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A 21 year old woman reports blurred vision in both eyes of uncertain duration.
The first step in the management of this patient is:
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Correct!
Each of the answer choices may eventually play a role in management, but thorough ophthalmological examination comes first.
This is congenital nystagmus (also called “infantile nystagmus syndrome”), an oscillatory disorder that begins within the first six months of life. Its distinguishing feature is that the oscillation has an atypical horizontal waveform that remains horizontal in upgaze and downgaze (“uniplanar”). It is unlike acquired nystagmus caused by brainstem or cerebellar lesions, which converts to upbeat on up gaze (“multiplanar”). Convergence often extinguishes the nystagmus in this condition, as you saw here. Some patients have strabismus and some have headshaking.
Not as evident in this video is that the eyes often enter a “null zone” on the way to side gaze, in which the nystagmus amplitude is reduced. Some patients will have a face turn that places the eyes into that null zone, where reduced nystagmus amplitude may allow improved visual acuity for straight-ahead viewing. When there is a major face turn, and visual acuity is clearly improved by that face turn, a major extraocular muscle surgery (Kestenbaum procedure) may be successful in eliminating the face turn. Otherwise there is no effective treatment.
In some patients, no cause is apparent. But often there is an underlying retinal disorder (photoreceptor dystrophy, albinism, aniridia, amblyopia) that should be discoverable—although often untreatable. In some cases formerly labeled as idiopathic, optical coherence tomography has disclosed foveal dysplasia. Hence the need for thorough ophthalmologic examination.
If that is negative, or if there is an afferent pupil defect, MRI is needed to rule out optic nerve or chiasm pilocytic astrocytoma or dysplasia. Electronystagmography is an elegant way to characterize the nystagmus waveform, but it is difficult to perform in youngsters and not necessary to make the presumptive diagnosis. Genetic counseling is meaningful only after a thorough ophthalmological examination. Are you surprised that this form of nystagmus was not diagnosed earlier in this patient? It may have been, but for unexplained reasons, she denied having been told why her eyes wiggle.
This is congenital nystagmus (also called “infantile nystagmus syndrome”), an oscillatory disorder that begins within the first six months of life. Its distinguishing feature is that the oscillation has an atypical horizontal waveform that remains horizontal in upgaze and downgaze (“uniplanar”). It is unlike acquired nystagmus caused by brainstem or cerebellar lesions, which converts to upbeat on up gaze (“multiplanar”). Convergence often extinguishes the nystagmus in this condition, as you saw here. Some patients have strabismus and some have headshaking.
Not as evident in this video is that the eyes often enter a “null zone” on the way to side gaze, in which the nystagmus amplitude is reduced. Some patients will have a face turn that places the eyes into that null zone, where reduced nystagmus amplitude may allow improved visual acuity for straight-ahead viewing. When there is a major face turn, and visual acuity is clearly improved by that face turn, a major extraocular muscle surgery (Kestenbaum procedure) may be successful in eliminating the face turn. Otherwise there is no effective treatment.
In some patients, no cause is apparent. But often there is an underlying retinal disorder (photoreceptor dystrophy, albinism, aniridia, amblyopia) that should be discoverable—although often untreatable. In some cases formerly labeled as idiopathic, optical coherence tomography has disclosed foveal dysplasia. Hence the need for thorough ophthalmologic examination.
If that is negative, or if there is an afferent pupil defect, MRI is needed to rule out optic nerve or chiasm pilocytic astrocytoma or dysplasia. Electronystagmography is an elegant way to characterize the nystagmus waveform, but it is difficult to perform in youngsters and not necessary to make the presumptive diagnosis. Genetic counseling is meaningful only after a thorough ophthalmological examination. Are you surprised that this form of nystagmus was not diagnosed earlier in this patient? It may have been, but for unexplained reasons, she denied having been told why her eyes wiggle.