meningioma

meningioma. A meningioma is a typically slow-growing tumor that arises from the Meninges, the protective membranes surrounding the Brain and Spinal cord. Most are considered benign (World Health Organization grade I) and are often discovered incidentally on Medical imaging performed for other reasons. While they are the most common primary intracranial tumor, their behavior and required management depend significantly on their histological grade, location, and associated symptoms.

Signs and symptoms

Symptoms are highly dependent on the tumor's location and size, often presenting due to Mass effect on adjacent neural structures. Common presentations include new-onset Headache, Seizure activity, or progressive Focal neurologic deficit such as Weakness or Sensory loss. Tumors near the Olfactory groove may cause Anosmia, while those compressing the Optic nerve or Optic chiasm can lead to Visual field deficit or Papilledema. Spinal tumors frequently cause Back pain, Radiculopathy, or Myelopathy. Notably, many meningiomas, especially smaller ones, are asymptomatic and are found incidentally during evaluation for unrelated conditions like Head trauma or Migraine.

Causes and risk factors

The exact cause of most sporadic meningiomas is unknown, but several established risk factors exist. A strong association exists with Neurofibromatosis type 2, a genetic disorder caused by mutations in the NF2 gene on Chromosome 22. Prior exposure to Ionizing radiation, particularly from therapeutic radiation for conditions like Tinea capitis or Acute lymphoblastic leukemia, is a well-documented environmental risk. Other factors include female sex, with a 2:1 female-to-male ratio, suggesting a hormonal influence linked to Progesterone receptor expression; increasing age, with peak incidence in the seventh decade; and certain genetic syndromes like Cowden syndrome and Werner syndrome.

Diagnosis

Diagnosis is primarily radiological, with Magnetic resonance imaging (MRI) with Gadolinium contrast being the gold standard, typically showing a well-circumscribed, dural-based, homogeneously enhancing mass. Computed tomography (CT scan) may reveal Hyperostosis of adjacent bone or intratumoral Calcification. Advanced imaging techniques like Magnetic resonance spectroscopy and Perfusion MRI can help differentiate meningiomas from other lesions like Schwannoma or Metastasis. Definitive diagnosis and World Health Organization grading (I, II, or III) require Histopathological examination of tissue obtained via Biopsy or Surgical resection, such as during a Craniotomy.

Treatment

Management strategies range from observation with serial MRI for small, asymptomatic tumors to active intervention. The primary treatment for symptomatic or growing tumors is maximal safe Surgical resection, often guided by Intraoperative MRI or Neuronavigation, with the goal defined by the Simpson grading scale. For tumors in high-risk locations like the Cavernous sinus or for residual or recurrent disease, Radiation therapy is a mainstay, including Stereotactic radiosurgery (e.g., Gamma Knife, CyberKnife) and Fractionated radiation therapy. Medical therapies, such as the Somatostatin analogue Octreotide or the Angiogenesis inhibitor Bevacizumab, are considered in select, refractory cases. Clinical trials through organizations like the Alliance for Clinical Trials in Oncology are exploring novel agents.

Prognosis

Prognosis is generally favorable for World Health Organization grade I meningiomas, with high rates of long-term control following complete Surgical resection. However, recurrence rates are higher for Atypical meningioma (grade II) and Anaplastic meningioma (grade III) tumors. Factors associated with poorer outcomes include incomplete resection, higher histological grade, certain molecular subtypes (e.g., loss of Chromosome 1p), and location in the Skull base. Long-term complications can include persistent Focal neurologic deficit, Hydrocephalus requiring shunting, or adverse effects from Radiation therapy like Radiation necrosis.

Epidemiology

Meningiomas account for approximately 30% of all primary CNS tumors, making them the most frequently reported primary intracranial neoplasm. Incidence increases with age, with the highest rates in individuals aged 65–74, and they are more common in women than men. According to data from the Central Brain Tumor Registry of the United States (CBTRUS) and the Surveillance, Epidemiology, and End Results (SEER) program, the overall incidence is about 8.83 per 100,000 persons. There is a higher reported incidence in Black populations compared to White populations. The prevalence is substantial due to the typically indolent nature of most tumors and increased detection via modern Medical imaging. Category:Central nervous system tumors Category:Neuro-oncology