1. Posterior Stroke and the H.I.N.T.S exam
Prepared by Shane Barclay MD

2. Posterior Stroke Presentation
Often patients will only present with one symptom: Vertigo The differential is ‘peripheral’ causes of vertigo versus ‘central’ causes.

3. Definition of Vertigo
Perception of movement (rotational or otherwise) where no movement exists
Pathophysiology
Mismatch or asymmetric activity of visual, vestibular, and/or proprioceptive systems
Must distinguish peripheral from central cause
Peripheral: 8th CN, vestibular apparatus
Central: Brainstem, cerebellum

4. Case
86 year old woman presented with a 2 day history of fairly sudden onset severe vertigo and nausea. No vomiting. One to two weeks prior described a mild viral URTI with some sinus ‘fullness’. PHx: HTN – controlled Meds: HCTZ Exam: CN normal, finger to nose normal, heel/shin normal. Strength and reflexes normal. CV/chest benign. Dix- Halpike exam non conclusive. Slight ataxia on walking. Labs – CBC, glucose, lytes, GFR – normal.

5. “Frequency of False-Negative MRIs and non-lacunar infarcts”
Neurology July 8, 2014
“Frequency of False-Negative MRIs and non-lacunar infarcts”
Saber Tehrani AS et al.
105 patients over 13 yrs were reviewed. All presented with acute vestibular syndrome (days to weeks of continuous vertigo, nausea or vomiting, head-motion intolerance, gait unsteadiness and nystagmus).
Early MRI (within 48 hrs of symptoms) was 47% sensitive for detecting acute infarcts of < 10 mm (most involving the inferior cerebellar peduncle or lateral medulla)
and 92% sensitive for infarcts > 10 mm
Detailed beside exam including HINTS was > 99% sensitive for diagnosing infarcts of all sizes. (HINTS was false negative in only one case)

6. Differentiating Central versus Peripheral Vertigo
Benign Positional Vertigo
Migranous Vertigo
Vestibular Neuritis
Meniere’s
Viral Labyrinthitis
Drug Toxicity

7. Differentiating Central versus Peripheral Vertigo
PERIPHERAL CENTRAL
Benign Positional Vertigo Cerebellar infarct
Migranous Vertigo Vestibulobasilar TIA
Vestibular Neuritis Chiari Malformation
Meniere’s Multiple Sclerosis
Viral Labyrinthitis Neoplasms
Drug Toxicity

8. Clinical Features Peripheral Vertigo Onset Sudden Severity
Intense spinning
Pattern
Paroxysmal, intermittent
Aggravated by position/movement
Yes
Nausea/diaphoresis
Frequent
Nystagmus
Horizontal
Fatigue of symptoms/signs
Hearing loss/tinnitus
May occur
Abnormal tympanic membrane
CNS symptoms/signs
Absent

9. Clinical Features Peripheral Vertigo Central Vertigo Onset Sudden
Sudden or slow
Severity
Intense spinning
Ill defined, less intense
Pattern
Paroxysmal, intermittent
Constant
Aggravated by position/movement
Yes
Variable
Nausea/diaphoresis
Frequent
Nystagmus
Horizontal
Vertical or multidirectional
Fatigue of symptoms/signs No
Hearing loss/tinnitus
May occur
Does not occur
Abnormal tympanic membrane
CNS symptoms/signs
Absent
Usually present

10. Diagnosis
Sensitivity of Studies Preference is for MRI due to greater sensitivity

11. Journal of the American Heart Association
HINTS Exam
Stroke
September 2009
Journal of the American Heart Association
HINTS to Diagnose Stroke in the Acute Vestibular Syndrome: Three-Step
Bedside Oculomotor Examination More Sensitive Than Early MRI Diffusion-Weighted Imaging
Jorge C. Kattah, Arun V. Talkad, David Z. Wang, Yu-Hsiang Hsieh
and David E. Newman-Toker

12. Diagnosis Test Sensitivity HINTS 100% MRI (24hrs) 68.40% MRI (48hrs)
81%
CT non con
26%

13. HINTS Exam
3 Components
1. Head Impulse test of vestibulo-ocular reflex function
2. Observation for Nystagmus in primary, right, and left gaze
3. Alternate cover Test for Skew deviation.

