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| ==Background==
| | #REDIRECT[[Internuclear ophthalmoplegia]] |
| [[File:Ino v2.png|thumbnail|Internuclear opthalmoplegia, courtesy of sketchy medicine]] | |
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| *Disruption of conjugate gaze.
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| *Results in [[diplopia]] when looking contralateral (to affected eye).
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| *Localized to Midbrain or Pons.
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| *Paramedian Pontine Reticular Formation (PPRF) is the conjugate gaze center for horizontal eye movements. Innervates ipsilateral Abducens (CN VI) nucleus. Abducens nucleus signals ipsilateral lateral rectus to contract and sends a second via MLF to contralateral oculomotor (CN III) nucleus, causing contraction on the contralateral medial rectus.
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| *Lesions in the Medial Longitudinal Fasiculus (MLF) result in intranuclear ophthalmoplegia (INO).
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| *Associated with one and one-half syndrome (lesion involving the PPRF and ipsilateral MLF)
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| ==Clinical Features==
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| *Weakness in adduction of affected eye with limitation in horizontal gaze.
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| *May result in horizontal [[diplopia]]
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| *Horizontal [[nystagmus]] in unaffected eye
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| *Convergence remains intact (differentiates CN III palsy from INO)
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| ==Differential Diagnosis==
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| *[[Multiple sclerosis]] (often presents with bilateral internuclear ophthalmoplegia)
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| *[[CVA|Cerebrovascular disease]]
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| *[[brain tumor|Malignancy]] located in brainstem and 4th ventricle
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| *[[third nerve palsy|CN III palsy]]
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| ==Evaluation==
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| *Neurologic exam
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| *The use of optokinetic tape is highly sensitive for testing for INO
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| *[[brain MRI]]
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| ==Management==
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| *Symptoms will often resolve on their own. Patients with cerebrovascular disease are less likely to have recovery.
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| *Patching of eye can aid in relief of diplopia
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| *Diframpadine, potassium channel blocker, has been used in patients with demyelinating disease
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| ==References==
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| <references/>
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| Ropper A, Klein J, Samuels M. Adams and Victor's Principles of Neurology 10th Edition. McGraw-Hill Education / Medical; 2014.
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| <references/>
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| Serra A, Skelly MM, Jacobs JB, et al. Improvement of internuclear ophthalmoparesis in multiple sclerosis with dalfampridine. Neurology 2014; 83:192.
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| [[Category:Neurology]]
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| [[Category:Symptoms]]
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