What are the other Names for this Condition? (Also known as/Synonyms)

• Meningioma of the Olfactory Groove
• OGM (Olfactory Groove Meningioma)

What is Olfactory Groove Meningioma? (Definition/Background Information)

• Meningioma is a mostly benign and slow-growing tumor that arises from the meninges which is the membranous tissue encasing the brain and spinal cord (central nervous system or CNS). The meninges consist of three layers, namely the outer layer (dura mater), the middle layer (arachnoid mater), and the inner layer (pia mater); together, they form the protective lining around the CNS
• The World Health Organization (WHO) classifies meningiomas based on their behavior as benign (grade I), atypical (grade II), and malignant (grade III) tumors. The grade and histologic subtype of the tumor is determined by a pathologist after examining a tissue biopsy of the tumor, under a microscope. Meningiomas are also classified based on their sites of origin within the CNS
• While there may be a set of non-specific symptoms observed, certain symptoms are specific to the tumor location. The exact location of a meningioma is generally identified on the basis of radiological imaging studies. These factors, along-with the histopathological subtyping, help the healthcare provider in better understanding the tumor and planning treatment (surgical) approaches accordingly
• Meningioma that develops in the olfactory groove, which is the area of nasal cavity/skull base behind the nose bridge, is called the Olfactory Groove Meningioma (OGM). It is relatively common for a meningioma to develop at this location. The olfactory system serves the function of smell and breathing
• Meningiomas of any histologic subtype i.e., belonging to WHO grade I (benign), WHO grade II (atypical), or WHO grade III (malignant) tumors may involve the olfactory groove. However, a vast majority of these tumors are grade I. Based on certain study reports, the following subtypes are noted:
  • Grade I: Meningothelial meningioma (constitute over 50% of the tumors), fibrous meningioma, transitional meningioma, metaplastic meningioma, angiomatous meningioma, and secretory meningioma
  • Grade II: Atypical meningioma (most common among grade II tumors), clear cell meningioma, and chordoid meningioma
  • Grade III: Papillary meningioma and anaplastic meningioma
• WHO grade I tumors are low-grade slow-growing tumors that are not known to infiltrate into the surrounding tissues; they also offer a very high chance for surgery to be curative. WHO grade II tumors grow faster than grade I tumors but are not usually infiltrative. However, there is a possibility of tumor recurrence as a higher grade tumor after treatment. WHO grade III tumors are malignant and infiltrative; they also have a tendency to recur as a higher grade tumor (grade IV) following treatment
• Thus, the lower the tumor grades, the better are the outcomes. However, large-sized meningiomas, even if they are low-grade, can compress the surrounding structures causing significant signs and symptoms. Therefore, the size of the tumor is also an important determinant for treatment purposes and measuring overall outcomes
• The cause of Olfactory Groove Meningioma is not well understood, but some genetic factors may be involved. In general, the risk factors for meningioma may include ionized radiation exposure, hormonal factors in women, breast cancer history, and a family history of meningiomas. Most of the tumors are noted in middle-aged adults
• Tumors at these locations can cause reduced sense or complete loss of smell, headaches, and vision impairment including double vision. The initial symptoms are usually depression and mental disturbances. The diagnosis of Olfactory Groove Meningioma is usually delayed, until they grow to large sizes. Complications associated with malignant tumors include metastasis to other organs of the body
• Once diagnosed, the treatments for Olfactory Groove Meningioma may include a combination of surgery, radiation therapy, and chemotherapy, based on the grade of the tumor. In a majority, the prognosis is good, since most of these tumors are benign (WHO grade I tumors) and a complete tumor excision/removal is often achieved

Who gets Olfactory Groove Meningioma? (Age and Sex Distribution)

• Olfactory Groove Meningioma is a fairly common tumor that accounts for 14% of all basal meningiomas (at the base of the brain meningioma). Nearly 8-10% of meningiomas are found at this location
• A majority of the tumors are diagnosed in adults in the fifth and sixth decade (ages 40 to 60 years)
• Both males and females are affected, and a female predominance is noted (female-male ratio is 2:1)
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Olfactory Groove Meningioma? (Predisposing Factors)

Olfactory Groove Meningioma is a subtype of meningioma and the predisposing factors for meningioma, in general, include:

