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Transcranial doppler monitoring of both middle and posterior cerebral arteries can increase microembolic signals detection: a pilot study
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Abstract(s)
Introdução: Os acidentes vasculares cerebrais da circulação posterior representam 15–25% dos eventos isquémicos cerebrais e, embora menos frequentes do que os da circulação anterior, têm relevância clínica devido às dificuldades diagnósticas e ao risco limitação funcional e recorrência de eventos isquémicos. Os sinais microembólicos (MES) detetados por Doppler transcraniano (TCD) associam-se fortemente a aterosclerose de grandes vasos, mas podem ocorrer em várias etiologias. A monitorização de rotina de MES centra-se na avaliação das artérias cerebrais médias (ACM), negligenciando frequentemente as artérias cerebrais posteriores (ACP). O nosso objetivo foi avaliar se a inclusão da monitorização bilateral das ACP ao protocolo de rotina das ACM aumenta o número de MES detetados em doentes com AVC isquémico agudo, bem como analisar a sua relação com a etiologia do mesmo, bem como com a ecogenicicidade das estenoses ateroscleróticas carotídeas, com o grau de estenose arterial a montante, prognóstico funcional dos doentes aos 90 dias e a recorrência de eventos isquémicos até um ano.
Métodos: Estudo prospetivo, realizado num único centro, tendo sido incluídos doentes com AVC isquémico agudo de forma consecutiva e com qualquer etiologia, admitidos nas primeiras 48 horas após o início dos sintomas. Todos os doentes realizaram monitorização TCD de 30 minutos das artérias cerebrais média (ACM) e posterior (ACP) para deteção de MES. Os MES foram analisados quanto à sua presença e intensidade na análise espetral. Avaliou-se o outcome funcional dos doentes aos 90 dias (escala de Rankin modificada) e a recorrência de AVC, acidente isquémico transitório (AIT) ou embolismo sistémico até 360 dias. Os outcome foram comparados entre os grupos com e sem MES, com análise adicional por etiologia do AVC e presença de estenose arterial no território a montante da artéria monitorizada. O estudo encontra-se registado em ClinicalTrials.gov (ID: 06735274).
Resultados: Entre 260 doentes, foram detetados MES em 17 (6,5%), com uma mediana de 3 eventos/hora (IQR 2–15). A deteção foi unilateral em 71% e ipsilateral ao hemisfério afetado em 76%. A monitorização da ACP permitiu identificar 4 casos adicionais positivos para MES (23,5% do total de positivos). Os doentes com MES apresentaram valores mais elevados de NIHSS (p = 0,047). A presença de MES na ACM associou-se a menor probabilidade de independência funcional aos 90 dias (OR ajustado 0,107, IC 95%: 0,022–0,526; p = 0,006). A taxa de recorrência foi de 8,1%, sendo mais elevada nos subgrupos com MES. A presença de MES associou-se a eventos isquémicos (log-rank p = 0,04; HR ajustado para ACP MES-positiva: 15,6, IC 95%: 1,5–157,8; p = 0,02). O número de MES foi mais elevado nos doentes com aterosclerose de grandes vasos (p < 0,01), enquanto a intensidade dos MES foi significativamente superior nos AVC cardioembólicos (p < 0,01). A presença e número de MES aumentaram com a gravidade da estenose, mas a intensidade dos mesmos foi inferior nos doentes com estenose carotídea ou vertebral a montante (p < 0,05).
Conclusão: Os nossos resultados demonstram que as características dos MES variam consoante a etiologia do AVC: a aterosclerose de grandes vasos associa-se a maior número de MES mas menor intensidade, enquanto os AVC cardioembólicos apresentam menos MES, mas de maior intensidade. A presença de MES associou-se a maior risco de recorrência quando detetada na ACP e a pior prognóstico funcional quando detetada na ACM. A monitorização da ACP permitiu identificar casos adicionais de MES, reforçando o valor clínico de avaliar ambos os territórios na fase aguda do AVC.
