Brain Tumor - Symptoms, Causes, Complications, Prevention and Treatment

Brain tumor definition

Any abnormal cell growth is called a tumor. If the tumor formation is seen in the brain, it is called a brain tumor. There are chances of a tumor turning into cancer (malignant tumors). Some tumors remain non-cancerous (non-malignant or benign).

The brain and spinal cord comprise the central nervous system (CNS), which plays an important role in maintaining bodily functions, such as movements, sensations, awareness, thoughts, memory, speech, and linguistics. The development of a tumor in the brain could not only induce the ill effects of cancer but also disturb the abilities of the brain, which can trickle down to inadequate performance of bodily functions. A neuro-oncologist can manage brain tumors.

Brain tumor meaning

• The word “brain” is a derivation from Old English “braegen," which originated from the Proto-Germanic source “bragnan” (source also of Middle Low German bregen, Old Frisian, and Dutch brein). All the derivations describe it as a “soft, greyish mass which fills the cranium of any vertebrate."
• The word “tumor” has the Latin “tumere” which says anything about swelling or becoming large. “Tumere," in turn, has been borrowed from the Proto-Indo-European root "teue," which has been incorporated in various words that have underlying themes of swelling or bigger than the rest, etc.

Global incidence rate of brain tumors

As such, the term “brain tumours" comprises not only the various types of cancers that differ with the site of origin but also various types of cancers of the brain; it is difficult to list all brain cancers. Currently, according to the 2020 Globocan data, the death of patients suffering from brain and central nervous system cancer ranked 12th on the list of all cancer deaths worldwide.

A 2008 study mentioned that the annual global age-standardized incidence of primary malignant brain tumors could be estimated around: 

• ~3.7 per 1,00,000 for males and 
• 2.6 per 1,00,000 for females.

Higher rates of primary malignant brain tumors could be seen within developed countries (males, 5.8 and females, 4.1 per 1,00,000) when compared with underdeveloped countries (males, 3.0 and females, 2.1 per 1,00,000). Also, higher rates of primary malignant brain tumors are seen in males, while females develop higher rates of non-malignant tumors, usually meningiomas.



Understanding the global emphasis of brain tumor from its ever-increasing prevalence and incidence, World Brain Tumor Day has been observed every year on the 8th of June with the intent of increasing public awareness about brain tumors.

Brain tumor incidence in India

While the Indian incidence of central nervous system (CNS) tumors could range from 5-10 patients per 1,00,000 population, the prevalence of brain tumors in the general population has been increasing, accounting for about 2% of malignancies (cancers).

Few Indian studies and registries on brain tumors from Tata Memorial Hospital (TMH), National Institute of Mental Health and Neurosciences (NIMHANS), and All India Institute of Medical Sciences (AIIMS) demonstrated that between 2010-2014, a total of 4295 cases were recorded, in which 1847 (43%) were female and 2448 (57%) were male patients.



A 2020 study from Gujarat Cancer and Research Institute, Ahmedabad, involving 242 Indian children (pediatric patients) demonstrated that boys were more likely to contract with brain tumors when compared to that of girls, with the cerebellum being the most common site of tumor development, followed by the brain’s hemispheres.

Brain tumor symptoms

As explained earlier, the common brain tumor not only induces the ill effects of cancer but also could disturb the brain's workings, which trickles down into inadequate bodily functions. Nevertheless, it must be understood that different types of brain tumors could induce different symptoms basing on the site and the type of tumor.

Regardless of the type, the common symptoms of brain tumor include: 

• Headaches: One of the common signs of brain tumor, severe headaches worsen in the early morning or with activity.
• Sleeping issue: Sleep problems such as insomnia, restless legs syndrome, narcolepsy, and sleep apnea.
• Seizures: Seizures are a medical condition that can occur due to uncontrolled electrical activity in the brain. Patients suffering from brain tumours may experience various types of seizures depending upon the type of tumour and the site of its occurrence. The different types of seizures could include: 
• Myoclonic
• Single or multiple muscle jerks, twitches, and spasms
• Tonic-Clonic (Grand Mal)
• Loss of body tone and consciousness, followed by muscle contractions.
• Uncontrolled body functions, such as uncontrolled bladder function
• Development of a 30-second period of no respiration resulting in the blue, purple, white, or green shading of skin colour. 
• Sensory
• The patients may experience changes in sensation such as in smell, vision, and/or hearing etc. These may occur in patients without losing consciousness.
• Complex partial
• Loss of situational awareness or a partial/total loss of consciousness. At times, it is associated with muscle twitching and repetitive and unintentional movements. 
• Memory loss: In some cases, brain tumour causes memory loss along with changes in personality.
• Nausea: it is usually accompanied by vomiting.
• Fatigue: Muscle fatigue – The patients may not be able to exert their maximal force in response to contractile activity.
• Drowsiness: Can be associated with insomnia or even with healthy sleep. 
• Alterations in daily life: In general, and daily activities such as walking, etc., changes may be seen. 
• The brain tumour position also influences the development of the symptoms. The various locations which help in the development of various symptoms include: 
• Cerebellum: Imbalance and difficulty with fine motor skills 
• Frontal lobe of the cerebrum: Loss of initiative, altered judgment, sluggishness, and muscle weakness or paralysis.
• Occipital or temporal lobe of the cerebrum: Partial/complete vision loss.
• The temporal and frontal lobe of the cerebrum: Altered speech, hearing, issues with memory, or emotions, such as aggressiveness, etc. Comprehension loss or linguistic retrieval difficulty (searching for words).
• The parietal or frontal lobe of the cerebrum: Altered tactile and pressure perception, weakness on one side of the body.
• Pineal gland: Inability to look upward.
• Pituitary gland: Issues in lactation (breast milk secretion) and oligomenorrhea (altered menstrual periods). 
• Brain stem: Dysphagia (difficulty swallowing), facial numbness or weakness.
  

