Table of Contents
How many types of INO are there?
INO is classified into three main types: Unilateral. This condition affects only one eye. Bilateral.
What causes INO?
The most common causes of INO are multiple sclerosis and brainstem infarction. Other causes include head trauma, brainstem and fourth ventricular tumors, Arnold-Chiari malformation, infection, hydrocephalus, and lupus erythematosus.
What is internuclear ophthalmoplegia?
Internuclear ophthalmoplegia or ophthalmoparesis (INO) is an ocular movement disorder that presents as an inability to perform conjugate lateral gaze and ophthalmoplegia due to damage to the interneuron between two nuclei of cranial nerves (CN) VI and CN III (internuclear).
What is bilateral INO?
Bilateral INO is less common than unilateral INO, and is more often seen in patients with multiple sclerosis. Bilateral INO is characterized by bilateral manifestation of INO discussed previously in addition to a vertical gaze-evoked nystagmus on upward gaze.
Where is the lesion in INO?
pons
Internuclear ophthalmoplegia (INO) is a disorder of horizontal ocular movement due to a lesion in the brain stem (usually in the pons, specifically along the medial longitudinal fasciculus between the VI and III nuclei).
Where is the lesion in internuclear ophthalmoplegia?
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.
What is Webino?
Wall-eyed bilateral internuclear ophthalmoplaegia (WEBINO) is a rare neuro-ophthalmological condition characterised by dissociated abducting nystagmus, impaired convergence and supranuclear vertical gaze palsy.
What is the function of the MLF?
The MLF is a fiber tract located directly ventrolateral to the oculomotor nucleus that interconnects the oculomotor nucleus, trochlear nucleus, and abducens nucleus (Figure 1). The MLF serves to facilitate yoked eye movements (i.e., simultaneous abduction of the right eye and adduction of the left or vice versa).
Is the MLF in the medulla?
The medial longitudinal fasciculus (MLF) is an area of crossed over tracts, on each side of the brainstem. These bundles of axons are situated near the midline of the brainstem.
What is Oculopharyngeal muscular dystrophy OPMD?
Oculopharyngeal muscular dystrophy (OPMD) is a rare genetic muscle disorder with onset during adulthood most often between 40 and 60 years of age. OPMD is characterized by slowly progressive muscle disease (myopathy) affecting the muscles of the upper eyelids and the throat.
What is a heliotrope rash?
Heliotrope rash is one of the characteristic skin manifestations of juvenile dermatomyositis. It is a reddish-purple rash on the upper eyelids that is usually bilateral. Case Presentation. We report a boy who presented with unilateral heliotrope rash, Gottron’s papules, and muscle weakness.
What causes MLF lesion?
The underlying pathology is a unilateral lesion in the dorsal pontine tegmentum that affects the pontine lateral gaze center and the adjacent MLF. Multiple sclerosis is the usual cause. Other causes include brainstem glioma, infraction, or myasthenia gravis.
Why is convergence normal in internuclear ophthalmoplegia?
The affected eye adducts normally in convergence because convergence does not require signals from the horizontal gaze center. This finding distinguishes internuclear ophthalmoplegia from 3rd cranial nerve palsy.
What are the types of internuclear ophthalmoplegia?
Earlier investigators had originally designated two types of internuclear ophthalmoplegia: an anterior type, in which the medial rectus muscle is paralyzed for conjugate movements toward the side of the lesion but functions normally in convergence and the lateral rectus muscle operates normally on lateral gaze,…
What is the prognosis of internuclear ophthalmoplegia?
When the cause of the internuclear ophthalmoplegia is MS, infection, or trauma, most people show a complete recovery. Full recovery is less favorable if the cause is a stroke or other cerebrovascular problem.
What are the etiologies of ophthalmoplegia?
A number of etiologies have been implicated in INO and ‘INO plus’ syndromes 1-3,8: Furthermore, a pseudointernuclear ophthalmoplegia can be seen in conditions causing complex ophthalmoplegia such as myasthenia gravis or Miller Fisher syndrome 1,9.
Can MRI help diagnose internuclear ophthalmoplegia?
The physical examination in most patients with internuclear ophthalmoplegia helps practitioners to arrive at a diagnosis. However, investigations like neuroimaging assist in finding the underlying cause. MRI can be a valuable tool in this regard, and up to 75% of patients may have a visible lesion.