Irritation to the nerves of the cervical spine can be caused by mechanical pressure anywhere along their path – from their roots near the spine to their endings in the muscle or skin. Disc herniation and bony encroachment are two of the most common causes of nerve irritation.
a) Disc herniation or disc bulge: Caused by trauma or degeneration to the discs in the cervical spine that results in the softer central portion herniating through the outer ring of the disc. This herniation of the disc can press on the nerve causing pain into the neck, shoulder and also down the arm.
Cervical disc herniation can either occur spontaneously following a trauma, or it may be preceded by a history of neck pain over a number of years. It is usually characterised by a constant aching sensation in the neck, with referred pain into shoulder and down the arm, that may develop into tingling and numbness.
b) Bony encroachment: Any condition that occurs as a result of growth or movement of the cervical vertebrae that decreases the space for the adjacent spinal cord and nerves. Compression of the cervical spinal nerves can cause referred pain that radiates into the shoulder and down the arm.