It means that spinal nerve root effacement is occurring by disc prolapse & degeneration or stenosis .By the reason of that, it may cause weakness in the leg, leg/thigh pain and numbness, tingling. Few persons also face generalized body weakness and numbness due to other nerve irritation on back. If he suffers continuous weakness and notice reduced strength of muscle bulk in both the legs, please arrange an appointment with a neurologist right away who will evaluate the possibilities here. These “red flags” could be indicative of compression of the spinal cord and its nerve branches and early treatment is essential if permanent damage needs to be avoided. Further referral to a physiotherapist for spinal exercises could be beneficial and may produce relief of symptoms. Hope this helps.
The spine is made up of segments of bone or vertebrae, which are divided by cushioning disks, which the disks keep the bones separated and allow for easy movement. On an X-ray or scan, the bone is round and more solid in color and larger, and then comes the smaller, less solid-appearing round disks. It's sort of like cartilage in a bone joint, it keeps the bones from rubbing against each other. The other part of the report about nerve root effacement is when the nerves that come out of the spinal cord and go towards other parts of the body, they sometimes get pushed on by, say, that bulging disk, or impinged on, or damaged, or rubbed against.
So, you have a disk that is squeezing out from its normal position, kind of like when you squeeze on a tube of toothpaste, the paste squeezes out the top. Some injury or strain on your spine has squeezed the disk out a little bit from between the back bones, since your MRI said "small" disc protrusion. In other words, it's not a great big bulge there, rather it's a small one, indicating not too much change in the situation with your spine. You also do not have any nerve being impinged on or disturbed in any way, which if you did, that can lead to that nerve not working very well, or causing tingling or numbness or pain.
Many people have pain in their lumbar spine as a normal aging process, which L-5 is the almost last vertebral bone in your spine, near the bottom, and S-1 is the beginning of the sacral bone or tailbone, so it's the disk that is between those two bones that is doing this bulging thing. Usually if a patient has pain or any other symptoms in their low back or possibly in their legs or feet, along with a scan that shows there's been some damage of some kind there, a doctor will prescribe physical therapy, so as to strengthen the muscles that help hold the spine in place, and thus hopefully prevent the disk from getting any worse. A doc will also sometimes prescribe some sort of pain medicine, too, depending on symptoms.