The family ask the nurse caring for a patient with increased intracranial pressure (ICP). What is the normal range for ICP?

A. 5–20 mm Hg: An intracranial pressure of 20 mm Hg is generally considered elevated and associated with increased risk of cerebral ischemia. Including this value in the normal range is inaccurate. Sustained pressures at this level require clinical intervention. B. 0–20 mm Hg: While ICP values up to 20 mm Hg may be tolerated briefly, they are not considered normal. Pressures approaching 20 mm Hg suggest intracranial hypertension rather than normal physiology. This range is too broad for normal ICP. C. 5–15 mm Hg: Normal intracranial pressure in adults typically falls between 5 and 15 mm Hg. This range reflects balanced cerebrospinal fluid dynamics and adequate cerebral perfusion. Values within this range are expected in individuals without intracranial pathology. D. 0–15 mm Hg: An ICP of 0 mm Hg is not physiologically typical in adults. While the upper limit aligns with normal values, the lower limit makes this range inaccurate. Normal ICP does not usually fall to zero.