1. The under drainage problems of Low-Pressure Hydrocephalus Patients: A clinical study Vaner Köksal /Recep Tayyip Erdoğan University Introduction; font size 9 - 12 Normal pressure hydrocephalus (NPH) is one of the few causes of reversible dementia. NPH occurswith varying combinations or degrees of each component of the classical clinical triad, which is first described by Hakim and Adams in 1965, consisting of gait disturbance, urinary incontinence, and dementia. It is also described as the idiopathic adult hydrocephalus syndrome in recent years. (The mean intracranial pressure may be normal, mildly elevated or low.) In this study, the low-pressure hydrocephalus cases with shunt systems working improperly or problems about the pressure settings of the valves are mentioned. Materials and Methods Patients presenting with the clinical signs and symptoms of spontaneous normal-pressure hydrocephalus (NPH) were selected between the years 2008-2015. There was no other history of cerebral pathology in these cases. Two times lumbar puncture (LP) for CSF drainage was performedfirstly and then CSF pressures of the cases were measured during LPs. CSF drainage amount of approximately 40-50 milliliter was provided. Patients who benefit from after LP were diagnosed as NPH and also according to CSF pressures required shunt valve was decided. Then, ventriculo-peritoneal shunts were performed from the anterior coher point. Cases were divided into two maingroups according to the CSF pressure: CSF pressure is higher than and lower than 100 mm H2O pressure. Results The VP shunt surgery was performed to 28 patients with NPH (Or: 28 patients were operated). 17 of the patients were male and 11 were female. The ages of the patients ranged between 65 and 81. The mean age was 74.6'i. (Or: The mean age was 74.6 ranging between 65 and 81) The standard medium pressure reservoir valve was the first choice in 21 patients. The adjustable valves were preferred in 7 patients. The mean follow-up time was 2 years (ranging between 6 mo-4 yrs). Standard medium pressure valve insufficiency occurred in 3 patients during follow-up, they were replaced with the adjustable valves. Also insufficient drainage was occurred in two cases with adjustable valves despite excessive reduction of pressure settings of the valves. The revision surgery were performed with standard low-pressure shunt valves to these cases. Clinical symptoms resolved completely in 26 of the cases. Conclusions The decreasing elasticity of the brain especially after seventh decade makes the neural tissue easily affected even from minimal pressure increments and as a result classical triad findings occur. Gravity helps to remove the excess CSF from the intracranial compartment. Therefore, shunt is good choice of treatment as compared with the cisternal fenestration. References 1.Bugalho P, Alves L, Ribeiro O. Normal pressure hydrocephalus: a qualitative study on outcome. Arq Neuropsiquiatr. 2013 Nov;71(11):890-5. 2.Gölz L, Lemcke J, Meier U. Indications for valve- pressure adjustments of gravitational assisted valvesin p atients with idiopathic normal pressure hydrocephalus. Surg Neurol Int. 2013 Oct 15;4:140.