Transcranial Doppler Microemboli Monitoring for Stroke Risk Stratification in Blunt Cerebrovascular Injury.

OBJECTIVES: To assess whether microemboli burden, assessed noninvasively by bedside transcranial Doppler ultrasonography, correlates with risk of subsequent stroke greater than 24 hours after hospital arrival among patients with blunt cerebrovascular injury. The greater than 24-hour time frame provides a window for transcranial Doppler examinations and therapeutic interventions to prevent stroke. DESIGN: Retrospective cohort study. SETTING: Level I trauma center. PATIENTS: One thousand one hundred forty-six blunt cerebrovascular injury patients over 10 years. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We identified 1,146 blunt cerebrovascular injury patients; 54 (4.7%) experienced stroke detected greater than 24 hours after arrival. Among those with isolated internal carotid artery injuries, five of nine with delayed stroke had positive transcranial Dopplers (at least one microembolus detected with transcranial Dopplers) before stroke, compared with 46 of 248 without (risk ratio, 5.05; 95% CI, 1.41-18.13). Stroke risk increased with the number of microemboli (adjusted risk ratio, 1.03/microembolus/hr; 95% CI, 1.01-1.05) and with persistently positive transcranial Dopplers over multiple days (risk ratio, 16.0; 95% CI, 2.00-127.93). Among patients who sustained an internal carotid artery injury with or without additional vessel injuries, positive transcranial Dopplers predicted stroke after adjusting for ipsilateral and contralateral internal carotid artery injury grade (adjusted risk ratio, 2.91; 95% CI, 1.42-5.97). No patients with isolated vertebral artery injuries had positive transcranial Dopplers before stroke, and positive transcranial Dopplers were not associated with delayed stroke among patients who sustained a vertebral artery injury with or without additional vessel injuries (risk ratio, 0.90; 95% CI, 0.21-3.83). CONCLUSIONS: Microemboli burden is associated with higher risk of stroke due to internal carotid artery injuries, but monitoring was not useful for vertebral artery injuries.