Problem Solving Disorders of CSF

Spontaneous intracranial hypotension (SIH) is a debilitating medical condition, which is perpetuated by the continuous loss of cerebrospinal fluid (CSF) at the level of the spine, and is the top differential diagnosis for patients presenting with orthostatic headache. Neuroimaging plays a crucial role in the diagnostic work-up and monitoring SIH, as it provides objective data in the face of various clinical symptoms and very often a normal opening pressure on lumbar puncture. Brain MRI frequently demonstrates typical signs of CSF depletion and includes homogenous dural enhancement, venous distention, subdural collections, and brain sagging. Three types of CSF leaks may be distinguished: (1) ventral dural leaks due to microspurs, (2) leaking spinal nerve root cysts, (3) or direct CSF venous fistula. The quest for the leak may be the fabled search for the needle in the haystack, scrutinizing the entire spine for a dural breach often the size of pin. The main role of spine imaging is the correct classification and precise localization of CSF leaks. Precise localization of the CSF leak site is crucial to successful treatment, which is generally a targeted percutaneous epidural patch or surgical closure when conservative measures fail to provide long-term relief. Modern imaging techniques play an essential role for understanding of the anatomy of the cerebrospinal fluid (CSF) spaces and ventricular system, as well as the hydrodynamics of CSF flow, and consequently in the assessment of the different types of hydrocephalus. Obstructive (non-communicating) hydrocephalus is a complex disorder resulting from an obstruction/blockage of the CSF circulation along one or more of the narrow apertures connecting the ventricles, being the most common type of hydrocephalus in children and young adults. On the other hand, communicating hydrocephalus is defined as a cerebrospinal fluid flow circulation abnormality outside the ventricular system that produces an increase in the ventricular size. Most cases are secondary to obstruction of CSF flow between the basal cisterns and brain convexity and include common conditions such as subarachnoid hemorrhage and meningitis (infectious and neoplastic). In a subset of communicating hydrocephalus, no CSF obstruction can be demonstrated as occurs in normal pressure hydrocephalus (NPH), a complex entity with poorly understood cerebrospinal fluid dynamics. Neuroradiology plays an essential role in the diagnosis of hydrocephalus, and in distinguishing this condition from other causes of ventriculomegaly.