What is a myelogram?<br />A myelogram is a radiographic study combining the use of a contrast medium with a fluoroscopy to evaluate abnormalities of the spinal cord and its nerve root branches.<br />usually completed within 30 to 60 minutes<br />
Contrast Medium <br />Types,<br />oil-based, <br />water-soluble, <br />air-contrast.<br />Currently, <br />Non ionic, water soluble iodine-based media<br />Dosage,<br />Generally 6-17 ml <br /><ul><li>Recommended by manufacturer and varies with the medium concentration.</li></li></ul><li> Injection of Contrast Medium <br />where? into the subarachnoid space.<br />Lumbar Puncture (L3-L4) Cervical Puncture (C1-C2)<br />The radiologist looks at the spine under fluoroscopy to find the best location to position the needle. <br />The skin is cleaned, then numbed with local <br /> anesthetic.<br /> The needle is inserted and the contrast medium is injected through it into the subarachnoid space. <br />
Puncture Positions<br />Body position for lumbar puncture:<br />Prone position.<br />Left lateral position, with spine flexed to widen the interspinous space.<br />Body position for cervical puncture:<br />Erect position.<br />Prone position, with the head flexed to open the interspinous space. <br />
Imaging Technique<br />After injection, the table is tilted slowlyto allow the CM to reach different levels in the spinal canal. (A footrest and shoulder straps or supports will keep the patient from sliding)<br />under fluoroscopy, spot films are taken by the radiologist in different positions. <br />the table tilt is adjusted to concentrate the CM in the interested area. <br />Conventional x-ray images is taken by the technologist as requested. <br />
patient prparation<br /><ul><li>Remove any metal objects or clothing that might interfere with the x-ray images.
Injectable sedative-muscle relaxant at 1 hour before the examination, to reduce anxiety and relax the patient.
Solid foods are avoided for several hours before the exam.
Increase patients fluid intake the day before a scheduled myelogram.</li></li></ul><li>Position images(B) <br />1- CERVICAL MYELOGRAPHY<br />>Horizontal beam lateral <br />Cp: c4-c5<br />>Swimmer’s lateral-horizontal beam<br />Cp: c7<br />2- THORACIC MYELOGRAPHY<br />> Lateral decubitus (RT & LT)<br />>Lateral-vertical beam (RTorLT) <br /> Cp : T7<br />
X-rays usually have no side effects in the diagnostic range.</li></li></ul><li>Risks<br /><ul><li> The effective radiation dose from this procedure is about the same as the average person receives from background radiation in 16 months.
headache may follow the myelographydue to the leakage of a small amount of CSF from the needle insertion site.</li></ul>Benefits outweighs<br />
Limitations of Myelography<br />It’s only sees inside the spinal canal and the very proximal nerve roots. Abnormalities outside these areas may be better imaged with MRI.<br /> <br />It may be difficult to inject contrast material in patients with structural defects of the spine or some forms of spinal injury.<br />Myelography usually is avoided during pregnancy ( If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby).<br /> <br />
This procedure has largely been replaced by non-invasive MRI or CT procedures <br />