**Question:** Which of the following is not a feature of normal pressure hydrocephalus: September 2011

A. Increased intracranial pressure
B. Cerebrospinal fluid (CSF) shunt placement
C. Progressive dementia
D. Sleep disturbances and mood changes

**Core Concept:** Normal pressure hydrocephalus (NPH) is a rare neurological disorder characterized by the accumulation of cerebrospinal fluid (CSF) within the brain, leading to increased intracranial pressure and clinical symptoms. The condition is typically diagnosed when the intracranial pressure remains within normal limits (10-20 cmH2O) despite the presence of clinical symptoms.

**Why the Correct Answer is Right:** B. Cerebrospinal fluid (CSF) shunt placement is a common treatment for hydrocephalus, specifically when the intracranial pressure is elevated. Since the condition described in the question is normal pressure hydrocephalus, the presence of a CSF shunt is not typical and therefore not a feature of NPH.

**Why Each Wrong Option is Incorrect:**

A. Increased intracranial pressure (10-20 cmH2O): As mentioned earlier, NPH is characterized by normal intracranial pressure despite the presence of clinical symptoms. Thus, increased intracranial pressure is not a feature of NPH.

C. Progressive dementia: Dementia is a common symptom of NPH, making it a feature of NPH.

D. Sleep disturbances and mood changes: Sleep disturbances and mood changes are often observed in NPH patients, making them a feature of NPH.

**Clinical Pearl / High-Yield Fact:** Normal pressure hydrocephalus (NPH) is a distinct clinical syndrome characterized by the triad of gait disturbance, cognitive impairment, and urinary incontinence. The etiology is often unknown, and the condition is typically associated with aging. Diagnosis typically involves the Hakim test, which assesses the patient's ability to adjust to a change in the water level in a standing/seated position.

**Correct Answer:** B. Cerebrospinal fluid (CSF) shunt placement - As explained above, NPH is characterized by normal intracranial pressure despite clinical symptoms, so the presence of a CSF shunt is not a feature of NPH.