II. Findings: Suggestive of central causes
- 
                          Nystagmus
                          - Vertical or torsional Nystagmus (pure Horizontal Nystagmus may occur with either peripheral or central cause)
- No Nystagmus on Horizontal Head Impulse Test
- Persists <6 seconds after Dix-Hallpike Maneuver
- Fixation of eyes on object does not inhibit Nystagmus
- Requires weeks to months to resolve
 
- Episodes last hours to days
- Severe imbalance impairs standing and walking
- No Hearing Loss or Tinnitus in most central cases
- Acute Vestibular Syndrome (Posterior Circulation in 25% of cases)
- Positive HiNTs Exam Criteria (at least 1 of 3 positive) are suggestive of Cerebellar CVA or Brainstem CVA (100% sensitive, 96% specific)- Normal Horizontal Head Impulse Test (no saccade/correction on head rotation) OR
- Nystagmus that changes direction (or Vertical Nystagmus or torsional Nystagmus) OR
- Skew Deviation on Alternate Eye Cover Test in which uncovered eye demonstrates quick vertical gaze corrections
 
- Risk Factors
III. Causes: Central Vertigo
- Non-Vascular Central Causes of Vertigo (CN 8 or CNS)- Tumor- Acoustic Neuroma (Vestibular Schwannoma)
- Infratentorial ependymoma
- Brainstem glioma
- Medulloblastoma
- Neurofibromatosis
 
- Migraine Headache
- Multiple Sclerosis
- Degenerative Ataxia Disorders or Cerebellar Syndromes- See Ataxia
- Multiple System Atrophy
- Friedreich's Ataxia
- Parkinsonism-Plus Syndrome (PPS, Atypical Parkinsonism)
 
 
- Tumor
- Vascular disease related transient cerebral anoxia or CVA- Dizziness Causes not vertebrobasilar specific
- Specific anoxia to vertebrobasilar system- Vessel specific- Brainstem Infarct (associated with Hearing Loss)- Anterior Inferior Cerebellar Artery Infarction
- Anterior Vestibular Artery Infarction
 
- Brainstem Infarct (no Hearing Loss)- Posterior Inferior Cerebellar Artery infarction
- Labyrinthine Artery Infarction
 
 
- Brainstem Infarct (associated with Hearing Loss)
- Precipitating conditions
 
- Vessel specific
 
IV. Imaging
- 
                          MRI Brain (preferred)- Consider repeating MRI at 3-7 days if posterior CVA is suspected but negative on initial MRI
- Initial MRI in first 48 hours misses 15% of posterior strokes
 
- 
                          CT Head
                          - Cannot reliably exclude posterior CVA (high False Negative Rate)
 
