HINTS Exam (If any 1 of 3 abnormal, sensitivity 100% and specificity 96% for central cause)

• Should be done only on patients with continuous symptoms
  

1. Head impulse testing

• Rapid left-and-right head rotation while patient fixates their eyes on examiner's nose
• Normal test (central cause) - patient's eyes remain fixed on target
• Abnormal test (peripheral cause) - patient's eyes undergo corrective saccade back to target on affected side
  

2. Nystagmus testing on left and right gaze
   

• Peripheral cause - horizontal-beating nystagmus in one direction (i.e. the nystagmus always beats towards one direction regardless of which direction the patient is looking)
  
• Central cause - Rotary or vertical nystagmus -or- alternating horizontal nystagmus (i.e. the nystagmus changes direction depending on which direction the patient is looking)
  

3. Testing of skew

• Alternate covering of Left and Right eye
  
• Peripheral cause - no skew
  
• Central cause - vertical ocular mis-alignment of eyes (one eye will have a gaze higher/lower than the other and will have to correct once un-covered) as cover is alternated back and forth between eyes
  

How to do the HINTS Exam


H&P - Helpful findings

• Multiple prodromal episodes of dizziness – Predictive of central cause (CVA)
• Headache or neck pain – Predictive of central cause (CVA, vertebral artery dissection) with positive LR = 3.2. Absence of pain not as predictive.
• Any neurologic signs, esp. truncal ataxia (unable sit upright with arms crossed) and severe gait instability – Strongly predictive of central cause
• Horizontal head impulse test (vestibular-ocular reflex) – If normal, predictive of central cause (positive LR 18.4, negative LR 0.16)
• Gaze-evoked nystagmus (right-beating nystagmus on right gaze and left-beating nystagmus on left gaze) = dysfunction of gaze-holding structures in brainstem and cerebellum – If abnormal, predictive of central cause (specificity 92%, sens 38%)
• Vertical ocular misalignment on alternate cover test – If abnormal skew deviation, predictive of central cause (specificity 98%, sens 30%)
• Diffusion-weighted MRI is good but not perfect - Sensitivity 83% for ischemic CVA

H&P - Not Helpful findings

• Differentiating type of dizziness (vertigo, presyncope, unsteadiness)
• Onset of dizziness (sudden vs gradual)
• Provocative head movement (eg. Hallpike-Dix)
• Proportionality of sx such as severity of dizziness, vomiting, gait impairment (eg. severe gait impairment with mild dizziness does not mean central cause)
• Hearing loss
• Patterns and vectors of nystagmus
• Noncontrast head CT has sensitivity of only 16% for acute ischemic CVA

Source: http://academiclifeinem.blogspot.com/2011/12/paucis-verbis-acute-vestibular-syndrome.html
Source: http://emcrit.org/podcasts/posterior-stroke/