BACKGROUND AND PURPOSE: Several studies have evaluated the use of MR imaging markers for the prediction of outcome after shunt surgery in idiopathic normal pressure hydrocephalus with conflicting results. Our aim was to investigate the predictive value of a number of earlier proposed morphologic MR imaging markers in a large group of patients with idiopathic normal pressure hydrocephalus. MATERIALS AND METHODS: One hundred sixty-eight patients (mean age, 70 Ϯ 9.3 years) with idiopathic normal pressure hydrocephalus, subjected to standardized quantification of clinical symptoms before and after shunt surgery, were included in the study. Outcome was calculated using a composite score. Preoperative T1, FLAIR, and flow-sensitive images were analyzed regarding the presence of 13 different morphologic MR imaging markers. RESULTS: The median Evans index was 0.41 (interquartile range, 0.37-0.44). All patients had an aqueductal flow void sign present and white matter hyperintensities. The median callosal angle was 68.8°(interquartile range, 57.7°-80.8°). Dilated Sylvian fissures were found in 69%; focally dilated sulci, in 25%; and widening of the interhemispheric fissure, in 55%. Obliteration of the sulci at the convexity was found in 36%, and 36% of patients were characterized as having disproportionately enlarged subarachnoid space hydrocephalus. Sixty-eight percent of patients improved after surgery. None of the investigated MR imaging markers were significant predictors of improvement after shunt surgery. CONCLUSIONS: Disproportionately enlarged subarachnoid space hydrocephalus, a small callosal angle, and the other MR imaging markers evaluated in this study should not be used to exclude patients from shunt surgery. These markers, though they may be indicative of idiopathic normal pressure hydrocephalus, do not seem to be a part of the mechanisms connected to the reversibility of the syndrome. ABBREVIATIONS: DESH ϭ disproportionately enlarged subarachnoid space hydrocephalus; EI ϭ Evans index; iNPH ϭ idiopathic normal pressure hydrocephalus

Objective: We examined clinical and imaging findings of suspected idiopathic normal pressure hydrocephalus (iNPH) in relation to vascular risk factors and white matter lesions (WMLs), using a nested case-control design in a representative, population-based sample.Methods: From a population-based sample, 1,235 persons aged 70 years or older were examined with CT of the brain between 1986 and 2000. We identified 55 persons with hydrocephalic ventricular enlargement, i.e., radiologic findings consistent with iNPH. Among these, 26 had clinical signs that fulfilled international guideline criteria for probable iNPH. These cases were labeled suspected iNPH. Each case was matched to 5 controls from the same sample, based on age, sex, and study cohort. Data on risk factors were obtained from clinical examinations and the Swedish Hospital Discharge Register. History of hypertension, diabetes mellitus (DM), smoking, overweight, history of coronary artery disease, stroke/TIA, and WMLs on CT were examined. Risk factors associated with iNPH with a p value ,0.1 in x 2 tests were included in conditional logistic regression models. Idiopathic normal pressure hydrocephalus (iNPH) is probably more common than previously supposed. We have recently reported that 5.9% of persons older than 80 years have this disorder. 1 Treatment with shunt surgery improves symptoms in more than 80% of patients. 2 Despite this, iNPH is underdiagnosed and undertreated.1,3 Furthermore, little is known about the underlying disease mechanisms. It is important to learn more about risk factors for the disease in order to understand pathophysiologic mechanisms and suggest preventive measures. Vascular risk factors, such as hypertension, diabetes, and ischemic heart disease, have previously been associated with iNPH in hospital-based, case-control studies.4-9 Also, cerebral white matter lesions (WMLs), which are associated with small vessel disease and white matter ischemia, 10 are common in iNPH. 11,12 It has therefore been suggested that vascular mechanisms may be related to the development of iNPH. However, previous studies on risk factors have not been population-based. Furthermore, there are no previous epidemiologic investigations regarding WMLs in iNPH.

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Objective To describe survival and causes of death in 979 treated iNPH patients from the Swedish Hydrocephalus Quality Registry (SHQR), and to examine the influence of comorbidities, symptom severity and postoperative outcome. Methods All 979 patients operated for iNPH 2004–2011 and registered in the SHQR were included. A matched control group of 4890 persons from the general population was selected by Statistics Sweden. Data from the Swedish Cause of Death Registry was obtained for patients and controls. Results At a median 5.9 (IQR 4.2–8.1) year follow-up, 37% of the iNPH patients and 23% of the controls had died. Mortality was increased in iNPH patients by a hazard ratio of 1.81, 95% CI 1.61–2.04, p < 0.001. More pronounced symptoms in the preoperative ordinal gait scale and the Mini-mental State Examination were the most important independent predictors of mortality along with the prevalence of heart disease. Patients who improved in both the gait scale and in the modified Rankin Scale postoperatively (n = 144) had a similar survival as the general population (p = 0.391). Deaths due to cerebrovascular disease or dementia were more common in iNPH patients, while more controls died because of neoplasms or disorders of the circulatory system. Conclusions Mortality in operated iNPH patients is 1.8 times increased compared to the general population, a lower figure than previously reported. The survival of iNPH patients who improve in gait and functional independence is similar to that of the general population, indicating that shunt surgery for iNPH, besides improving symptoms and signs, can normalize survival.

Background There is little knowledge about the factors influencing the long-term outcome after surgery for idiopathic normal pressure hydrocephalus (iNPH). Objective To evaluate the effects of reoperation due to complications and of vascular comorbidity (hypertension, diabetes, stroke and heart disease) on the outcome in iNPH patients, 2-6 years after shunt surgery. Methods We included 979 patients from the Swedish Hydrocephalus Quality Registry (SHQR), operated on for iNPH during 2004-2011. The patients were followed yearly by mailed questionnaires, including a self-assessed modified Rankin Scale (smRS) and a subjective comparison between their present and their preoperative health condition. The replies were grouped according to the length of follow-up after surgery. Data on clinical evaluations, vascular comorbidity, and reoperations were extracted from the SHQR. Results On the smRS, 40% (38-41) of the patients were improved 2-6 years after surgery and around 60% reported their general health condition to be better than preoperatively. Reoperation did not influence the outcome after 2-6 years. The presence of vascular comorbidity had no negative impact on the outcome after 2-6 years, assessed as improvement on the smRS or subjective improvement of the health condition, except after 6 years when patients with hypertension and a history of stroke showed a less favorable development on the smRS. Conclusion This registry-based study shows no negative impact of complications and only minor effects of vascular comorbidity on the long-term outcome in iNPH.