What are reliable beside assessments which can help differentiate peripheral causes of vertigo from central ones?
A 3-step bedside oculomotor examination looking at head impulse testing, nystagmus and test of skew deviation (HINTS) appears more sensitive for central causes of vertigo than early MRI when applied by an experienced clinician.
Among the differential for sudden onset persistent vertigo with nausea are peripheral causes such as vestibular neuritis and labyrinthitis as well as more sinister central causes such as stroke or demyelination of the brainstem or cerebellum. Due to bone related artifacts, CT scan has a notoriously poor sensitivity for detecting acute posterior circulation infractions (approximately 16%).  MRI with Diffuse Weighted Imaging (DWI) remains the golden standard imagining modality for detecting ischemia but is often not available in a timely manner.
The findings from the HINTS study emphasized the need for careful neuro-opthomological assessments beyond the standard neurological exam in patients with acute vertigo. The presence of a skew deviation in particular was felt to allow for good differentiation of lateral brain stem strokes from peripheral causes of vertigo.
As of November 2015, no guidelines have been published that reflect the results of this trial.
- Single center, prospective, cross-sectional study
- Setting: Urban, academic regional stroke referral center for 25 community hospitals (~700 stroke admissions per year)
- Enrollment: 1999-2008
- Patient with symptoms of acute vestibular syndrome (acute vertigo, nausea, vomiting, and/or gait changes) and at least one vascular risk factor: smoking,hypertension, diabetes, hyperlipidemia, atrial fibrillation, eclampsia, hypercoagulable state, recent cervical trauma, or prior stroke or previous myocardial infarction.
- Able to provide informed consent
- History of recurrent vertigo with or without auditory symptoms
- Mean age: 62 years (SD=13 years)
- Gender: 65% men
- Number of vascular risk factor:
- 1: 30%
- >1: 70%
- Patients by final etiology of vertigo:
- Peripheral cause:25/101
- Central cause: 76/101 (Stroke: 69/101)
- HINTS testing carried out by a single neuro-opthomologists: Head Impulse, Nystagmus and Test of Skew deviation
- Horizontal Head Impulse testing is considered negative if fixation is maintained and positive if a corrective saccade is seen after the head impulse. Negative is normal.
- Nystagmus is consistent with peripheral cause if it is predominantly unidirectional horizontal nystagmus and increases in intensity when the patient looks in the direction of the nystagmus fast phase
- Test of Skew Deviation: Accomplished by prism cross-cover test for ocular alignment
- In those with vertical misalignment or head tilt without an INO, head-upright fundus photography was conduct to look for ocular tilt reaction
- All patients received imagining (98 with MRIs and 3 with CT). Examiner was blinded to imaging results but not to clinical history, general neurological examination, or obvious oculomotor findings.
Comparisons are Dangerous HINTS findings vs. MRI
- Benign HINTS (abnormal h-HIT plus direction-fixed horizontal nystagmus plus absent skew)
- Dangerous HINTS (normal/untestable h-HIT or direction changing horizontal nystagmus present/untestable or skew deviation present/untestable)
- Sensitive for stroke
- 100% vs. 88% (8 patients had falsely negative initial MRI scans. Follow up MRI, an average of 3 days after, showed ischemic stroke.)
- Specificity for stroke
- 96% vs. 100%
- Negative Likelihood Ratio for stroke
- 0.00 (0.00–0.12) vs. 0.12 (0.06–0.22)
- Examiner was blinded to imaging results but not to clinical history, general neurological examination, or obvious oculomotor findings.
- Ability to detect skew deviation by clinicians other than a neuro-opthomologist is likely lowered than was in the study
- All patients had at least one vascular risk factor and 3/4 of patients CNS etiologies for their vertigo. The proportion of vertigo that is central in etiology in patients presenting to the ED with first episode of vertigo is likely much lower (closer to 25%). 
- National Institutes of Health and Agency for Healthcare Research and Quality
- Chalela JA, Kidwell CS, Nentwich LM, Luby M, Butman JA, Demchuk AM, Hill MD, Patronas N, Latour L, Warach S. Magnetic resonance imaging and computed tomography in emergency assessment of patients with suspected acute stroke: a prospective comparison. Lancet. 2007;369:293–298.
- Norrving B, Magnusson M, Holtas S. Isolated acute vertigo in the elderly; vestibular or vascular disease? Acta Neurol Scand. 1995;91:43– 48.