Metabolic insult causing re-expression of old stroke (MICROS) presenting as stroke mimics

BACKGROUND: Metabolic insult causing re-expression of old stroke (MICROS), one of the stroke mimics, is characterized by reappearance of impairment of past stroke and can be mistaken for a stroke recurrence. The aim of the present study was to identify the clinical characteristics of MICROS in emergency stroke care, and to investigate predictive factors for distinguishing MICROS from stroke recurrences. METHODS: In our Stroke Center, 519 consecutive patients admitted with suspected stroke in June 2016 to December 2017. MICROS was defined as an acute deterioration of neurological deficits of the previous stroke despite no evidence for stroke recurrences. Among the 70 patients with a past history of stroke, 14 were MICROS, 5 were transient ischemic attack, 15 were other stroke mimics, and 36 were stroke recurrences, respectively. We evaluated the clinical characteristics of MICROS and compared MICROS with stroke recurrences. RESULTS: The causes of MICROS were infectious disease (including influenza and pneumonia) in 4, transient somnolence after syncope in 4, hypo/hyperglycemia in 2, medication overdoses in 1, and anxiety in 3. Eight of the 14 MICROS patients were admitted within 4 hours after the symptom onset. In MICROS patients, fever (>37 degrees C) was observed more frequently than those with stroke recurrences though the difference was not statistically significant. CONCLUSION: MICROS might be associated with fever, syncope, or serum glucose abnormality. MICROS patients sometimes visit the hospital emergency room within 4 hours, thus, distinction between MICROS and true stroke recurrences is important.