Small tumors (e.g., < 2.0 cm) usually are incidental findings at autopsy without having caused symptoms. Larger tumors may cause symptoms, depending on the size and location.

- Focal seizures may be caused by meningiomas that overlie the cerebrum.

- Progressive spastic weakness in legs and incontinence may be caused by tumors that overlie the parasagittal frontoparietal region.

- Tumors of the Sylvian aqueduct may cause myriad motor, sensory, aphasic, and seizure symptoms, depending on the location.

- Increased intracranial pressure eventually occurs, but is less frequent than in gliomas.

- Diplopia (Double vision) or uneven pupil size may be symptoms if related pressure causes a third and/or sixth nerve palsy.

There is a wide range of symptoms that patients show. Symptoms can lie dormant, but come about due to Obstructive hydrocephalus. These symptoms include:

- Intracranial pressure

- Headache

- Papilledema

- Vomiting

- Light headedness

- Impaired mental activity

- Gait instability

In rare and extreme cases, more severe symptoms can be observed:

- Memory disturbance

- Dementia

- Hemiparesis

- Seizures

- Hemorrhage

- Psychosis

Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing on nearby tissue. Many cases never produce symptoms. Occasionally seizures, dementia, trouble talking, vision problems, one sided weakness, or loss of bladder control may occur.

Risk factors include exposure to ionizing radiation such as during radiation therapy, a family history of the condition, and neurofibromatosis type 2. As of 2014 they do not appear to be related to cell phone use. They appear to be able to form from a number of different types of cells including arachnoid cells. Diagnosis is typically by medical imaging.

If there are no symptoms, periodic observation may be all that is required. Most cases that result in symptoms can be cured by surgery. Following complete removal less than 20% recur. If surgery is not possible or all the tumor cannot be removed radiosurgery may be helpful. Chemotherapy has not been found to be useful. A small percentage grow rapidly and are associated with worse outcomes.

About one per thousand people in the United States are currently affected. Onset is usually in adults. In this group they represent about 30% of brain tumors. Women are affected about twice as often as men. Meningiomas were reported as early as 1614 by Felix Plater.

Headaches as a result of raised intracranial pressure can be an early symptom of brain cancer. However, isolated headache without other symptoms is rarer, and other symptoms often occur before headaches become common. Certain warning signs for headache exist which make it more likely to be associated with brain cancer. These are as defined by the American Academy of Neurology: "abnormal neurological examination, headache worsened by Valsalva maneuver, headache causing awakening from sleep, new headache in the older population, progressively worsening headache, atypical headache features, or patients who do not fulfill the strict definition of migraine".

The brain is divided into 4 lobes and each lobe or area has its own function. A tumor in any of these lobes may affect the area's performance. The location of the tumor is often linked to the symptoms experienced but each person may experience something different.

- Frontal lobe tumors may contribute to poor reasoning, inappropriate social behavior, personality changes, poor planning, lower inhibition, and decreased production of speech (Broca's area).

- Temporal lobe: Tumors in this lobe may contribute to poor memory, loss of hearing, difficulty in language comprehension (Wernicke's area).

- Parietal lobe: Tumors here may result in poor interpretation of languages, decreased sense of touch and pain, and poor spatial and visual perception.

- Occipital lobe: Damage to this lobe may result in poor or loss of vision.

- Cerebellum: Tumors in this area may cause poor balance, muscle movement, and posture.

- Brain stem: Tumors on this can affect blood pressure, swallowing, and heartbeat.

Central neurocytoma, abbreviated CNC, is an extremely rare, ordinarily benign intraventricular brain tumour that typically forms from the neuronal cells of the septum pellucidum. The majority of central neurocytomas grow inwards into the ventricular system forming interventricular neurocytomas. This leads to two primary symptoms of CNCs, blurred vision and increased intracranial pressure. Treatment for a central neurocytoma typically involves surgical removal, with an approximate 1 in 5 chance of recurrence. Central neurocytomas are classified as a grade II tumor under the World Health Organization's classification of tumors of the nervous system.

The cerebellopontine angle is the anatomic space between the cerebellum and the pons filled with cerebrospinal fluid. This is a common site for the growth of acoustic neuromas or schwannomas. A distinct neurologic syndrome of deficits occurs due to the anatomic proximity of the cerebellopontine angle to specific cranial nerves. Indications include unilateral hearing loss (85%), speech impediments, disequilibrium, tremors or other loss of motor control.

Tumors within the nerve canaliculi initially present with unilateral sensorineural hearing loss, unilateral tinnitus, or disequilibrium (vertigo is rare, on account of the slow growth of neuromas). Speech discrimination out of proportion to hearing loss, difficulty talking on the telephone are frequent accompaniments. Tumors extending into the CPA will likely present with disequilibrium or ataxia depending on the amount of extension on the brainstem. With brainstem extension, midfacial and corneal hypesthesia, hydrocephalus, and other cranial neuropathies become more prevalent.

