NPHFactors Predicting Response to Shunting in Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is a potentially reversible progressive neurological condition disproportionately affecting the elderly population. Given current controversies regarding its exact definition, accurate incidence and prevalence figures are elusive. NPH was first described forty years ago as a triad of symptoms consisting of gait difficulties, urinary incontinence, and memory problems in patients with enlarged ventricles in the absence of increased intracranial pressure (ICP). The cause of primary, or idiopathic NPH (INPH) remains elusive, while secondary NPH results from intracranial insults such as head trauma, meningitis, or intracranial hemorrhage. NPH can be successfully treated with cerebrospinal fluid (CSF) shunting. However, the accurate diagnosis and treatment of patients with NPH remains problematic, despite significant advances in brain imaging and ICP physiology. Objectives - The primary aims of this study are: 1. to confirm the ability of external lumbar drainage to increase the success rate of selectively shunting patients with NPH compared to historical controls 2. to refine the diagnosis of NPH by determining whether the factors that change before and after lumbar drainage will predict failure to improve after shunting. A related aim is to assess the complications attributable to lumbar drainage. 3. to perform a preliminary evaluation of programmable shunt valves for NPH compared to historical controls using fixed-pressure valves. A related aim is to determine whether post-op objective analysis of gait, cognitive function and urinary symptoms will help refine the programmable shunt setting on an individual basis. Secondary study aims include: Investigating the pathophysiology of NPH by: 1) correlating cortical vein compliance measured by MRI flow quantification studies with CSF pressure waveform analysis; 2)assessing funduscopic changes before and during ELD; 3) performing and cross correlating CSF chemical analysis on screening positive and negative patients as well as screening-positive patients who are shunt responsive versus unresponsive.