**Core Concept**
Aschner's reflex, also known as the Aschner phenomenon, is a clinical sign observed in patients with certain neurological conditions. It is characterized by a sudden, brief, and painless increase in intracranial pressure, often associated with a loud noise or a sudden change in posture.

**Why the Correct Answer is Right**
Aschner's reflex is typically seen in patients with intracranial space-occupying lesions, such as tumors or cysts, that cause increased intracranial pressure. When the patient experiences a sudden change in posture or hears a loud noise, the increased pressure can cause a brief, painless headache. This phenomenon is thought to be due to the sudden alteration in cerebrospinal fluid (CSF) dynamics, which can lead to a temporary increase in intracranial pressure.

**Why Each Wrong Option is Incorrect**
* **Option A:** Aschner's reflex is not typically associated with meningitis, as it is a more chronic condition that does not usually cause sudden changes in intracranial pressure.
* **Option B:** While Aschner's reflex can be seen in patients with head injuries, it is not a specific sign of traumatic brain injury and can be seen in other conditions as well.
* **Option C:** Aschner's reflex is not a sign of normal pressure hydrocephalus (NPH), as NPH is a condition characterized by increased intracranial pressure due to an accumulation of CSF, but Aschner's reflex is more specific to space-occupying lesions.

**Clinical Pearl / High-Yield Fact**
Aschner's reflex is an important clinical sign that can indicate the presence of a space-occupying lesion in the brain, and it is essential to consider this sign in patients presenting with sudden headaches or changes in consciousness.

**Correct Answer:** C.