• Increasing age, since most tumors are detected in elderly adults
• Individuals who have been exposed to both low-dose and high-dose ionizing radiation have presented an increased incidence of these tumors
  • Dental X-rays are the most common situation of an individual being exposed to low-dose radiations
  • Studies have shown an increased incidence of meningiomas in individuals who have received multiple full oral dental X-ray examinations
• Individuals, who have undergone radiation therapy for squamous cell carcinoma of the head and neck region, are at an increased risk
• A positive family history of these meningeal tumors could place one at an elevated risk
• Hormonal factors: Studies have shown a correlation between hormones and meningiomas. An increased incidence of these tumors is noted in post-pubertal females compared to males. Histopathology studies have detected the presence of hormonal receptors for estrogen, progesterone, and testosterone, in a vast majority of meningiomas
• Breast cancer history: There is an increased incidence of meningioma in women diagnosed with breast cancer, since hormonal influence play an important role in the development of breast cancer. Therefore, hormones are believed to play a contributory role in the development of meningiomas
• Neurofibromatosis type 2 (NF2): It is a multisystem genetic disorder affecting the nervous system, skin, and skeletal muscles. Individuals with NF2 are known to develop meningiomas in 50-75% of the cases
• Obesity: Having excess body fat may increase one’s risk for meningioma; although, there is presently no conclusive evidence to link the two
• Inhalation of cigarette/tobacco smoke and excess consumption of nitrites in food are other potential risk factors that have been put forth by medical research

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Olfactory Groove Meningioma? (Etiology)

The exact cause of formation of Olfactory Groove Meningioma development is unknown. It is researched that certain genetic, environmental, and occupational factors may contribute towards the development of these tumors.

Overall, the following factors have been identified as playing a role in meningioma development:

• Abnormalities on the 22nd chromosome (loss of chromosome 22) in areas that confer suppression of tumor growth; this is reportedly noted in most meningiomas
• 25% of the tumors reportedly exhibit mutations involving the TRAF7 gene
• In individuals with the genetic disorder neurofibromatosis type 2 who develop these tumors, there is an involvement of the NF2 gene. Abnormalities in the NF2 gene are also noted in many cases (40-60%) of sporadic meningiomas
• Some meningiomas have extra platelet-derived growth factor receptors (PDGFR) and epidermal growth factor receptors (EGFR) that can contribute to tumor growth. These receptors are essential for normal cell growth and development
• It is reported that 50% of the tumors show estrogen receptors and 90% show progesterone receptors
• According to research, individuals with radiation therapy to the cranium (for unrelated conditions) have a four-fold risk for the development of meningiomas

It is possible that female hormones, exposure to ionizing radiation, or an inherited disorder of the nervous system, may cause abnormal cell divisions in the meninges. Studies to characterize these processes are currently underway.

Several studies have documented an altered rate of growth of meningioma in relation to menstrual cycles and pregnancy phases. A clear association between oral contraceptives and hormonal replacement therapy has not been yet established. Research is ongoing to study this association.

In general, it is known that tumors form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor.

What are the Signs and Symptoms of Olfactory Groove Meningioma?

The signs and symptoms of meningiomas may differ from one individual to another. It may be mild or severe, depending on several factors including the grade and size of the tumor. The onset of symptoms and speed of progression of the tumor can vary. Tumors that grow slowly and remain asymptomatic are usually diagnosed during certain radiological imaging studies of the head and neck region, which are performed for unrelated health conditions. 

The initial set of longstanding symptoms noted in Olfactory Groove Meningioma (OGM) are usually psychiatric disturbances (behavioral abnormalities), such as depression, and in some cases, a loss of smell (that may be partial and temporary). This factor, combined with older age of the adult, often leads to misdiagnosis and administration of long-term “improper” treatments based on mental health evaluations conducted by the healthcare provider. Thus, in a vast majority of OGM cases, the tumors grow to significant sizes before suitable imaging studies are ordered. Due to this, there is a delayed diagnosis, which is reportedly more often the norm than an exception, in most individuals with OGMs.