Early symptoms of brain tumor

One of the early symptoms of brain tumour in adults is headache.

The “classic” presentation of tumour headache refers to intense pain in the head upon waking up, with dullness, accompanied by feelings of nausea and vomiting. A study published in 1999 noted that several nonclassic findings such as: 

• Morning headache occurred in only 31.8% of patients.
• Headache was daily seen in only 10.6% of patients.
• Pain was more likely intermittent (88.4%) than constant.

One of the early signs of brain tumour in babies is increased head circumference.

Widely regarded as the initial signs of a brain tumour in babies is an abnormal increase in head size. The doctors confirm macrocephaly (increased head circumference) by measuring the baby's head circumference with ratio to that of the body.

The common symptoms of brain tumour in children include:

• Recurrent (repeated) vomiting
• Persistent (very frequent) headaches
• Changes in behaviour
• Abnormal movements of the eye
• Problems with balance or coordination
• Double vision or blurred vision
  

Brain tumor types

Brain tumour classification can be divided into two types:

1. Primary brain tumours
2. Secondary brain tumours

Primary brain tumours – the tumour/cancer developed in brain. Secondary brain tumours occur when cancers from distant locations metastasize, reaching the cranial cavity.

Differentiated by their site of occurrence and their composition (kinds of cells they are made of), there are more than 120 types of brain tumours. Depending on their malignancy or non-malignancy, all types of brain tumours are divided into: 

• Benign tumours, lesions, and cysts (usually do not develop into cancer)
• Graded brain tumours (has a 50% chance of cancer development)
• Brain cancers (typically malignant)

Benign Tumours, Lesions, and Cysts (Usually do not develop into cancer)

A few of the benign brain tumour types include:

• Meningioma
• Pituitary Adenoma
• Craniopharyngioma
• Schwannoma
• Nasopharyngeal Angiofibroma
• Choroid Plexus Tumour
• Dysembryoplastic Neuroepithelial Tumour
• Neurofibroma
• Hemangioblastoma
• Chondroma
• Giant Cell Tumour
• Osteoma
• Arachnoid Cyst
• Colloid Cyst
• Dermoid or Epidermoid Cyst
• Encephalocele

• Meningioma: The most common primary brain tumor (more than 30% of all brain tumors). These form in the meninges (outer tissue layers protecting the brain under the skull). Usually, it is seen more in women than in men. While 85% of meningiomas prove to be noncancerous, few can be persistent, which may not respond to treatment.
  
• Pituitary adenoma: Tumors that develop at a slow rate in the gland (usually the pituitary gland). About 10% of primary brain tumors are adenomas presenting with endocrinological and vision problems. Nevertheless, since adenomas are benign, they can be treated with surgery and/or medication.
  
• Craniopharyngioma: The tumours that grow adjacent to the pituitary gland, which appears as solid tumours or cysts and often compress nerves, blood vessels, or adjacent parts of the brain. They can cause endocrinological and vision concerns. 
  
• Schwannoma: Benign, slow-growing tumours appearing on the nerve sheath (a covering around the nerve fibres). They develop in middle-aged adults, which can often cause hearing loss (acoustic neuromas).
  
• Nasopharyngeal angiofibroma: Develops in the skull base (at the nose) and is usually seen in adolescent boys. Being the most common benign nasopharynx tumour, it spreads around the nose, causing congestion and nosebleeds, among other things.
  
• Choroid plexus tumour: One of the rare tumours arising in the choroid plexus (where cerebrospinal fluid is produced). Despite being, 90% of these tumours are benign. They most frequently occur in children who are under the age of 2 causing e hydrocephalus (cerebrospinal fluid build-up). This results in increased pressure on the brain, leading to skull enlargement.
  
