The intervertebral disks are situated within the joints that are between the bones in the spine. They are a flat disk shape and have a tough, fibrous outer layer and a gel-like inner layer. They cushion each joint and assist the spine in normal movement such as bending and twisting. A herniated disk occurs when the outer layer of the disk weakens and the inner layer presses against the outer layer.
Herniated disks can occur in a milder form, called a bulging disk, in which the disk to spreads past its normal boundaries in the joint, but the inner material stays within the disk. A severe form of herniated disk is called an extruded disk, in which the inner material pushes all the way out of the external layer of the disk into the spinal column. Pain can be caused by the inner material of the disk irritating the nerves it comes in contact with, or from the inflammation of the disk putting pressure on a nerve.
The main symptom of herniated disk is back or neck pain. This pain can be worse when sitting than standing. The pain can worsen after coughing, sneezing, bending forward, or lifting. People with herniated disks may also experience pain, numbness, tingling, or weakness in the arms and/or legs.
Your doctor will carry out a physical exam to try to determine the source of your pain. He is likely to order an MRI to be able to visualize disk. Sometimes herniated disks cannot be seen on MRI results. In this case, the doctor may carry out a discography, a procedure in which dye is injected into the intervertebral disk to determine if it is damaged.