Case Report: Internuclear Ophthalmoplegia
Diplopia in a young adult patient
A 27 yo male presented to the clinic with diplopia worsening over the past week. Pt reported diplopia onset when looking either to the left or right with both eyes open.
During examination, it was noted that both eyes completely lacked adduction in both right and left gaze. Nystagmus was also noted in either eye when abducting. Visual acuity, pupil function, and all other physical examination findings were within normal limits.
Differential:
Bilateral Duane’s Type 2 - Typically congenital and symptoms noted within first decade of life
Internulcear Ophthalmoplegia (INO) - Typically caused by demyelinating disease (multiple sclerosis), brainstem infarct/stroke, or space occupying lesion - patient is the right age for this
Myasthenia Gravis (MG) Associated Pseduo-INO - MG can cause ophthalmoplegia that is often transient
Other Congenital Ophthalmoplegia - Such as Kearne-Sayre Syndrome, however at 27, Kearne-Sayre has often progressed to multiple nerve/muscle groups, and has been diagnosed, often with surgical intervention already attempted
Patient tentatively diagnosed with internuclear ophthalmoplegia and sent for imaging. Internuclear ophthalmoplegia (INO) occurs when a lesion in the area of the medial longitudinal fasciculus (MLF) within the midbrain disrupts the interneuron between CNVI and CNIII. This causes an inability to conjugate lateral gazes between the two eyes and adduction becomes reduced, or nonexistent.
Imaging showed no signs of stroke or space occupying tumor. Scattered white matter lesions were noted. In absence of tumor, or evidence of stroke, the patient was diagnosed with intranuclear ophthalmoplegia secondary to demyelinating disease, and will begin further workup and treatment for multiple sclerosis.
Prognosis: INO secondary to demyelinating disease, infection or trauma often completely resolves within a few months to a year. INO secondary to cerebrovascular event tend to have less favorable outcomes for toward total recovery, and should undergo further stroke-protocol evaluation and treatment as necessary.