What Is White Matter Disease?

Cerebral white matter is a place where nerve fibers inside the brain accumulate. Because its area is lighter than the surface layer of the brain where the cell body gathers, it is named white matter. Myelin damage of central nervous cells in white matter of the brain can cause white matter disease.

White matter

Toxic leukoencephalopathy is caused by multiple toxic factors: craniocerebral irradiation; drug treatment, such as certain anti-tumor drugs, antibiotics and immunological preparations: drugs of abuse, such as toluene, ethanol, heroin, etc .; Toxins, etc. Among these factors, craniocerebral irradiation and antitumor chemotherapy are well-established causes of toxic white matter disease. With the widespread application of radiotherapy and chemotherapy for cancer patients, more and more cancer patients have iatrogenic white matter damage. In order to better understand this disease, the author

Preliminary mental state examinations, including tests to evaluate inattention, a three-word delayed recall test to identify memory impairments, clock drawing to evaluate visual dysfunction, and alternating motion sequences to evaluate brain function. If the results of the mental state examination are suspicious, further neuropsychiatric tests may be performed. If no defects are found in the first two types of tests of the preliminary mental state examination, no detectable brain damage can be determined; if abnormalities are found in the first two types of tests, neuroimaging tests can be performed. Weighted magnetic resonance imaging is the method of choice, and it is an important method to distinguish early or mild white matter disease from mental illness. CT can only show severe white matter damage.

The most significant clinical manifestation of leukoencephalopathy is a change in mental state, that is, at least one of the defects of attention, memory, visual space skills, executive function, and emotional state without aphasia. Mild cases show chronic consciousness with inattention, memory loss, and emotional dysfunction; more severe cases have severe sequelae such as dementia, loss of consciousness, stiffness, and coma. The opposite is true for gray matter, which involves speech, behavior, or sensory function. If focal necrosis occurs in the white matter of the brain, changes in mental state are more prominent than general signs such as hemiplegia, sensory disturbances, and vision loss. The distribution of toxic white matter disease is usually diffuse, and its clinical grade is generally parallel to the severity of white matter damage. Attach importance to tumor radiochemotherapy for leukoencephalopathy

A history of exposure to white matter toxins, such as radiotherapy, chemotherapy and immunotherapy, and exclusion of other causes of white matter damage, such as hereditary demyelinating disease ; Have solid neuroradiological evidence, or typical neuropathological results.

Why are craniocerebral irradiation and anti-tumor chemotherapy a very well-defined cause of toxic white matter disease? Because with the rising incidence of tumors and the widespread application of tumor radiotherapy, chemotherapy and immunotherapy, more and more leukoencephalopathy caused by anti-tumor therapy, so we further understand the leukoencephalopathy caused by tumor radiochemotherapy Has important clinical significance.

White matter radiotherapy

The degree of neurotoxicity caused by craniocerebral irradiation is related to the total dose, time, dose-segmentation scheme and irradiation volume received. The leukoencephalopathy caused by irradiation is divided into three phases, namely the acute response period, the longer-lasting delayed response period, and the severe delayed response period. In the acute reaction period, the white matter of the brain is spotted and reversible edema; in the longer delayed reaction period, the white matter is extensively edema and demyelinating lesions occur; while in the severe delayed reaction period, cerebral vascular necrosis and thrombosis occur, which in turn causes the myelin sheath axis Suddenly disappeared. Some scholars abroad have conducted statistics on patients with leukoencephalopathy caused by craniocerebral radiotherapy from 1980 to 1994, and studied 748 patients who received total cranial therapeutic radiation through 29 projects; 368 patients who received 18 projects Patients with prophylactic exposure were studied. It was found that 213 patients who received total cranial therapeutic radiation and 100 patients who received prophylactic radiation developed white matter disease, and the occurrence of neurobehavioral disorders was related to the patient's age, the total dose of radiation, the volume of radiation, and the timing of radiation treatment. At the same time, it was found that white matter disease was mainly caused by total cranial irradiation, and local irradiation rarely occurred. There are also foreign scholars who have studied 100 patients with malignant astrocytoma who have been exposed to local radiotherapy and found that there are very few patients with neurobehavioral disorders. However, after treatment, patients with a survival period of more than 1 year have white matter The number of patients has increased year by year. A long-term study on the efficacy of craniocerebral radiotherapy for low-grade malignant gliomas found that postoperative radiotherapy can significantly increase the risk of leukoencephalopathy and significantly reduce the quality of life of patients. Therefore, multiple aspects should be given when choosing radiotherapy. trade off.

Chemotherapeutic leukoencephalopathy

The neurological toxicity caused by antitumor drugs has attracted the attention of the medical community. With the increase in the intensity of chemotherapy and the increase in the dose of drugs, reports of leukoencephalopathy caused by chemotherapy have gradually increased. Studies have found that cisplatin, cytarabine, fluorouracil, carmofur, levamisole, methotrexate, fludarabine, sedans, carmustine, ifosfamide, etc. can cause white matter Diseases, of which methotrexate, carmustine and cisplatin are the most common. The neurotoxicity caused by chemotherapy is related to the route, dose and method of administration. The combined application of chemotherapy drugs and craniocerebral irradiation is more harmful, such as the combination of cisplatin plus methotrexate and radiation therapy. Some scholars abroad have studied the situation of 1304 patients with acute lymphoblastic leukemia who were treated with intravenous methotrexate at a dose of 1000 mg per square meter of body surface area. The results were in 1218 evaluable patients. Only 95 cases or 7.8% had acute neurotoxicity.