Background: Posterior circulation strokes account for 15–25% of ischemic events and, although less frequent than anterior circulation strokes, they are clinically relevant due to diagnostic challenges and the persistent risk of disability and recurrence. Microembolic signals (MES) detected by transcranial Doppler (TCD) are strongly associated with large artery atherosclerosis but may occur across several etiologies. Routine MES monitoring focuses on the middle cerebral arteries (MCA), often neglecting the posterior cerebral arteries (PCA). Our objective was to evaluate whether the inclusion of bilateral PCA monitoring in addition to routine MCA monitoring increases the detection of MES in patients with acute ischemic stroke, as well as to analyze their relationship with stroke etiology, carotid plaque echogenicity, upstream arterial stenosis severity, functional outcome at 90 days, and recurrence of ischemic events up to one year. Methods: This was a prospective single-center study of consecutive patients with acute ischemic stroke of any etiology, admitted within 48 hours of symptom onset. All patients underwent 30-minute TCD MES monitoring of both middle cerebral artery (MCA) and PCA arteries. MES were analyzed for both presence and intensity from the background signal. We evaluated functional outcome at 90 days using the modified Rankin Scale, and assessed for recurrence of stroke, TIA, or systemic embolism within 360 days. Outcomes were compared between MES-positive and MES-negative groups, with subgroup analysis based on stroke etiology and presence of arterial stenosis on the upstream territory. This study is registered at ClinicalTrials.gov (ID: 06735274). Results: Among 260 patients, MES were detected in 17 (6.5%), with a median rate of 3 counts/hour (IQR 2–15). Detection was unilateral in 71% and ipsilateral to the stroke side in 76%. PCA monitoring identified 4 additional MES-positive cases (23.5% of all positives). MES-positive patients had higher NIHSS scores (p = 0.047). MES in the MCA was associated with reduced odds of functional independence at 90 days (adjusted OR 0.107, 95% CI 0.022–0.526, p = 0.006). Recurrence occurred in 8.1% overall, with higher rates in MES-positive subgroups. MES presence predicted ischemic events (log-rank p = 0.04; adjusted HR for PCA MES-positive: 15.6, 95% CI 1.5–157.8, p = 0.02). MES burden was highest in large artery atherosclerosis (p < 0.01), while MES intensity was significantly greater in cardioembolic strokes (p < 0.01). MES presence and burden increased with stenosis severity, but MES intensity was lower in patients with upstream carotid and vertebral stenosis (p < 0.05). Conclusion: Our findings show that MES characteristics differ by stroke etiology, with large artery atherosclerosis associated with higher burden and lower intensity, and cardioembolism with fewer but more intense signals; MES presence correlated with recurrence when detected in the PCA and poorer outcomes when detected in the MCA, while PCA monitoring revealed additional cases and showed embolic patterns comparable to those in the MCA, highlighting the value of assessing both circulations.
Background: Posterior circulation strokes account for 15–25% of ischemic events and, although less frequent than anterior circulation strokes, they are clinically relevant due to diagnostic challenges and the persistent risk of disability and recurrence. Microembolic signals (MES) detected by transcranial Doppler (TCD) are strongly associated with large artery atherosclerosis but may occur across several etiologies. Routine MES monitoring focuses on the middle cerebral arteries (MCA), often neglecting the posterior cerebral arteries (PCA). Our objective was to evaluate whether the inclusion of bilateral PCA monitoring in addition to routine MCA monitoring increases the detection of MES in patients with acute ischemic stroke, as well as to analyze their relationship with stroke etiology, carotid plaque echogenicity, upstream arterial stenosis severity, functional outcome at 90 days, and recurrence of ischemic events up to one year. Methods: This was a prospective single-center study of consecutive patients with acute ischemic stroke of any etiology, admitted within 48 hours of symptom onset. All patients underwent 30-minute TCD MES monitoring of both middle cerebral artery (MCA) and PCA arteries. MES were analyzed for both presence and intensity from the background signal. We evaluated functional outcome at 90 days using the modified Rankin Scale, and assessed for recurrence of stroke, TIA, or systemic embolism within 360 days. Outcomes were compared between MES-positive and MES-negative groups, with subgroup analysis based on stroke etiology and presence of arterial stenosis on the upstream territory. This study is registered at ClinicalTrials.gov (ID: 06735274). Results: Among 260 patients, MES were detected in 17 (6.5%), with a median rate of 3 counts/hour (IQR 2–15). Detection was unilateral in 71% and ipsilateral to the stroke side in 76%. PCA monitoring identified 4 additional MES-positive cases (23.5% of all positives). MES-positive patients had higher NIHSS scores (p = 0.047). MES in the MCA was associated with reduced odds of functional independence at 90 days (adjusted OR 0.107, 95% CI 0.022–0.526, p = 0.006). Recurrence occurred in 8.1% overall, with higher rates in MES-positive subgroups. MES presence predicted ischemic events (log-rank p = 0.04; adjusted HR for PCA MES-positive: 15.6, 95% CI 1.5–157.8, p = 0.02). MES burden was highest in large artery atherosclerosis (p < 0.01), while MES intensity was significantly greater in cardioembolic strokes (p < 0.01). MES presence and burden increased with stenosis severity, but MES intensity was lower in patients with upstream carotid and vertebral stenosis (p < 0.05). Conclusion: Our findings show that MES characteristics differ by stroke etiology, with large artery atherosclerosis associated with higher burden and lower intensity, and cardioembolism with fewer but more intense signals; MES presence correlated with recurrence when detected in the PCA and poorer outcomes when detected in the MCA, while PCA monitoring revealed additional cases and showed embolic patterns comparable to those in the MCA, highlighting the value of assessing both circulations.
Description
This study is registered at ClinicalTrials.gov (ID: 06735274).
Keywords
sinais microembólicos acidente vascular cerebral ultrassonografia Doppler transcraniano Microembolism stroke ultrasound transcranial Doppler