Perinatal Arterial Ischemic Stroke in Monochorionic Twins: A Retrospective Observational Single-Center Cohort Study.

Background: Monochorionic twins, characterized by placental sharing and vascular anastomoses, carry a high risk of brain injury, including perinatal arterial ischemic stroke (PAIS). However, the pathophysiology and timing-related risk factors of PAIS remain unclear.

Methods: Retrospective cohort of all monochorionic twins with neuroimaging-confirmed PAIS born from 2005 to 2024 and evaluated at a Dutch national referral center. PAIS timing was classified as presumed antenatal, direct perinatal, or postnatal onset. Risk factors and neurodevelopmental outcomes, including cerebral palsy and cognitive impairment, were assessed.

Results: Eighteen cases of PAIS were identified among 1183 twin pairs born <35 weeks' gestation (1.5%). Mean gestational age at birth was 29.4 weeks (95% CI, 28.3-31.5), and mean birth weight was 1258 (95% CI, 1062-1453) grams. Pregnancy complications were identified in 89%: twin-to-twin transfusion syndrome (n=13), twin anemia polycythemia sequence (n=1), and single fetal demise (n=2). In twin-to-twin transfusion syndrome/twin anemia polycythemia sequence, PAIS was diagnosed in the recipient twin in 12 of 14 (86%) cases. Regarding stroke onset, 6 occurred antenatally, 7 direct perinatally, and 5 occurred in the postnatal period. Stroke patterns involved the middle cerebral artery (anterior, posterior, or main branch) in 10 of 18 (56%); anterior cerebral artery in 1 of 18 (6%), perforator arteries arising from middle cerebral artery, or anterior cerebral artery in 7 of 18 (38%); and posterior cerebral artery in 1 of 18 (6%). Among 7 infants with main branch middle cerebral artery stroke, 2 died in the fetal or neonatal period, and all 4 with a follow-up assessment developed unilateral spastic cerebral palsy. Among 6 infants with perforator stroke and follow-up, 2 had hemiparesis at 24 months corrected age.

Conclusions: PAIS in monochorionic twins predominantly affects the recipient twin and can occur in the antenatal, direct perinatal, or postnatal period, with variable stroke patterns and outcomes. We recommend dedicated fetal and postnatal neuroimaging in complicated preterm-born monochorionic twins to detect PAIS and allow early rehabilitation therapy.