Commonest Type of Intracranial Tumour is:
**Core Concept**
The question is testing the knowledge of the most common type of intracranial tumor, which is a critical aspect of neurosurgery and neurology. The correct answer is related to the epidemiology of brain tumors, which is influenced by factors such as age, sex, and genetic predisposition.
**Why the Correct Answer is Right**
The correct answer is meningioma, which is a type of tumor that arises from the meninges, the protective membranes surrounding the brain and spinal cord. Meningiomas are typically benign (non-cancerous) and account for approximately 30% of all primary brain tumors. They are more common in women and tend to occur in middle-aged to elderly individuals. The pathogenesis of meningiomas involves genetic mutations, such as alterations in the NF2 gene, which leads to the activation of the PI3K/AKT signaling pathway, promoting cell proliferation.
**Why Each Wrong Option is Incorrect**
**Option A:** Glioblastoma is a malignant brain tumor, but it is not the most common type of intracranial tumor. It is the most aggressive and deadliest form of brain cancer, but its incidence is lower than meningioma.
**Option B:** Acoustic neuroma is a type of vestibular schwannoma, which is a benign tumor that arises from the Schwann cells of the vestibulocochlear nerve. While it is a common type of intracranial tumor, it is not the most common type.
**Option C:** Cerebellar astrocytoma is a type of glioma that arises from the cerebellum. It is a rare type of brain tumor and not the most common type of intracranial tumor.
**Clinical Pearl / High-Yield Fact**
Meningiomas are often asymptomatic and may be discovered incidentally on imaging studies. They can be challenging to differentiate from other types of brain tumors, and a definitive diagnosis requires histopathological examination.
**Correct Answer: C. Meningioma**