We disagree with the recommendation to use the HINTS Exam as the gold standard for detecting posterior stroke from the April article titled, “How not to miss posterior circulation stroke.”¹ The usefulness of the HINTS exam is limited to patients who have underlying nystagmus, which represents less than a quarter of patients with posterior stroke. Instead, we advocate for use of the the National Institutes of Health Stroke Scale (NIHSS) combined with a test of skew and a test of gait to screen for stroke in patients presenting with dizziness, vertigo, ataxia, and imbalance.

Problems with HINTS

1. The HINTS exam requires underlying nystagmus.² In the setting of a patient with nystagmus, a normal response to the head impulse test (defined as the subject being able to keep eyes on target) can be sensitive for stroke.
2. Over 75 percent of patients with posterior stroke do not present with nystagmus so the HINTS exam cannot be used.³
3. The interrater reliability of the HINTS exam is, at best, moderate, and requires significant training to perform.^4,5

NIHSS: An Underrated Screen for Posterior Stroke

There is a widespread misconception that NIHSS is insensitive for posterior stroke. In fact, NIHSS is highly sensitive for stroke, because it contains multiple elements that directly test the brainstem, cerebellum, and occipital region.⁶ The sensitivity of detecting a stroke approaches or surpasses that of diffusion weighted MRI in the early phase, and unlike the HINTS exam, it is a useful screen in all patients with posterior stroke symptoms, not just those with nystagmus.^6,7,8

It is important to remember that the NIHSS was originally developed to quantify all stroke types, not just middle cerebral artery strokes. It is intended to capture as much functional and testable brain volume as possible, and redundant or unreliable elements were removed. Thus, it is applicable to interior circulation as well as posterior circulation strokes by its very design.⁹

Additionally, the NIHSS is the most commonly used screen for acute stroke and the majority of emergency clinicians know its elements and can perform the NIHSS with a high interrater reliability between emergency clinicians and neurologists.¹⁰

What Are the Gaps in the NIHSS?

The lack of balance testing has been noted as the most common reason for posterior strokes with NIHSS of zero. The authors thus recommend adding a test of truncal stability, which can also be tested with gait.¹¹

The NIHSS does not include a test of skew, which can be an important sign of posterior stroke. It is the most easily performable section of the HINTS exam and is applicable even when no nystagmus is present.