View source for Internuclear opthalmoplegia

==Background==
[[File:Ino v2.png|thumbnail|Internuclear opthalmoplegia, courtesy of sketchy medicine]]

*Disruption of conjugate gaze.
*Results in [[diplopia]] when looking contralateral (to affected eye).
*Localized to Midbrain or Pons.
*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. 
*Lesions in the Medial Longitudinal Fasiculus (MLF) result in intranuclear ophthalmoplegia (INO).
*Associated with one and one-half syndrome (lesion involving the PPRF and ipsilateral MLF)

==Clinical Features==
*Weakness in adduction of affected eye with limitation in horizontal gaze. 
*May result in horizontal [[diplopia]]
*Horizontal [[nystagmus]] in unaffected eye
*Convergence remains intact (differentiates CN III palsy from INO)

==Differential Diagnosis==
*[[Multiple sclerosis]] (often presents with bilateral internuclear ophthalmoplegia)
*[[CVA|Cerebrovascular disease]]
*[[brain tumor|Malignancy]] located in brainstem and 4th ventricle
*[[third nerve palsy|CN III palsy]] 

==Evaluation==
*Neurologic exam
*The use of optokinetic tape is highly sensitive for testing for INO
*[[brain MRI]] 

==Management==
*Symptoms will often resolve on their own. Patients with cerebrovascular disease are less likely to have recovery.
*Patching of eye can aid in relief of diplopia
*Diframpadine, potassium channel blocker, has been used in patients with demyelinating disease

==References==
<references/>
Ropper A, Klein J, Samuels M. Adams and Victor's Principles of Neurology 10th Edition. McGraw-Hill Education / Medical; 2014.
<references/>
Serra A, Skelly MM, Jacobs JB, et al. Improvement of internuclear ophthalmoparesis in multiple sclerosis with dalfampridine. Neurology 2014; 83:192.


[[Category:Neurology]]
[[Category:Symptoms]]