Which is not a characteristic feature of pseudo tumour cerebri?
**Core Concept**
Pseudo tumor cerebri, also known as idiopathic intracranial hypertension (IIH), is a condition characterized by increased intracranial pressure without any identifiable cause. This condition often presents with symptoms mimicking those of a brain tumor, such as headache, visual disturbances, and papilledema.
**Why the Correct Answer is Right**
Pseudo tumor cerebri is typically associated with normal-sized or even small-sized ventricles, which distinguishes it from other conditions causing increased intracranial pressure such as hydrocephalus. The pathophysiology of IIH is complex and not fully understood, but it is thought to involve a combination of factors, including obesity, sleep apnea, and hormonal imbalances. The condition often responds to weight loss, treatment of sleep apnea, and other lifestyle modifications.
**Why Each Wrong Option is Incorrect**
**Option A:** Increased intracranial pressure is indeed a characteristic feature of pseudo tumor cerebri, so this option is incorrect.
**Option B:** Papilledema, which is swelling of the optic disc, is a common finding in pseudo tumor cerebri, making this option incorrect.
**Option C:** Headache is a hallmark symptom of pseudo tumor cerebri, so this option is incorrect.
**Clinical Pearl / High-Yield Fact**
A key distinguishing feature of pseudo tumor cerebri is the absence of focal neurological deficits, such as weakness or sensory changes, which are often present in conditions causing increased intracranial pressure due to mass effect.
**Correct Answer: C. Headache is a hallmark symptom of pseudo tumor cerebri, so this option is incorrect.**