Pediatric cerebral arteriovenous malformation diagnosed 11 years after neonatal thalamic hemorrhage: illustrative case.

backgroundArteriovenous malformations (AVMs) are known as congenital vascular disorders. However, ruptured AVMs in neonates are extremely rare. A hypothesis suggests that micro-AVM or de novo AVMs enlarge during childhood, eventually acquiring the pathological features of adult AVMs. The authors describe a case of a pediatric AVM diagnosed 11 years after neonatal intracerebral hemorrhage. OBSERVATIONS: A 16-day-old neonate presented with sudden vomiting and convulsions. CT revealed a left thalamic hemorrhage extending into the left lateral ventricle. MRI showed no bleeding sources, including AVMs. By the age of 3 years, the patient developed West syndrome and was administered multiple antiseizure medication. At 5 years of age, the patient experienced convulsive status epilepticus, primarily on the right side of his body. A focal impaired awareness seizure due to the previous hemorrhage was considered. The patient remained seizure free until 11 years of age, when generalized seizures developed. MRI revealed a left thalamic AVM classified as Spetzler-Martin grade IV. The patient has been scheduled to undergo stereotactic radiosurgery. LESSONS: Pediatric AVMs can undergo dynamic changes, including enlargement and de novo formation, acquiring the pathological features of adult AVMs. AVMs should be considered as a potential source of neonatal intracranial hemorrhage, necessitating long-term follow-up. https://thejns.org/doi/10.3171/CASE25124.