What is normal ICP in adults?

Normal ICP in adults refers to normal intracranial pressure, which is the pressure inside the skull and around the brain. Intracranial pressure is measured in millimeters of mercury or mmHg, or sometimes in centimeters of water. In a healthy adult in supine position, normal ICP ranges from 5 to 15 mmHg, with most medical textbooks citing 7 to 15 mmHg as normal for adults at rest. Some sources extend normal up to 20 mmHg, but sustained pressures above 20 mmHg are generally considered elevated and intracranial hypertension. ICP is produced by the balance of brain tissue, cerebrospinal fluid or CSF, and blood volume inside the rigid skull, as described by the Monro-Kellie doctrine. ICP can fluctuate with coughing, sneezing, or straining, temporarily rising to 30 to 50 mmHg, which is normal if it quickly returns to baseline. Normal ICP in adults is slightly higher than in children, and is measured invasively through an external ventricular drain or intraparenchymal monitor in neurocritical care. Elevated ICP above 20 to 25 mmHg can be dangerous and can indicate head injury, brain tumor, hydrocephalus, stroke, or brain infection, and requires emergency treatment to prevent brain damage. If you are concerned about headaches or pressure, you should seek medical evaluation rather than trying to measure ICP yourself.