The signs and symptoms of Olfactory Groove Meningioma may include:

• Tumors may be well-defined and of varying sizes
• Partial or complete loss of smell (anosmia), usually one side of the nose is affected initially
• Depression - it is amongst the most common symptom noted
• Personality changes: When the tumor grows to significant sizes, it can result in lack of interest (apathy), mental health retardation, and severe depression
• Headaches
• Nausea and vomiting
• Blurred vision
• Large-sized tumors that affect the optic nerve can cause loss of visual acuity, swelling of the optical disc (due to increased intracranial pressure), and partial/total vision loss
• Muscle weakness; weakness in arms or legs, particularly on one side of the body (hemiparesis)
• Bladder incontinence is noted later (rare)
• Unsteady gait
• Increased intracranial pressure due to cerebrospinal fluid (CSF) drainage obstruction. This may result in nausea, vomiting, headaches, and seizures

Malignant tumors are highly aggressive and infiltrative. In case of malignancy, the onset of signs and symptoms may be rapid.

Large tumors (over 4-6 cm in size) can cause significant signs and symptoms. Most of the tumors are single, but occasionally multiple tumors can be detected growing simultaneously (particularly in individuals with neurofibromatosis type 2), either in the brain region or in association with the spinal cord. The associated symptoms of the underlying condition, if any present, may be noted.

How is Olfactory Groove Meningioma Diagnosed?

A vast majority of meningiomas may remain undiagnosed because they are asymptomatic. Often, the slow appearance of symptoms may result in the healthcare provider attributing the origin of such symptoms as part of a normal aging process. The slow development of symptoms, or a presence of mild symptoms, may also contribute to a delayed detection and diagnosis of these tumors. The tumors may be detected when there is a sudden worsening of symptoms prompting the healthcare provider to perform radiological studies of the brain.

A diagnosis of Olfactory Groove Meningioma may include the following tests and exams:

• Complete physical examination with thorough evaluation of the individual’s medical history (including family history of NF2)
• Assessment of the presenting signs and symptoms
• Visual field tests; tests to assess visual acuity
• Neurological, motor skills, and cognitive assessment:
  • Checking intellectual ability, memory, mental health and function, language skills, judgment and reasoning, coordination and balance, reflexes, sensory perceptions (space, sight, hearing, touch)
  • The healthcare provider/neurologist may use the Karnofsky Performance Scale in order to assess the neurological functioning of the individual’s central nervous system (CNS)
• University of Pennsylvania smell identification test (UPSIT): A test to evaluate the olfactory system function. It is particularly used for neurological disturbances/conditions causing a reduced sense of smell
• Electromyography with nerve conductivity tests
• Imaging tests including:
  • X-ray of head and neck; X-ray of the spine
  • Computerized tomography scan (CT scan) of head and neck region and vertebral column; CT with contrast
  • Magnetic resonance imaging scan (MRI scan) of the brain and spinal cord; with contrast agents such as gadolinium
  • Cerebral angiographic studies or magnetic resonance angiography: An angiogram involves injecting dye into the bloodstream, which makes the blood vessels to appear visually on X-rays. The X-ray may show a tumor in the brain or the blood vessels leading into the tumor
  • Magnetic resonance spectroscopy: This radiological technique is used to study the chemical profile of the tumor. It is often performed with and compared to corresponding MRI scan images of the affected region
  • Positron emission tomography (PET scan): A PET scan is a nuclear medicine imaging technique that uses three-dimensional images to show how tissue and organs are functioning. It may be performed to detect any malignancy, and if there is a metastasis (spread) of the tumor to other regions
• Cerebrospinal fluid analysis, where a spinal tap or lumbar puncture procedure may be performed: This diagnostic test is used to remove a sample of cerebrospinal fluid (CSF) from the spaces in and around the brain and spinal cord. The sample is removed from the lower spinal cord using a thin needle, and it is then checked for the presence of cancer cells

Tissue biopsy: A biopsy of the affected region (brain) is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy sample under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy sample under a microscope by a pathologist is helpful in arriving at a conclusive diagnosis. 

There are two ways to perform a biopsy:

• First, a biopsy can be performed as part of a surgical procedure to remove the brain tumor
• Second, a stereotactic needle biopsy can be performed when the tumor is deep within the brain or located in a sensitive area. In this procedure, the surgeon drills a small hole (called a burr hole) into the skull. A thin needle, guided by CT or MRI scanning, is then inserted through the hole to help in the removal of tissue

A differential diagnosis (both radiological and pathological) to eliminate other conditions or tumor types may be considered, before arriving at a definitive diagnosis.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Olfactory Groove Meningioma?

