❑ Also known as Myelogram ❑ is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Anatomy & Physiology is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain. It begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column.
It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging from 1/2 inch thick in the cervical and lumbar regions to 1/4 inch thick in the thoracic area. The spinal cord is connected to 31 pairs of spinal nerves, each roughly corresponding to a segment of the vertebral column: 8 cervical spinal nerve pairs (C1-C8), 12 thoracic pairs (T1- T12), 5 lumbar pairs (L1-L5), 5 sacral pairs (S1-S5), and 1 coccygeal pair. The brain and spinal cord are enclosed in three continuous, protective membranes called meninges. 3. Pia mater
2. Arachnoid
1. Dura mater
3 Layers of the Meninges Dura mater – ( Latin, "hard mother"), is the outermost layer, and it forms a tough protective coating. It is separated from the Arachnoid by the subdural space and from the vertebral periosteum by the epidural space. Arachnoid mater – is the middle protective layer. It is a thin, weblike membrane without blood vessels that lies between the dura and pia maters. Pia mater – ( Latin, "tender mother"), is the innermost protective layer. It is very thin and contains many nerves and blood vessels that nourish the underlying cells of the brain and spinal cord.
The space between the arachnoid and the underlying pia mater ❑ Filled with CSF ❑ Bathes brain and spinal cord with nutrients ❑ Cushions against shock and blows ❑ Where contrast media is injected for myelograms Cerebrospinal fluid (CSF) is the tissue fluid of the brain and spinal cord. It surrounds and cushions the structures of the central nervous system.
Total adult CSF volume is 150 ml usually consists of 24 articulating vertebrae, and nine fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs. It houses and protects the spinal cord in its spinal canal, and hence is commonly called the spine, or simply backbone. ➢ The cause of arm or leg numbness, weakness, or pain. ➢ Narrowing of the spinal canal (spinal stenosis). ➢ A tumor or infection causing problems with the spinal cord or nerve roots. ➢ A spinal disc that has ruptured (herniated disc). ➢ Inflammation of the membrane that covers the brain and spinal cord. ➢ Problems with the blood vessels to the spine. Blood in the CSF -the presence of blood in the CSF indicates probable irritation within the spinal canal, which can be aggravated by the contrast medium. Arachnoiditis (inflammation of the arachnoid membrane) - the contrast medium may increase the severity of the inflammation. Increased intracranial pressure - tapping of the subarachnoid space with needle insertion may cause severe complications to patient as the pressure equalizes between the areas of brain and the spinal cord.
Recent lumbar puncture (within 2 weeks of the current procedure) -Performing Myelography on a patient who has had a recent lumbar puncture may result in extravasations of the contrast medium outside the subarachnoid space through the hole left by the previous puncture.
➢ Previous reaction to the same contrast medium. Non-ionic, water-soluble, iodine-based contrast media. Water soluble contrast media provides excellent radiographic visualization of the nerve roots, is easily absorbed into the vascular system, and is excreted by the kidneys. ❑ Omnipaque (Iohexol) – a nonionic, water soluble contrast that is less toxic than contrast media previously used in myelography. ❑ Isovist (Iotrolan) – another nonionic, water- soluble contrast agent that tests have shown to be even less toxic than Omnipaque.
DOSAGE: ✓ The dosage is recommended by the manufacturer and varies with the concentration of the medium used and the area of the spine under examination. ✓ In general, a range of approximately 9-15 ml is used. Injectable sedative/muscle relaxant usually is administered 1 hour before the examination to reduce anxiety and relax the patient.
The type and amount of premedication used are determined by the radiologist or technologist who performs the procedure.
Premedication of the patient for Myelography is rarely necessary. Solid foods should be avoided for several hours before the exam, but fluids may be continued. The patient should be well hydrated before the procedure. Informed consent should be secured. The patient should remove all clothing and don a patient gown. The procedure should be fully explained to the patient, and an adequate history should be taken. Vital signs are taken before commencement of the procedure to serve as a baseline. Some drugs should be stopped one or two days before Myelography. These include certain antipsychotic medications, antidepressants, blood thinners, and some other drugs. The most important type of medication that must be stopped is blood thinners (anticoagulants).
▪ Do NOT take dipyridamole (Persantine) or warfarin (Coumadin) within 72 hours to the test. These medications are often referred to as blood thinning pills.
Introduction of contrast medium for myelography is through the puncture of subarachnoid space. Generally two locations are used as puncture sites: ❑ Lumbar (L3-L4) ❑ Cervical (C1-C2) Of these two locations, the lumbar area is safer and easier on the patient and is used most often for the procedure. After the puncture site has been selected the radiologist may use fluoroscopy to facilitate needle placement. Body position for lumbar puncture: 1. Prone position. 2. Left lateral position, with the spine flexed to widen the interspinous space. Body position for cervical puncture: 1. Erect position. 2. Prone position, with the head flexed to open the interspinous space. The procedure begins with a lumbar puncture. The lumbar site is cleaned and a local anesthetic is applied. The lumbar puncture needle is inserted generally at the level of L3- L4. The needle is slowly advanced until spinal fluid flows from the lumen of the needle (after withdrawal of stilette). The stylet is returned and the needle advanced an additional 2 mm to ensure that the entire bevel of the needle is within the subarachnoid space. A small amount of spinal fluid is withdrawn to maintain stasis and to provide a sample. Contrast medium is injected under fluoroscopic guidance. Under fluoroscopic guidance, an AP or PA, or both, oblique's, and a lateral of the spine are generally taken. Before overhead imaging, the patient is tilted slightly toward the feet to allow pooling of the contrast material in the subarachnoid space between low L1. PA and lateral spine Prone decubitus spine Lateral flexion and extension images to demonstrate dynamic stenosis, spinal stability, and degree of movement of disk protrusion. The patient should be on bed rest for 8-24 hours, with the head slightly elevated. The patient should drink plenty of fluids. The patient should be instructed to notify the physician or medical staff if he or she experiences severe headache or nausea and vomiting.
DYE
NO DYE
LUMBAR MYELOGRAM - AP VIEW