Normal pressure hydrocephalus-an overview of pathophysiological mechanisms and diagnostic procedures.

Normal pressure hydrocephalus (NPH) is an important differential diagnosis of neurodegenerative diseases. The prevalence of dementia is increasing in line with the worldwide increase in life expectancy. NPH can be divided into idiopathic (iNPH) and secondary (sNPH) which is important in terms of clinical symptoms, future progress, and the outcome of possible treatment. The full clinical triad is not prevalent in all of the cases and the pathophysiology of iNPH remains unclear. Diagnosis is based on the evaluation of clinical symptoms (Hakim's triad) combined with an MRI assessment, evaluation of CSF dynamic parameters by different methods such as a tap test, lumbar infusion test (LIT), and external lumbar drainage (ELD). Despite the development of diagnostic techniques and strategies in management, NPH remains to be a challenge for the specialists despite more than 50 years of research. However, results of this research have brought new opportunities in the diagnosis, therapy, and quality of life as well as survival time of NPH patients with improved symptoms. The aim of this article is to present the pathophysiological hypotheses of NPH and an overview of the diagnostic techniques used for the evaluation of NPH patients.