BACKGROUND: The ventriculoperitoneal shunt remains, despite recent advances, the mainstay of treatment for hydrocephalus. Although it is used as a routine practice, and besides its recorded and documented safety, it often malfunctions due to a variety of reasons, most commonly referred to as obstruction, breakage, migration and infection. A usual finding of those children suspected to magnetic resonance imaging is the detection of a rim of hyperintensity in the periventricular white matter (halo).

CASE REPORT: We describe the case of a 7-year-old male patient, treated 4 years ago for an infratentorial ependymoma, who developed hydrocephalus at the time of clinical presentation. During his previous follow-up, he was disease-free but developed clinically evident acute shunt malfunction, accompanied by imaging findings on magnetic resonance imaging (MRI) consisting of interstitial edema surrounding the supratentorial ventricular system, with additional involvement of the floor of the fourth ventricle. This peculiar and novel imaging finding subsided after successful management of hydrocephalus.

CONCLUSIONS: At present, contemporary computed tomography and MRI modalities constitute the gold standard in order to assess and follow-up patients with established hydrocephalus. Periventricular interstitial edema is a well-established imaging feature of acute hydrocephalus and, in cases of ventriculoperitoneal shunt, of shunt malfunction. Besides that, a newly described, to the best of our knowledge, imaging feature could be the distinction of that signal alteration at the floor of the fourth ventricle. It seems to have prognostic significance regarding the adequacy of management of hydrocephalus, as it disappeared after its successful treatment.

Keywords: Brain Edema, ependymoma, Fourth Ventricle, Hydrocephalus, Child, Diagnosis, Differential, Equipment Failure, Lethargy, Magnetic Resonance Imaging, Tomography, X-Ray Computed, Ventriculoperitoneal Shunt, Vomiting