Head impulse — normal

The eyes stay locked on the target through the thrust, with no catch-up saccade. Reassuring in a well patient — but in someone with acute continuous vertigo who cannot walk, a NORMAL impulse is the worrying, central sign.

A normal head impulse means the eyes stay on target with no catch-up saccade — reflex gain near 1.0. In a well patient that is reassuring. In someone with acute, continuous vertigo who cannot stand or walk, it is the dangerous finding: an intact reflex points away from the labyrinth and toward a central cause, usually cerebellar or brainstem. The bedside version — a catch-up saccade means an abnormal (peripheral) reflex, none means a normal one — is from the head-impulse literature (Halmagyi & Curthoys 1988); the quantitative divide often quoted, a video-HIT gain below about 0.7 with a saccade reading peripheral, comes from later vHIT work, not from the bedside HINTS study.

HINTS-plus adds a bedside hearing check to the three eye signs. New unilateral hearing loss alongside acute vestibular syndrome raises concern for an AICA-territory stroke, because AICA supplies both the inner ear — through its internal auditory (labyrinthine) branch — and the brainstem and cerebellum, so new hearing loss does not reliably mean the cause is peripheral. Hearing is assessed by audiogram or finger rub, not by the eyes; it is named here because it changes how a normal-looking HINTS is read (Newman-Toker).