Transcranial Doppler Ultrasound Evidence of Active Cerebral Embolization in COVID-19

Abstract

Objective: To report six consecutive patients with confirmed coronavirus disease-2019 (COVID-19) who underwent Transcranial Doppler (TCD) ultrasonography evaluation for cerebral microemboli in the setting of suspected or confirmed acute ischemic stroke.

Methods: Patient data were obtained from medical records from Northwestern Memorial Hospital, Chicago, IL between May and June 2020. All patients with confirmed COVID-19 who underwent clinical TCD ultrasonography for microemboli detection were included.

Results: A total of eight TCD studies were performed in six patients with COVID-19 (4 men and 2 women, median age 65±5), four with confirmed ischemic stroke and two with refractory encephalopathy. Microemboli were detected in three male patients, two patients had suffered a confirmed ischemic stroke and one who developed prolonged encephalopathy. Microemboli of varying intensity were identified in multiple vascular territories in two patients, and microemboli persisted despite therapeutic anticoagulation in a third patient. Of the three patients without evidence of microemboli on TCD ultrasonography, two patients had suffered a confirmed ischemic stroke, while one remained with refractory encephalopathy.

Conclusions: TCD ultrasonography for microemboli detection identified three patients with confirmed COVID-19 with evidence of cerebral arterial microemboli, including one who was therapeutically anticoagulated. TCD ultrasonography provides a non-invasive method for evaluating cerebral microemboli in patients with COVID-19 and may be useful in assessing response to treatment in cases with suspected or confirmed disorders of hypercoagulability. Further studies investigating the prevalence of cerebral microemboli and associated risk factors are needed to characterize their pathogenic mechanism and guide therapeutic interventions in hospitalized COVID-19 patients.

Keywords: COVID-19; Cerebrovascular disease/Stroke; Embolism; Ultrasound; Viral infections.

Fig. 1

Neuroimaging results of patients with cerebral microemboli detected. A.) Case 1. CT brain demonstrating right middle cerebral artery territory hypodensity at the time of acute stroke identification. B.) Case 1. Conventional cerebral angiogram demonstrating the inability to recanalize the right middle cerebral artery occlusion despite multiple stent retriever passes with concurrent eptifibatide infusion. C.) Case 1. TCD doppler waveform demonstrating multiple microembolic signals (17-28 decibels) in the right middle cerebral and anterior cerebral arteries. D.) Case 2. TCD doppler waveform demonstrating a 14-decibel right middle cerebral artery microembolus as well as one of the numerous small 9–10 decibel microemboli that occurred throughout the recording and subsequently resolved after initiation of heparin infusion. E.) Case 2. Diffusion weighted MRI brain demonstrating punctate subacute infarcts in the right hemispheric white matter. F.) Case 2. Corresponding apparent diffusion coefficient map MRI brain confirming punctate subacute infarcts in the right hemispheric white matter. G.) Case 3. CT brain acquired during the patient's first hospitalization for COVID-19 demonstrating the patient's known chronic infarct in the left posterior cerebral artery territory. H.) Case 3. Diffusion weighted MRI brain demonstrating acute infarcts in the left occipital lobe, pons and cerebellum. I.) Case 3. TCD doppler waveform demonstrating 24-decibel right posterior cerebral artery microembolus.