Brain tumor are intracranial neoplasms, including both tumor lesions of cerebral tissues, and nerves, membranes, vessels, and endocrine structures of the brain. They are manifested by focal symptoms, depending on the topic of the lesion, and general cerebral symptoms. The diagnostic algorithm includes examination by a neurologist and an ophthalmologist, Echo-EG, EEG, CT and MRI of the brain, MR angiography, etc. The most optimal is surgical treatment, supplemented by chemo and radiotherapy according to indications. If it is impossible, palliative treatment is carried out.
General information
Brain tumor account for up to 6% of all neoplasms in the human body. The frequency of their occurrence ranges from 10 to 15 cases per 100 thousand people. Traditionally, cerebral tumors include all intracranial neoplasms — tumors of cerebral tissue and membranes, formations of cranial nerves, vascular tumors, neoplasms of lymphatic tissue and glandular structures (pituitary and pineal gland). In this regard, brain tumors are divided into intracerebral and extracerebral. The latter include neoplasms of the cerebral membranes and their vascular plexuses.
Brain tumor can develop at any age and even be congenital. However, the incidence among children is lower, does not exceed 2.4 cases per 100 thousand children. Cerebral neoplasms can be primary, initially originating in brain tissues, and secondary, metastatic, caused by the spread of tumor cells due to hemato- or lymphogenic dissemination. Secondary tumor lesions are 5-10 times more common than primary neoplasms. Among the latter, the proportion of malignant tumors is at least 60%.
A distinctive feature of cerebral structures is their location in a limited intracranial space. For this reason, any volumetric formation of intracranial localization to one degree or another leads to compression of brain tissues and an increase in intracranial pressure. Thus, even benign brain tumors by their nature, when they reach a certain size, have a malignant course and can lead to a fatal outcome. With this in mind, the problem of early diagnosis and adequate timing of surgical treatment of cerebral tumors is of particular relevance for specialists in the field of neurology and neurosurgery.
Causes
The occurrence of cerebral neoplasms, as well as tumor processes of other localization, is associated with exposure to radiation, various toxic substances, and significant environmental pollution. Children have a high incidence of congenital (embryonic) tumors, one of the causes of which may be a violation of the development of cerebral tissues in the prenatal period. A traumatic brain injury can serve as a provoking factor and activate the latent tumor process.
In some cases, brain tumors develop against the background of radiation therapy for patients with other diseases. The risk of the appearance of a cerebral tumor increases with the passage of immunosuppressive therapy, as well as in other groups of immunocompromised individuals (for example, with HIV infection and neuroAIDS). Predisposition to the occurrence of cerebral neoplasms is noted in certain hereditary diseases: Hippel-Lindau disease, tuberous sclerosis, phacomatosis, neurofibromatosis.
Classification
Among the primary cerebral neoplasms, neuroectodermal tumors predominate, which are classified into:
- tumors of astrocytic genesis (astrocytoma, astroblastoma)
- of oligodendroglial genesis (oligodendroglioma, oligoastroglioma)
- of ependymal genesis (ependymoma, choroid plexus papilloma)
- tumors of the epiphysis (pineocytoma, pineoblastoma)
- neuronal (ganglioneuroblastoma, gangliocytoma)
- embryonic and low-grade tumors (medulloblastoma, spongioblastoma, glioblastoma)
- pituitary neoplasms (adenoma)
- tumors of cranial nerves (neurofibroma, neurinoma)
- formations of cerebral membranes (meningioma, xanthomatous neoplasms, melanotic tumors)
- cerebral lymphomas
- vascular tumors (angioretticuloma, hemangioblastoma)
Intracerebral cerebral tumors are classified by localization into sub- and supratentorial, hemispheric, tumors of the middle structures and tumors of the base of the brain.
Metastatic brain tumors are diagnosed in 10-30% of cases of cancerous lesions of various organs. Up to 60% of secondary cerebral tumors are multiple in nature. The most common sources of metastases in men are lung cancer, colorectal cancer, kidney cancer, in women — breast cancer, lung cancer, colorectal cancer and melanoma. About 85% of metastases occur in intracerebral tumors of the hemispheres of the brain. Metastases of uterine body cancer, prostate cancer and malignant gastrointestinal tumors are usually localized in the posterior cranial fossa.
