Suddenly Have Dizziness Lasting Hour(s)? Quick Way to Determine if Due to Stroke vs Inner Ear Problem

 

When a person suddenly experiences dizziness lasting hour(s) that does not subside even when still, the main concern is whether a stroke has occurred. There is a type of stroke that occurs in the cerebellar region of the brain which will not affect speech nor result in any type of paralysis. In this situation, the vast majority will go to the ER to get further evaluation. However, even in the ER, a HINTs examination (which can also be done at home) may be performed in under 1 minute to quickly assess likelihood of stroke vs something more benign like an inner ear infection (vestibular neuritis). In fact, in the first 24 hours of a cerebellar stroke, the HINTs bedside exam is MORE accurate than a MRI scan! [reference]

The video above demonstrates how a HINTs examination is performed. HINTs, an acronym for Head Impulse, Nystagmus, and Test of Skew, is a cluster of 3 bedside tests.

The head impulse test starts by flexing the patient’s head down slightly and moving their head slowly back and forth while having their eyes maintain fixed focus straight ahead. The head is then moved quickly and unexpectedly to one side while the patient tries to maintain straight target focus. The test is considered normal if the eyes stay focused on target without slippage.

However, if the eyes are dragged off the straight ahead target, even briefly, the test would be considered abnormal suggesting an inner ear vestibular problem.

Please note that there needs to be a minimum 50% weakness of the inner ear vestibular system in order for this test to be positive.

Next, check the patient’s eyes for any nystagmus which are involuntary repetitive eye twitching. To evaluate for nystagmus, have the patient move the eyes in all the cardinal directions: left, right, up, and down.

Normally, nystagmus should be absent. However, if nystagmus is present, note which direction the eye is beating towards. The direction of nystagmus is defined by the direction of the quick phase.

An inner ear or vestibular cause for dizziness is suggested if the nystagmus is horizontal and the direction remains the same regardless of which direction the eye is looking.

A neurologic cause for dizziness is suggested if the nystagmus changes direction with eye movement. Neurologic cause for dizziness is also suggested if vertical or torsional nystagmus is present in any eye position.

The skew test, also known as the cover test, involves the patient focusing straight on a target while the clinician covers and uncovers each eye, observing for any vertical movement of the uncovered eye. Normally, the uncovered eye remains steady. However, if it moves up or down, this indicates a vertical skew deviation, which can suggest a serious brain disorder involving the brainstem or cerebellum instead of a more benign cause due to an inner ear vestibular problem. Collectively, when all 3 HINTs exams are performed in a dizzy patient, it is 95% accurate in identifying a central cause like stroke or peripheral origin like vestibular neuritis.

Accuracy is further increased when performing a HINTs-plus test when adding a fourth sign which is the presence of a one-sided, new-onset hearing loss which would suggest labyrinthitis (vestibular neuritis does not have any hearing changes).

The only downside to the HINTs examination is how rarely it applies to any given patient. Only 2% of all strokes are cerebellar strokes and only 3% of all ER visits is due to dizziness.

References
Usage of the HINTS exam and neuroimaging in the assessment of peripheral vertigo in the emergency department. J Otolaryngol Head Neck Surg. 2018;47:54. 

HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009 Nov;40(11):3504-10. 

H.I.N.T.S. to Diagnose Stroke in the Acute Vestibular Syndrome—Three-Step Bedside Oculomotor Exam More Sensitive than Early MRI DWI. Stroke. 2009 Nov; 40(11): 3504–3510.