The causes of low back pain can be complex, and there are many structures in the spine that can cause pain. Doctors will ask patients to describe the location, severity and type of pain, in addition to the history of the pain: when the patient started to feel it, and any activities or positions that make the pain better or worse.
Lower Back Pain Classifications
A diagnosis will typically classify the patient’s condition as one of three types of pain.
- Axial low back pain, the most common type of back pain, is confined to the lower back and does not travel into the buttocks or legs. The pain can be sharp or dull, and can be severe enough to limit everyday activities, such as standing and walking. It usually worsens with certain activities (such as sports) or physical positions (such as sitting for long periods) and is relieved by rest. Most low axial back pain is acute – meaning it is short-lived and heals within six to 12 weeks – but can last longer and become chronic.
- Lumbar radiculopathy (sciatica) is the second most common type of pain caused by a lower back problem. Caused by conditions that compress the nerve roots of the sciatic nerve, the pain is more severe in the leg than in the back. Symptoms are pain, numbness and/or weakness that is felt in the lower back (if at all) and on only on one side of the lower body, affecting the buttock, leg, foot, or the entire length of the leg.
- Low back pain with referred painis pain in the lower back that also radiates to the groin, buttock and upper thigh, but rarely below the knee. Patients describe the pain as dull and achy with varying intensities. Low back pain with referred pain is similar to axial pain and is managed with similar treatments.
The classification of pain is important in guiding the right treatment plan. For example, with some types of radicular pain, specific extension exercises might initially be prescribed to move the pain up the sciatic nerve and back to its source in the lower back.
Watch: Sciatic Nerve Anatomy Video
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Additional Diagnostic Tests and Scans
When pain is severe and is not relieved within 6 to 12 weeks, a specific diagnosis becomes more important to determine further treatment. Additional diagnostic tools include:
- X-ray. Provides information on the bones in the spine; used to test for spinal instability, tumors and fractures.
- CT scan. Captures cross-section images of the vertebrae and spinal discs; can be used to check for herniated disc or spinal stenosis.
- Myelogram. Allows identification of problems within the spine, spinal cord and nerve roots. An injection of contrast dye illuminates the spine prior to an x-ray or CT scan.
- MRI scan. Displays detailed cross-section of the components of the spine. Useful to assess issues with lumbar discs and nerve roots, as well as ruling out causes of lower back pain like spinal infections or tumors.
- Read more with Diagnostic Studies for Back Pain.
Typically the spine specialist will have a good idea of the cause of the patient’s pain from the symptoms and physical exam, and will use the above diagnostic tests to confirm and clarify the diagnosis and/or to rule out other possible causes of the symptoms.
It is also important to note that sometimes low back pain actually has no identifiable anatomical cause, but this doesn't mean that the pain doesn't exist. Even with no clear cause of pain, the patient's pain is still real and should be treated.