Brain tumor symptoms
An earlier manifestation of the cerebral tumor process is focal symptoms. It can have the following mechanisms of development: chemical and physical effects on the surrounding cerebral tissues, damage to the wall of the cerebral vessel with hemorrhage, vascular occlusion by metastatic embolus, hemorrhage into metastasis, compression of the vessel with the development of ischemia, compression of the roots or trunks of cranial nerves. Moreover, at first there are symptoms of local irritation of a certain cerebral area, and then there is a loss of its function (neurological deficit).
As the tumor grows, compression, edema and ischemia spread first to the tissues adjacent to the affected area, and then to more distant structures, causing the appearance of symptoms “in the neighborhood” and “in the distance”, respectively. General cerebral symptoms caused by intracranial hypertension and cerebral edema develop later. With a significant volume of cerebral tumor, a mass effect (displacement of the main brain structures) is possible with the development of dislocation syndrome – the insertion of the cerebellum and the medulla oblongata into the occipital foramen.
- A local headache may be an early symptom of a tumor. It occurs as a result of irritation of receptors localized in cranial nerves, venous sinuses, walls of sheathed vessels. Diffuse cephalgia is noted in 90% of cases of subtentorial neoplasms and in 77% of cases of supratentorial tumor processes. It has the character of deep, quite intense and bursting pain, often paroxysmal.
- Vomiting is usually a general cerebral symptom. Its main feature is the lack of connection with food intake. With a tumor of the cerebellum or IV ventricle, it is associated with a direct effect on the vomiting center and may be the primary focal manifestation.
- Systemic dizziness can occur in the form of a feeling of sinking, rotation of one’s own body or surrounding objects. During the manifestation of clinical manifestations, dizziness is considered as a focal symptom indicating a tumor lesion of the vestibulocochlear nerve, bridge, cerebellum or IV ventricle.
- Motor disorders (pyramidal disorders) are in the role of primary tumor symptoms in 62% of patients. In other cases, they occur later due to the growth and spread of the tumor. The earliest manifestations of pyramidal insufficiency include the increasing anisoreflexion of tendon reflexes from the extremities. Then there is muscle weakness (paresis), accompanied by spasticity due to muscle hypertonicity.
- Sensory disturbances mainly accompany pyramidal insufficiency. Clinically manifested in about a quarter of patients, in other cases they are detected only during neurological examination. A disorder of the musculoskeletal sense can be considered as the primary focal symptom.
- Convulsive syndrome is more characteristic of supratentorial neoplasms. In 37% of patients with cerebral tumors, epiprimes are a manifest clinical symptom. The occurrence of absences or generalized tonic-clonic seizures is more typical for tumors of median localization; paroxysms like Jackson’s epilepsy — for neoplasms located near the cerebral cortex. The nature of the aura of the epiprime often helps to establish the topic of defeat. As the neoplasm grows, generalized epiprimes are transformed into partial ones. With the progression of intracranial hypertension, as a rule, there is a decrease in epiactivity.
- Disorders of the mental sphere during manifestation occur in 15-20% of cases of cerebral tumors, mainly when they are located in the frontal lobe. Lack of initiative, sloppiness and apathy are typical for tumors of the frontal lobe pole. Euphoria, complacency, gratuitous gaiety indicate a lesion of the frontal lobe basis. In such cases, the progression of the tumor process is accompanied by an increase in aggressiveness, malice, negativism. Visual hallucinations are characteristic of neoplasms located at the junction of the temporal and frontal lobes. Mental disorders in the form of progressive deterioration of memory, impaired thinking and attention act as general cerebral symptoms, since they are caused by growing intracranial hypertension, tumor intoxication, damage to associative tracts.
- Congestive optic nerve discs are diagnosed in half of patients more often in later stages, but in children they can serve as the debut symptom of a tumor. Due to increased intracranial pressure, transient blurring of vision or “flies” in front of the eyes may appear. With the progression of the tumor, there is an increasing deterioration of vision associated with atrophy of the optic nerves.
- Changes in the fields of vision occur when the chiasm and visual tracts are affected. In the first case, heteronymous hemianopia is observed (loss of the opposite halves of the visual fields), in the second — homonymous (loss of both right or both left halves in the visual fields).
- Other symptoms may include hearing loss, sensorimotor aphasia, cerebellar ataxia, oculomotor disorders, olfactory, auditory and gustatory hallucinations, autonomic dysfunction. When a brain tumor is localized in the hypothalamus or pituitary gland, hormonal disorders occur.
