Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. 2009. HINTS to diagnose stroke in the acute vestibular syndrome. Three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke 40:3504–10
Why this study is important
Posterior circulation strokes are extremely difficult to diagnose in the emergency department, and even with the gold standard of imaging (MRI), this diagnosis can still be missed. In addition to helping identify posterior circulation strokes, the exam can also be used to exclude patients with a peripheral lesion who do not merit advanced imaging for their symptoms.
What we already know about the topic
“Dizziness” accounts for 2.6 million patient visits in emergency departments throughout the country each year, and approximately 1 in 20 patients is diagnosed with peripheral vertigo. However, some studies have shown that 25% or more are incorrectly diagnosed posterior circulation strokes. CT scans are only about 16% sensitive in detecting these, MRIs also have a relatively high false negative rate, and fewer than half of patients have obvious neurological features, making this extremely difficult to identify in the emergency department.
Brief overview of the study
Patients meeting all criteria for Acute Vestibular Syndrome (AVS) including rapid onset of vertigo, nausea, vomiting, and unsteady gait were included. Included patients were screened either in the emergency department or from admitted stroke patients with clinical features of AVS. HINTS exam was performed by a neuro-opthamologist on all subjects who then were admitted and underwent a diagnostic MRI to evaluate for central lesions. Patients with negative diagnostic imaging and normal HINTS exams (24%) were confirmed to have peripheral lesions with caloric testing, and patients with abnormal HINTS exams (76%) were found to have a central lesion on MRI. Per their results, having at least one abnormal HINTS exam component was 100% sensitive and 96% specific for stroke.
Only 101 subjects were identified over a period of nine years, meaning the criteria for a positive AVS screening was probably extremely selective, possibly excluding a large number of patients with posterior circulation strokes. Additionally, all HINTS exams were conducted by a neuro-opthamologist who was far more practiced in performing HINTS exams than the average emergency physician. This study also only included patients with active vertiginous symptoms concerning for central lesions, so it’s not useful for episodic vertigo.
Take home points
The HINTS exam is potentially a very useful tool decide if your patient is high or low-risk for a posterior circulation stroke, but until we get more evidence that the screening test works in the hands of ED providers, you’ll probably still have to order that CT or MRI if you’re on the fence about a patient.
***Potential HINTS pitfall: Remember that the HINTS exam only applies to patients with ACTIVE vertiginous symptoms. Performing the exam could potentially lead to unnecessary imaging if your non-vertiginous patient has a normal vestibulo-ocular reflex (one of the features concerning for a central lesion).
See Scott Weingart’s demonstration on how to properly perform the HINTS exam http://emcrit.org/podcasts/posterior-stroke/