Abstracts

Rationale: Visual hallucinations and/or loss of vision are symptoms commonly related to acute stroke or migraine with aura. However, the differential can include other neurological processes. We present a case report of a patient who presented with right homonymous hemianopsia found to be due to focal seizures without alteration of awareness. Methods: A 52-year-old man with history of essential hypertension and diabetes mellitus type II presented with acute onset of right homonymous hemianopsia that began one week prior. He also reported seeing “flashing lights” intermittently for the past week followed by a left temporal headache, which was unusual for him. He further reported episodes of transient right-sided numbness for last several weeks. On arrival, his vital signs were stable. His initial exam revealed only right homonymous hemianopsia. Relevant laboratory workup included hyponatremia with serum sodium 117mml/L. A non-contrast CT head was obtained which did not show any acute abnormality. CTA head and neck demonstrated extensive soft atheromatous plaque involving left proximal ICA resulting in a short segment of stenosis corresponding to approximately 70% stenosis of the left ICA origin by NASCET criteria and left fetal PCA. Preliminary hypothesis was ischemic stroke in left occipital lobe. MRI head was obtained which demonstrated a punctate area of restricted diffusion in left occipital lobe as well as chronic left occipital lobe infarct. However, these occipital lobe infarcts did not appear to involve the territory to explain his complete right homonymous hemianopsia. On day 2 of hospitalization, he began having brief episodes of seeing colors and shapes that spread throughout his right visual field and evolved in complexity lasting one to three minutes. Results: Routine EEG was obtained due to concern for seizures. Two such episodes were captured with correlating electrographic seizure in left occipital region which resolved when he reported that these visual phenomena had ceased. He was started on levetiracetam with resolution of clinical seizure activity. Over the next few days, his right visual field slowly recovered to the point of no appreciable visual field deficit. Conclusions: We present an interesting case of new onset occipital lobe epilepsy with visual hallucinations and post-ictal visual field deficit, which initially presented as a stroke mimic with acute onset right homonymous hemianopsia. This is most likely secondary to the chronic left occipital lobe infarct which was likely related to his left ICA stenosis and fetal left PCA, possibly induced by hyponatremia lowering the seizure threshold. The abrupt onset and quality of ictal hallucinations is also noticeably different from visual aura commonly encountered in patients with migraine, which could have been considered given his concurrent headache. Thus, although occipital epilepsy with visual hallucinations is rare, it is important to be aware of this condition and consider it as a differential diagnosis for new onset hemianopsia with hallucinations. Funding: No funding