Lower Back Pain
Part 4: Exams and Tests
Medical history
Because many different conditions may cause back pain, a thorough medical history will be performed as part of the examination. Some of the questions you are asked may not seem pertinent to you but are very important to your doctor in determining the source of your pain.
Your doctor will first ask you many questions regarding the onset of the 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. The doctor will ask you questions referring to the red flag symptoms. He or she will ask if you have had the pain before. Your doctor will ask about recent illnesses and associated symptoms such as coughs, fevers, urinary difficulties, or stomach illnesses. In females, the doctor will want to know about vaginal bleeding, cramping, or discharge. Pain from the pelvis, in these cases, is frequently felt in the back.
Physical examination
To ensure a thorough examination, you will be asked to put on a gown. The doctor will watch for signs of nerve damage while you walk on your heels, toes, and soles of the feet. Reflexes are usually tested using a reflex hammer. This is done at the knee and behind the ankle. As you lie flat on your back, one leg at a time is elevated, both with and without the assistance of the doctor. This is done to test the nerves, muscle strength, and assess the presence of tension on the sciatic nerve. Sensation is usually tested 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 with you, the doctor 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 defecation. Thus, a rectal examination is essential to make sure that you do not have nerve damage in this area of your body.
Imaging
Doctors can use several tests to "look inside you" to get an idea of what might be causing the back 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 often little to be gained in obtaining X-rays for patients with acute back pain. Because about 90% of people have improved within 30 days of the onset of their back pain, most doctors will not order tests in the routine evaluation of acute, uncomplicated back pain.
Plain X-rays are generally not considered useful in the evaluation of acute back pain, particularly in the first 30 days. In the absence of red flags, their use is discouraged. Their use is indicated if there is significant trauma, mild trauma in those older than 50 years of age, people with osteoporosis, and those with prolonged steroid use. Do not expect an X-ray to be taken.
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. A myelogram now is usually done in conjunction with a CT scan and, even then, only in special situations when surgery is being planned.
Magnetic resonance imaging (MRI) scans are a highly detailed test and are 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.
MRI may also be considered after one month of symptoms to rule out more serious underlying problems.
MRIs are not without problems. Bulging of the discs is noted on up to 40% of MRIs performed on people without back pain. Other studies have shown that MRIs fail to diagnose up to 20% of ruptured discs that are found during surgery.
A CT scan is an X-ray test that is able to produce a cross-sectional picture of the body. CT scan is used much like MRI.
Nerve tests
Electromyogram or EMG is a test that involves the placement of very small needles into the muscles. Electrical activity is 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.
Blood tests
Sedimentation rate or C-reactive protein are blood tests that can indicate whether or not inflammation is present in the body.
Complete blood count (CBC) is used to detect elevations of white blood cells and anemia.
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