Cerebrospinal fluid dynamics

Hydrocephalus is far more complicated than a simple disorder of CSF circulation. Historically, it has been diagnosed using clinical and psychomotor assessment plus brain imaging. The role of physiological measurement to aid diagnosis becomes more appreciated in current clinical practice. This has been reflected by recently formulated guidelines for the management of normal pressure hydrocephalus. Clinical measurement in hydrocephalus is mainly related to intracranial pressure (ICP) and cerebral blood flow. This review lists and discusses most common forms of the methods: CSF infusion study, overnight ICP monitoring, assessment of slow ICP waves, testing pressure reactivity, cerebral autoregulation, CO2 reactivity and PET-CBF studies combined with MRI co-registration. The basics of CSF dynamics modelling are presented and the principles of the assessment of functioning of the implanted hydrocephalus shunts are also discussed. The descriptions of multiple forms of measurement along with clinical illustrations are mainly based on in-house experience of a multidisciplinary group of scientists and clinicians from Cambridge, UK.