Nystagmus/ Upbeat nystagmus:
These are rhythmic,involuntary and jerky movements of the eyeball when they are fixed on an object.
It signifies the disturbance of ocular posture.
Examination:
1.Eliminate the weakness of extraocular muscles.
2.Ask the patients to look forward.Observe for pendular nystagmus.
3.Ask the patient to fixate his vision on your index finger held at 60cm distance,kept atleast 5sec laterally on both sides in turns.
4.Place your fingers above and below his head to examine in vertical plane.
How to describe?
1.Pendular/jerky
2.Direction - direction of fast component
3.Plane of testing - horizontal/ vertical
4.Plane of oscillatory movements of nystagmus- horizontal/vertical/ rotatory
5.Amplitude -
a) Fine less than 1mm
b) Medium - 1-3mm
c) Coarse - more than 3 mm
6.Grading
Grade I - present only with eccentric gaze.
Grade ll - present in primary gaze and increase in intensity with gaze in the direction of fast component.
Grade III - fast component continue to beat even with gaze in direction of the slow component.
Location of pathology:
Nystagmus increases in upgaze - Cerebellar vermis
Nystagmus decrease in upgaze - Medulla
Causes:
1. Cerebellar or medullary lesions
2. Wernicke’s encephalopathy
3. Drug intoxication
#nystagmus
#cns
#neurology
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