Discover how to recognize the cause of your patient's vertigo and identify whether it's life-threatening. In this video, from our Emergency Procedures Masterclass, you'll learn how to perform and interpret the three elements of the HINTS exam in order to differentiate between central vertigo and peripheral causes.
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[00:00:00] The HINTS exam helps to differentiate central and potentially life-threatening causes of vertigo from vestibular neuritis, which is benign. It's comprised of three tests. First, the head impulse test; second, the test of skew; and third, the nystagmus assessment. HIT stands for head impulse test. This test uses the vestibulo-ocular reflex to predict whether the vertigo is
[00:00:30] peripheral or central in patients with ongoing, constant vertigo and nystagmus. This reflex allows your eyes to stay focused on an object, despite head movement. Go ahead, try this now. Shake your head quickly from left to right, up and down, and look at the center of the screen. Your eyes will be able to read the words without any trouble. As you can imagine, this reflex came in very handy for a caveman running away from a saber-toothed tiger.
[00:01:00] The caveman would surely not survive if he couldn't focus on the direction he was going, while bouncing up and down, running through the jungle. This test is only performed on a patient who has active and persistent vertigo and nystagmus. You're trying to see if the eighth cranial nerve, the vestibulocochlear nerve, has been affected by a virus. To perform this test, ask the patient to stare at your nose, hold their head in your hands and move ahead 30 degrees to the side and rapidly bring it to the midline,
[00:01:30] while staring at their eyes. This method is preferred because it will avoid potentially over-rotating the neck and causing spine or artery damage. If the vestibulo-ocular reflex is affected by a virus, the eyes will keep moving in the direction of movement and then quickly jerk back to looking at your eyes. This is called the corrective saccade and will only happen in one direction, so be sure to test both sides. If there is a normal vestibulo-ocular reflex, then the eighth cranial nerve
[00:02:00] is not affected and your exam is very concerning for a central cause of vertigo. However, if the reflex is not working and you observe a corrective saccade, then you are reassured that the cause of the vertigo is likely peripheral, but you still must continue with the two other components of the HINTS exam, to be 100% sure. Again, please note you should not apply this test to patients who have episodic vertigo or are no longer symptomatic
[00:02:30] or do not have nystagmus. Here's an example of a patient with vestibular neuritis and, therefore, the head impulse test showing a corrective saccade. Notice that when the patient's head is moved quickly towards his left side, you see a corrective saccade but you don't see it in the other direction. Here is one more example of a patient with corrective saccade and, therefore, a peripheral cause of vertigo.
[00:03:00] A very important thing to remember is that the brain can learn to compensate for this corrective saccade and so it's important to perform the test randomly to avoid a false negative result. Also, be very careful in elderly patients, who may have severe neck arthritis because the rapid head movement could lead to vertebral or arterial injury. The second component of the HINTS exam, is evaluation for nystagmus. Ask your patient to look slightly to the left and then
[00:03:30] slightly to the right and look for direction-changing nystagmus. The key here is not to have your patient focus on your finger because that can suppress the nystagmus. When evaluating nystagmus, the fast component of the beating, is what determines the direction. Look for bidirectional or vertical nystagmus. Presence of this type of nystagmus points to a central cause of vertigo, meaning stroke. Here's an example of a
[00:04:00] unidirectional nystagmus, which is reassuring. Notice that the fast phase of the beating is always towards the left, no matter which direction the patient is asked to look. This patient has a unidirectional nystagmus and was diagnosed with vestibular neuritis, as the other components of the HINTS exam were also reassuring. This is a pathologic bidirectional nystagmus.
[00:04:30] When the patient is asked to look to her right, the fast phase is towards the right and when the patient looks to the left, the fast phase changes direction towards the left. Most patients with a central cause of their vertigo do not demonstrate this finding, but if it's seen, it's highly specific for a central cause and a stroke. The last component of the HINTS exam, is the test of skew. Ask the patient to look at
[00:05:00] your nose and cover one eye and then move your hand quickly to cover the other eye. Look to see if there's any vertical movement or diagonal or slanted movement, as the eye is uncovered. Do this for both eyes, looking at each eye. Abnormal vertical correction
[00:05:30] is about 98% specific for a central cause of vertigo, so abnormal vertical correction is bad. Here's a video of the test of skew being performed on a patient. The patient is asked to look at your nose and when you uncover the right eye, notice that the eye is skewed and moves medially and diagonally upward, to look at your nose. This patient has a cerebellar stroke. So, to review, in a patient with acute, persistent vertigo and nystagmus and a normal neurologic exam,
[00:06:00] a HINTS exam with a head impulse test showing a corrective saccade and with unidirectional nystagmus and no abnormal test of skew, means that the patient has vestibular neuritis and can possibly be discharged home. On the other hand, if any of the three components of the HINTS exam are abnormal, for example, no corrective saccade with head impulse testing or vertical or bidirectional nystagmus or abnormal test of skew, the patient needs
[00:06:30] admission to the hospital and neuroimaging.