Olfactory groove meningioma (OGM) is a rare tumor that develops in the brain’s outer layers. It grows along the nerves that connect the brain to the nose and most commonly affects a person’s sense of smell. OGMs are typically noncancerous.
OGM cells tend to develop slowly and do not spread from their original site. Doctors call these benign. Meningioma is a tumor that develops in the brain and spinal cord’s outer layer, known as the meninges.
This article explains the symptoms, causes, and treatments for OGM.
An OGM is a
The meninges are three protective layers that cover the brain,
- Dura mater: This is the tough, thick outer layer.
- Arachnoid mater: This is the thin middle membrane.
- Pia mater: This delicate, innermost layer follows the shape of the brain.
Sometimes, clusters of cells grow from the arachnoid mater through the dura mater and into the space around the eye. These are called arachnoid cap cells and are usually harmless. OGMs and other meningiomas can develop from these cells. An OGM develops in a groove at the base of the skull.
According to a 2022 case report, OGMs are a
They are more common in females than males. In the United States, OGMs may develop in around 0.008% of females and 0.003% of males yearly.
However, the American Cancer Society considers meningiomas to be the
OGMs do not often cause symptoms until they reach at least
When they occur, symptoms most commonly include the following:
Other symptoms might include:
Tumors develop as a result of
- errors as cells split
- damage to the DNA of the cells from outside sources
- genes that parents pass on to children
- genetic conditions that cause excessive tumor growth, which might include:
- neurofibromatosis type 2
- schwannomatosis – a rare form of neurofibromatosis
- Gorlin syndrome
- radiation-linked factors, such as:
- radiation therapy for other conditions
- exposure to ionizing radiation
- hormonal factors, including:
- having obesity
- alcohol use disorder
A doctor often
A doctor may also arrange checkups and monitor the growth of the tumor
According to a
- relieve compression on the frontal lobe
- restore vision and sense of smell
- remove all of the tumor to prevent it from returning
Surgeons can achieve this through two possible surgical procedures: craniotomy and endoscopic endonasal approach (EEA).
A craniotomy involves removing a section of the skull, and EEA involves entering through the nose to perform surgery on the brain or top of the spine.
Both procedures may require a hospital stay of around 5–7 days and roughly 2–3 weeks of recovery at home.
Doctors may also propose stereotactic radiation therapy for people, depending on the location of the tumor.
Craniotomy involves the
- removing part of the skull
- completing necessary surgical procedures
- reattaching the skull
For people with an OGM, a surgeon will remove part or all of the tumor where possible while preserving the surrounding brain tissue.
This type of surgery involves inserting a lighted, flexible tube called an endoscope through the nose. During the procedure, a neurosurgeon and an ear, nose, and throat surgeon work together to remove the tumor.
A 2018 review concluded that EEA surgery is
Stereotactic radiation therapy
A doctor may also request this procedure if the tumor is
People who receive stereotactic radiation will often be able to return to most typical activities within a week, although they might not experience immediate improvements in their sense of smell. Radiation therapy might cause nausea, headaches, and fatigue as side effects.
Most people with an OGM have a good outlook and remain tumor-free for 5 years. A 2018 study found that in a sample of 43 people who received treatment for an OGM, the tumor returned within 5 years for
The study authors identified certain factors and features of the tumor that may make recurrence more likely, including:
- swelling, or edema, around the tumor
- a soft texture in the tumor instead of hard tissue
- an overgrowth of bony tissue near the tumor — hyperostosis
- thickening of the dura mater around the tumor — dural tail sign
A 2021 analysis followed the symptoms of 17 people who underwent OGM resection. The researchers found that people showed overall cognitive impairment straight after the procedure but that this improved in most areas over the next year.
However, scores ranking cognitive flexibility, memory, inhibition, and attention remained lower after a year than the average scores of people without an OGM.
An OGM develops in the brain’s outer layer and grows along the nerves connecting the brain to the nose. They grow slowly and may not show symptoms for years. However, this rare, benign tumor can affect vision, sense of smell, and cognition.
Treatment often involves removing part or all of the tumor, either through open surgery on the skull or via the nose. Most people recover fully and have a good outlook. However, the tumor returns for some people.