MLF syndrome – Internuclear Ophthalmoplegia


MLF syndromeInternuclear 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 in MLF syndrome is generally preserved. In other words (When the normal eye looks to the right, the affected eye does not follow it, therefore remains in the center. This will also cause nystagmus of the normal eye since it gets confused and it does not know whether to stay on the right or go back to the center like the affected eye.)



MLF syndrome - Internuclear Ophthalmoplegia

MLF syndrome 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. In older patients with one-sided lesions a stroke is a distinct possibility. Other causes are possible.



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) 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 which, simply put, involves paralysis of all conjugate horizontal eye movements other than abduction of the eye on the opposite side to the lesion.


MLF syndrome – Internuclear Ophthalmoplegia – MADE EASY
This video tutorial is brought to you by: Ali Feili, M.B.A., M.D.

More info on MLF syndrome:

✔ FREE Medical Videos:
✔ Website:
✔ Facebook:
✔ Twitter:
✔ Google Plus:
✔ Patron:
✔ Pinterest:
✔ Instagram:

This information is intended for educational purposes only, and should not be interpreted as medical advice. Please consult your physician for advice about changes that may affect your health.

What is MLF syndrome
What is Internuclear Ophthalmoplegia
MLF syndrome symptoms
Internuclear Ophthalmoplegia Symptoms
MLF syndrome video lecture
Internuclear Ophthalmoplegia video lecture
MLF syndrome Made easy
Internuclear Ophthalmoplegia made easy
MLF syndrome explained
Internuclear Ophthalmoplegia explained

(Visited 172 times, 4 visits today)

Other Videos You Might Like:

0 0 votes
Article Rating
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Oldest Most Voted
Inline Feedbacks
View all comments