Brain herniation happens when swollen or shifting brain tissue gets pushed into spaces it does not belong. The squeeze can shut off blood flow and press on vital cables, so warnings appear fast and snowball.
The first alert is a headache that spikes from bad to unbearable within minutes. It feels like the head is over-filled and may come with sudden vomiting that shoots out without nausea.
Eye signs show up next. One pupil shrinks to a pin-point while the other balloons larger, and both may stop reacting to light. Trying to look side-to-side leaves one eye stuck in neutral.
Body weakness flips sides. An arm or leg that was moving normally goes limp, and the weak side may switch places as the brain shifts. The person cannot squeeze your hand or lift a leg off the bed.
Breathing changes rhythm. You count fast, shallow breaths that suddenly flip to long, slow gasps, then back again, as if the brain’s breathing metronome is breaking.
Consciousness slips away in steps. The person answers questions slowly, then speaks only in single words, then moans, then nothing. Each stage can pass in minutes.
| Body Part | What You See | Quick Check |
|---|---|---|
| Head | Pain jumps from bad to worst | Ask 1-10 scale twice |
| Eyes | One big pupil, one tiny, light stuck | Flashlight beam test |
| Arm/Leg | Weak side swaps, can’t lift | “Squeeze my hand” |
| Breath | Fast-slow flip, gasping loops | Count breaths 15 sec |
| Voice | Words→moans→none | Track answers each minute |