Biomarkers in chronic adult hydrocephalus

Chronic communicating hydrocephalus in adults is now recognised as one of the causes for reversible dementia, with an occurrence of 1–10% among patients with a diagnosis of dementia [1,2]. Data from Sweden suggest an incidence of 3.36 surgical operations for chronic hydrocephalus per 100,000 inhabitants per year [3,4]. However, it is thought that normal pressure hydrocephalus is significantly underestimated because many cases go unreported and untreated [5]. The term chronic hydrocephalus of adult-onset (CAH) encompasses a variety of conditions that include normal pressure hydrocephalus (NPH) of the idiopathic or secondary variety (depending on whether there is a known cause such as trauma, subarachnoid haemorrhage, meningitis, and tumour), communicating hydrocephalus due to a disturbance of CSF dynamics, non-tumoural aqueductal stenosis, and compensated arrested hydrocephalus. We are still in the process of understanding the pathophysiological mechanisms underlying hydrocephalus in adults, even though 40 years have passed since Hakim and Adams first coined the term "Normal Pressure Hydrocephalus" [6].Biological markers have traditionally been used in clinical practice in order to support a diagnosis, or monitor the progression of a disease by measuring levels longitudinally. The definition as given by the Biomarkers Definition Working Group was "A characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacological responses to a therapeutic intervention."[7]. Biomarkers can assist us in this task as they provide an insight to the changes of the cerebral milieu associated with the condition. In order for their use to be established in routine clinical practice, they should demonstrate high sensitivity and specificity. Biomarkers have long been used in the neurosciences for these exact reasons [8-13]. Some well established biomarkers in the field of neurodegenerative disorders and dementias