Metastatic brain tumors are secondary foci that arise due to local aggressive growth, hematogenous and lymphogenic metastasis of malignant neoplasms of other localizations. In 30% of patients, they are asymptomatic. In other cases, brain tumors manifest themselves as headaches, dizziness, nausea, vomiting, focal symptoms, mental and emotional disorders. When the spinal cord is affected, pain, sensory and motor disorders occur. The diagnosis is made taking into account the history, symptoms, CT, MRI and other studies. Treatment is radiotherapy, less often surgical removal or chemotherapy.
General information
Metastatic brain tumors are a group of malignant neoplasms of various origins that have arisen in the spinal cord or brain as a result of the spread of primary tumor cells. Brain metastases are detected in every fifth cancer patient. According to various data, metastatic spinal cord injury is observed in 30-70% of patients. According to researchers, secondary CNS lesions are about 10 times more common than primary ones.
The peak incidence occurs at 50-70 years, men and women suffer equally often. Sometimes the symptoms of a metastatic brain tumor become the first signal of the appearance of another neoplasm. For example, 10% of lung cancer patients seek help for the first time due to the occurrence of neurological disorders. The prognosis is usually unfavorable, secondary brain damage is one of the leading causes of death in malignant tumors. The treatment is carried out by specialists in the field of oncology and neurology.
Causes
Metastases in the central nervous system can occur with malignant neoplasms of any localization. From 30 to 60% of the total number of metastatic brain tumors appear in lung cancer, from 20 to 30% – in breast neoplasms. The third place in prevalence is occupied by metastases in melanomas (10%), the fourth – in colon cancer (5%). Less often, metastatic brain tumors are found in lymphomas, sarcomas and thyroid neoplasms.
Sometimes the cause of secondary processes in the brain is the infiltrative growth of neoplasms of the nasopharyngeal region. Secondary damage to the spinal cord as a result of aggressive growth of the primary focus can be detected with neoplasms of the vertebrae, abdominal form of Burkitt’s lymphoma and other volumetric processes localized near the spinal canal. Among the rare oncological diseases, sometimes complicated by metastatic brain tumors, are testicular teratoma and choriocarcinoma. For unknown reasons, malignant tumors of the ovaries, cervix and bladder rarely metastasize to the brain.
80% of metastatic brain tumors are located in the area of the large hemispheres, 15% – in the cerebellum, 5% – in the brain stem. Most secondary foci in the spinal cord are localized at the level of the lower thoracic or upper lumbar vertebrae. Lesions of the dura mater account for about 10% of the total number of metastatic brain tumors. More than 70% of metastases are multiple, which worsens the prognosis. The histological structure of the secondary tumor is similar to that of the primary neoplasm. Symptoms are caused by both the direct pressure of the node on the nerve structures, and perifocal edema of the surrounding tissues.
Symptoms
Metastatic brain tumor is manifested by headaches, dizziness, nausea, vomiting, seizures, impaired consciousness, sensory disorders and focal neurological symptoms. Mental and emotional disorders are possible: emotional instability, drowsiness, lethargy, cognitive disorders, personality changes, etc. The severity of symptoms of a metastatic brain tumor varies greatly – from minor memory or mood disorders to severe seizures.
Bursting headaches, nausea and disorders of consciousness indicate an increase in intracranial pressure. Especially persistent nausea is observed in children. Epileptiform seizures are detected in 30% of patients with metastatic brain tumors, and people over 45 years of age suffer mainly from them. Focal symptoms vary. There may be a decrease or loss of sensitivity, visual disturbances, hearing disorders, paralysis and paresis of the extremities. Disorders occur on the side opposite to the location of the metastatic brain tumor.
The dynamics of neurological disorders also differ. In some patients, there is a gradual aggravation of disorders, in others, disorders develop suddenly, according to the type of stroke. The cause of the sudden appearance of symptoms may be hemorrhage into a metastatic brain tumor or embolism of a vessel by a fragment of a neoplasm. Sometimes there is a remitting course of the disease, in which focal and extra-cerebral disorders undulate and weaken.
Symptoms
The first manifestation of a metastatic brain tumor is usually pain. Initially, the pain syndrome is not intense and unstable, it occurs only with coughing and sudden movements. Subsequently, the pain increases, appears spontaneously, worries constantly, does not disappear even after sleep or prolonged rest. Progressive sensitivity disorders and motor disorders are revealed. Hyperesthesia develops, followed by hypesthesia, and then anesthesia.
