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This 17 year old man is reporting blurred vision of 2 weeks’ duration.
The likely cause for this disorder is:
Incorrect
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Correct!
This is acquired pendular nystagmus. The eyes are oscillating with two slow phases in a circular or elliptical conjugate trajectory—“multivector nystagmus”
or, casually, “egg-beater nystagmus.” The amplitude of the nystagmus often differs between the two eyes (“dissociated nystagmus”). Multiple sclerosis
affecting the brainstem is the most common cause, but brainstem tumors, trauma, and metabolic disorders can also be responsible. By the way, when multiple
sclerosis is the cause, expect also to find optic neuropathy causing impaired vision in both eyes.
The eye movement abnormality you saw here is not superior oblique myokymia, which causes a rotary (torsional) oscillation limited to one eye. Pineal tumors compressing the dorsal midbrain can cause nystagmus, but it is upbeat. The nystagmus of dorsolateral medullary (Wallenberg) infarction is typically horizontal-rotary jerk. Be sure you distinguish between this circular or elliptical motion (like an eggbeater) and torsional (or rotary) motion, in which the eyes turn around a fixed point (like a screwdriver).
Why did this patient report “blurred vision” rather than the illusion of seeing objects as oscillating (“oscillopsia”)? When foveation time is brief, the patient may describe vision as blurred, not noting that the viewed objects are also moving.
Medication treatment of this form of nystagmus (memantine, gabapentin, clonazepam) is worth trying, although efficacy is variable at best.
The eye movement abnormality you saw here is not superior oblique myokymia, which causes a rotary (torsional) oscillation limited to one eye. Pineal tumors compressing the dorsal midbrain can cause nystagmus, but it is upbeat. The nystagmus of dorsolateral medullary (Wallenberg) infarction is typically horizontal-rotary jerk. Be sure you distinguish between this circular or elliptical motion (like an eggbeater) and torsional (or rotary) motion, in which the eyes turn around a fixed point (like a screwdriver).
Why did this patient report “blurred vision” rather than the illusion of seeing objects as oscillating (“oscillopsia”)? When foveation time is brief, the patient may describe vision as blurred, not noting that the viewed objects are also moving.
Medication treatment of this form of nystagmus (memantine, gabapentin, clonazepam) is worth trying, although efficacy is variable at best.