What is the normal intracranial pressure (ICP) at rest?

• A. -5 to 5 mmHg
• B. 0-10 mmHg
• C. 10-20 mmHg
• D. 15-25 mmHg

Answer: (B)

Intracranial pressure is the pressure inside the skull balancing brain tissue, cerebrospinal fluid, and blood. In a resting adult, this pressure is kept very low, typically around 0 to 10 mmHg. Reading within this range means the brain is being perfused normally without pressure signs of edema or herniation risk. Values above this range suggest rising ICP; once ICP climbs into higher ranges (such as 10–20 mmHg or more), cerebral perfusion can be compromised and clinical concern increases. Negative values are not considered normal in vivo, and the higher ranges listed (10–20 or 15–25) reflect elevated ICP rather than a normal resting state.