The chief complaint of vertiginous symptoms can be daunting, and the differential is quite long. Approximately 15% of patients presenting to the emergency department (ED) with dizziness have a dangerous underlying cause.1 We present a case of a 40-year-old female with a sudden onset of what she describes as vertigo, in the setting of intermittent diplopia. The patient was found to have a left medial rectus palsy consistent with a left internuclear ophthalmoplegia. Internuclear ophthalmoplegia (INO) is an abnormal gaze that is characterized by the weakness or inability to adduct the affected eye. This occurs secondary to a lesion in the brain affecting the medial longitudinal fasciculus (MLF) most commonly in the pons; however, this pathway can also be affected in the midbrain.2 The diagnosis in our patient was confirmed after an MRI revealed an acute infarct of the left dorsal pons involving the medial longitudinal fasciculus, resulting in the observed left INO. The patient was admitted to the hospitalist service with neurology consultation for further stroke workup. Ultimately, the stroke was deemed cryptogenic in etiology with hyperlipidemia and obesity as the patient’s risk factors. She was discharged home after three days in the hospital on daily aspirin and high-intensity statin. Upon six-month follow up she had near resolution of her symptoms.

Topics: Internuclear Ophthalmoplegia, INO, Vertigo, Stroke, Neurology