Diagnosing Disc Problems

Lumbar herniated disc. Click to enlarge

A medical diagnosis (also known as a "clinical diagnosis") focuses on determining the cause of a patient's back, neck pain or other symptoms. There are three steps to arriving at a clinical diagnosis for a pinched nerve or disc pain:

  1. Physical examination. Depending on the patient’s symptoms, a physical exam may include one or more of the following tests:
    • Nerve function in certain parts of the leg or arm – tapping different areas with a reflex hammer, with little or no reaction possibly indicative of a compressed nerve root. Sensory tests may also be conducted, utilizing hot and cold to determine how the nerve roots react to such stimuli.
    • Muscle strength – In order to get a better understanding of whether the spinal nerve root is compressed by a herniated disc, the doctor will likely conduct a neurological exam to assess muscle strength. The doctor may also ask the patient to undress in order to view the muscles, particularly whether there is muscle atrophy, twitching or any abnormal movements.
    • Pain with palpation or motion - Palpating certain structures can give some idea of what really is generating pain. For example:
      • Pain over the sacroiliac joint to palpation may indicate the patient has sacroiliac joint dysfunction.
      • Pain with straightening the leg can be indicative of a pinched nerve.
      • Pain with pressure on the low back may indicate pain from a degenerative disc.
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  1. Review of specific symptoms. A complete review of symptoms will include the location of the pain, a description of how the pain feels, and whether certain activities, positions or treatments make the pain feel better or worse.
  2. Review of medical history. A full medical background is important to rule out (or identify) other possible conditions that may cause the patient's pain. The history includes information such as any recurring health problems, previous diagnoses, past treatments and surgeries, reactions to those treatments, current medications, family history of illness, and any other health concerns.
  3. Diagnostic tests. After forming an opinion on the cause of the patient's pain, a diagnostic test may be ordered to confirm the disc problem and/or to gain additional information, such as the location of a herniated disc and impinged nerve roots. Diagnostic tests may include:
    • CT scanComputerized tomography (CT) scans work like x-rays in that an x-ray beam is shot through the body, with a computer reformatting the image into cross sections of the spine.
    • MRI scanMagnetic Resonance Imaging (MRI) allows doctors a sensitive and accurate assessment of the spinal nerves and anatomy, including disc alignment, height, hydration and configuration.
    • Discogram – If surgery for disc pain is considered, some practitioners may recommend a discogram with the goal of confirming which disc is painful. In this test, radiographic dye is injected into the disc, with the belief that a patient is suffering from disc pain (degenerative disc disease) if the injected dye recreates the normal pain. This test is controversial as to whether or not it is a valid, accurate test, and many doctors do not use discography except in rare situations.

MRI Is Not a Medical Diagnosis

The test findings on an MRI scan or other test are not in and of themselves a diagnosis of a herniated disc or degenerated disc. Many people over the age of 30 will have some level of a disc problem, but few will have pain associated with it.

Quite simply, a patient's physical exam findings and symptoms need to match the MRI or other test findings to arrive at an accurate medical diagnosis.

Only then can an effective treatment plan for the patient be prescribed, whether that entails treating a pinched nerve from a herniated disc, disc pain from a degenerative disc disease, or some other condition.