14. HINTS Exam HEAD IMPULSE (or Head Thrust)
Have patient fix their eyes on your nose
Move their head in the horizontal plane to the left and right.
When the head is turned towards the normal side the vestibular ocular reflex remains intact and eyes continue to fixate on the visual target
When the head is turned towards the affected side, the vestibular ocular reflex fails and the eyes make a corrective saccade to re-fixate on the visual target. It is reassuring if the reflex is abnormal (due to dysfunction of the peripheral nerve) ie abnormal means it is a peripheral cause of vertigo.

15. HINTS Exam
NYSTAGMUS
Peripheral causes of vertigo (ie BPV) can give HORIZONTAL nystagmus but ONLY in one direction. Move the head right, left or up and down and the nystagmus will ONLY be in one direction.
However if you have the patient look to the left and there is left beating nystagmus and then have the patient look to the right and there is right beating nystagmus, that is known as direction changing nystagmus and that is BAD. ie occurs with central cause of nystagmus.
Vertical nystagmus is always BAD.

16. HINTS Exam
TEST of SKEW
Skew is also known as vertical dysconjugate gaze and is a sign of a central lesion.
1. Have pt look at your nose with their eyes and then cover one eye
2. Then rapidly uncover the eye and quickly look to see if the eye moves to re-align.
3. Repeat on each eye
(4. or if pt complains of binocular diplopia that is a positive test too)

17. Summary Patient presents with Continuous Vertigo and no hearing loss.
1 Head Impulse
Normal patient, eyes will remain fixed on the target (your nose)
Peripheral Vertigo Pt – rapid rotation of the head toward the affected side will result in loss of fixation and movement of the eyes away from the target.
With Central Vertigo, there is typically NO corrective saccade.
i.e. you want there to be saccade motion

18. Summary Patient presents with Continuous Vertigo and no hearing loss.
2. Nystagmus - Normal Pt’s will have NO nystagmus - Pt’s with peripheral vertigo cause will have unidirectional, horizontal nystagmus - Pt’s with central vertigo can have rotatory or vertical nystagmus, or direction changing nystagmus (right beating nystagmus when looking right and left beating nystagmus when looking left) i.e. you want there to be unidirectional, horizontal nystagmus.

19. Summary Patient presents with Continuous Vertigo and no hearing loss.
3. Test of Skew - Normal Pt’s will have no skew deviation. - Pt’s with peripheral vertigo will also not have any skew deviation - Pt’s with central vertigo will have misalignment and therefore as the cover is moved off from the eye, a slight correction (up or down) will occur. i.e. you want the patient to NOT have any skew deviation.

20. Summary Patient presents with Continuous Vertigo and no hearing loss.
So, you can rule out a central cause of vertigo if:
Pt has no corrective saccade with head impulse
Pt has unidirectional horizontal nystagmus.
Pt has no skew deviation.
If the patient has any of the following along with suggestive history, they should be admitted for further evaluation (MRI) for possible central stroke:
Pt has no corrective saccade with head impulse.
Pt has rotatory or vertical nystagmus or direction changing nystagmus
Pt has misalignment and correction of eyes with uncovering of the eye.

21. HINTS – Summary
Head Impulse You want the Head Impulse test to be ABNORMAL to reassure you the patient has a peripheral cause of vertigo. Nystagmus You want the nystagmus to be fast beating in ONLY ONE DIRECTION to reassure you the patient has a peripheral cause of vertigo. Test of Skew You want PERFECT VERTICAL ALIGNMENT of the eyes to reassure you the patient has a peripheral cause of vertigo

22. Head Thrust Test Pt with peripheral cause of vertigo – there is corrective saccade

23. Nystagmus – Central Nystagmus is in both directions

24. Test of Skew Positive test for Central lesion

25. HINTS Exam
If ANY one of the HINTS exam components is positive, the patient needs a neurological consult/MRI. A positive HINTS exam: 100% sensitive and 96% specific for the presence of a central lesion.