An Unusual Stroke Mimic: Paradoxical Gaze Preference with Elevated CSF Protein Responsive to Levetiracetam and Thiamine: A Case Report

Introduction: Stroke mimics often present similarly to acute ischemic stroke, yet have markedly different causes, management strategies, and outcomes. We report a diagnostically complex case that convincingly resembles a right middle cerebral artery (MCA) syndrome, only for subsequent findings to contradict that impression. Case Presentation: A 78-year-old man with vascular risk factors developed acute confusion, gait instability, right gaze preference, left-sided neglect, and mild left hemiparesis (NIHSS = 9). Non-contrast CT and CT angiography (CTA) revealed no hemorrhage or large-vessel occlusion. MRI on hospital days 2 and 4 showed no diffusion-restricted lesion, and CT perfusion was unremarkable. EEG demonstrated focal right-hemispheric slowing without epileptiform discharges. The patient exhibited striking improvement after initiation of levetiracetam, and later, additional cognitive gains after empiric thiamine for alcohol use. Lumbar puncture revealed elevated cerebrospinal fluid (CSF) protein (114 mg/dL) and glucose (71 mg/dL), with a normal nucleated cell count (1 CU MM). Infectious and paraneoplastic panels were negative, and cytology revealed no malignant cells. CT chest/abdomen/pelvis showed no malignancy but noted an indeterminate adrenal lesion, with a follow-up MRI abdomen characterizing the lesion as an adrenal adenoma. Conclusion: The case demonstrates diagnostic tension between clinical certainty and evolving data. Serial negative MRI and rapid improvement on levetiracetam and thiamine challenged the presumed stroke diagnosis, while elevated CSF protein raised the possibility of an autoimmune or paraneoplastic process. This overlap between seizure-related deficits, thiamine deficiency, and potential paraneoplastic encephalopathy is rarely reported and underscores the need for flexible reasoning in “stroke mimic” presentations. When a textbook focal neurological syndrome is unconfirmed by imaging, clinicians should maintain a broad differential including seizure-related and immune-mediated etiologies. Empiric antiseizure therapy and thiamine can be both diagnostic and therapeutic. CSF analysis remains indispensable in uncovering occult autoimmune or paraneoplastic pathology.