Normal pressure hydrocephalus: survey on contemporary diagnostic algorithms and therapeutic decision-making in clinical practice

Background. There is no agreement on the best diagnostic criteria for selecting patients with normal pressure hydrocephalus (NPH) for CSF shunting. The primary objective of the present study was to provide a contemporary survey on diagnostic algorithms and therapeutic decision-making in clinical practice. The secondary objective was to estimate the incidence of NPH. Method. Standardized questionnaires with sections on the incidence of NPH and the frequency of shunting, evaluation of clinical symptoms, and signs, diagnostic studies, therapeutic decision-making and operative techniques, postoperative outcome and complications, and the profiles of different centers, were sent to 82 neurosurgical centers in Germany known to participate in the care of patients with NPH. Findings. Data were analyzed from 49 of 53 centers which responded to the survey (65%). The estimated annual incidence of NPH was 1.8 cases/100.000 inhabitants. Gait disturbance was defined as the most important sign of NPH (61%). There was a wide variety in the choice of diagnostic tests. Cisternography was performed routinely only in single centers. Diagnostic CSF removal was used with varying frequency by all centers except one, but the amount of CSF removed by lumbar puncture differed markedly between centers. There was poor agreement on criteria for evaluation of continuous intracranial pressure recordings regarding both the amplitude and the relative frequency of B-waves. Both periventricular and deep white matter lesions were present in about 50% of patients being shunted, indicating that vascular comorbidity in NPH patients has gained more acceptance. Programmable shunts were used by more than half of the centers, and newer valve types such as gravitational valves have become more popular. Conclusions. According to the present survey, new diagnostic and therapeutic concepts on NPH have penetrated daily routine to a certain extent. Wide variability, however, still exists among different neurosurgical centers.