The possible complications associated with Olfactory Groove Meningioma include:

• Emotional and mental stress for both the patients and the caretakers, due to the diagnosis and treatment of a brain tumor
• Permanent damage to the olfactory region causing total loss of smell
• Large undetected tumors can severely affect brain function and be disabling or even life-threatening, due to mass effect/compression of brain tissue
• Large tumors may also press against the skull (or other) bones causing it to expand
• Trouble with concentration
• Dementia including personality changes causing a reduced quality of life
• Peritumoral brain edema (PTBE): Presence of fluid around the tumor region in the brain resulting in severe symptoms and complications
• Complications due to an underlying genetic disorder, if any present, may be observed
• Malignant Olfactory Groove Meningiomas may rarely spread (metastasize) outside the brain, to other sites of the body resulting in severe complications

Complications may arise from surgery, radiation therapy, or other treatment modalities. These may lead to long-term side effects, particularly in children and older adults.

Surgical complications:

• Damage to the muscles, vital nerves, and blood vessels, during surgery to remove the tumor; injury to unaffected brain tissue during surgery
• Post-surgical infection at the wound site is a potential complication
• Post-operation neurological defects may be observed
• Sometimes, removing the tumor can worsen the signs and symptoms in some individuals
• Invasive procedures to remove large-sized tumors carry a higher risk for post-operative complications
• The complications may rarely include heart attack, pneumonia, and pulmonary embolism (blockage of lung artery) causing chest pain and shortness of breath
• Recurrence of the tumor after surgery may be observed, especially if the tumor extends into the paranasal sinuses (from where, total tumor removal is difficult); malignant tumors often have very high recurrence rates

Chemotherapy side effects depend on the type of chemotherapy medication used and may include:

• Nausea and vomiting
• Hair loss
• Mouth sores
• Loss of appetite
• Diarrhea
• Fatigue
• Increased risk for infections
• Easy bruising
• Infertility

Radiation therapy can cause short-term side effects. It depends on the type used and may include:

• Nausea and vomiting
• Hair loss
• Dryness of mouth; loss of taste
• Headaches
• Fatigue
• Skin color changes; usually darkening of skin on the face and neck may be noted
• Speech and hearing difficulties
• Memory issues
• Seizures

Long-term side effects (seen after 6 months or beyond) may include loss of memory, impaired brain function, and appearance of symptoms that mimic stroke.

How is Olfactory Groove Meningioma Treated?

The treatment modality for meningioma is chosen, depending on the size, type (whether the tumor is benign, atypical, or malignant), and stage of the tumor, tumor growth rate, age and health status of the individual. Usually, tumors that are small, slow-growing and benign may be observed and no treatment necessitated, based on the healthcare provider’s assessment. Often, a multidisciplinary team of specialists including otolaryngologists, neurologists, oncologists, surgeons, radiation therapy experts, and other healthcare professionals are involved in managing the condition.

The treatment measures for Olfactory Groove Meningioma may include:

• Wait and watch approach by the healthcare provider (typically for WHO grade I and II tumors):
  • Observation of the tumors is often recommended in individuals with small-sized tumors, slow-growing tumors, tumors with no significant signs and symptoms, elderly patients, individuals where treatment, such as surgery, may be too risky, and individuals, who do not prefer surgical treatment for a variety of reasons (opting out of surgery through personal preference)
  • This approach may not be advised in individuals where the tumor develops in the background of an underlying genetic condition such as neurofibromatosis
  • Recurring imaging scans may be taken to observe the rate of tumor growth; if the tumor is small and growing slowly, then there may be no need for invasive procedures
• Symptomatic treatment may involve the use of antiseizure medications, painkillers, systemic steroids (to reduce inflammation), and administration of anti-depressants
• Placement of ventriculoperitoneal (VP) shunt: It is an invasive procedure that involves the use of a medical device called a VP shunt. The device is placed in the ventricles of the brain to treat hydrocephalus, and thus helps relieve excess CSF pressure on the brain

Surgical treatment: Surgery to remove the entire tumor or just part of the tumor depends on several factors including the risk assessment by a neurosurgeon, with respect to the potential injury to nearby brain tissues. It is also considered based on the location, size, and overall health of the individual. A complete removal of the tumor can result in a cure in many patients.

