Idiopathic normal pressure hydrocephalus--neurosurgical management of dementia!

IdIopathIc normal pressure hydrocepha-lus (iNPH) is a condition of disturbed cerebrospinal fluid (CSF) dynamics, of unknown cause, giving rise to ventricular enlargement with a normal intracranial pressure. 1 The phenomenology of iNPH is characterised by a slowly progressive impairment of gait and balance, cognitive deterioration, and urinary incontinence. 2 Treatment of iNPH is surgical, most often ventriculo-peritoneal shunts. 3 Selection of patients for surgery is generally based on symptoms and signs, CT or MRI verified ventriculomegaly and most often the results of different CSF dynamic supplementary tests. Patients at risk for developing iNPH is the aging population. 4 As the population is aging due to a higher longevity in most of the developed but also developing countries, the prevalence of iNPH is very likely to increase. Also, elderly patients are looking for an improved quality of life, and are no longer willing to accept disabilities of ageing. INPH is associated with many co-morbidities as a result of age-related conditions and other at-risk diseases, such as cerebrovascular disease and Alzheimer´s disease. A high rate of Alzheimer's disease (AD) pathology on cortical biopsy 5 as well as subcortical white matter disease (SAE) on magnetic resonance imaging 6 in patients with shunt-responsive iNPH suggests that iNPH, AD and SAE are interrelated and may share common pathophysiologcial mechanisms, e.g. an age-related stagnation of cerebrospinal fluid circulation. 7 This was the background for a prospective clinical study carried out in Europe from 2004 to 2009, involving 12 study centers. In the European idiopathic NPH trial both " typical " and " questionable " NPH (the latter presenting with co-morbidity) candidates were included and shunted solely based on clinical and radiological grounds. CSF dynamics (TAP-TEST, Rout and compliance measurements) were performed in every patient, however, patients were shunted irrespective of the CSF dynamic test results , and three and 12 months outcome of shunting was measured using pre-and postoperative measurement of motor and cognitive test batteries. Among the study aims, one important question was whether the outcome of shunted patients with NPH is affected by the presence of dementia. The important cutoff separating " typical " from " questionable " iNPH patients was the MMSE score. Patients classified as " typical " had to show a mild to moderate cognitive impairment (MMSE scores greater than or equal to 21) with onset together with or after the gait disturbance, and including impaired wakefulness, slowness, and memory deficits, …