Internuclear ophthalmoplegia
| Internuclear ophthalmoplegia | |
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| Schematic demonstrating right internuclear ophthalmoplegia, caused by injury of the rightmedial longitudinal fasciculus. | |
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Internuclear ophthalmoplegia (INO) is a disorder ofconjugate lateral gaze in which the affected eye shows impairment ofadduction. When an attempt is made to gaze contralaterally (relative to the affected eye), the affected eye adducts minimally, if at all. The contralateral eyeabducts, however withnystagmus. Additionally, the divergence of the eyes leads to horizontaldiplopia. That is if the right eye is affected the patient will "see double" when looking to the left, seeing two images side-by-side.Convergence is generally preserved.[1]
Signs and symptoms
The clinical presentation is consistent with the following:[2]
- Horizontaldiplopia
- Dizziness on lateral gaze
Causes
The disorder is caused by injury or dysfunction in themedial longitudinal fasciculus (MLF), a heavily myelinated tract that allows conjugate eye movement by connecting theparamedian pontine reticular formation (PPRF)-abducens nucleus complex of the contralateral side to theoculomotor nucleus of the ipsilateral side.
In young patients with bilateral INO,multiple sclerosis is often the cause. In older patients with one-sided lesions a stroke is a distinct possibility. Other causes are possible.[3]
Variants
Arostral lesion within the midbrain may affect the convergence center thus causing bilateral divergence of the eyes which is known as the WEBINO syndrome (Wall Eyed Bilateral INO)[4] as each eye looks at the opposite "wall".
If the lesion affects thePPRF (or the abducens nucleus) and theMLF on the same side (the MLF having crossed from the opposite side), then the "one and a half syndrome" occurs, with paralysis of all conjugate horizontal eye movements other than abduction of the eye on the opposite side to the lesion.
Diagnosis
Can be seen in multiple sclerosis, stroke, and other pathologies.[5] Accompanying symptoms includescanning speech,intention tremor, incontinence, and nystagmus.[6]
Treatment
In terms of treatment,Dalfampridine shows improvement in such cases per the American Academy of Ophthalmology[2]
See also
References
- ↑"Internuclear Ophtalmoplegia".Archived from the original on 2018-07-28. Retrieved2021-07-07.
- ↑2.02.1"Internuclear Ophthalmoplegia - EyeWiki".eyewiki.aao.org.Archived from the original on 2 August 2022. Retrieved5 September 2022.
- ↑Keane JR (May 2005)."Internuclear ophthalmoplegia: unusual causes in 114 of 410 patients".Arch. Neurol.62 (5): 714–7.doi:10.1001/archneur.62.5.714.PMID 15883257.Archived from the original on 2016-03-03. Retrieved2021-07-07.
- ↑Lana MA, Moreira PR, Neves LB (December 1990). "Wall-eyed bilateral internuclear ophthalmoplegia (Webino syndrome) and myelopathy in pyoderma gangrenosum".Arq Neuropsiquiatr.48 (4): 497–501.PMID 2094199.
- ↑Gold, Daniel R."D.O."Neuro-Ophthalmology Virtual Education Library. Spencer S. Eccles Health Sciences Library, University of Utah.Archived from the original on 30 September 2019. Retrieved30 September 2019.
- ↑"Internuclear Ophthalmoplegia".The Lecturio Medical Concept Library.Archived from the original on 9 July 2021. Retrieved7 July 2021.
External links
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