A broad-based disc protrusion occurs when more than 25 percent but less than 50 percent of the disc material's circumference is extended beyond the spinal bone borders, according to the American Journal of Neuroradiology. A disc is bulging when over 50 percent of the disc material's circumference is overextended.
A disc has either a broad-based protrusion or a bulge, but not a broad-based bulge, according to the Laser Spine Institute. Disc protrusions in the cervical and lumbar spines can press on nerves and cause symptoms such as tingling, numbness, neck and back pain, and a decline in physical mobility. A patient with a broad-based disc protrusion in the lumbar spine may experience sciatica, which is pain that travels from the lower back to the feet when the protrusion compresses the sciatic nerve.