Brain tumors are tumors which take origin from brain tissue or its outer coverings (membranes), skull bone or malignant (cancerous) tumors which spread to brain from other organs (metastasis).
There are many brain tumor types including gliomas, meningiomas, schwannomas, pituitary adenomas, pineal tumors, embryonal tumors, medulloblastomas, PNET, mixed neuro-glial tumors, etc. Of these brain tumors, some tumors are of good character, benign, not malignant while slightly more than half of them are unfortunately considered ‘brain cancers’ and thus malignant.
Brain Tumors Locations
Brain tumors can be seen anywhere in the brain from brain surface (brain cortex, shell), down to the deep nuclei (basal ganglia), diencephalon (thalamus), brain stem (mesencephalon-midbrain, pons, medullo oblongata) and inside the brain cavities (ventricles) in which brain liquid (cerebrospinal fluid) circulates.
Symptoms of Brain Tumor
Symptoms of brain tumor are of broad spectrum and vary according to the location, size, and the nature of the tumor. Persistent, new-onset headache resistant to pain-killer medications, weakness in arms/legs, numbness, sensory impairments, epileptic attacks (fits) are the major findings of a growing brain tumor. Personality change, aggressiveness, visual field cuts, loss of smell (anosmia), paralysis in limbs, decrease in intellectual capacity may indicate a tumor in frontal lobe; complex partial seziures (fits), memory deficits, difficulty in understanding spoken language may be the signs of a temporal lobe tumor; flash-light fits, visual cuts may point out an occipital (back) lobe tumor. Imbalance, hearing loss, tinnitus, facial paralysis, numbness in face, paralysis in eye movements, hoarseness, difficulty swallowing may indicate an underlying cerebellar and/or brain stem tumor.
How are Brain Tumors Diagnosed?
Magnetic resonance imaging (MRI) and computed tomography (CT) and in some instances PET-CT scans are diagnostic tools in the visualization and delineating the characteristic of brain tumors. Contemporary neuro-oncological approach mandates the biopsy and tissue diagnosis in almost all patients with brain tumors.
Treatment of Brain Tumors
Micro-neurosurgical removal of brain tumors as radical as possible while preserving the normal functioning of the brain under neuronavigation and neuromonitoring techniques by experienced neurosurgeons is the first and the most crucial step in the management of brain tumors. Subsequently, radiotherapy and/or chemotherapy maybe required too if the pathology reveals a malignant or a tumor at a borderline grade (i.e, Grade 2 astrocytoma, atypical meningioma).
Craniotomy is a basic neurosurgical term that denotes the removal of a piece of skull (which is to be placed back and fixed by mini-titanium plates in the end of the surgery) in oder to reach and remove the tumor under a surgical microscope which enables neurosurgeons to magnify the exposed area by many folds for a safer surgery.
Neuronavigation tool enables me to make the scalp cut (incision) and craniotomy as minimaly as possible since i plan the surgery beforehand based on the MR images of the patient registered in neuronavigation system which navigates me during the course of the surgery as well.
Post operative (after surgery) course of a patient with a brain tumor is pretty much straigh-forward unless we encounter any serious complications; 1-2 days of intensive care unit (ICU) stay and followed by 3-6 days of ward stay to take care of the wound and administering medical treatment is my routine. Patients are generally mobilized on post operative first day and are free to have shower on post operative 3rd day.
Brain Tumor Types
Glial tumors (gliomas) are tumors that originate from glial cells (i.e, supporting cells to the main brain cells, aka, neurons) and they generally behave aggressive, thus most of them are considered to be malignant. Of glial tumors; astrocytomas are the most common and aggressive, infiltrative type and grade 3 (anaplastic) and grade 4 (glioblastoma multiforme, GBM) are the most malignant glial tumors in the order of increasing malignancy. Grade 2 astrocytomas may behave more like grade 3 or grade 1 and thus molecular and genetic profiling of these gliomas are important in predicting the prognosis (course of the disease). Grade 1 (pilocytic and subependymal giant cell astrocytomas) maybe considered the only benign gliomas and the complete surgical resection generally results in a cure with a very low incidence of tumor recurrence.
Oligodendrogliomas are the second most common glial tumors and they grow slower than astrocytomas with a slightly better prognosis and they present with epileptic seizures (fits) more frequently than astrocytomas.
Epandymomas are the least common glial tumors and they originate from the ependymal cells lining the inner surface of the brain cavities (ventricles).
Meningiomas are -unlike gliomas- generally act benign and around 80-85% of them are considered good-natured and grade 1 tumors. 10-15% are atypical (grade 2) and only around 1-3% are malignant (grade 3). They arise from arachnoid cap cells and tend to adhere to the dura matter (outer covering of brain). Micro-neurosurgical complete resection of meningiomas mostly result in cure and the subsequent radiotherapy is indicated in some cases of atypical meningiomas and in all cases of malignant meningiomas.
Skull base tumors are brain tumors that take origin and infiltrate the bases of the cranium-skull (front, side, back) and these tumors include mostly meningiomas, schwannomas, metastasis(es), glomus jugulare tumors, epidermoid/dermoid tumors.
Pituitary adenomas are the tumors of the pituitary gland which secretes hormones-essential for the healthy human. Therefore, tumors of this region may cause hormonal imbalance and defects in vision since their close proximity to the optic nerves (i.e, nerve for vision)
Craniopharngiomas are mostly encountered in childhood and even though they are mostly good-natured, they pose a challenge in surgical resection since they get calcified and adhere to the surrounding critical vessels and nerves.
Schwannomas (i.e, acoustic neurinomas) are another mostly benign brain tumor group and meticulous micro-neurosurgical resection is required in their treatment. Gamma knife radiosurgery may also be considered for some small schwannomas less than 2.5 cm in size with no obvious compression onto the brain stem.
Intraventricular tumors are brain tumors located inside the brain cavities (ventricles). Choroid plexus papillomas, ependymomas, subependymomas, meningiomas, gliomas, colloid cysts comprise most of these tumors.
Pineal tumors arise from or near the pineal gland which is located in the junction of the midbrain and thalamus (major relay nucleus), tumors of region are challenging tumors and micro-neurosurgical resection is required in most instances.
Medulloblastomas are the most malignant brain tumors in children and they originate from cerebellum.
Metastatic brain tumors are cancers which spread to brain from other cancers in the body. Complete surgical removal of solitary (single) metastasis generally enable local control in the brain; However, prognosis of these patients are dependent on the behaviour of the primary source of the cancer in the body.