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Internuclear ophthalmoplegia

AI overview

Internuclear ophthalmoplegia (INO) is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction.

Key points
  • The disorder is caused by injury or dysfunction in the medial longitudinal fasciculus (MLF).
    source quote
    The disorder is caused by injury or dysfunction in the medial longitudinal fasciculus (MLF), a heavily myelinated tract that allows conjugate eye movement by connecting the paramedian pontine reticular formation (PPRF)- abducens nucleus complex of the contralateral side to the oculomotor nucleus of the ipsilateral side.
  • In young patients with bilateral INO, multiple sclerosis is often the cause.
    source quote
    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.
    source quote
    In older patients with one-sided lesions a stroke is a distinct possibility.
  • A rostral lesion within the midbrain may cause bilateral divergence of the eyes known as WEBINO syndrome.
    source quote
    A rostral 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)
  • Lesion affecting the PPRF and MLF on the same side results in one and a half syndrome.
    source quote
    If the lesion affects the PPRF (or the abducens nucleus) and the MLF on the same side (the MLF having crossed from the opposite side), then the " one and a half syndrome " occurs
Symptoms
  • The affected eye adducts minimally, if at all, when attempting to gaze contralaterally.
    source quote
    When an attempt is made to gaze contralaterally (relative to the affected eye), the affected eye adducts minimally, if at all.
  • The contralateral eye abducts with nystagmus.
    source quote
    The contralateral eye abducts , however with nystagmus .
  • Divergence of the eyes leads to horizontal diplopia.
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    Additionally, the divergence of the eyes leads to horizontal diplopia .
  • Accompanying symptoms include scanning speech, intention tremor, incontinence, and nystagmus.
    source quote
    Accompanying symptoms include scanning speech , intention tremor , incontinence, and nystagmus.
Diagnosis
  • INO can be seen in multiple sclerosis, stroke, and other pathologies.
    source quote
    Can be seen in multiple sclerosis, stroke, and other pathologies.
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Internuclear ophthalmoplegia
Schematic demonstrating right internuclear ophthalmoplegia, caused by injury of the right medial longitudinal fasciculus.
SpecialtyOphthalmology 

Internuclear ophthalmoplegia (INO) is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction. When an attempt is made to gaze contralaterally (relative to the affected eye), the affected eye adducts minimally, if at all. The contralateral eye abducts, however with nystagmus. Additionally, the divergence of the eyes leads to horizontal diplopia. 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]

Vestibulo-ocular reflex

The disorder is caused by injury or dysfunction in the medial longitudinal fasciculus (MLF), a heavily myelinated tract that allows conjugate eye movement by connecting the paramedian pontine reticular formation (PPRF)-abducens nucleus complex of the contralateral side to the oculomotor nucleus of the ipsilateral side. [citation needed]

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.[2]

A rostral 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)[3] as each eye looks at the opposite "wall".

If the lesion affects the PPRF (or the abducens nucleus) and the MLF 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.[citation needed]

Can be seen in multiple sclerosis, stroke, and other pathologies.[4] Accompanying symptoms include scanning speech, intention tremor, incontinence, and nystagmus.[5]

  1. ↑ "Internuclear Ophtalmoplegia".
  2. ↑ 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.
  3. ↑ 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. doi:10.1590/s0004-282x1990000400016. PMID 2094199.
  4. ↑ Gold, Daniel R. "D.O." Neuro-Ophthalmology Virtual Education Library. Spencer S. Eccles Health Sciences Library, University of Utah. Retrieved 30 September 2019.
  5. ↑ "Internuclear Ophthalmoplegia". The Lecturio Medical Concept Library. Retrieved 7 July 2021.