How can a problem in the neck feel like shoulder pain?
The nerves that supply the shoulder muscles and skin sensation around the shoulder run back and forth from the neck (cervical spine).
Injury to the cervical spine or these nerves as they exit the spinal canal into the collection of nerves called the brachial plexus can cause significant pain that can appear to be coming from the shoulder itself. This is possible because the same nerves that bring pain signals to the brain when there is truly a problem with the shoulder are the nerves involved when the cervical spine is responsible for shoulder pain.
Mechanism of injury to the cervical spine can vary from whiplash type injury or direct blows to the head or neck. In a whiplash type injury, the neck is placed through a sudden motion that can stretch or tear ligaments and muscles. The paravertebral muscles respond by going into spasm that can cause the vertebrae to alter their alignment. This altered alignment can cause pain in the cervical spine and because of irritation if the exiting nerves, can cause pain that appears to be from the shoulder as well. Sometimes even trivial injuries can cause significant irritation of the spinal nerves.
Bone spurs in the cervical spine from arthritis can cause compression of the nerves as they exit the spinal canal. As arthritis affects the many joints in the neck, the body responds by manufacturing bone spurs that decrease the motion in the cervical spine. As these bone spurs grow in size, they can start to occupy spaces that would normally be taken by nerves or the spinal cord. When the nerves become irritated by compression from the bone spurs or osteophytes, the lining around the nerve can become inflamed and trigger pain in the location of the end point of the nerve (hand, elbow, arm or shoulder). In some situations, these osteophytes can place pressure on the nerve to the point that the blood supply to the nerve is compromised. This condition can be similar to a herniated disc in the spine, and in addition to pain in the arm or shoulder, weakness of the muscles in the arm can occur as well.
How is a cervical spine disorder diagnosed?
The diagnosis of shoulder or arm pain caused by nerve irritation in the neck, or radiculopathy, can be made through a thorough physical exam, X-rays of the cervical spine, nerve conduction tests and MRI.
X-rays of the Cervical spine can demonstrate the alignment of the spine and any osteophytes that may have developed in an arthritic process. Most fractures and dislocations of the spine can be seen on plain x-rays, although further studies are sometimes needed to sharpen the diagnosis. X-rays are excellent for evaluating bony structures, but lack the ability to see nerves, discs, and ligaments. For these structures, MRI is an excellent study.
An MRI or Magnetic Resonance Image is a test that is done by a radiologist that allows visualization of non- bony structures. MRI’s allow nerves, tendons, cartilage, and other soft tissues to be seen with significant clarity. Cervical spine MRI is ideal for visualization of herniated discs as well as many other problems in the cervical spine. This test can be very helpful when the source of pain is not clear.
Nerve conduction tests (sometimes called EMG’s) are performed to evaluate the status of the nerves as they travel out of the cervical spine and into the arm and hand. Through these tests, physicians are able to identify not only the location of nerve compression, but the extent of the damage that has been done to a nerve by compression, laceration, stretching or tearing.
How are cervical spine disorders treated?
Many cervical spine problems can be treated without surgery. Physical therapy and anti-inflammatory medication are the mainstays of treatment. Only when symptoms are severe or non-surgical treatment has failed is surgery considered. Physical therapy may consist of stretching exercises to the muscles of the neck as well as treatments to reduce inflammation. Ice and heat are frequently used to reduce inflammation of the tissues and increase blood flow and improve flexibility. Manipulative mobilization of spinal segments can be helpful to decrease pain and increase motion. Eventually, strengthening exercises may be prescribed for patients with pain caused by fatigue of the muscles of the neck.