What can cause ophthalmoplegia?
Ophthalmoplegia can be caused by congenital abnormalities, trauma, complications of viral infections, or disorders that affect the nervous system, including multiple sclerosis, cerebral tumours, migraines, and vascular (blood vessel) disease such as that associated with diabetes.
Why is there nystagmus in internuclear ophthalmoplegia?
This is thought to be a compensatory response to overcome the weakness of the adducting eye explained by Herring’s law of equal innervation. Increased innervations to the medial rectus muscle are accompanied by an increase in innervation to its yoke muscle, the contralateral lateral rectus, resulting in nystagmus.
How is INO diagnosed?
Your doctor will ask you to focus on their nose, and then rapidly shift your gaze to a finger held out to the side. If the eye overshoots when turning to the side, it’s a sign of INO. You may also be tested for back-and-forth motion of the abducting eye (nystagmus).
What is bilateral internuclear ophthalmoplegia?
Internuclear ophthalmoplegia (INO) is an eye movement disorder caused by a lesion in the medial longitudinal fasciculus (MLF) located in the midbrain. Adduction paralysis of both eyes and bilateral abduction nystagmus are the main features of INO.
What causes external ophthalmoplegia?
External ophthalmoplegia is usually caused by muscle disorders or mitochondrial diseases such as Graves’ disease or Kearns-Sayre syndrome. Other common causes include: migraines. thyroid disease.
What is external ophthalmoplegia?
Collapse Section. Progressive external ophthalmoplegia is a condition characterized by weakness of the eye muscles. The condition typically appears in adults between ages 18 and 40 and slowly worsens over time.
What is parinaud’s syndrome?
Parinaud syndrome is defined as a constellation of upward gaze palsy, convergence retraction nystagmus, light-near dissociation, and bilateral lid retraction.
What is ipsilateral INO?
The activation of the contralateral medial rectus and ipsilateral lateral rectus muscle produces horizontal conjugate eye movement. The side of the INO is named by the side of the adduction deficit, which is ipsilateral to the MLF lesion.
What kind of movement disorder is internuclear ophthalmoplegia?
Internuclear ophthalmoplegia is an ocular movement disorder caused by a lesion of the medial longitudinal fasciculus.[1] It is characterized by impaired adduction of the ipsilateral eye with nystagmus of the abducting eye.
How does internuclear ophthalmoplegia affect the horizontal gaze?
Internuclear ophthalmoplegia occurs due to a lesion in the medial longitudinal fasciculus (MLF) by blocking the connection between the contralateral sixth nerve nucleus and the ipsilateral third nerve nucleus, thus affecting horizontal gaze.
How is internuclear ophthalmoplegia related to MLF damage?
Internuclear ophthalmoplegia (INO) is a deficit in the control of conjugate eye movements, which results from damage to the medial longitudinal fasciculus (MLF).
What causes eye movement in the internuclear area?
Internuclear ophthalmoplegia (INO) is a disorder of eye movements caused by a lesion in an area of the brain called the medial longitudinal fasciculus (MLF). The most common causes of INO are multiple sclerosis and brainstem infarction. Other causes include head trauma, brainstem and fourth ventricu …