Clinical Reasoning: A 59-Year-Old Man With Acute-Onset Encephalopathy and Aphasia.

Assessing patients with acute encephalopathy presents significant challenges because of the wide range of underlying causes. This complexity is further intensified when seizures are involved, making the selection of effective management even more critical. In this case, a 59-year-old man was evaluated at the emergency department for acute-onset confusion and aphasia, which later on was complicated by seizures. Stroke was initially ruled out, and valproate therapy was instituted. EEG showed slow background activity, CSF was normal, and brain MRI showed bilateral cortical T2 hyperintensities with diffusion restriction involving the insula and cingulate gyrus. The neuroimaging findings narrowed the differential and pointed to the final diagnosis. In this case, we walk through the differential diagnosis of acute encephalopathy, highlighting the importance of a systematic diagnostic approach and considering the wide variety of etiologies, with an emphasis on those with specific treatments. The presence of key clinical and radiologic data guides the clinician to reach the final diagnosis.