What is a Spine Stress Test?
The spine is a complex functional anatomic structure. The human spine has adapted to upright stature and must withstand forces several times the weight of the body while allowing complex motion and protection of the sensitive spinal cord and nerve roots. Stress tests are designed to uncover problems that are not apparent on testing performed when the body is at rest.
Cardiologists use a form of Stress Test to determine if there blockages in the coronary arteries in patients that are experiencing chest pain during activity but not at rest. In these cases the chest xray and the EKG of the heart are usually normal when the the patient is at rest. A cardiac stress test increases the functional demands on the heart and tests for areas where the blood flow is restricted and thereby preventing the heart from meeting the demands of the Stress applied. A stress test evaluates the functional reserve of an organ and uncovers abnormalities that are missed (false negative results) in tests with the organ at rest.
Spine surgeons and attorneys are familiar with another form of Spinal Stress Test
/Standing Flexion/Extension Radiographs of the spine. Conventional radiographs (AKA “x-rays”) of the spine are obtained with the patient lying down in a position where the spine is at rest and there are limited stresses on the spine. Standing Flexion/Extension radiographs test the spine under physiologic loads and evaluate for excessive spinal motion that is known as “segmental Instability”. This radiographic form of Spinal Stress Test
has been accepted by insurance companies and surgeons as the Gold Standard for evaluating for “spinal instability” for which the preferred treatment is spinal fusion.
Unfortunately, Flexion/Extension views evaluate the bones but not the discs and nerves because these structures are not visible using radiographs (i.e. x-rays). Soft tissue structures (e.g. intervertebral discs and nerves) are best seen using MRI and may be compressed in one position (during weight-bearing and with flexion/extension) whereas there is not disc herniation or nerve compression when the stresses are removed from the spine when the patient is lying down while the patient is supine.
Stress Test MRI displays the 30-40% of abnormalities that are present when the patient is standing but not visible when the individual is scanned when the patient is supine and the stresses are relieved (and the patient’s symptoms are relieved.