New Onset Double Vision in Multiple Sclerosis

Primary Cause

The American Academy of Neurology suggests that in a patient with multiple sclerosis presenting with new onset diplopia, the most likely cause is internuclear ophthalmoplegia (INO) from a demyelinating lesion in the medial longitudinal fasciculus (MLF) of the brainstem 1

Sixth nerve palsy is the most common cranial neuropathy overall, presenting with horizontal diplopia worse at distance and in lateral gaze toward the affected side, according to the American Academy of Ophthalmology 2, 1
The American Academy of Neurology notes that third and fourth nerve palsies can also occur but are less common in MS 1
Isolated cranial nerve VI palsy is most common in adults, though MS lesions typically involve the pons with other neurologic findings, as stated by the American Academy of Ophthalmology 2

The American Academy of Neurology recommends that multiple cranial nerve palsies suggest extensive brainstem involvement 1
Pupil-involving third nerve palsy requires urgent evaluation to exclude aneurysm or compressive lesion, according to the American Academy of Neurology 1
Progressive symptoms or failure to resolve warrant immediate neuroimaging, as suggested by the American Academy of Neurology 1
Associated posterior circulation symptoms (vertigo, ataxia, dysarthria) suggest brainstem stroke, according to the American Academy of Neurology 3

The American Academy of Neurology states that MRI brain and orbits with contrast is the examination of choice to identify demyelinating plaques and assess for acute lesions 1
MRI provides superior detection of posterior circulation and brainstem lesions compared to CT, as noted by the American Academy of Neurology 4
The American Academy of Ophthalmology recommends a complete motility examination including cover-uncover testing, assessment for INO pattern, and evaluation for nystagmus 5
Testing for binocular fusion and stereopsis to assess functional impact is suggested by the American Academy of Ophthalmology 5

The American Academy of Neurology suggests high-dose corticosteroids for acute MS relapses causing diplopia, though be aware of potential adverse effects including central serous retinopathy 2
Referral to neurology or neuro-ophthalmology for comprehensive evaluation and MS disease-modifying therapy optimization is recommended by the American Academy of Ophthalmology 2
Prism glasses may provide temporary relief while awaiting recovery, typically over 6 months, according to the American Academy of Ophthalmology 2, 3
Eye patching can eliminate diplopia but removes binocular vision, as noted by the American Academy of Neurology 3
Botulinum toxin or strabismus surgery may be considered for persistent cases after 6 months if no recovery occurs, as suggested by the American Academy of Ophthalmology 2, 3

The American Academy of Ophthalmology warns not to assume vasculopathic sixth nerve palsy in MS patients without considering demyelinating etiology, as MS-related palsies require different management 2
Failure to identify INO pattern (impaired adduction with contralateral abduction nystagmus) may delay MS diagnosis, according to the American Academy of Neurology 2
The American Academy of Neurology advises not to rely on CT imaging for brainstem pathology—MRI is essential for detecting demyelinating lesions 4
In MS patients under 50, if sixth nerve palsy shows no recovery by 6 months, approximately 40% demonstrate serious underlying pathology warranting further evaluation, as noted by the American Academy of Ophthalmology 2
Bilateral sixth nerve involvement should raise concern for increased intracranial pressure or meningeal process, not just MS plaques, according to the American Academy of Ophthalmology 2