The HINTS-negative stroke
A 71-year-old man with hypertension, smoking, and hyperlipidemia presents at 4 hours after the sudden onset of severe rotational vertigo and vomiting. He is well-appearing apart from the symptoms. No headache. No focal weakness. No diplopia. No dysarthria he or his family have noticed. He is on aspirin 81 mg daily.
A 71-year-old man with hypertension, smoking, and hyperlipidemia presents at 4 hours after the sudden onset of severe rotational vertigo and vomiting. He is well-appearing apart from the symptoms. No headache. No focal weakness. No diplopia. No dysarthria he or his family have noticed. He is on aspirin 81 mg daily.
Spontaneous left-beating horizontal nystagmus that is direction-fixed (still beats left on left gaze, left on right gaze — Alexander's law-positive). Head impulse to the RIGHT produces a corrective catch-up saccade. Head impulse to the LEFT is normal. No skew on alternate cover test. All three components of HINTS appear to be REASSURING for a peripheral cause.
By HINTS criteria alone, the exam favors which cause?
When asked to sit at the edge of the bed, he is unable to maintain upright posture without leaning heavily on the rail; when assisted to standing, he falls backward and to the RIGHT despite full strength in both legs. This is wildly out of proportion to the nystagmus and exam findings. Bedside finger-rub hearing is symmetric. Walking is not attempted.
Which additional finding makes you most concerned for a CENTRAL cause despite the apparently peripheral HINTS?
Acute right AICA-distribution stroke (cerebellar with labyrinthine involvement)
- 1.AICA strokes are the great mimic of vestibular neuritis. They can produce ipsilesional vestibular hypofunction (because the labyrinthine artery is a branch of AICA) — giving an abnormal head impulse on the side of the stroke — alongside cerebellar dysfunction.
- 2.HINTS sensitivity is high but not perfect; the most common failure mode is AICA stroke with labyrinthine involvement appearing peripheral. Recent posterior circulation stroke literature reports a ~5-10% miss rate for HINTS used in isolation.
- 3.Adjunct bedside tests that catch the misses: truncal stability ('can the patient sit unsupported?'), new unilateral hearing loss on bedside finger-rub hearing testing (a sign of AICA territory), and any new focal neurologic finding (dysarthria, ataxia of a limb, sensory level).
- 4.MRI with DWI within the first 24-48 hours has a 10-20% false-negative rate for small posterior fossa strokes — repeat imaging at 72 hours or longer is sometimes needed if clinical suspicion remains high.
- 5.Time-from-onset to clot retrieval matters in basilar territory; AICA-distribution strokes are typically not amenable to thrombectomy but may be candidates for tPA in the appropriate window with appropriate imaging.