Exams and Tests
Because many different conditions may cause back pain, your doctor will take a thorough medical history as part of the examination. Some of the questions may not seem pertinent to you. But the questions are important to your doctor in determining the source of your pain.
Your doctor will first ask questions about the onset of pain. (Were you lifting a heavy object and felt an immediate pain? Did the pain come on gradually?) He or she will want to know what makes the pain better or worse. He or she will ask if you have had the pain before.
The doctor also will ask about recent illnesses and their symptoms such as coughs, fevers, urinary difficulties, or stomach illnesses. If you are a woman, the doctor will want to know about any vaginal bleeding, cramping, or discharge. Pain from the pelvis is frequently felt in the back.
Your doctor will then give you a thorough physical exam. He or she will watch for signs of nerve damage while you walk on your heels, toes, and soles of your feet. The doctor may test your reflexes using a reflex hammer. This is usually done at the knee and behind the ankle. As you lie flat on your back, you'll be asked to elevate one leg at a time, both with and without the doctor's assistance. This is done to test nerves and muscle strength and to assess the presence of tension on the sciatic nerve. The doctor may test sensation using a pin, paper clip, broken tongue depressor, or other sharp object to assess any loss of sensation in your legs.
Depending on what the doctor suspects is wrong, he or she may perform an abdominal examination, a pelvic examination, or a rectal examination. These exams look for diseases that can cause pain referred to your back. The lowest nerves in your spinal cord serve the sensory area and muscles of the rectum, and damage to these nerves can result in inability to control urination and bowel movement. Thus, a rectal examination may be needed to make sure that you do not have nerve damage.
Doctors can use several tests to "look inside you" to get an idea of what might be causing the pain. No single test is perfect in that it identifies the absence or presence of disease 100% of the time
If there are no "red flags," there is little reason for imaging during the first 4 to 6 weeks of acute back pain. Because about 90% of people have improved within 30 days after the pain starts, most doctors will not order tests in the initial evaluation of acute, uncomplicated back pain.
Plain X-rays are generally not considered useful in the evaluation of back pain, particularly in the first 30 days. In the absence of red flags, their use is discouraged. They may be needed if there is significant trauma, mild trauma in those older than 50, osteoporosis, or prolonged steroid use.
Myelogram is an x-ray study in which a radio-opaque dye is injected directly into the spinal canal. Its use has decreased dramatically since MRI scanning and the test is now usually done along with a CT scan. Even then, it's only done in special situations when surgery is being planned.
An MRI is a highly sophisticated test and is very expensive. The test does not use x-rays but very strong magnets to produce images. Their routine use is discouraged in acute back pain unless a condition is present that may require immediate surgery, such as with cauda equina syndrome or when red flags are present and suggest infection of the spinal canal, bone infection, tumor, or fracture. An MRI may be considered after 12 weeks of symptoms to rule out more serious underlying problems.
MRIs are not problem free. Bulging of the discs is noted on many MRIs done on people without back pain. Such findings can lead to unnecessary treatment.
Electromyogram or EMG is a test that involves placing very small needles into the muscles. Electrical activity is then monitored. Its use is usually reserved for more chronic pain and to predict the level of nerve root damage. The test is also able to help the doctor distinguish between nerve root disease and muscle disease.