Spinecare Topics
Surgical Interventions
DISCOGRAPHY
Background: Advancements in technology has led to improved imaging, which has further led to an increased understanding of the origin of spinal pain. For example, magnetic resonance imaging (MRI) provides us with detailed imaging of soft tissue elements of the intervertebral disc as well as the spinal cord and nerve roots. The sensitivity of MRI provides detailed imaging of degenerative processes of the spine and its contents. It can be used to assess small regions of structural compromise.
Recent research has demonstrated that changes within the disc as well as disc protrusion can be the primary source of back pain. The principle challenge is with determining whether the changes detected are clinically significant. A specialized imaging procedure referred to as discography can be used to evaluate discs in the neck (cervical), mid back (thoracic), and low back (lumbar) to help determine whether the pain is primarily arising from an interverbral disc. The use of discography can help assess other changes involving the disc. It can also be used to help determine which therapeutic intervention would be most appropriate.
Procedures: Discography must be performed by an experienced, qualified professional. The procedure may be performed by a surgeon, interventional radiologist, and/or a pain management specialist. The procedure is performed during imaging guidance usually in the form of a fluoroscopic C-arm unit. The procedure may be performed on an alert, unsedated, ambulatory patient with the use of a local anesthetic. Conscious sedation can be utilized as needed. The patient is usually placed face down (prone) on a tilting table next to a fluoroscopic imaging unit. The tabletop is movable and can be rotated or tilted. Pads are used to position the patient. Fluoroscopy is performed to guide needle placement into each disc and to identify the disc to be evaluated. Under image guidance a specialized needle is slowly and precisely placed into the intervertebral disc to be evaluated. The needle is advanced incrementally with periodic radiographic checks lasting a few milliseconds. The needle tip is progressed and placed as near to the center of the disc as possible.
Following needle placement into the center of the intervertebral disc a contrast agent is injected under fluoroscopic guidance. While observing the flow of contrast on the imaging screen, the assisting technologist will observe the patient for any signs of pain or discomfort. The disc is typically injected with contrast until there is leakage of material outside the disc or until the region is filled to a capacity determined by increased resistance. The injection process will continue until one of the following occurs, endpoint is reached preventing further contrast administration, pain is manifested, or at least 4 ml of saline solution has been injected suggesting that there is leakage. A typical disc in the low back will accept approximately 1.5 to 3.5 ml of fluid depending on the integrity and the size of the disc. If the patient does not experience any pain or distress, the injection is voluntarily stopped. The total time of injection is recorded along the pre-injection pressure and injection endpoint characteristics.
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