Patients with metastatic brain tumors report muscle weakness and fatigue during physical exertion. Over time, muscle weakness turns into paresis, and paresis turns into paralysis. The zone of sensory and motor disorders is determined by the level and localization of a metastatic brain tumor. When the lateral parts are affected, Brown-Secar syndrome may be detected. With tumors in the posterior or anterior parts, symmetrical disorders are usually observed.
With lesions of the cervical region, spastic tetraplegia occurs, with neoplasms of the thoracic region – spastic lower paraplegia, with processes in the lumbar region – sluggish lower paraplegia, with metastases in the sacrum area – paralysis of the flexor muscles of the lower extremities. All metastatic brain tumors are characterized by increasing pelvic disorders. Rapid formation of pressure sores is possible, especially with damage to the lower parts of the spinal cord.
Diagnostics
The diagnosis is made by an oncologist and a neurosurgeon, taking into account clinical manifestations and additional research data. Anamnestic data play an important role: suspicion of a malignant tumor or the presence of an already diagnosed neoplasm of extra-cerebral localization, as well as the condition after surgical or conservative treatment for this pathology. It should be borne in mind that sometimes the symptoms of a metastatic brain tumor become the first manifestation of a pathological process in another organ.
Warning signs regarding brain tumors are headaches, nausea, epileptiform seizures (found in 35% of patients) and progressive focal symptoms. Suspicion of a secondary process in the spinal cord occurs with prolonged increasing pain, motor and sensory disorders and disorders of the pelvic organs. The main instrumental methods of diagnosis of metastatic brain tumors are CT and MRI. Usually, studies begin with a more accessible CT of the brain and CT of the spine, and full information about the number, size and location of foci is obtained during MRI with contrast enhancement. In case of spinal cord injury, lumbar puncture with cerebrospinal fluid tests is also informative.
Treatment
Patients are prescribed anticonvulsants, steroids, painkillers and psychotropic drugs. The main method of treatment of metastatic neoplasms of the brain is usually radiotherapy, which is used separately, in combination with chemotherapy or surgery. An indication for surgical treatment is the presence of operable solitary metastasis (a secondary focus with an undetectable primary process) or a single metastasis with a controlled primary neoplasm.
Usually, operations are performed for metastatic brain tumors located in the cerebellum, temporal and frontal lobes, that is, in areas with a relatively low operational risk. After surgery, radiotherapy or chemotherapy is prescribed. Sometimes the purpose of surgical treatment is not the removal of a metastatic brain tumor, but an emergency reduction of life-threatening intracranial pressure. If necessary, such interventions can be carried out repeatedly.
Chemotherapy is usually ineffective. The exception is situations when the primary neoplasm reacts well to cytostatics, for example, with breast cancer, small cell lung cancer or lymphoma. Patients with a metastatic brain tumor sensitive to chemotherapy are prescribed medications that can penetrate the blood-brain barrier. Chemotherapy is necessarily supplemented with other methods of treatment (usually radiotherapy).
A promising modern method of treating metastatic brain tumors is 3D conformal radiation therapy – irradiation with thin beams of radiation directed at the tumor. This technique allows for maximum impact on the tumor with minimal radiation load on healthy tissues. The procedure is carried out under the supervision of an MRI or CT scan. The method has a number of advantages over traditional operations (painlessness, noninvasiveness, absence of anesthesia and postoperative period). It is indicated for multiple metastatic brain tumors and at high operational risk due to the peculiarities of the location of metastasis.
With secondary foci in the spinal cord, the same methods are used as with brain damage. The appointment of corticosteroid drugs can reduce pain in 85% of patients, radiotherapy – in 70% of patients. Half of the patients have improved motor functions on the background of radiotherapy. Surgical interventions are carried out with the insensitivity of metastatic brain tumors to radiotherapy, with the progression of neurological disorders or compression of nervous tissue by a bone fragment. Anterior decompression or laminectomy is performed. After surgery, local radiotherapy is prescribed (with the exception of neoplasms that are insensitive to radiation therapy).
Forecast
The prognosis for metastatic brain tumors is usually unfavorable. The average life expectancy since the detection of a secondary focus is 6-8 weeks. With solitary metastases and single metastases in combination with primary neoplasms that respond well to therapy, timely treatment can extend the average life expectancy of patients with metastatic brain tumors up to 10 months from the moment of diagnosis.
