Sudden Onset Fluent Aphasia: Stroke or Seizure?

Conventional understanding of acute onset language deficits indicates that fluent aphasias are due to perisylvian lesions in the dominant hemisphere, most often in the setting of acute stroke. Case studies and retrospective analyses, however, suggest the need to keep ictal phenomena as an alternative diagnostic possibility. The following case illustrates an epileptic mechanism of sudden onset fluent aphasia mimicking an acute stroke presentation. We utilize the case to illustrate means by which to differentiate stroke versus ictal etiology by way of electroencephalography/response to antiseizure drugs as well as perfusion/diffusion imaging. We review the literature case reports to demonstrate that isolated fluent aphasia typically localizes to left-hemispheric, temporal foci. Finally, we provide a brief synthesis of potential neurologic mechanisms by which left temporal lesions may cause fluent aphasia.