Spinal stenosis describes a narrowing of the spinal canal and compression of spinal nerves, according to Spine-health.com. "Secondary to anterolisthesis" means the narrowing is due to spondylolisthesis, a condition in which one vertebra slips forward over the one below it. L4-L5 indicates the fourth and fifth lumbar vertebrae are involved.
Anterolisthesis is synonymous with spondylolisthesis, a very common cause of low back pain that occurs in middle-aged and older adults, states Spine-health.com. There are two types of spondylolisthesis: isthmic spondylolisthesis and a degenerative type, which typically occurs in older adults.
Isthmic spondylolisthesis occurs when one of the small bones of the spine sustains a fracture, usually at an early age. Pain and other symptoms of nerve compression usually do not show up until later in life. The most common location for this condition is the lowest portion of the lumbar spine, between the fifth lumbar and first sacral vertebrae, or L-5 and S-1. However, it sometimes occurs higher in the lumbar spine at the level of the second and third, or fourth and fifth, lumbar vertebrae, according to Spine-health.com.
Degenerative spondylolisthesis happens due to normal aging and weakening of the muscles and ligaments that support the spine. It occurs most frequently in adults over 50 years of age, and is more common in women and people over 65, according to Spine-health.com. The condition frequently causes spinal stenosis, with symptoms of lower back pain that radiates down one or both legs. Other symptoms include tight hamstrings and a feeling of tiredness or heaviness in the legs. The most common location for this condition is between the fourth and fifth lumbar vertebrae, or L-4 to L-5.