The Straight Leg Raise Test: Testing for Herniated Discs

The straight leg raise test is a diagnostic test to conform the diagnosis of a herniated disc as the cause of the patients lower back pain and radiating pain towards the thighs and feet.

The cause of transient back pain, also known as acute back pain, is due to back spasms, which are caused by overstretching or overstraining of the muscle. The cause of back pain that continues to linger for months, or become progressively worse, is typically due to disc conditions that affect the spinal nerves. The discs, when healthy are able to retain their interior volume, which involves a mixture of water, proteins, cartilage stem cells, and chondroitin. The discs, when healthy, elevate the vertebral bodies at the front of the spine to separate them. The discs, when unhealthy, may bulge outwards or lose their inner materials through cracks in its outer walls. These changes to the discs may cause either their outer wall or ejected materials to press into the spinal canal or the spinal nerves that emerge from the spinal canal. This impingement of the nerve may affect several body processes simultaneously, including our reflexes, sensations, conscious motor movement, and even autonomic processes. Autonomic body processes are those that work whether we think about them or not, such as our breathing and the peristalsis of food through our digestive system. The earliest signs of nerve impingement may be back pain. The back pain may be accompanied by associated neurologic symptoms related to the dysfunction of the nerve, including muscle weakness, numbness, and tingling.



Back pain with radiculopathy (pain that radiates down an arm or leg) is often, but not always, caused by bulging discs or herniated discs that press on one of the nerve roots of the spine. When patients experience back pain with radiculopathy, they are advised to consult with a doctor immediately.

During the physical examination with the physician, the doctor will ask when the pain started and whether or not a trauma caused the condition you are now in. Next, the doctor will ask you where the pain in your back is, and the severity of the pain (on a scale from one to ten). Next the doctor will want to see how you walk and ask to bend, twist, flex, and extend your back and inquire which of these movements bother you.

Next, the doctor will want to find out the extent of the neurologic changes in your leg/foot as a result of the back pain condition. The doctor will first test your reflexes to see if one leg is more sensitive than the other. The doctor may perform the Straight Leg Raise Test to determine if the lower back pain is due to a herniated disc condition. The Straight Leg Raise test is also known as the Lazarevi?'s sign and Lasègue's sign.

Technique. This is a test to see if a certain movement causes sciatic pain, which will be a strong indicator of a herniated disc it the fifth lumbar spinal nerve (at L5). The doctor has a patient lie on his back, on the floor or exam room table, with his or her leg straight and towards the laying surface. The doctor will then begin to raise the straight leg off of the table/ground and towards the patient's body. If the patient experiences sciatic pain when the leg is between 30 and 70 degrees, it is a positive finding of back pain and leg pain caused by a herniated disc. Sciatic pain is severe lower back pain that radiates to the hips and feet and is often accompanied by muscle weakness and the loss of bladder or bowel control.