Parkinsonism in Idiopathic Normal Pressure Hydrocephalus or Hydrocephalic Presentation in Parkinson's Disease: A Report of Three Cases.

Idiopathic normal pressure hydrocephalus (iNPH) occasionally presents with parkinsonism, in addition to its classic triad of symptoms. However, it remains unclear whether such parkinsonism reflects an inherent manifestation of iNPH or comorbid Parkinson's disease, and whether it is levodopa-responsive. We report three patients exhibiting both hydrocephalus and parkinsonism. Two improved with both levodopa and shunt surgery; one improved only with levodopa and not with spinal tap. In one dual responder, dopamine transporter uptake improved postoperatively, and motor symptoms remained stable despite tapering levodopa. These cases highlight the heterogeneity of this overlapping condition, including a potentially reversible, levodopa-responsive parkinsonism due to hydrocephalus-induced dopaminergic dysfunction that can be ameliorated by shunt surgery.