From the Guidelines
The HINTS exam is a crucial bedside test for differentiating central from peripheral causes of vertigo, and it should be performed by specially trained practitioners to maximize its sensitivity and accuracy. The HINTS exam assesses three key components: the Head Impulse test, Nystagmus evaluation, and Test of Skew 1. A normal head impulse test, direction-changing nystagmus, or presence of skew deviation suggests a central cause like stroke, while an abnormal head impulse, unidirectional nystagmus, and absence of skew typically indicate a peripheral cause such as vestibular neuritis 1.
Key Components of the HINTS Exam
- Head Impulse test: observe for corrective saccades when turning the patient's head quickly
- Nystagmus evaluation: look for direction-changing nystagmus
- Test of Skew: check for vertical misalignment of the eyes
The HINTS exam has been shown to be even more sensitive than early MRI for the detection of infarct, with a sensitivity of 100% compared to 46% for early MRI 1. However, it is essential to note that the accuracy of the HINTS exam depends on the skill and training of the examiner, and subtle findings can be difficult to detect for inexperienced examiners 1.
Importance of the HINTS Exam in Clinical Practice
- The HINTS exam can help differentiate central from peripheral causes of vertigo, reducing the need for unnecessary imaging and improving patient outcomes
- It is particularly useful in acute vestibular syndrome when imaging may be normal or unavailable
- The exam should be performed within the first 48 hours of symptom onset for maximum diagnostic value 1
In patients with isolated acute vestibular syndrome (AVS), the HINTS exam can help identify those who are at low risk for central causes like stroke, and therefore may not require imaging 1. However, if the HINTS exam is not available or is inconclusive, imaging may be required to rule out stroke or other central causes 1.
From the Research
HINTS Exam Overview
- The HINTS (Head Impulse, Nystagmus, and Test of Skew) exam is a bedside test used to diagnose central causes of acute vestibular syndrome (AVS) 2.
- AVS is a clinical syndrome characterized by vertigo, nystagmus, head motion intolerance, ataxia, and nausea/vomiting 3.
- The HINTS exam assesses how the eyes move in response to rapidly turning a person's head, the direction of involuntary eye movements, and whether the eyes are aligned or misaligned 2.
Diagnostic Accuracy
- The clinical HINTS examination has been shown to be 94.0% sensitive and 86.9% specific for diagnosing central causes of AVS 2.
- The video-assisted HINTS examination has been shown to be 85.0% to 100% sensitive and 38.9% to 100% specific 2.
- A meta-analysis found that the HINTS exam had a sensitivity of 96.7% and specificity of 94.8% when performed by neurologists 3.
- However, when performed by emergency physicians, the sensitivity was 83% and specificity was 44% 3.
Clinical Utility
- The HINTS exam has been shown to be useful in ruling out central causes of vertigo in patients presenting to the emergency department (ED) 2, 3.
- However, the exam is often under-utilized in the ED, with neuroimaging being used more frequently 4.
- A retrospective chart review found that the HINTS exam was frequently used in patients who did not meet criteria to receive the exam, and its diagnostic value was limited 5.
Limitations and Future Directions
- The evidence for the HINTS exam is of low certainty, and more high-quality studies are needed to fully assess its diagnostic accuracy and clinical utility 2.
- Future research should include more studies on the use of video-assistance and the exam's accuracy across different providers and specialties 2.
- Additional training of emergency physicians may be required to improve the test's sensitivity and specificity 5.