Olfactory groove meningiomas
February 15, 2009
“Olfactory groove meningiomas are benign tumors that grow along the midline floor of the anterior cranial fossa. Delayed diagnosis is the rule rather than the exception. Despite advances in imaging and therapeutic measures, the average size of these tumors at the time of surgical resection has not changed over the past few decades.
Olfactory groove meningiomas comprise about 14% of all basal meningiomas. The peak incidence is between ages 40 and 60 years, and twice as many women as men are affected.
Cranial radiation is a definite risk factor for developing meningiomas. Patients with a history of cranial radiation therapy have a 4 times greater rate of meningioma formation compared with the general population.
Surgical resection is the treatment of choice for most olfactory groove meningiomas. A bifrontal craniotomy is the preferred surgical approach. Using this technique, the bony skull covering the anterior frontal lobes is removed and the dural layer opened. Through an interhemispheric approach, the tumor, adjacent brain parenchyma, and the vasculature are visualized. The blood supply to the tumor is identified and detached. The tumor is removed by debulking along with the affected piece of underlying dura and bone. The dural layer is then closed using an allograft substitute, and the bone flap is replaced. Radiation therapy is generally reserved for recurrences that are refractory to surgical resection.
Recovery is typically slow, but as the edema in the frontal lobes subsides, the patient’s clinical status improves. It is only at this time that any residual permanent neurologic deficit can be assessed.
Morbidity and mortality associated with operative treatment of olfactory groove meningiomas have improved greatly over the past 3 decades. A 15% mortality rate reported about 20 years ago has decreased to nearly 0% as a result of current microsurgical techniques and advances in perioperative care.
Olfactory groove meningiomas, despite being slow growing and relatively uncommon, are among the largest tumors found intracranially. Advances in diagnostic and therapeutic measures notwithstanding, these tumors continue to grow and achieve astonishing sizes before they are discovered. This is because the tumor is located in a relatively “silent” area of the brain, which allows the mass to continue to grow slowly before neurologic decline is evident.”
*Every source states different statistics. These just happen to be the ones I found today.