Ischemic Amnesia: Causes and Outcome.

Background And Purpose: We aimed to describe the frequency and characteristics of acute ischemic stroke and transient ischemic attacks presenting predominantly with amnesia (ischemic amnesia) and to identify clinical clues for differentiating them from transient global amnesia (TGA).

Methods: We retrospectively analyzed and described all patients presenting with diffusion-weighted imaging magnetic resonance imaging-confirmed acute ischemic stroke/transient ischemic attacks with antero- and retrograde amnesia as the main symptom over a 13.5-year period. We also compared their clinical features and stroke mechanisms with 3804 acute ischemic stroke from our ischemic stroke registry.

Results: Thirteen ischemic amnesia patients were identified, representing 0.2% of all patients with acute ischemic stroke/transient ischemic attack. In 69% of ischemic amnesia cases, amnesia was transient with a median duration of 5 hours. Ischemia was not considered in 39% of cases. Fifty-four percent of cases were clinically difficult to distinguish from TGA, including 15% who were indistinguishable from TGA. 1.2% of all presumed TGA patients at our center were later found to have ischemic amnesia. Amnesic strokes were more often cardioembolic, multiterritorial, and typically involved the posterior circulation and limbic system. Clinical clues were minor focal neurological signs, higher age, more risk factors, and stroke favoring circumstances. Although all patients were independent at 3 months, 31% had persistent memory problems.

Conclusions: Amnesia as the main symptom of acute ischemic cerebral events is rare, mostly transient, and easily mistaken for TGA. Although clinical clues are often present, the threshold for performing diffusion-weighted imaging in acute amnesia should be low.