Intervertebral Disc Disease
The spinal cord is protected by bony vertebrae. To allow shock absorption and flexion of the spine, the vertebrae are separated by soft cushions (intervertebral discs). These cushions are similar to jelly donuts: they have a firm exterior and a soft middle. Due to age or genetics, the outer portion degenerates and the soft center is pushed out (ruptured) without warning when the spine moves. When the disc ruptures, the center is expelled with high velocity and force, bruising the spinal cord that lies above it. The spinal cord swells from the impact and becomes compressed by the surrounding bone. Pressure on the spinal cord impairs nerve conduction along the spinal column. Symptoms of intervertebral disc disease range from acute pain to paralysis. The area of the body affected depends on the location of the disc rupture. Diagnosis of IVDD requires physical examination to localize the lesion followed by imaging studies with a myelogram (radiographs with contrast material) or MRI. Treatment depends on the severity of the signs. Mild cases benefit from strict rest and pain management. Patients with acute paralysis require emergency surgery to restore normal nerve conduction and prevent permanent nerve damage.