Overview of Straight Leg Raise Test
The straight leg raise test, also referred to as the Lasegue test, is a key part of a doctor’s examination when a patient has lower back pain. This test checks if the large nerve that runs from your lower back to the back of each leg, called the sciatic nerve, is being affected by any irritation in your lower spine. This issue is most commonly caused by a bulging or ruptured spinal disk pressing against the nerve, but it can also be due to other conditions like swelling in the joints connecting your spine’s bones.
As one of the most frequently used clinical tests, the straight leg raise test helps doctors decide whether a patient needs to see a specialist. It also guides spine surgeons when deciding on treatment options.
Lower back pain is one of the most common reasons people miss work. Often, this pain can shoot from the buttocks down the leg, and this is known as sciatic pain. This test plays an essential part in telling apart patients with just lower back pain compared to those who also have nerve root symptoms affecting their legs. Knowing early on if there is a nerve root problem is vital because it allows doctors to tailor treatment specifically for the patient, reducing the impact on their ability to function.
Though some studies suggest this test may not always be completely accurate in diagnosing the problem, it remains a valuable tool for both general doctors and spine surgeons. Used alongside appropriate imaging tests, it can contribute to getting the right diagnosis and treatment plan for each patient.
The aim of this article is to describe how the straight leg raise test is done, explain what happens in the body during the test, review past research, and discuss how useful this commonly used test is.
Anatomy and Physiology of Straight Leg Raise Test
The straight leg raise test is a simple technique doctors use to identify irritation or inflammation along the nerves in your lower back and leg. It works by flexing your lower limb, meaning you bend your leg at the hip joint. Sometimes, this movement can cause discomfort due to various reasons. One of these reasons could be that the surface space where your nerve root moves can be affected by physical constraints or pressure.
Think of nerve roots like branches of a tree that connect your spinal cord to your limbs. In a typical situation, these nerve roots have enough room to maneuver about 4 mm. However, during the straight leg raise test, this movement can be hindered by several factors.
It’s also important to note that you can have pressure on the nerve roots, leading to a narrow nerve passage, and not feel any symptoms. This, known as foraminal stenosis, can be detected in an MRI scan even if you don’t feel any discomfort. Therefore, a positive result from the straight leg raise test may not necessarily mean that there is mechanical pressure, but could be due to the irritation of the nerve root.
This test was originally developed by Charles Lasegue, a French clinician, who noticed that carrying weight and bending the hip and knee could worsen sciatica, a type of pain affecting the nerve pathway from your back to your legs. His student, JJ Forst, further developed the test and suggested that the pain might be due to pressure on the sciatic nerve by the hamstring muscle, the muscle at the back of your thigh.
However, the straight leg raise test as we know it today is attributed to Dr. Lazar Lazarevic, a Serbian neurologist. He was the first to use the test as a way to identify sciatic pain by stretching the sciatic nerve. This was based on his work with six patients. Because of the confusion in attributing the origin of the test, it’s generally recommended to described it simply as the straight leg raise test.
Why do People Need Straight Leg Raise Test
The “straight leg raise test” is a simple examination that doctors often use to check for problems with the cushion-like discs in your spine or irritation of the nerves that run down your back and into your legs. These issues could trigger pain in your lower back and legs. This test is particularly good at spotting a condition called disc herniation (where one of the discs in your back gets damaged and bulges outwards) and nerve compression (when a nerve is squeezed).
Furthermore, the straight leg raise test can also serve as a “neurodynamic evaluation test”. This might sound complicated, but it’s just a way of checking if the nerves in your back and legs are under too much strain or being squished.
So, if you’re experiencing any of the following symptoms, your doctor might ask you to do a straight leg raise test:
* Pain in your lower back
* Pain in your buttock
* Pain in your leg
When a Person Should Avoid Straight Leg Raise Test
The straight leg raise test is a test that doctors use to check for certain health issues. It needs you, the patient, to be in a specific position and move certain joints. There are some situations, though, where you won’t be able to do this test:
- Firstly, if you do not give consent for the test, it cannot be performed.
