Myelography is the radiographic examination of the spinal cord and emerging nerve roots following injection of contrast material into the subarachnoid space (the space between the spinal cord and the bony vertebrae). This type of contrast radiography should be done in those animals where results of noncontrast vertebral radiography (survey x-rays) do not fully define a disorder affecting the spinal cord. It is used to differentiate and pinpoint various types of spinal cord injuries and disorders. A myelogram should be considered if positive findings are essential for diagnosis and prognosis or to determine a precise site for surgery.
The technique to perform myelography requires training to perform correctly. General anesthesia is administered to keep the patient still during the procedure. The dye is usually injected into the spinal canal in the lumbar (lower back) area in dogs and cats with spinal cord disease, irregardless of where the injury or disease may be suspected. In normal animals, the dye flows evenly along the spinal cord towards the head. If a disorder such as a herniated disk is present, the dye column is not present or is displaced at the location of the injury and swelling. This provides information to the veterinarian as to where a surgical incision should be made.
Myelography is not without undesirable consequences in some cases. Side effects may include seizures during recovery. Keeping the head elevated will help prevent increased intracranial pressure as well as decreasing the flow of the dye into the brain.