To describe the movement disorders phenotype present in Idiopathic Normal Pressure Hydrocephalus (iNPH).

iNPH is commonly identified with the clinical triad of gait dysfunction, memory impairment, and urinary incontinence. While gait dysfunction is a key diagnostic feature, it exhibits considerable variability with patients presenting with frontal gait, parkinsonian, or other gait patterns. Furthermore, many individuals with iNPH also present with parkinsonian features, such as akinesia (lower body-predominant) and tremor. Limited data is available regarding the spectrum of movement disorders in iNPH.

This is a retrospective study describing movement disorders in patients meeting the Japanese guidelines criteria for probable and definite iNPH seen at the University of Connecticut’s NPH clinic between January 2020 and June 2023.

Out of the 135 patients in the NPH clinic, 54 (40%) patients met the inclusion criteria. Of these, thirty-one (57%) were male, with a mean age of 77 years + 7, and mean duration of symptoms of 3.9 years + 2.92. Bradykinesia (98%) was the most prevalent movement disorder followed by tremor (81%), dystonia (80%), rigidity (65%), hypomimia (30%), and hypophonia (19%). Asymmetrical bilateral involvement was notably observed in patients with bradykinesia (91%), tremor (24%), dystonia (43%), and rigidity (15%). Among those with tremor, 40 (74%) exhibited an action tremor, with dystonic tremor identified in 15%. Gait patterns were diverse, with Parkinsonian gait reported in 43% and frontal gait in 40% of patients.

Our study broadens our understanding  of the movement disorder spectrum in iNPH important for diagnostic purposes. Compared to previously reported data, our cohort had higher prevalence of tremors and dystonia.  Additionally, asymmetry was noted commonly in this population. Further studies are needed to better understand the pathophysiology of movement disorders associated with iNPH.