Commonest type of intracranial tumor is
**Core Concept**
The question is testing the knowledge of the most common type of intracranial tumor. Intracranial tumors can be primary (originating within the brain) or metastatic (originating from other parts of the body). Primary intracranial tumors can be further classified into various types, including gliomas, meningiomas, and others.
**Why the Correct Answer is Right**
The most common type of intracranial tumor is a meningioma. Meningiomas arise from the meninges, the protective membranes surrounding the brain and spinal cord. They are typically slow-growing and can be benign or malignant. The exact mechanism of meningioma formation is not fully understood, but it is believed to involve genetic mutations and activation of various signaling pathways. The most common location for meningiomas is the cerebral convexity, followed by the sphenoid ridge and falx cerebri.
**Why Each Wrong Option is Incorrect**
**Option A:** Glioblastoma multiforme is a type of glioma, but it is not the most common type of intracranial tumor. Glioblastoma multiforme is a highly malignant and aggressive tumor with a poor prognosis.
**Option B:** Pituitary adenomas are common intracranial tumors, but they are not the most common type. Pituitary adenomas arise from the pituitary gland and can cause a variety of endocrine disorders.
**Option C:** Cerebral metastases are the most common intracranial tumors in adults, but they are not primary intracranial tumors. Cerebral metastases originate from other parts of the body, such as the lung or breast.
**Clinical Pearl / High-Yield Fact**
Meningiomas are often asymptomatic until they cause mass effect or compression of surrounding structures. A classic clinical presentation of meningioma is the "sphenoid wing syndrome," characterized by diplopia, ptosis, and facial pain due to compression of the oculomotor nerve.
**Correct Answer: D. Meningioma.