent position. The C7 nerve root is assessed by applying resistance in the opposite direction while the elbow is held in a straight position -- or against the wrist held in a forward bent position. Weakness caused by carpal tunnel syndrome is different than with cervical radiculopathy. In the hand, the median nerve supplies muscles that move the thumb. The tip of the thumb is held against the tip of the pinkie finger as the tester attempts to pull them apart to assess weakness in these muscles.
Treatment for cervical radiculopathy and carpal tunnel syndrome aim to decrease nerve compression. Physical therapy is often prescribed for both conditions. Heat, ultrasound and electrical stimulation are used to decrease pain -- both in the neck and the carpal tunnel. For cervical radiculopathy, stretches are performed to improve flexibility and reduce tightness in the neck muscles. Traction -- stretching of the spine to decrease pressure on the spinal nerves -- is performed by the therapist or with a traction machine. As the nerve compression decreases in the cervical spine, symptoms in the hand begin to resolve. Surgery may be required to treat severe nerve root compression. Part of the vertebra may be removed or fused to relieve pressure on the nerve. In additional to pain-relieving interventions, splinting is often used to treat carpal tunnel syndrome. A splint is worn to keep the wrist in a straight position to relieve pressure on the median nerve. The splint is worn at night and as much as possible during the day. Surgery may be required to treat carpal tunnel syndrome if conservative treatment fails. The transverse carpal ligament -- the "roof" of the carpal tunnel -- is cut to relieve pressure on the median nerve.
- North American Spine Society: Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care
- NetterImages: Dermatomes of the Upper Limb
- Riverside Community College: Peripheral Nerves and Muscles -- Cervical and Brachial Plexus
- Lock Haven University: Myotomes
- The Open Orthopaedics Journal: Carpal Tunnel Syndrome -- A Review of the Recent Literature
- Musculoskeletal Journal of Hospital for Special Surgery: Cervical Radiculopathy -- A Review
- Comstock/Comstock/Getty Images