For example, involvement of CN V from a cerebellopontine mass lesion often results in loss of the ipsilateral (same side of the body) corneal reflex (involuntary blink).

Patients with larger tumours can develop Bruns nystagmus ('dancing eyes') due to compression of the flocculi.

The most common symptom of the papillary tumor is a headache. Because headaches are so common, most people think nothing of it. This is why brain tumors are so dangerous. There are not a lot of symptoms that go along with them so people tend to wait a long time before seeking medical help. Most of the time people will go see a doctor when their headaches become consistent and start to never go away. This symptom however occurs secondary to hydrocephalus, which is a result from compression of the cerebral aqueduct. The cerebral aqueduct is a narrow channel in the midbrain, which connects the third and fourth ventricles. When a tumor blocks the pathway of the cerebrospinal fluid, this will cause headaches in the patient. Often when hydrocephalus occurs, a shunt is put in place in order to alleviate the pressure. In one case study, an endoscopic third ventriculostomy was performed as a first line procedure to treat the hydrocephalus and also for diagnostic purposes.

In some cases, patients have had progressive diplopia, or double vision. Also, although not in all cases, patients sometimes suffer from nausea and vomiting.

Hemangiopericytoma located in the cerebral cavity is an aggressive tumor of the Mesenchyme with oval nuclei with scant cytoplasm. "There is dense intercellular reticulin staining. Tumor cells can be fibroblastic, myxoid, or pericytic. These tumors, in contrast to meningiomas, do not stain with epithelial membrane antigen. They have a grade 2 or 3 biological behavior, and need to be distinguished from benign meningiomas because of their high rate of recurrence (68.2%) and metastases (Maier et al. 1992; Kleihues et al. 1993 )."

Malignant meningioma is a rare, fast-growing tumor that forms in one of the inner layers of the meninges (thin layers of tissue that cover and protect the brain and spinal cord). Malignant meningioma often spreads to other areas of the body.

The World Health Organization classification system defines both grade II and grade III meningiomas as malignant. Historically, histological subtypes have also been used in classification including:

- clear cell (WHO grade II),

- chordoid (WHO grade II),

- rhabdoid (WHO grade III), and

- papillary (WHO grade III)

Benign or low grade meningiomas (WHO grade I) include meningothelial, fibrous, transitional, psammomatous, angiomatous, microcystic, secretory, lymphoplasmacyte-rich, and metaplastic.

A hemangiopericytoma (HPC) is a type of soft tissue sarcoma that originates in the pericytes in the walls of capillaries. When inside the nervous system, although not strictly a meningioma tumor, it is a meningeal tumor with a special aggressive behavior. It was first characterized in 1942.

Papillary tumors of the pineal region (PTPR) were first described by A. Jouvet et al. in 2003 and were introduced in the World Health Organization (WHO) classification of Central Nervous System (CNS) in 2007. Papillary Tumors of the Pineal Region are located on the pineal gland which is located in the center of the brain. The pineal gland is located on roof of the diencephalon. It is a cone shaped structure dorsal to the midbrain tectum. The tumor appears to be derived from the specialized ependymal cells of the subcommissural organ. Papillary tumors of the central nervous system and particularly of the pineal region are very rare and so diagnosing them is extremely difficult.

Neuroendocrine adenoma of the middle ear (NAME) is a tumor which arises from a specific anatomic site: middle ear. NAME is a benign glandular neoplasm of middle ear showing histologic and immunohistochemical neuroendocrine and mucin-secreting differentiation (biphasic or dual differentiation).

This uncommon tumor accounts for less than 2% of all ear tumors. While patients present with symptoms related to the middle ear cavity location of the tumor, the tumor may expand into the adjacent structures (external auditory canal, mastoid bone, and eustachian tube). Patients come to clinical attention with unilateral (one sided) hearing loss, usually associated with decreased auditory acuity, and particularly conductive hearing loss if the ossicular bone chain (middle ear bones) is involved. Tinnitus (ringing), otitis media, pressure or occasionally ear discharge are seen. At the time of otoscopic exam, the tympanic membrane is usually intact, with a fluid level or mass noted behind the ear drum. Even though this is a "neuroendocrine" type tumor, there is almost never evidence of neuroendocrine function clinically or by laboratory examination.