• Neurofibroma: Benign, painless tumours that can grow not only in the brain but also in the nerves of the body and on the spinal cord.
  
• Dysembryoplastic neuroepithelial tumour: A neuronal-glial brain tumour (made of neurons and supporting cells), dysembryoplastic neuroepithelial tumour is a rare tumour originating in the brain and spinal cord in children and teens causing seizures.
  
• Hemangioblastoma: These benign tumours of the cerebral blood vessels, which can usually be removed through surgery. Rarely, they appear in multiple sites as a symptom of Von Hippel-Lindau (hereditary disease).
  
• Chondroma: Very rare benign tumours formed in cartilage found in the base of the skull base and the paranasal sinuses. They usually originate within 10–30 years of age. Slow growth eventually causes either bone fracture or increased bone growth, pressuring the brain.
  
• Giant cell tumour: Usually affecting the bones of the limbs, these rare tumours can also be found within the skull. Most giant cell tumours are benign, occurring between 20–40 years of age.
  
• Osteoma: Slow-growing benign tumours seen on the facial bones and skull base, usually without any symptoms. Nevertheless, breathing, vision, or hearing loss can be seen with large osteomas growing in certain areas of the brain.
  
• Arachnoid cyst: Common benign cysts that develop at birth in the meninges (membranes surrounding the brain filled with cerebrospinal fluid). They cause no symptoms and usually are left untreated.
  
• Colloid cyst: A benign mass appearing in the third ventricle of the brain, which blocks the cerebrospinal fluid pathways, resulting in hydrocephalus and headaches. With surgery, these can be removed, especially in the case of extreme hydrocephalus.
  
• Dermoid or epidermoid cyst: Slow-growing lesions originate from leftover skin tissue from embryonic development, which can be treated with surgery.
  
• Encephalocele: A birth defect in which a sac-like protrusion is seen in the meninges. This rare birth defect is seen due to the failure of partial closure of the neural tube during the embronic stage. The neural tube is seen in the spinal cord and in the brain. Encephaloceles could be seen either in the skull base, or at the top or between the forehead and nose or at the back of the skull. These encephaloceles can cause deformities in the face and cranium that are repaired with surgery. 
  

Graded Brain Tumours (has a 50% chance of cancer development)

• Glioma
• Ependymal Tumours
• Hemangiopericytoma
• Germ Cell Tumours
• Pineal Tumours

• Glioma: A common brain tumour that can also be found in the spinal cord at times; these gliomas originate from the glial cells. Comprising about 33% of all brain tumours, there are several types of glioma tumours, such as: 
• Astrocytomas: Usually seen in young adults or children and can be surgically removed.
• Oligodendrogliomas: An aggressive brain tumour 
• Ependymal Tumours: Rare tumours that arise from the walls of the central canal of the spinal cord or from the ventricles. The various types of ependymal tumours include:
• Subependymoma: Benign tumours growing from the ventricular wall into the spinal fluid spaces in the brain, blocking the flow of spinal fluid flow.
• Myxopapillary ependymoma: Slow-growing benign tumours from the ependyma of the filum terminale, occurring between 30–50 years of age. 
• Ependymoma: Similar to gliomas, these ependymomas possess specific genetic mutations. Depending on the origin site, their behaviour differs.
• Hemangiopericytoma: Rare skull base tumours involving blood vessels that could be either benign or malignant. In the head region, they are usually seen around the paranasal sinuses and the nasal cavity.
• Germ Cell Tumours: When germ cells get transported (accidentally) into the brain during fetal development, it results in benign or malignant germ cell tumours. Germ cells usually develop into eggs (in the female) or sperm (in the male). 
• Pineal Tumours: Developed in the pineal gland region, pineal tumours can cause hydrocephalus through the blockage of cerebrospinal fluid pathways. Usually, a lumbar puncture or, in some cases, a simple blood test is done to find markers necessary for the pineal tumour diagnosis. In other cases, surgery for biopsy is recommended.
  

Brain Cancers (Typically malignant)

• Chordoma
• Chondrosarcoma
• Medulloblastoma
• Olfactory Neuroblastoma
• Lymphoma
• Gliosarcoma
• Rhabdomyosarcoma
• Paranasal Sinus Cancer
• Atypical Teratoid/Rhabdoid Tumor (AT/RT)

