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Brainstem Ocular Motor Disorders
Acute Comitant Esotropia
What is it?
Recent-onset diplopia and comitant esotropia when fixating a distant target
Full ocular versions and ductions
Common causes: accommodative esotropia, breakdown of latent esophoria, spasm of the near reflex, high myopia
Uncommon (but serious) causes: increased intracranial pressure, subarachnoid hemorrhage, acute thalamic or brainstem lesion, meningoencephalitis
What does it look like?
Core neuro-ophthalmic features
Diplopia
Full ocular versions and ductions
Comitant esotropia when fixating a distant target
Eyes are often aligned when fixating a near target
Possible accompanying neuro-ophthalmic features
Episodic convergence, miosis, and accommodation, which are components of the synkinetic near response, as part of “spasm of the near reflex”
Intermittent back-and-forth conjugate saccadic movements (“volitional flutter”)
Papilledema
Possible other accompanying features
Hyperopic refractive error
Headache
Ear pain
Reduced consciousness
Impaired cognition
Ataxia
Extremity weakness and numbness
Possible imaging features
Ventriculomegaly
Cerebellar, thalamic, or midbrain lesion
Meningitis
Subarachnoid hemorrhage
Dural venous sinus thrombosis
Lumbar puncture may show an elevated opening pressure or abnormal constituents suggesting meningitis or subarachnoid hemorrhage
What else looks like it?
Bilateral sixth nerve palsies, which should be accompanied by incomitant esotropia
What should you do?
Look for sedative medications that could have caused a decompensated esophoria
Look for signs of spasm of the near reflex
Convergence movements that interrupt ocular versions
Episodic miosis and pseudomyopia
Look for an uncorrected hyperopic refractive error
Tip:
accommodative esotropia rarely has its onset after age 3 and rarely includes diplopia
Look for high myopia
Tip:
the esotropia of high myopia may have a subacute onset
Exclude signs of an underlying brain lesion
Order brain MRI if you cannot attribute the esotropia to sedative medication, accommodative esotropia, spasm of the near reflex, or high myopia
Order lumbar puncture if MRI is normal and there are features to suggest a neurologic illness
What will happen?
Most cases without other neurologic features will be caused by decompensated esophoria, accommodative esotropia, or spasm of the near reflex, but…
Tip:
distinguishing between decompensated esophoria and spasm of near reflex may be difficult
Accommodative esotropia can be corrected with the appropriate hyperopic glasses prescription
Diplopia of decompensated esophoria is easily palliated with base-out prism
Eye muscle surgery is indicated only if
Esotropia has not resolved after at least 9 months
Esotropia is large
Patient does not want to wear glasses with prism
Trap:
eye muscle surgery for spasm of the near reflex carries a risk of consecutive exotropia (See
Spasm of Near Reflex
)
Brainstem Ocular Motor Disorders
Internuclear Ophthalmoplegia
Skew Deviation
Dorsal Midbrain Syndrome
Thalamic or Tegmental Midbrain Syndrome
Unilateral Pontine Syndrome
Bilateral Pontine Syndrome
Dorsolateral Medullary (Wallenberg) Syndrome
Ototoxic Vestibulo-ocular Dysfunction Syndrome
Acute Upgaze Deviation
Acute Downgaze Deviation
Acute Comitant Esotropia
Omnidirectional Slow Saccades
Omnidirectional Saccadic Pursuit