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34 Cards in this Set
- Front
- Back
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Wong states that nystagmus is _______ initiated by _________.
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involuntary eye oscillations
fundamental imbalance of slow eye movements |
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What type of nystagmus only contains slow eye movements?
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pendular nystagmus
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What type of nystagmus has a fast phase which looks like a sawtooth pattern?
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jerk nystagmus
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When you name a type of nystagmus pendular or jerk what you are naming the nystagmus after?
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waveform
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How do you usually define a jerk nystagmus in records?
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By the direction of the fast phase
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What are the three categories of jerk nystagmus waveforms?
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1. Decreasing velocity waveform
2. Increasing velocity waveform 3. Constant velocity waveform |
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What are the 2 main categories of nystagmus (very broad)?
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Congenital and acquired
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Which type of nystagmus is usually accompanied by oscillopsia, congenital or acquired?
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Acquired
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If you had a dizzy patient with nystagmus what can you assume?
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That the nystagmus is newly acquired
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Is all oscillopsia caused by nystagmus?
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No
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What are the 5 causes of oscillopsia?
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1. Vestibular disease
2. EOM paresis 3. Saccadic Dyskinesia 4. Central oscillopsia 5. Nystagmus |
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What are the 2 types of Vestibular Nystagmus?
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Central
Peripheral |
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What are 5 types of nystagmus that occur in eccentric gaze?
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1. Gaze-evoked
2. Centripetal 3. Rebound 4. Dissociated 5. Brun's nystagmus |
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What are some causes of acquired pendular nystagmus, which is most common?
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1. MS
2. Spasmus nutans 3. Oculopalatal tremor 4. Oculomasticatory myorhythmia MS is most common |
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What causes peripheral vestibular nystagmus?
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UNILATERAL disease of the vestibular organ and nerve.
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Does bilateral disease of vestibular organ and nerve cause oscillopsia?
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No
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What waveform does peripheral vestibular nystagmus have?
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Jerk:
Mixed horizontal-torsional Constant velocity |
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Does peripheral vestibular nystagmus follow Alexander's law?
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yes
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What law states that nystagmus intensity increases during gaze in the direction of the fast phases?
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Alexander's Law
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What are the 6 types of CENTRAL vestibular nystagmus?
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1. Downbeat
2. Upbeat 3. Torsional 4. Seesaw 5. Periodic Alternating 6. Positional |
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How do you define downbeat nystagmus?
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Eyes drift upward and
Make a corrective saccade back downward. |
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What disruption causes downbeat nystagmus?
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disruption to the posterior canal projections to the tegmentum of the brainstem.
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If you see conjugate downbeat nystagmus in primary gaze then what do you expect will happen in left or right gaze?
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An increase in the frequency
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What are the 4 most common causes of downbeat nystagmus?
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1. Arnold Chiari Malformation
2. Cerebellar degeneration (SCA) 3. Idiopathic 4. MS |
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What are the 5 hypotheses for pathogenesis for downbeat nystagmus?
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1. Loss of inhibition of anterior canal projections
2. Loss of purkinje cells 3. Otolith imbalance 4. Impaired neural integrator 5. Impairment of downward pursuit reflects imbalance of smooth pursuit |
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What drug might you use for downbeat nystagmus?
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Aminopyradines
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What do aminopyradines do?
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Potassium-channel blocker
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What 3 aminopyradines did we learn about?
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3,4-diaminopyradine
4-aminopyradine Baclofen |
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What is a possible side effect of aminopyradines (esp baclofen?)
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Seizures
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What drug beside aminopyradines can be used for downbeat (as well as gaze-evoked) nystagmus?
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Acetazolamide
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What does acetazolamide do?
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An oral carbonic anhydrase inhibitor
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What else is acetazolamide used for?
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Glaucoma
Endolymphatic hydrops |
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When is it especially useful to use acetazolamide for downbeat nystagmus?
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When it's AW episodic ataxia, type 2
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When is acetazolamide contraindicated?
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Sulfa allergy
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