Increased Intracranial Pressure — Signs & Assessment
A patient's blood pressure is climbing while their heart rate drops — most students think cardiac. But in a neuro patient, this triad means the brain is herniating.
Core Concept
Increased intracranial pressure (ICP) develops when the volume inside the rigid skull exceeds compensatory capacity (normally 5–15 mmHg in adults). Early signs are subtle: restlessness, confusion, headache (worse in the morning or with coughing/straining), and a decreasing level of consciousness — the earliest and most reliable indicator. As ICP rises, you see pupil changes: ipsilateral pupil dilation with sluggish or absent light response from CN III compression. Late signs form the Cushing's triad — widening pulse pressure (systolic climbs, diastolic drops), bradycardia, and irregular respirations. This is a brainstem compression response and signals impending herniation. Projectile vomiting without preceding nausea is another late finding. In infants, look for a bulging fontanel, high-pitched cry, and poor feeding. The progression follows a predictable path: mental status changes first, then pupil changes, then vital sign changes last. By the time Cushing's triad appears, the window for intervention is closing rapidly.
Watch Out For
Don't confuse Cushing's triad (hypertension, bradycardia, irregular respirations from ICP) with Cushing's syndrome (cortisol excess — moon face, buffalo hump). Students frequently mistake late signs for early signs — vital sign changes like Cushing's triad are late and ominous, not early warnings. A unilaterally fixed, dilated pupil indicates ipsilateral herniation, not a bilateral finding — bilateral fixed pupils signal a more advanced, potentially irreversible stage.
Clinical Pearl
Early ICP = the mind goes first. Late ICP = the vitals go last. If you're catching it on the monitor, you're already behind — catch it at the bedside with mental status.
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