The decision of when to do an MRI for patients with low back or neck pain depends upon assessing the risk of a serious condition being present as revealed by warning symptoms in the history or signs in the physical examination.
How does an MRI Machine Work?
Unlike traditional x-rays or computerized axial tomography otherwise known as CT Scan, MRI (Magnetic Resonance Imaging) does not use any radiation and thus as far as scientifically known, it is much safer than x-rays. The patient is placed in a very strong magnetic field which causes the hydrogen protons in the body to become excited and because the magnetic field applied is uniform, these protons become similarly aligned. The magnetic field is rapidly turned on and off repeatedly which causes the protons to relax and emit radiofrequency waves. From this change the MRI machine can compute a picture of the tissues of the body particularly the brain, spinal cord, major nerves and other soft tissues. MRI detects slight differences in water content in soft tissues to detect abnormalities.
What Abnormalities can an MRI detect?
The MRI can show derangments from normal anatomy including:
MRI is superior to CT Scan in evaluating disorders of the spine as regards nerve compression. However sometimes CT Scan is needed to evaluate fine detail in the vertebrae because cortical bone, the tough outer layer of bone, has a low water content.
The Importance of Warning Symptoms or Signs:
The vast majority of neck or low back pain sufferers will improve without surgery. Only about 2% will ever need an operation. A physician can usually determine the potential seriousness of a condition causing pain by obtaining a detailed history and performing a thorough examination. If there are no warning symptoms or signs in the history or physical findings suggestive of a dangerous condition, then for most patients an MRI is not necessary before a trial of conservative treatment for at least a month.
Symptoms that the patient experiences or has in the history which may indicate a serious condition include:
Signs on examination which may indicate a serious condition include:
Which Area of the Spine should be Studied?
Most of the time patients with cervical spine problems have neck pain and upper extremity complaints while those with lumbar spine problems have low back pain and lower extremity complaints but sometimes it is not so clear.
Pain at the level of the shoulder blades can come from the lower cervical spine or upper thoracic spine. Generally if it also radiates to the arm then it comes from the cervical spine. Pain from the lower thoracic region can be similar to pain from the lumbar spine. If there are significant signs of lower extremity weakness, increased reflexes, bladder, bowel, or sexual dysfunction in a setting where the patient complains of low back pain then it may be wise to do a thoracic MRI if the lumbar does not show the cause. Similarly a very low cervical problem or high thoracic problem be hard to localize with a study of only the cervical or thoracic spine alone.
Most MRIs of the cervical usually show the lower brain so lesions near the junction of the cervical spinal cord and brain are usually identified somewhat on cervical MRI.
To know the need to go for an MRI, consult a spine health specialist online --> https://www.icliniq.com/ask-a-doctor-online/spine-health-specialist
Last reviewed at:
19 Jul 2019 - 3 min read
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