Occipital Sinus Pericranii Superseding Both Jugular Veins: Description of Two Rare Pediatric Cases BACKGROUND AND IMPORTANCE: The extracranial venous drainage of the brain is pro- vided mainly by the jugular veins with the variable participation of extrajugular pathways. CLINICAL PRESENTATION: Two cases of occipital sinus pericranii (SP) were observed. A 6-year-old girl presented with a progressively enlarging occipital lump; she was otherwise asymptomatic. An 8-year-old boy presented with mild nuchal headache. In the former case, neuroimaging examinations confirmed the diagnosis of SP; in the latter, SP was noticed on magnetic resonance imaging because it was neglected at physical examination. In both subjects, the radiological examination also showed bilateral occlusion of the jugular veins with ventricular dilation and herniation of cerebellar tonsils into the foramen magnum. CONCLUSION: Exceptionally, SP was noticed to represent the main venous drainage of the underlying brain, thereby compensating for the intracranial hypertension due to venous engorgement. Preservation of SP was advised, and any surgical or endovascular treatment was contraindicated. KEY WORDS: Brain venous drainage, Jugular vein occlusion, Posterior cranial fossa, Sinus pericranii, Vascular anomaly, Venous varix Neurosurgery 72:E1054–E1058, 2013 DOI: 10.1227/NEU.0b013e31828baab4 www.neurosurgery-online.com T he jugular veins are usually the main drainage of the intracranial compartment in physio- logical conditions. 1 Extrajugular pathways assume a prominent function in the case of occlusion, especially when bilateral, of these veins, the vertebral veins plexus becoming the main alternative for the cerebral blood outflow. 2 In this report, we describe 2 rare pediatric cases showing bilateral occlusion of the jugular veins in which an occipital sinus pericranii (SP) provided the venous drainage of the brain and discuss the peculiar features of this exceptional vascular pattern with the aim to contribute to a better understanding of its pathogenesis, taking into account congenital and acquired factors. CLINICAL PRESENTATION Case 1 This 8-year-old boy had zoster ophthalmicus at the age of 4 years, complicated by bilateral amaurosis and left transverse sinus thrombosis. At that time, a magnetic resonance imaging (MRI) study of the brain was performed; neither hydrocephalus nor Chiari type I malformation were noticed. Three years later, he complained with a severe nuchal headache. A new brain MRI demonstrated Chiari type I malformation and hydrocephalus. A computed tomography (CT) scan revealed the atresia of the right jugular foramen and the synostosis of the right petro- occipital suture with a compensating growth of the petrous bone, which appeared more pneu- matized than the contralateral one. A digital subtraction angiography showed the lack of opacification of the right internal jugular vein, with the right transverse sinus being drained by a hypertrophic occipitomastoid emissary vein into a large subcutaneous venous varix. A condi- tion of intracranial venous engorgement, with hypertrophy of extrajugular pathways, namely vertebral and perimesencephalic veins, as well as cavernous sinuses and facial veins, was also present (Figure 1). Physical examination confirmed the presence of a soft, painless scalp mass in the occipital region that was previously unnoticed. Paolo Frassanito, MD* Luca Massimi, MD* Gianpiero Tamburrini, MD* Massimo Caldarelli, MD* Alessandro Pedicelli, MD‡ Concezio Di Rocco, MD* *Pediatric Neurosurgery, Catholic Univer- sity Medical School, Rome, Italy ‡Radiol- ogy, Catholic University Medical School, Rome, Italy Correspondence: Paolo Frassanito, MD, Pediatric Neurosurgery, Catholic University Medical School, Largo Agostino Gemelli, 8, 00168 Rome, Italy. E-mail: paolo.frassanito@gmail.com Received, November 6, 2012. Accepted, January 22, 2013. Published Online, February 12, 2013. Copyright ª 2013 by the Congress of Neurological Surgeons ABBREVIATION: SP, sinus pericranii. CASE REPORT TOPIC CASE REPORT E1054 | VOLUME 72 | NUMBER 6 | JUNE 2013 www.neurosurgery-online.com Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited.