Back pain tests

Examinations and tests

Medical history

• Because many different conditions may cause back pain, a thorough medical history will be recorded 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 many 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

• 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 usually done at the knee, behind the ankle, and on the soles of the feet. 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, paperclip, 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, he or she may perform an abdominal examination, a pelvic examination or a rectal examination. These examinations 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 defaecation.

Blood and urine tests, stool samples, vaginal swabs

• If your doctor suspects that pain is caused by a problem in the abdomen such as a kidney or uterine infection he or she may organise a variety of blood, urine, stool or swab tests to exclude these problems.

Imaging

• Doctors can use several tests to ‘look inside you’ to get an idea of what might be causing the back pain. However no single test is perfect in that it can identify the absence or presence of disease 100% of the time.
• The medical literature is very clear: if there are no red flags, there is little to be gained in imaging acute back pain. Because about 90% of people improve 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 back pain, particularly in the first 30 days. In the absence of red flags their use is discouraged. They are generally used if there is significant trauma, mild trauma in those older than 50, people with osteoporosis and those with prolonged steroid use. If you do not fall into one of these groups, do not expect an X-ray to be taken.
• Ultrasound of the abdominal organs may have a role in excluding disease causing pain referred to the back such as kidney stones or infection.
• 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. The test is now 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 sophisticated test that 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, tumour 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.

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.