CASE REPORT De novo intracranial aneurysm formation following endovascular treatment of giant aneurysm in an infant: case report Bartley Mitchell & Debadutta Dash & William Humphries & Michel Mawad Received: 18 October 2011 /Accepted: 21 November 2011 /Published online: 14 December 2011 # Springer-Verlag 2011 Introduction Pediatric intracranial aneurysms account for less than 5% of the total incidence of intracranial aneurysms in the general population, and they are particularly infrequent in patients younger than 5 years of age. In children less than 1 year of age, intracranial aneurysms are encountered even less fre- quently, and the presenting symptoms, arterial location, pathology, and prognosis can be markedly different from adult intracranial aneurysms. Due to their relative rarity, determining an accurate prevalence is mired with difficulty, with ranges from 0.5% to 4.6% [1–3]. For example, intra- cranial hemorrhage is the initial presenting finding in greater than 70% of pediatric intracranial aneurysms [4, 5], with hemorrhage being more prevalent in younger ages. Addi- tionally, in the pediatric population, it has been noted that the incidence of aneurysms on the middle cerebral artery (MCA) is three times more common than other intracranial vascular location [4]. Giant aneurysms (>2.5 cm) are found more commonly in the pediatric population than in adults, although no clear underlying pathology has been consistently demonstrated in these instances. In many cases of aneurysms in very young children (i.e., less than 1–2 years of age), the underlying pathology can be linked to trauma [6], structural abnormalities [7], infection, con- nective tissue disorders, or other genetic abnormalities, though there are ongoing investigations into the underlying genetic pathology in cerebral aneurysms. To date, at least four genetic loci have been associated with intracranial aneurysm formation, although it is estimated that these account for only a small fraction the genetic influence that may be involved in aneurysm formation [8, 9]. We describe the unusual case of an infant who had a strong family history of intracranial aneurysms who pre- sented with two temporally distinct and spatially separated intracranial aneurysms. This case represents a unique case in which two de novo aneurysms formed in a child less than 1 year of age and were successfully treated with endovas- cular coiling, with evidence of complete aneurysm oblitera- tion at the 1 year follow-up period. No genetic locus could be isolated in this case, despite having such a strong imme- diate familial history of intracranial aneurysms. This case highlights the gap in knowledge of potential genetic markers for the de novo formation of intracranial aneurysms as well as the importance of close follow-up. Case presentation A 9-month-old boy experiencing fever for 5 days without an identified infectious source, was admitted with non-bilious, non-bloody vomiting, and a complex partial seizure starting from the right face and progressing to the right arm and body. Initial computed tomography of the head showed a left temporal intracranial hemorrhage with a distal left MCA aneurysm (Fig. 1). The patient did not present with any B. Mitchell (*) : W. Humphries Department of Neurosurgery, Baylor College of Medicine, 1709 Dryden, Suite 750, Houston, TX 77030, USA e-mail: bartley.mitchell@bcm.edu D. Dash Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA M. Mawad Department of Radiology, Baylor College of Medicine, One Baylor Plaza, MS 360, Houston, TX 77030, USA Childs Nerv Syst (2012) 28:645–648 DOI 10.1007/s00381-011-1647-y