radiation myelopathy
Introduction
Introduction to radiation-induced myelopathy Radioactive myelopathy is a damage to the spinal cord caused by ionizing radiation, usually caused by industrial accidents and medical radiation therapy. The degree of damage is related to radiation intensity, duration, location of the exposure, and tolerance to the individual. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: hair loss
Cause
Causes of radiation-induced myelopathy
(1) Causes of the disease
Radioactive myelopathy is more common in nasopharyngeal carcinoma, esophageal cancer, thyroid cancer, mediastinal tumor, and spinal tumor after radiotherapy.
(two) pathogenesis
The possible mechanisms are:
1 direct damage to the spinal cord tissue by radiation;
2 spinal cord blood supply damage caused by secondary spinal cord injury;
3 venous endothelium injury, leading to venous occlusion, resulting in local exudation, hemorrhagic necrosis;
4 The body produces an allergic reaction to radiation damage, due to allergic demyelination changes and cell-like necrosis of the spinal cord.
There are also views that late spinal cord injury is not caused by direct action on nerve cells, but damage to target cell populations. The most likely target cell population is glial cell population and endothelial cell population. After glial cell population is damaged, Segmental demyelination occurs in the white matter and nerve roots.
Radioactive spinal cord injury mainly involves white matter. It varies according to different stages and degree of injury. The naked eye sees swelling and softening of the spinal cord. The butterfly-shaped structure of the cut surface disappears or is pale yellow, and the texture is hard. The focal coagulation necrosis is seen under the microscope. Demyelination of nerve fibers can also be seen in tissue dissolution, liquefaction, necrosis, vacuolization, degeneration of nerve cells and glial cells, pyknosis and disappearance, increased capillary vessels, thickened wall, glassy degeneration, lumen Occlusion; there are old bleeding around, glial scar formation and a small amount of inflammatory cell infiltration, edema and gliosis in the surrounding tissue.
Prevention
Radioactive myelopathy prevention
1. Mainly the prevention and treatment of primary disease, as well as strict control of radiotherapy indications.
2. Strengthen the management of radiological protection and waste radioactive sources.
3. Radiotherapy and early administration of vitamin B1, B12, B6 and neurokinetic metabolism drugs.
Complication
Radioactive myelopathy complications Complications
In addition to common limb movements, sensory disturbances, and autonomic dysfunction, there may be other signs and symptoms of radiation injury, such as: hair loss, digestive dysfunction, and hematopoietic dysfunction.
Symptom
Symptoms of radiation-induced myelopathy Common symptoms Muscular atrophy, sensory disturbance, hand-foot numbness, paralysis, spinal cord disease, post-radiation brachial plexus...
The latency of radioactive myelopathy varies, and the clinical manifestations are diverse, mainly divided into the following four types:
1. Early transient type: Symptoms appear after about 3 months of incubation after radiation therapy, showing subjective sensory symptoms and very mild objective sensory disturbances, and gradually relieve after 3 months.
2. Lower motor neuron damage type: manifested as upper, lower limb motor neuron damage signs, limb weakness, muscle atrophy, sputum reflexes weakened or disappeared, may be related to selective damage of spinal cord anterior horn cells.
3. Acute paraplegia or quadriplegia type: After the radiation treatment, the acute onset of the incubation period is a certain period of time, and the peak is developed within a few hours to several days. Afterwards, the condition is stable and may be caused by vascular lesions.
4. Chronic progressive radiation myelopathy: This type is the most common, the incubation period is 3 months to 5 years, an average of 18 months, usually for insidious onset, but can also be acute after the incubation period, the earliest symptoms with the most abnormal sensation Commonly, patients complain of numbness or worms in the hands and feet, ants or acupuncture sensations, often radiating from the neck along the spine to the limbs, which can be aggravated during neck flexion and extension, ie low (upward) head electric shock sign (Lhermitte sign), neck There may be pain in the shoulders, and weakness or paralysis of one or more limbs, progressive loss of sensation, and dysfunction of the stool after about 1 year. The physical examination may indicate partial spinal cord injury, half-cut syndrome or transverse damage. Regardless of the damage, the primary lesion should be located within the segment of the irradiated spinal cord. Cerebrospinal fluid examination of the spinal canal patency, may have a slight increase in protein, spinal cord MRI can be seen with spinal cord swelling, lesions are mostly long, strip-like slightly longer or longer T1, long T2 signal, some cases of lesion enhancement, enhanced lesions located at the edge of the spinal cord ( Within the white matter) or dominated by the edges.
Examine
Radioactive spinal cord disease examination
1. Cerebrospinal fluid examination: the spinal canal is smooth, and there may be a slight increase in protein.
2. Other blood tests: including liver function, kidney function, blood sugar, blood sedimentation routine examination; rheumatism series, immunoglobulin electrophoresis and other serological tests related to autoimmunity, have differential diagnosis significance.
3. CT scan of the cervical thoracic segment or the corresponding part of MRI: Excluding tumor metastasis, the early stage of the disease is enlarged, and there is a flaky long T1 and long T2 signal lesion in the white matter.
4. Chest X-ray examination: Exclusion of lung tumors, abdominal ultrasound, myelography, radionuclide scanning, exclusion of tumor metastasis.
5. Electromyography and neurophysiological examination: with diagnostic significance.
Diagnosis
Diagnosis and diagnosis of radiation myelopathy
According to the history of radiation exposure and the manifestations of spinal cord lesions, diagnosis is not difficult.
Chronic radiation-induced myelopathy is a rare disease of occult disease associated with radioactive irradiation. It often passes the acute onset or insidious attack after the incubation period. It needs to be differentiated from lung cancer metastasis or paraneoplastic syndrome. It can be used for chest X-ray examination to exclude lung tumors. Abdominal B-ultrasound, myelography, cervical or thoracic CT scan or radionuclide scan and corresponding part of MRI, exclude tumor metastasis.
It still needs to be differentiated from intramedullary tumor and syringomyelia, and the value of spinal MRI is relatively high.