Neurofibromatosis type II (also known as MISME syndrome - multiple inherited schwannomas, meningiomas, and ependymomas) is a genetic condition which may be inherited or may arise spontaneously. The main manifestation of the condition is the development of symmetric, benign brain tumors in the region of the cranial nerve VIII, which is the "auditory-vestibular nerve" that transmits sensory information from the inner ear to the brain. Many people with this condition also experience visual problems. NF II is caused by mutations of the "Merlin" gene, which seems to influence the form and movement of cells. The principal treatments consist of neurosurgical removal of the tumors and surgical treatment of the eye lesions. Historically the underlying disorder has not had any therapy due to the cell function caused by the genetic mutation. However, new drug research and some clinical trials have shown some promise in having beneficial effects. Collaborative research to find better treatments is ongoing, such as the work of the Synodos NF-2 Consortium of scientists.

Common symptoms include seizure, headaches, nausea and vomiting, memory loss, changes to personality, mood or concentration; and localized neurological problems.

The kind of symptoms produced depends more on the location of the tumor than on its pathological properties. The tumor can start producing symptoms quickly, but occasionally is an asymptomatic condition until it reaches an enormous size.

The clinical spectrum of the condition is broad. In other words, people with NF II may develop a wide range of distinct problems.

1. Acoustic nerve: 90% of the patients show bilateral acoustic schwannomas on magnetic resonance imaging (MRI).

2. Other cranial nerves and meninges: About 50% of patients develop tumours in other cranial nerves or meningiomas.

3. Spinal cord: About 50% of the patients develop spinal lesions. Only 40% of the spinal lesions are symptomatic. The spinal tumours in NF II are separated in two groups. Intramedullary lesions are located within the spinal tissue and usually belong to the so-called spinal astrocytomas or ependymomas. The extramedullary lesions are located within the small space between the surface of the spinal cord and the bony wall of the spinal canal. These tumours belong to the schwannomas and meningiomas.

4. Skin: If children show neurofibromas, a diagnostic procedure should be performed to decide which form of neurofibromatosis causes the alterations.

5. Eyes: Studies on patients with NF II show that more than 90% of the affected persons suffer eye lesions. The most common alteration in NF II is the juvenile subcapsular cataract (opacity of the lens) in young people.

"Presenting symptoms" (initial concern that brings a patient to a doctor) of a lesion of the nervus vestibulocochlearis due to a tumour in the region of the cerebello-pontine angle are the following: hearing loss (98%), tinnitus (70%), dysequilibrium (67%), headache (32%), facial numbness and weakness (29% and 10% respectively).

"Clinical signs" (alterations that are not regarded by the patient and that can be detected by the doctor in a clinical examination) of the lesion in discussion are: abnormal corneal reflex (33%), nystagmus (26%), facial hypesthesia (26%).

Evaluation (study of the patient with technical methods) shows the enlargement of the porus acousticus internus in the CT scan, enhancing tumours in the region of the cerebello-pontine angle in gadolinium-enhanced MRI scans, hearing loss in audiometric studies and perhaps pathological findings in electronystagmography. Some times there are elevated levels of protein in liquor study.

In NF II, acoustic neuromas usually affect young people, whereas in sporadic forms of acoustic neuromas, the appearance of the tumour is limited to the elderly.

There are two forms of the NF II:

- The "Wishart-Phenotype" is characterized by multiple cerebral and spinal lesions in patients younger than 20 years and with rapid progression of the tumours.

- Patients that develop single central tumours with slow progression after age of 20 are thought to have the "Feiling-Gardner-Phenotype".

Chiasmal syndrome is the set of signs and symptoms that are associated with lesions of the optic chiasm, manifesting as various impairments of the sufferer's visual field according to the location of the lesion along the optic nerve. Pituitary adenomas are the most common cause; however, chiasmal syndrome may be caused by cancer, or associated with other medical conditions such as multiple sclerosis and neurofibromatosis.

Glioblastoma, also known as glioblastoma multiforme (GBM), is the most aggressive cancer that begins within the brain. Initially, signs and symptoms of glioblastoma are non-specific. They may include headaches, personality changes, nausea, and symptoms similar to those of a stroke. Worsening of symptoms often is rapid. This may progress to unconsciousness.

The cause of most cases is unclear. Uncommon risk factors include genetic disorders such as neurofibromatosis and Li–Fraumeni syndrome, and previous radiation therapy. Glioblastomas represent 15% of brain tumors. They can either start from normal brain cells or develop from an existing low-grade astrocytoma. The diagnosis typically is made by a combination of CT scan, MRI scan, and tissue biopsy.

There is no clear way to prevent the disease. Typically, treatment involves surgery, after which chemotherapy and radiation therapy are used. The medication temozolomide is used frequently as part of chemotherapy. High dose steroids may be used to help reduce swelling and decrease symptoms. It is unclear whether trying to remove all or simply most of the cancer is better.

