Objectives: Intraoperative MRI (iMRI) is used mainly in the adult neurosurgical population. The main indications for iMRI usage are resection control and updated intraoperative navigation capabilities. In this paper we present our experience using this technique in children. Specific advantages of iMRI for this age group are discussed. Methods and Results: We retrospectively reviewed 31 pediatric neurosurgical procedures in which a portable iMRI system was used. The indications for iMRI usage were preoperative navigation, resection control during tumor removal, shunt placements, and needle biopsy. In 7 children the use of the iMRI changed the course of the surgical procedure. Operative morbidity and mortality were not increased with use of the iMRI. Conclusions: iMRI systems have advantages for the pediatric neurosurgical population, including both real-time basic navigation and improved resection control.

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In most of the children with posthemorrhagic hydrocephalus (PHH), multidisciplinary follow-up is performed, with the focus on consequences of prematurity, cerebral palsy (CP) and hydrocephalus. A large fourth ventricle is common in these children but imaging performed in order to document ventricles and tissue damage is not oriented to exclude coexisting rare pathologies. We report a 3-year-old child with spastic CP, secondary to prematurity and PHH. A ventriculoperitoneal shunt was inserted at the age of 2 months. On follow-up imaging the child demonstrated well-drained supratentorial ventricles with a persistent large fourth ventricle. Because of a neurological change in spasticity and new-onset torticollis, a repeat MRI was performed, suggesting a cystic, nonenhancing lesion of the fourth ventricle. The surgical exploration revealed a large dermoid of the fourth ventricle. We analyze the differential diagnosis of a clinically significant large fourth ventricle in a shunted child with PHH and CP. This includes conditions without pressure in the posterior fossa such as tissue loss due to cerebellar atrophy, or pathologies causing a true increase in pressure of the fourth ventricle (isolated fourth ventricle, cystic lesions and neoplasms of the fourth ventricle). Neurologically compromised children pose additional challenges in reaching a definitive diagnosis and hence require a careful regular assessment of their clinical status with additional well-timed imaging with appropriate protocols to allow appropriate treatment when indicated and to avoid morbidity due to delayed diagnosis. We present a rare coexistence of a dermoid tumor within the fourth ventricle in a CP child with PHH and express the dilemmas associated with its management.