Diagnostics
The initial examination of the patient includes an assessment of the neurological status, an ophthalmologist’s examination, echo-encephalography, EEG. When examining the neurological status, the neurologist pays special attention to the focal symptoms, which allows to establish a topical diagnosis. Ophthalmological examinations include visual acuity testing, ophthalmoscopy and determination of visual fields (possibly with the help of computer perimetry). Echo-EG can register the expansion of the lateral ventricles, indicating intracranial hypertension, and displacement of the median M-echo (with large supratentorial neoplasms with displacement of cerebral tissues). The presence of epiactivity of certain areas of the brain is displayed on the EEG. According to the indications, an otoneurologist’s consultation may be appointed.
Suspicion of volumetric brain formation is an unambiguous indication for computer or magnetic resonance imaging. CT of the brain allows you to visualize a tumor formation, differentiate it from local edema of cerebral tissues, determine its size, identify the cystic part of the tumor (if any), calcifications, necrosis zone, hemorrhage into metastasis or surrounding tissue, the presence of mass effect. MRI of the brain complements CT, allows you to more accurately determine the spread of the tumor process, assess the involvement of borderline tissues in it. MRI is more effective in diagnosing neoplasms that do not accumulate contrast (for example, some brain gliomas), but it is inferior to CT, if necessary, to visualize bone-destructive changes and calcifications, to distinguish the tumor from the area of perifocal edema.
In addition to standard MRI in the diagnosis of a brain tumor, MRI of cerebral vessels (examination of vascularization of neoplasm), functional MRI (mapping of speech and motor zones), MR spectroscopy (analysis of metabolic abnormalities), MR thermography (control of tumor thermal destruction) can be used. PET of the brain makes it possible to determine the degree of malignancy of a brain tumor, identify a tumor recurrence, and map the main functional zones. SPECT with the use of radiopharmaceuticals that are tropic to cerebral tumors makes it possible to diagnose multi-focal lesions, assess the malignancy and degree of vascularization of the neoplasm.
In some cases, stereotactic biopsy of a brain tumor is used. In surgical treatment, the collection of tumor tissues for histological examination is carried out intraoperatively. Histology allows you to accurately verify the neoplasm and establish the level of differentiation of its cells, and hence the degree of malignancy.
Brain tumor treatment
Conservative therapy of a brain tumor is carried out in order to reduce its pressure on cerebral tissues, reduce existing symptoms, and improve the patient’s quality of life. It may include painkillers (ketoprofen, morphine), antiemetic pharmaceuticals (metoclopramide), sedatives and psychotropic drugs. To reduce swelling of the brain, glucocorticosteroids are prescribed. It should be understood that conservative therapy does not eliminate the root causes of the disease and can only have a temporary relieving effect.
The most effective is surgical removal of a cerebral tumor. The technique of surgery and access are determined by the location, size, type and prevalence of the tumor. The use of surgical microscopy allows for a more radical removal of the neoplasm and minimizes injury to healthy tissues. Stereotactic radiosurgery is possible for small tumors. The use of CyberKnife and Gamma Knife techniques is permissible for cerebral formations up to 3 cm in diameter. With severe hydrocephalus, bypass surgery can be performed (external ventricular drainage, ventriculoperitoneal bypass surgery).
Radiation and chemotherapy can complement surgery or be a palliative treatment. In the postoperative period, radiation therapy is prescribed if the histology of the tumor tissues has revealed signs of atypia. Chemotherapy is performed with cytostatics selected taking into account the histological type of tumor and individual sensitivity.
Forecast
Prognostically favorable are benign brain tumors of small size and localization available for surgical removal. However, many of them tend to relapse, which may require repeated surgery, and each surgical intervention on the brain is associated with traumatization of its tissues, entailing a persistent neurological deficit. Tumors of malignant nature, hard-to-reach localization, large size and metastatic nature have an unfavorable prognosis, since they cannot be radically removed. The prognosis also depends on the age of the patient and the general condition of his body. Elderly age and the presence of concomitant pathology (heart failure, CRF, diabetes mellitus, etc.) complicates the implementation of surgical treatment and worsens its results.
Prevention
Primary prevention of cerebral tumors consists in the exclusion of oncogenic environmental influences, early detection and radical treatment of malignant neoplasms of other organs to prevent their metastasis. Prevention of relapses includes the exclusion of insolation, head injuries, and taking biogenic stimulants.
