Predictors of Ventriculoperitoneal Shunt Revision in Patients with Idiopathic Normal Pressure Hydrocephalus.

OBJECTIVE Few studies have focused on predictive factors of ventriculoperitoneal (VP) shunt revision in patients with idiopathic normal pressure hydrocephalus (iNPH). This study aims to determine whether comorbidities and baseline symptoms are associated with the need for shunt revision. METHODS A retrospective review of patients with iNPH treated with VP shunts by the senior author from 1993 to 2013 was conducted. Demographics and baseline symptoms were compared between patients with and without shunt revision. The need for revision, total number of revisions, and time to first revision were examined. Statistical analysis was performed using simple logistic, linear, and Poisson regression, and a multivariate analysis was performed. RESULTS A total of 347 patients with iNPH who received VP shunts were included. One hundred patients (28.8%) required shunt revision, with an average of 1.38 ± 0.76 revisions per patient. Mean time to revision was 19.2 ± 31.7 months. Gait and cognitive symptoms were associated with fewer revisions (incidence rate ratio, 0.45 and 0.67; P = 0.03 and 0.004, respectively). Headaches and urinary incontinence showed a greater time to revision (32.0 and 12.0 months; P = 0.014 and <0.0005, respectively). Gait instability demonstrated decreased time to revision (P < 0.0005). CONCLUSIONS Preoperative symptoms, such as headaches, gait instability, cognitive decline, and urinary incontinence, were significantly correlated with number of revisions and time to first revision. These factors should be considered during the initial counseling of prognosis for patients with iNPH receiving VP shunts.