• Craniotomy: It is a surgical procedure wherein a tiny hole is created in the cranium to access and remove the tumor. The main goal of surgery is to remove as much tumor as possible without damaging the surrounding brain tissue
• Transnasal endoscopic surgery: It is a procedure to remove small-sized tumors through the nose
• In some individuals, the tumor is partially removed, so as not to cause brain damage, resulting in unwanted additional symptoms. A partial removal is usually considered in slow-growing grade I benign tumors
• Microsurgery: The surgery is performed using microsurgical techniques, which can help minimize damage to the accompanying nerve. Since the tumor mostly affects the covering around the nerves, it can be completely removed without affecting the nerve in most cases. The following techniques may be employed:
  • Subtotal removal; when the tumor is incompletely removed
  • Near total removal; when most of the tumor is removed and there is very little tumor remnants
  • Total tumor removal; when the tumor is removed completely
• In some cases, embolization of the tumor may be performed, in order to shrink the tumor size, before major invasive procedures are undertaken. In embolization, the blood supply to the tumor is cut-off, resulting in its shrinkage. This also helps reduce blood loss during a surgical resection
• Radiosurgery for individuals who cannot undergo surgery or have recurrent tumors
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals

Surgical procedures to remove brain tumors carry risks, including infection, possible damage to healthy brain tissue, swelling, or possible fluid build-up in the brain.

Radiation therapy: There are a variety of radiation therapy methods that can be used to treat the tumors. Radiation therapy is performed either after removal of the tumor (to destroy any remaining meningioma cells), or in individuals where surgical removal procedure is not an option. Radiation therapy is helpful to reduce the rate of recurrence. It is also recommended for individuals where the tumor is removed partially.

The types of radiation therapy include:

• Standard external radiation beam therapy using a beam of high-energy X-rays; it is the most common form of radiation therapy used to treat cancers
• 3-dimensional conformal radiation therapy, where 3-d images of the tumor are created using radiological imaging scans to help design appropriate radiation therapy beam size and angles
• Intensity modulated radiotherapy (IMRT): It is a procedure that uses computer-controlled linear accelerators to deliver precise radiation to a malignant tumor
• Stereotactic radiosurgery using Gamma Knife or CyberKnife technique
• Proton radiation therapy: It is a form of external beam therapy using high-energy proton beams to destroy the tumor cells
• Fractionated radiation therapy: It is a good option for individuals whose tumors are too large for radiosurgery, or if the tumor is in a sensitive location. In this therapy, small doses of radiation are administered for a certain set period

Some individuals may experience a few side effects, while others may experience none. These may include fatigue, headaches, hair loss, and scalp irritation. Radiation therapy beams may affect the pituitary gland causing it to dysfunction (bringing about hormonal changes in the body).

Chemotherapy: A large number of meningiomas (especially those classified as benign tumors) usually do not respond to chemotherapy. Hence, chemotherapy is not recommended as a treatment option for treating these tumors. However, the healthcare provider will determine if chemotherapy should be considered as a treatment option on a case-by-case basis.

• Chemotherapy may be beneficial in individuals diagnosed with atypical and malignant tumors. Whether to use chemotherapy as a treatment modality is determined by healthcare provider on case-by-case basis
• Chemotherapy for those tumors that are atypical and/or cannot be effectively treated by surgery or radiation therapy. The administration of some drugs may slow the rate of growth of the tumor

The following chemotherapy agents and methods have been used in atypical and malignant tumors with varying beneficial results:

• Immunotherapy to stimulate an affected individual’s immune system
• Somatostatin analogs which prevent the release of growth hormones
• Hydroxyurea, epidermal growth factor receptor inhibitors, platelet-derived growth factor receptor inhibitors, and vascular endothelial growth factor inhibitors

There are side effects for chemotherapy, which depends upon the type and dose of drugs administered. The common chemotherapy side effects include nausea, vomiting, hair loss, loss of appetite, headache, fever, chills, and weakness.

Clinical trials: In certain tumors with advanced stages of tumor progression, there may be some newer treatment options, currently on clinical trials, which can be considered for some patients depending on their respective risk factors.

Regular observation and periodic checkups to monitor the condition is strongly recommended following treatment. In order to avoid a relapse, or be prepared for a recurrence, the entire diagnosis, treatment process, drugs administered, healthcare recommendations post-treatment, etc. should be well-documented and follow-up measures initiated.

