Isolated Internuclear Ophthalmoplegia (INO) caused by a lacunar infarction: a case report and review of the literature

Castellano Vicente, Alberto José; Pérez Rodríguez, Abigail; Rosón González, Mirian; Martínez López, Estela; Pire García, Paula; Méndez Burgos, Alejandro; Cantador Pavón, Estefanía; López Carbonero, Juan Ignacio; Sobrino García, Pilar; Villa López, Marta.

Introduction: Midbrain and pontine strokes are well defined in literature as etiologies of internuclear ophthalmoplegia (38%), multiple sclerosis (34%) or unusual cases (28%) . Only 30-52% of these ischemic lesions could be identified by MRI. Our objetive is taking into consideration that lacunar brainstem infarctions with positive MRI can be also a cause of isolated INO.

Method: We present a 72 year-old male with mRS=0 and history of hypertension for which he was taking amlodipine and a previous  left ischemic oculomotor palsy totally recovered for which he was on clopidogrel and pantoprazole daily. He was presented at the emergency room with sudden binocular diplopia 3 hours after onset.

Results: On examination, he showed normal gaze in primary position, restriction of the right eye adduction and left eye abduction showed tortional nystagmus. Convergence was impaired. The rest of the neurological examination was unremarkable. CTA showed no hemorrhage, great vessel oclussion nor intracraneal stenosis. He was admitted to the stroke unit where no arrhythmias were detected on the monitorization during one day.  Hypertensive cardiopathy was seen on the transthoracic echocardiogram but no embolic sources were found. Finally, MRI showed a right midbrain lacunar acute ischemic stroke. He was discharged home 2 days later on clopidogrel. At 90 days, the patient was totally recovered (mRS=0).

Conclusions: Isolated INO can be the sole manifestation of lacunar pontine stroke targeting longitudinal medial fasciculus, but it is ocassionally located in midbrain. It generally carries good prognosis.

ISOLATED INTERNUCLEAR OPHTHALMOPLEGIA (INO) CAUSED BY A LACUNAR INFARCTION: A CASE REPORT AND REVIEW OF THE LITERATURE