Parkinsonian symptoms in normal pressure hydrocephalus: a population-based study

It may be challenging to differentiate normal pressure hydrocephalus (NPH) from neurodegenerative disorders such as Parkinson's disease. In this population-based study, we wanted to describe the frequency of parkinsonian symptoms among individuals with and without NPH, and whether the motor examination part of the Unified Parkinson's Disease Rating Scale (UPDRS-m) score differs between these groups. Furthermore, we wanted to find out whether there was a relationship between UPDRS-m score, NPH symptoms, and radiological signs of NPH. A sample of 168 individuals over the age of 65 with and without self-reported symptoms of NPH underwent a computerized tomography of the brain and clinical examination, including UPDRS-m to grade parkinsonian symptoms. According to diagnostic guidelines, 38 fulfilled criteria for NPH, whereas 130 had unlikely NPH. Bradykinesia was significantly more common among those with NPH (79%) compared to those with unlikely NPH (32%) (p < 0.001). The corresponding figures for rigidity were 43 vs. 15% (p < 0.001), for postural instability 71 vs. 22% (p < 0.001), and for tremor at rest 5 vs. 6% (not significant). The total UPDRS-m score was significantly higher among individuals with NPH (median = 12) than without (median = 1) and correlated significantly with the degree of NPH symptoms (r = -0.72) and ventriculomegaly (r = 0.31). In this study, parkinsonian symptoms, except resting tremor, were frequent in individuals with NPH and correlated with the severity of NPH symptoms. Asymmetric symptoms were uncommon. We recommend a liberal use of neuroradiological imaging when investigating a patient with parkinsonian features.