Hydrocephalus can occur in association with other pathologies of the cerebrospinal fluid (CSF) system, e.g. cerebellar and posterior fossa anomalies, arachnoid cysts, Chiari malformation, and spina bifida. This chapter presents case studies to demonstrate clinical scenarios in patients with congenital pathologies of the CSF system with and without hydrocephalus suggestive of disturbed CSF dynamics causing the patients' symptoms or problems. Neurocognitive test batteries of various origins have been used to support outcome assessment in more systematic studies. Magnetic resonance imaging (MRI) has evolved in the past 5 to 10 years with improved dynamic imaging enabling assessment of CSF pulsations in relation to arterial pulsation and visualization of CSF pulsation in critical areas of interest. The better anatomical detail of membranes and webs in association with physiological CSF spaces will eventually change and improve the reasoning behind, approaches to, and techniques of surgical treatment.