Despite maximum treatment, the cancer usually recurs. The most common length of survival following diagnosis is 12 to 15 months, with fewer than 3% to 5% of people surviving longer than five years. Without treatment, survival is typically three months. It is the most common cancer that begins within the brain and the second most common brain tumor, after meningioma. About 3 per 100,000 people develop the disease a year. It most often begins around 64 years of age and occurs more commonly in males than females. Immunotherapy is being studied in glioblastoma with promising results.

Foroozen divides the causes of chiasmal syndromes into intrinsic and extrinsic causes. Intrinsic implies thickening of the chiasm itself and extrinsic implies compression by another structure. Other less common causes of chiasmal syndrome are metabolic, toxic, traumatic or infectious in nature.

Intrinsic etiologies include gliomas and multiple sclerosis. Gliomas of the optic chiasm are usually derived from astrocytes. These tumors are slow growing and more often found children. However, they have a worse prognosis, especially if they have extended into the hypothalamus. They are frequently associated with neurofibromatosis type 1 (NF-1). Their treatment involves the resection of the optic nerve. The supposed artifactual nature of Wilbrand's knee has implications for the degree of resection that can be obtained, namely by cutting the optic nerve immediately at the junction with the chiasm without fear of potentially resulting visual field deficits.

The vast majority of chiasmal syndromes are compressive. Ruben et al. describe several compressive etiologies, which are important to understand if they are to be successfully managed. The usual suspects are pituitary adenomas, craniopharyngiomas, and meningiomas.

Pituitary tumors are the most common cause of chiasmal syndromes. Visual field defects may be one of the first signs of non-functional pituitary tumor. These are much less frequent than functional adenomas. Systemic hormonal aberrations such as Cushing’s syndrome, galactorrhea and acromegaly usually predate the compressive signs. Pituitary tumors often encroach upon the middle chiasm from below. Pituitary apoplexy is one of the few acute chiasmal syndromes. It can lead to sudden visual loss as the hemorrhagic adenoma rapidly enlarges.

The embryonic remnants of Rathke’s pouch may undergo neoplastic change called a craniopharyngioma. These tumors may develop at any time but two age groups are most at risk. One peak occurs during the first twenty years of life and the other occurs between fifty and seventy years of age. Craniopharyngiomas generally approach the optic chiasm from behind and above. Extension of craniopharyngiomas into the third ventricle may cause hydrocephalus.

Meningiomas can develop from the arachnoid layer. Tuberculum sellae and sphenoid planum meningiomas usually compress the optic chiasm from below. If the meningioma arises from the diaphragma sellae the posterior chiasm is damaged. Medial sphenoid ridge types can push on the chiasm from the side. Olfactory groove subfrontal types can reach the chiasm from above. Meningiomas are also associated with neurofibromatosis type 1. Women are more prone to develop meningiomas.

Measurement of the degree of exophthalmos is performed using an exophthalmometer.

Most sources define exophthalmos/proptosis as a protrusion of the globe greater than 18 mm.

The term exophthalmos is often used when describing proptosis associated with Graves' disease.

Exophthalmos (also called exophthalmus, exophthalmia, proptosis, or exorbitism) is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral (as is often seen in Graves' disease) or unilateral (as is often seen in an orbital tumor). Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma.

In the case of Graves' disease, the displacement of the eye is due to abnormal connective tissue deposition in the orbit and extraocular muscles which can be visualized by CT or MRI.

If left untreated, exophthalmos can cause the eyelids to fail to close during sleep leading to corneal dryness and damage. Another possible complication would be a form of redness or irritation called "Superior limbic keratoconjunctivitis", where the area above the cornea becomes inflamed as a result of increased friction when blinking. The process that is causing the displacement of the eye may also compress the optic nerve or ophthalmic artery, leading to blindness.

Some clinically observed signs and symptoms include:

- Orbital pain

- Eyes displaced posteriorly into sockets (enophthalmos)

- Limitation of eye movement

- Loss of sensation (hypoesthesia) along the trigeminal (V2) nerve distribution

- Seeing-double when looking up or down (vertical diplopia)

- Orbital and lid subcutaneous emphysema, especially when blowing the nose or sneezing

- Nausea and bradycardia due to oculocardiac reflex

The syndrome is defined as the following changes:

- optic atrophy in the ipsilateral eye

- disc edema in the contralateral eye

- central scotoma (loss of vision in the middle of the visual fields) in the ipsilateral eye

- anosmia (loss of smell) ipsilaterally

This syndrome is due to optic nerve compression, olfactory nerve compression, and increased intracranial pressure (ICP) secondary to a mass (such as meningioma or plasmacytoma, usually an olfactory groove meningioma). There are other symptoms present in some cases such as nausea and vomiting, memory loss and emotional lability (i.e., frontal lobe signs).