- Secondly, if you have any issues that don’t allow you to lie down straight – like severe problems in your spine or advanced scoliosis (a condition where your spine has a sideways curve) – then also the test cannot be done.
- Additionally, if you have advanced disease in your knee or hip joints, making movements for the test very uncomfortable, then also the test may not be possible.
Who is needed to perform Straight Leg Raise Test?
The straight leg raise is a simple test that your doctor might do. Even though it’s straightforward, it’s essential for the tester to do it the right way. If not performed correctly, it might cause discomfort and may not give trustworthy results. Various medical professionals could conduct this test, including:
Your general family doctor is capable of performing this test. Surgeons who specialize in treating problems related to muscles and bones, or one who specializes in disorders of the nervous system can also carry out this test. Sports medicine specialists, who have training in preventing and treating injuries related to sports and fitness, will have the right expertise too.
Nurses, physical therapists (people who help with treatment, that includes exercises), and chiropractors (who specializes in treating health problems by pressing joints where they are not moving properly) could also complete this test. They are all trained and capable of making sure the test is carried out correctly, so you’re in good hands.
Preparing for Straight Leg Raise Test
Before conducting a straight leg raise test, doctors must get approval from the patient. This is called obtaining consent and it’s a crucial step that ensures the patient agrees to the procedure. Additionally, doctors need to respect the patient’s privacy. To help with this, a chaperone is usually present during the test. This helps keep the environment professional and comfortable for the patient.
How is Straight Leg Raise Test performed
The straight leg raise test is a simple procedure that doctors use to check if you’re experiencing pain in certain parts of your lower body. This test can help indicate problems like a pinched nerve in your back. Here’s how it goes:
1. You lie flat on your back.
2. The doctor slowly lifts your leg while keeping your knee straight.
3. If lifting your leg causes pain in the lower part of your leg (most commonly in areas related to the L5 or S1 nerve roots), then the test is positive – that could mean you have a problem.
If the pain shows up when your leg is lifted less than 45 degrees off the ground, that’s also counted as a positive result. Patients often ask the doctor to stop the test when the pain starts. Usually, bending the knee eases the pain in the buttock area.
To make the test more sensitive, some additional moves can be performed, like the Bragaad sign. In this maneuver, the doctor bends your foot upward (this is called dorsiflexion) while lifting your leg, and if it increases the pain, it further points towards a positive result.
Another additional action is the crossed straight leg test. In this test, the doctor slowly lifts your other leg (the one you’re not having pain in) while keeping your knee straight. If this causes pain in the leg where you were having the issue and if your leg is lifted at an angle of 40 degrees, then the test is positive. A positive result in this test might mean that you have a condition known as central disc herniation, which can cause severe irritation of the nerve root.
What Else Should I Know About Straight Leg Raise Test?
A straight-leg raise test is used to help figure out if a person has a herniated disk in their lower spine. This test involves you lying flat on your back while your healthcare provider lifts your leg up. If you feel pain, particularly down your leg, this could be a sign of a herniated disk.
This test is quite good at figuring out who doesn’t have a herniated disk. This means it has a “high sensitivity”. However, it’s not so good at identifying who does have a herniated disk. That’s what is meant by “low specificity”. It can sometimes show positive results because of other health problems.
There’s been some research on how good this test is, but the quality of the studies isn’t that great, and most were done on people who were already going in for surgery, which means the results may not apply to everyone.
Still, the straight-leg raise test helps healthcare providers decide whether more tests, like an X-ray or MRI, might be necessary. They can also aid healthcare providers in determining if you need to see a spine specialist.
If the test is positive it could mean nerve irritation and a potential trap, which might require a nerve root injection or surgery.
It’s also important to know that a positive straight-leg raise test doesn’t necessarily mean you have a herniated disk. It could also be a result of other health problems. So, healthcare providers use this test as part of their overall assessment of your lower back pain.