How can Olfactory Groove Meningioma be Prevented?

Presently, there are no specific methods or guidelines to prevent the formation of Olfactory Groove Meningioma. However, if it is associated with a genetic disorder, such as neurofibromatosis type 2 (NF2), the following points may be considered:

• Genetic counseling and testing: If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Regular health check-ups might help those individuals with a history of NF2 in the immediate family and help diagnose the tumor early

In general, the factors that can help reduce the incidence of meningioma and other brain tumor may include:

• Reducing exposure to radiation
• Avoiding cigarette smoke inhalation
• When feasible, it is recommended to decrease the frequency of oral X-rays
• Weight loss, in case one is obese or overweight; maintaining a good BMI
• Getting regular checkups following recovery from breast cancer or neurofibromatosis type 2
• Using safety gear including wearing helmets when playing sports or while riding two-wheelers
• Wearing seatbelts while driving automobiles to minimize the risk for head/body injury

It is important for healthcare providers to be vigilant when elderly adults present a combination of signs and symptoms that include behavioral disturbances/depression without a personal/family history of psychiatric illness or explainable cause, isolated or unattributed reduction in sense of smell, weakness, urinary incontinence, and/or reduced vision. In such cases, a thorough physical and neurological evaluation should be undertaken that also include radiological imaging studies of the head and neck region.

According to the U.S. Preventive Services Task Force (USPSTF), currently there is no standard testing protocols available for meningioma.

Regular medical screening at periodic intervals with blood tests, scans, and physical examinations are mandatory. Often several years of active vigilance are crucial and necessary.

What is the Prognosis of Olfactory Groove Meningioma? (Outcomes/Resolutions)

The prognosis of Olfactory Groove Meningioma may vary considerably from one individual to another and is dependent on a set of factors.

• In many cases, the prognosis is good with prompt diagnosis and adequate treatment, since a majority of Olfactory Groove Meningiomas are grade I benign tumors
• Factors that help in favorable prognoses with long survivals include age below 70 years, size of tumor less than 6 cm, WHO grade I tumor, and Karnofsky Performance Scale over 80. Age and WHO tumor grades are independent prognostic factors with respect to overall survival
• Large tumors (particularly 6 cm or over) offer challenges in their surgical removal; also, the risk for heart and lung associated complications following surgery is observed in almost 30% of the cases
• Incomplete tumor removal can result in recurrences, and the rate of recurrence is around 10% over an 8 year period (according to a particular case study)
• In general, the prognosis for malignant meningioma is typically poor, since these are aggressive tumors with high recurrence rates. These tumors are also known to spread to other body sites (metastasize)

Specifically, the prognosis of Olfactory Groove Meningioma may depend upon the following factors:

• Tumor histology or grade of the tumor: The lower the grade, the better is the prognosis
• Age of the individual: Older individuals generally have poorer prognosis than younger individuals
• Extent of residual tumor in the body following a surgical resection: A complete surgical excision with entire tumor removal presents the best outcome. In some cases, large portions of the tumor may be removed; or, only a small portion for tissue biopsy
• Location of the tumor is an important prognostic factor: Tumors at certain sites involving the central nervous system are more difficult to surgically excise and remove. They can also cause considerable neurological damage at certain sites in the brain and/or spinal cord
• Functional neurologic status based on neurological evaluation of the patient: A higher score on the Karnofsky Performance Scale indicates a more favorable outcome
• Metastatic spread, in case of a malignant tumor: Spread of the malignancy to other body sites portrays a poorer prognosis

In general, the prognosis of a central nervous system tumor may depend upon several factors, which include: 

• Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy
• Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
• The size of the tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
• Presence of certain genetic abnormalities
• Histological subtype of the tumor
• Individuals with bulky disease may have a poorer prognosis
• Involvement of other vital organs may complicate the condition
• The ease of accessibility and surgical resectability of the tumor (meaning, if the primary tumor can be removed completely). This is an important prognostic factor
• Whether the tumor is occurring for the first time or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur 
• Response to treatment and absence of post-operative complications: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
• Progression of the condition makes the outcome worse

An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment.

Additional and Relevant Useful Information for Olfactory Groove Meningioma:

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