HINTS is a 3-part neurologic exam designed to improve the sensitivity for detection of stroke in patients with acute vertigo / acute vestibular syndrome (AVS) compared with CT scanning and consists of:
Head Impulse test
Nystagmus - fast phase alternating with gaze direction suggests central cause
Test of Skew
CT scan has a low sensitivity for detecting posterior circulation stroke, while acute MRI scanning is better at 88% sensitivity but is not readily available in many centres
Details of the exam technique
Head impulse test
Head is rapidly rotated 20-40 degrees to one side or the other
Observe for one eye that lags in response to maintain forward gaze
Makes quick saccade movement to catch-up or correct
“Normal” test (no saccade/correction on head provocation) strongly suggests posterior CVA
specificity for stroke approaches 100%, but sensitivity is only 85%
thus while saccade/correction on testing suggests peripheral cause, it does not exclude posterior CVA
this is technically difficult as ideally one needs a slow motion video to reliably visualise the response
Nystagmus
Patient follows examiner's finger as they move it slowly in all directions
Patient should look up, down, left or right, as well as to eccentric positions (off-center)
Nystagmus should be present in all cases of acute vestibular system whether of peripheral or central cause
Findings suggestive of peripheral Vertigo
Horizontal Nystagmus suggests a peripheral cause (although it does not exclude a central cause)
Findings suggestive of central Vertigo (e.g. posterior CVA)
Vertical Nystagmus
Torsional Nystagmus
Nystagmus that changes direction
Rightward Nystagmus with rightward gaze
Leftward Nystagmus with leftward gaze
Skew test
Perform as with Alternate Eye Cover Test (also used to evaluate for horizontal strabismus in children)
Alternately cover one eye and then the other
Observe for quick vertical gaze corrections (abnormal)
Uncovered eye shifts to center from its abnormal, vertically displaced position
Abnormal skew test with quick vertical gaze corrections suggests a central cause (e.g. brainstem CVA)
Examiner may also see a head tilt at rest that often accompanies skew deviation
Interpretation of exam
peripheral vertigo is suggested by:
an abnormal (positive) head impulse test
unidirectional, horizontal nystagmus
absent skew deviation
central vertigo and thus possible posterior circulation stroke is suggested by:
a normal (negative) head impulse test
rotatory or vertical nystagmus, or direction-changing horizontal nystagmus
presence of skew deviation
a positive HINTS exam
this occurs if at least ONE of the three sections suggest a central cause
said to be 100% sensitive and 96% specific for posterior circulation stroke 1)