Myelography is a contrast X-ray examination of the subarachnoid (subarachnoid) space of the spinal cord. The technique is prescribed for symptoms of compression of the spinal cord or its roots of unclear etiology, suspicion of syringomyelia, arachnoiditis, malignant and benign neoplasia, and some other diseases. The study can be ascending or descending, in the first case, the introduction of a contrast agent is performed by lumbar, in the second – by suboccipital puncture.
Most often in neurology, myelography is prescribed to determine the causes of compression myelopathy and compression of spinal roots. The method allows to determine the location of pathological changes in hernias and ruptures of intervertebral discs, abscesses, narrowing of the spinal canal and tumors, to assess the feasibility of surgical treatment.
With the help of myelography, syringomyelia is diagnosed, which is characterized by the appearance of cavities in the spinal cord. An indication for the study may be spinal arachnoiditis, a tumor of the posterior cranial fossa, the presence of neurological symptoms (persistent pain syndrome, numbness and weakness in the extremities) with insufficient informativeness of conventional radiography. The possibility of examining the patient using CT or MRI of the spine significantly narrows the indications for myelography.
Myelography has general contraindications, the same for all radiographic examinations with the use of contrast agents. The procedure is not performed with intolerance to iodine preparations, thyroid diseases, kidney failure. In addition, contraindications for punctures are various skin lesions at the needle insertion site. Ascending myelography is contraindicated in the presence of deformities of the lumbar spine.
When planning an examination to detect hypersensitivity and intolerance to the contrast agent, the patient is preliminarily given an allergic test. It consists in intravenous administration of 2 ml of contrast agent. In case of nausea, weakness, vomiting, allergic reactions (rash, itching, cough, runny nose), myelography is replaced by other methods. Patients with epilepsy should inform the doctor about the antiepileptic drugs taken.
During 8-10 hours before the start of manipulation, the patient should refrain from eating and taking fluids. If myelography will be performed using a lumbar puncture, a cleansing enema is necessary before the examination. The training program includes premedication. The doctor may prescribe the use of m-holinoblockers (atropine) or sedatives. Before starting the procedure, the patient must remove all metal objects that can get into the study area (clothes with metal fittings, coins, phone).
Methodology of conducting
First, a puncture of the subarachnoid space is performed under local anesthesia. The position of the puncture needle during its introduction and during the entire examination is monitored by X-ray. Depending on the puncture site, ascending and descending myelography are distinguished. With ascending myelography, a puncture is made in the lumbar spine (lumbar puncture). Before contrast is introduced, cerebrospinal fluid is taken, which is sent for laboratory examination. Then the patient is shifted to the stomach, the upper part of the trunk and legs are additionally fixed with straps.
To prevent the penetration of the contrast agent into the brain, a roller is placed under the patient’s chin so that his head is tilted back. After that, a contrast agent (demirex, amnipak, etc.) is injected under X-ray control and the X-ray table is moved to a position with the head end tilted down. Since the contrast is heavier than the cerebrospinal fluid, it flows down to the patient’s head, gradually filling the entire subarachnoid space in this direction. Descending myelography is performed using a suboccipital puncture. After fixing the patient on the X-ray table, a contrast agent is injected and the table is tilted with the foot end down. The contrast flows down from the head to the feet.
When contrast is introduced, the patient may briefly feel warmth, burning, a rush of blood to the face, headache, salty taste in the mouth. After administration, nausea is possible, sometimes vomiting. In some cases, there is the appearance or increase of pain in the spine associated with a forced posture and the introduction of a puncture needle. After filling the subarachnoid space with a contrast agent, a series of X-ray images are produced. Then the contrast is evacuated, the needle is removed, the puncture site is treated and sealed with a plaster.
Recommendations after myelography vary depending on the selected contrast agent. As a rule, a twelve-hour bed rest is necessary, about eight hours the patient should spend with his head raised. Enhanced drinking is shown. For timely detection and relief of possible complications within 24 hours, the patient must be under constant supervision of a neurologist. Then he can return to his previous daily routine and diet.
In addition to the general complications observed with the use of various radiopaque techniques, sometimes there are adverse consequences associated with the puncture itself during myelography. Due to some leakage of cerebrospinal fluid from the puncture site and a decrease in pressure in the subarachnoid space, the patient may get sick or dizzy, nausea and even vomiting may appear. In rare cases, there is pain and impaired sensitivity in the puncture area, pain and cramps in the legs.