The cause of the back pain is most often diagnosed through a history and a physical exam. Only 10% of those suffering from acute back pain will require any special diagnostic testing.
In selected cases, clinical tests can help determine the cause and source of back pain. Because most symptoms of acute back pain resolve within four to six weeks, it is important to note that most, if not all, of these tests are not performed unless pain persists for more than four to six weeks.
History and Physical Examination
A physical examination by your physician will address how and when the back pain occurred. The doctor will ask about any earlier back injuries and will ask about your health history. Questions may include:
What events, actions, or positions started the pain?
Where does it hurt?
How long does the pain last?
Which activities increase the pain?
All aspects of a person's history are important, because different conditions may be related to a person's age and medical background.
The physical exam will also involve a detailed physical examination with particular emphasis on examination of the back. This involves:
Testing the range of motion of the spine
Determining the area of the tenderness
Assessing the strength of the lower limb muscles
Testing the power, tone, sensation and reflexes in the legs
"Straight leg-raising test' is very helpful in determining if sciatica is present. If raising a straightened leg off a couch or examining table is painful, it is likely that the sciatic nerve is irritated.
Nice To Know:
Not all causes of low back pain are due to problems in the spine. Other causes include:
It is no longer routine to order x-rays and other sophisticated imaging tests for people who first develop low back pain. These tests have not been found to be helpful in most instances - and most people with back pain tend to improve within a fairly short time. Thus, these tests are now usually reserved for those people still suffering back pain after four to six weeks.
However, if the history and physical examination suggest a serious cause for the back pain, tests may be ordered immediately. Such circumstances include:
People who experience sudden back pain from an injury (especially if they have fallen), in order to rule out a fracture
People who experience back pain at night, in order to rule out a tumor
People who have signs of an infection in their back; these signs may include fever and night sweats in addition to pain
People who have cancer that may have spread to the back
Bone scans are a method of studying bone structure or function by injecting into the bloodstream a medication that can be detected by a special scanning camera. Bone scans are appropriate for people with acute low back pain when there is the possibility of a spinal tumor, infection, or specific types of fractures.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is used to see internal structures of the body - including bone, discs, and nerves - without the use of x-rays. Magnetic radio frequency energy is used to transmit signals from the body into a computer.
The computer produces exceptionally clear images of the soft tissues and the bones. MRI is especially useful in detecting problems with the soft tissues - for example, problems with the discs in the spine.
An MRI will normally not be ordered unless the pain has persisted for four to six weeks, or neurological changes have been noted like a loss of the ankle reflex. An MRI can detect other problems in the back in addition to those originating in the spine.
Nice To Know:
Between 40% and 60% of people who have no back pain will show disc bulges on an MRI. Therefore, disc bulges on an MRI do not always signify a problem with the disc. A bulging disc usually only causes pain when it actually presses directly on a spinal nerve
For more detailed information about MRI, go to MRI
CT scans of the spine are sophisticated x-rays in which a computer is used to produce a detailed images of the spine. These images help diagnose specific back problems, including spinal nerve compression. The test is particularly valuable in the diagnosis of spinal stenosis.
For more detailed information about CT Scan, go to CT Scan
A myelogram is a special x-ray of the spine in which dye is injected into the spinal canal. The individual then lies on a table, which tilts in various directions, and spot x-rays are taken. This test helps the physician examine nerve structures that may be compressed within the spinal canal or as the nerve root exits the spinal canal. This test is often followed by a CT scan.
The myelogram is considered an invasive technique and carries an increased risk for complications. Because of this, this procedure is used in only special situations such as surgical planning. Myelography in general has been replaced by MRI and CT scans.
Electromyography (EMG) and nerve conduction studies may be useful for people whose back pain radiates down the leg and has lasted more than three to four weeks. Very thin needles are placed into the muscle in order to test the nerves and study the response time of the muscle. This testing is a powerful tool for assessing nerve involvement.
Nerve conduction tests are not normally performed until pain and neurological signs prove to be continuous, or muscles appear to be weak.
A procedure called discography involves an x-ray of the spine after a dye is injected into a disc space thought to be the source of the pain. Discography is an invasive procedure. However, some physicians find it useful in pinpointing a particular disc space as the source of pain, and will suggest this test for individuals who are planning to have back surgery.