• Chordomas: A rare type of bone cancer (<1%) seen in the skull base or the lower back. It can pressure the nearby nerve tissue with its invasion. Despite displaying benign tendencies with its slow growth, its refractory inclination is as lethal as a malignant as it keeps coming back to spread to other areas. 
• Chondrosarcoma: A malignant bone cancer that develops between 50-70 years of age, affecting the cartilage. This aggressive cancer could develop in the thighbone, arm, pelvis, etc, spreading to the head and spine. It could also develop directly in the face bones or skull base. 
• Medulloblastoma: One of the most common malignant brain tumors in pediatric patients (5-9 years), medulloblastoma arises in the cerebellum. It is of various types with varying aggressivity. 
• Olfactory Neuroblastoma: A rare malignancy associated with nose bleeds and difficulty breathing from the nose, olfactory neuroblastoma develops in the nose in the olfactory nerve (nerve transmitting olfactory impulses (smell) to the brain. Gradually, patients lose their sense of smell.
• Lymphoma: A type of tumor that forms in the lymphatic system (part of the body's immune system). Lymphomas can either spread from other body parts to the brain or form in the brain (primary central nervous system lymphomas) directly. Usually primary CNS lymphomas are often treated with chemotherapy and radiation.
• Gliosarcoma: Rare type of glioma combined with other supportive tissues. These can be aggressive and spread to other areas apart from being resistant to therapy.
• Rhabdomyosarcoma: A rare soft tissue cancer occurring not only in the head but also in many parts of the body (in muscles). Children have more of an affinity to develop rhabdomyosarcomas, which starts with complaints of the eyes or face. 
• Paranasal Sinus Cancer: Formed in the cells lining the hollow spaces of the bones around the nose (maxillary sinuses (in the cheekbones under the eyes) and the ethmoid sinuses (beside the upper nose)). 
• Atypical Teratoid/Rhabdoid Tumor (AT/RT): An embryonal tumor that typically affects children lesser than seven years of age. It is an aggressive cancer with low survival rates despite providing therapy.
  

Brain tumor risk factors

There are various risk factors that increase the propensity of developing a brain tumour. Despite the existence of one or various risk factors, brain tumour development may not be seen. There have been cases in which the development of brain tumours is seen even in patients without any risk factors and, similarly, cases with various risk factors with no development of brain tumours. The common risk factors that could increase a person’s risk of developing a brain tumour include:

• Age
• Gender
• Occupational exposures hazards
• Genetic history
• Infections and allergens
• Exposure to electromagnetic fields
• Exposure to ionizing radiation
• Head injury and seizures
• N-nitroso compounds

• Age: Although anyone at any age can develop a brain tumour, the propensity of brain tumours is higher among children and elderly older adults.
• Gender: The masculine gender (males) rather than the feminine (females) gender is likely to develop a brain tumour. Nevertheless, the type and location of the cancer origin can also contribute to the disparity. E.g., Meningioma is more common in women. 
• Occupational exposure hazards: It is common to find hazards and brain tumour risk factors in the workplace, and implementation of risk reduction strategies was the prime strategy to mitigate the risks. Some of the chemicals that increase the risk of brain tumours with prolonged exposure include pesticides, oil products, solvents, vinyl chloride, rubber, etc. Scientific evidence supports these possible risks, which are yet to be reinforced.
• Genetic history: Hereditary genetic factors can influence the development of brain tumours. They include: 
• Li-Fraumeni syndrome (a genetic disorder of increasing cancer risk)
• Neurofibromatosis (genetic condition of increasing cancer risk in brain and spinal cord)
• Nevoid basal cell carcinoma syndrome (a congenital multisystemic disease)
• Tuberous sclerosis (a genetic condition which causes the development of benign tumours) 
• Turcot syndrome (a rare genetic disorder causing small growths in the intestines, brain, or spinal)
• von Hippel-Lindau disease (a genetic condition causing benign tumour development)
• Infections and allergens: There could be various infections that increase the risk of infection, such as: 
• Epstein-Barr virus (increases the risk of central nervous system cancer and lymphoma). 
• Cytomegalovirus (its presence is seen in brain tumour tissue). 
• Allergens (anything that causes allergies) Studies demonstrated that patients displaying a history of skin allergies have a lower glioma risk.
• Electromagnetic fields: Despite a correlation, a proper causality hasn’t been established stating the role of electromagnetic fields in brain tumours. Exposure to electromagnetic energy can be experienced from power lines or increased cell phone use.
• Ionizing radiation: Any diagnosis or treatment containing exposure to the brain or head with ionizing radiation could trigger a brain tumour. Common ionizing radiation includes X-rays, CT scans, PET scans, etc. 
• Head injury and seizures: A link has been established between head trauma and meningioma; however, studies are yet to discover the connection between head trauma and glioma. Similarly, there have been cases of seizures presenting with a history of brain tumours, but studies are underway to discover vice versa.
• N-nitroso compounds: When animals eat nitrite and nitrate-containing foods, they generate N-nitroso compounds in their meat, which can't be removed even by processing. N-nitroso compounds can increase the risk of both childhood and adult brain tumours. In some cases, certain diets can induce the production of N-nitroso compounds endogenously. It can also be found in cured meats, cigarette smoke, and cosmetics.