Instrumental assessment of INPH: structural and functional neuroimaging.

INTRODUCTION: For the accurate diagnosis of idiopathic normal pressure hydrocephalus (iNPH) an accurate neuroimaging is essential. Disproportionately enlarged subarachnoid-space hydrocephalus (DESH) is a key neuroradiological feature and novel imaging techniques, including voxel-based morphometry and AI-assisted analyses are emerging as powerful tools to investigate iNPH pathophysiology. Converging evidence also suggests a role for dopaminergic dysfunction in iNPH. Molecular imaging of the dopamine transporter (DaT) enables the investigation of dopaminergic function and holds potential for advancing differential diagnosis and guiding treatment decisions in iNPH.

EVIDENCE ACQUISITION: A comprehensive literature search was conducted using MeSH key words. Studies assessing the role of structural and functional neuroimaging in iNPH. The evidence was summarized, and key results were provided.

EVIDENCE SYNTHESIS: DESH is crucial for accurate diagnosis and treatment planning. Advanced structural and functional imaging techniques are expanding our understanding of iNPH pathophysiology. Only few functional imaging studies have directly examined the dopaminergic dysfunction in iNPH and severe methodological limitations exist in both clinical classification and imaging processing. Nonetheless, evidence supports the presence of dopaminergic dysfunction in iNPH, which may be linked to specific clinical symptoms, aid in differential diagnosis, and be reversed with shunt surgery treatment.

CONCLUSIONS: This review covers the structural and functional imaging data in iNPH, providing a comprehensive outlook of the current knowledge, highlighting the limitations and possible future perspectives.