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Diagnostic Criteria
Listed below are diagnoscit criteria, clinical "pearls," and bedside tests that have resulted from research conducted at OMLAB.
a(hypo)chiasma by see-saw nystagmus plus chiasmal imaging
Clinical Pearl
If an infant has see-saw nystagmus, achiasma or hypochiasma may be present.
Obtain a chiasmal image.
benign nystagmus by alternate-cover test
Clinical Pearl
No non-alternating, acquired nystagmus reverses with alternate cover.
Bedside Test
In a patient with nystagmus of unknown origin:
1. Observe in primary position to confirm that it does not alternate direction
2. Perform alternate-cover test
3. If positive, the nystagmus is a benign form of infantile nystagmus
4. If negative, the nystagmus may be a benign form of infantile nystagmus or acquired nystagmus
5. Rule out infantile nystagmus by history or clinical characteristics
congenital nystagmus by pathognomonic waveforms
congenital nystagmus head tremor by alerting patient
Clinical Pearl
Head tremor associated with congenital nystagmus is easilly suppressed.
Bedside Test
In a patient with head tremor of unknown origin:
1. Bring the tremor to the patient's attention
2. If it stops, the tremor is due to a benign form of infantile nystagmus
3. If not, the tremor is acquired
saccadic intrusions and oscillations by ocular motility recordings
myasthenia gravis by OKN-Tensilon test
myasthenia gravis by saccadic gain-Tensilon test
spasmus nutans by waveform phase difference
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