Spine Testing and Diagnostics
X-rays provide detail of the bone structures in the spine, and are used to rule out instability (such as spondylolisthesis), tumors, and fractures. Images of bones are made by directing an x-ray beam through the body. The calcium in bone blocks penetration of the x-ray beam and the image of the bones is picked up as a shadow on a film positioned on the other side of the patient. X-rays do not capture the images of discs and nerve roots, since they don’t contain any calcium. X-rays should not be performed in women who may be pregnant.
CT scans (computerized tomography). This specialized x-ray shows the bony vertebrae in detail. Like an x-ray, a CT scan works by directing an x-ray beam through the body. Then a computer is used to reformat the image into cross sections of the spine. This process is repeated at different intervals. As a result, the spinal canal can be imaged and assessed for specific conditions. With its excellent bony detail, CT scans are very useful for assessing fractures. Through multiple views, CT scans will image specific conditions such as lumbar disc herniation and lumbar spinal stenosis. CT scans should not be performed on pregnant women.
MRI (magnetic resonance imaging). This non x-ray study allows an evaluation of the spinal cord and nerve roots. It produces detailed images of discs, the spinal cord, and other soft tissue, and is a great aid in assessing certain conditions (such as degenerative disc disease and isthmic spondylolisthesis). An MRI images the spine by using a magnet that goes around the body to excite hydrogen atoms. After the atoms return to their normal level of excitation, they emit energy that is picked up on a scanner. There is no radiation with the magnet, so the scans may be performed on pregnant women. However, patients with a pacemaker implanted in their heart should not have a scan because the magnetic field will cause the pacemaker to malfunction. Also, anyone who works around metal should first have an x-ray of their eye sockets to ensure there are no metal filings in their eyes, which the magnetic field may cause to migrate and damage the eye. The scan is performed while the patient is lying in a fairly tight tunnel for 45-60 minutes. Some patients may not be able to tolerate this confined space, however newer generation scanners are designed with more open space.
Myelogram (injection of a dye or contrast material into the spinal canal) is utilized to diagnose disorders of the spinal canal and cord, such as nerve compression causing pain and weakness. The test is usually performed on an outpatient basis at a hospital or other medical facility by a neuroradiologist. Neuroradiology is a sub-specialty of radiology that conducts studies of the central nervous system. A myelogram requires introduction of radiographic contrast media (dye) into the sac (dura) surrounding the spinal cord and nerves. The patient lies on his/her stomach during the test. After the skin area has been numbed, the dye is injected into the spinal sac followed by x-rays, CT, or MRI scans. After the images are processed, a neuroradiologist interprets the results and sends a report to the referring physician. Following the myelogram, the patient is taken to a recovery area where he/she rests lying down with the head elevated for several hours. Once at home, quiet non-strenuous activities are recommended for 24 hours to allow the puncture site to heal. Plenty of fluids (e.g. water, juice) should be consumed to clear the dye from the body.
CT scans (computerized tomography) with Myelogram. When combined with a myelogram, a CT scan provides for excellent nerve detail. The myelogram adds some additional risk and expense to the CT scan, but provides substantial information about the nerve roots. A myelogram consists of injecting a radiographically opaque dye (dye that is picked up by x-ray) into the sac around the nerve roots, which in turn lights up the nerve roots. The CT scan follows and shows how the bone is affecting the nerve roots. This is a very sensitive test for nerve impingement and can pick up even very subtle lesions (injuries). The main risk with CT scans is that they use x-ray beams and should not be performed on pregnant women. The main risk with a myelogram is the potential for a spinal headache. The spinal headache usually resolves in one to two days with rest and fluids, and seems to be more common for patients with a history of migraine headaches.
Discography, or discogram, is a diagnostic tool used to determine the structural integrity of an intervertebral disc (or discs) and to find out if a particular disc is responsible for the patient’s back pain. Provocative Discography is a form of discography that replicates the patient’s ‘discogenic’ pain. The term discogenic is defined as a pain syndrome characterized by local or radicular pain cause by nerve root compression. The test is performed on an outpatient basis in a hospital or medical facility, by either a radiologist or surgeon. As the discogram injection is not for treatment of pain, a steroid (anti-inflammatory medication) is not injected. However, sometimes a discographer will inject lidocaine (a numbing agent) into the disc to decrease the pain of the procedure. Fluoroscopy, an imaging technique that projects an x-ray type picture onto a monitor, is used to guide the spinal needle into the suspect intervertebral disc. A radiopaque dye is then injected through the spinal needle into the nucleus (center) of the disc. During the test, the dye pattern is evaluated for leaks occurring outside the intervertebral disc walls. At this time, the patient’s symptoms (e.g. back pain, tingling sensation) may be experienced due to the pressure created by the dye injection (provocative discography). Often, after the discogram is completed, a CT scan is performed to check the morphology (anatomy) of the disc. Discography is indicated when a patient’s symptoms are severe and persist despite conservative therapy, when the results of other diagnostic tests (e.g. MRI) prove inconclusive, and/or if a disc abnormality is suspected. The results of a discogram are used to confirm a diagnosis. There are a limited number of risks involved with a discogram.
Somatosensory Evoked Potentials (SSEP) are sometimes ordered to assess the speed of electrical conduction across the spinal cord. If the spinal cord is significantly pinched, the electrical signals will travel slower than usual. SSEP’s may also be used to monitor spinal cord function during surgical procedures, although since the spinal cord ends before the lumbar spine, this is usually of limited value during lumbar spinal surgery and it is used more often in cervical (neck) or thoracic (chest) spine surgery.
Functional Capacity Evaluations. The extensive set of tests that assess many factors affecting a patient’s ability to perform activities of daily living and work are Functional Capacity Evaluations. These tests include assessment of strength, flexibility, endurance, and body mechanics. Functional activities such as pushing, pulling, lifting, carrying, reaching and gripping are included in testing. The evaluation is broken down into three basic parts: intake interview, physical assessment, and functional assessment. Functional Capacity Evaluations are performed by licensed physical therapists. The testing usually takes 3-4 hours.
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