Idiopathic normal pressure hydrocephalus concomitant with progressive supranuclear palsy

Recent studies by us and others have unveiled a frequent coexistence of idiopathic normal pressure hydrocephalus (iNPH) with neurodegenerative movement disorders, including progressive supranuclear palsy (PSP). This study aims to explore the clinical and radiological characteristics of patients with iNPH who also had comorbid with PSP, referred to as iNPHc + PSP.

We retrospectively analyzed patients with iNPH admitted to our department between 2009 and 2024. We adhered to the established clinical criteria for iNPH and the Movement Disorder Society (MDS)-PSP criteria for probable or possible PSP with minor modifications.

Among 85 iNPH patients, 18 were categorized as having iNPHc + PSP (21.2 %). Clinically, comorbid PSP led to impaired vertical eye movement, axial-dominant parkinsonism, and a propensity to fall backward in iNPH (p = 0.022, p = 0.002, and p < 0.005, respectively). Radiologically, comorbid PSP demonstrated a shortened mesencephalic tegmentum length in the magnetic resonance imaging and an asymmetrical deficit of dopamine transporter activities in the DaTscan (p = 0.0005, p = 0.0129, respectively). Lumboperitoneal shunt (LPS) surgery improved the modified Rankin scale (p = 0.038) and the iNPH grading scale (total score, p = 0.003; gait disturbance, p = 0.020; urinary incontinence, p = 0.026) one-year after surgery.

PSP can coexist with iNPH, and detailed clinical and radiological assessment can aid in detecting this comorbidity. Importantly, LPS surgery can improve outcomes of patients with iNPHc + PSP.