According to MayoClinic.com, a pinched nerve occurs when too much pressure is placed on one or more nerve roots--offshoots of the spinal cord--at the point where they exit the spine. The pressure on the nerve root causes the nerve to become inflamed, which disrupts its function. If a structure or tissue is impinging a nerve root in the neck, it often causes radiating pain into one of the arms. Once the pressure on the nerve is relieved, nerve function is restored.
Disc Herniation or Bulge
A disc herniation or bulge in the neck or cervical spine is one of the more common causes of pinched nerves. According to Dr. Richard Staehler of the peer-reviewed website Spine-Health, a cervical disc herniation--which is the displacement of intervertebral disc material into the spinal canal--typically develops in people 30- to 50 years-old. Although a herniated cervical disc may be caused by trauma or injury to the cervical spine, most of the symptoms experienced occur spontaneously. Due to the anatomy of the cervical spine, the two levels where herniated discs are most common are between the fifth and sixth cervical vertebrae and the sixth and seventh cervical vertebrae. Because there's not much space between the cervical spine's vertebral bodies, the intervertebral discs typically are not very large. The space where the nerve roots exit the spine is also small, so even a minor cervical disc herniation can irritate the nerve root and generate pain.
Degenerative Joint Disease
According to the website Spine Universe, a pinched nerve in the neck may be caused by a bone spur compressing the nerve root. Degenerative joint disease, also known as DJD or osteoarthritis, may create bone spurs and is often seen on the cervical spine X-rays of middle-aged and elderly individuals. The degenerative process--while often painless and not necessarily a precursor to bone spur formation and nerve root impingement--may begin in any of the cervical spine's joints.
Over time, the degeneration may cause changes in neighboring joints. Degeneration may begin in the intervertebral disc, causing the joint space to narrow. As joint space is lost, the joint's normal movement is altered, and the surrounding joints experience unusual forces, which lead to and inflammation in the joint and bone spur formation. Pinched nerves due to bony impingement are relatively common and it's not unusual for the pain to radiate into the shoulder and arm.
Spinal Tumor
Spinal tumors may cause pinched nerves in the neck or neck pain, although it's a much less common cause of pinched nerves than herniated discs or bone spurring. If a spinal tumor, also known as a space occupying lesion, is the suspected cause of the pinched nerve or neck pain, it can be definitively diagnosed by advanced imaging techniques, such as MRI. According to Spine Universe, tumors also can be differentiated from degenerative conditions by the presence of generalized symptoms including the following: recent unintentional weight loss, excessive fatigue and lethargy, chronic, low-level fevers and night sweats. If a person is experiencing these symptoms and has had cancer before, this is another indication that a spinal tumor may be present. Most neck tumors are the result of cancer cells that have spread from the lungs, prostate, kidney or breast.
