Altered glymphatic system in idiopathic normal pressure hydrocephalus

Area of Science:

• Neuroimaging
• Neuroscience
• Radiology

Background:

• Idiopathic normal pressure hydrocephalus (NPH) is a neurological condition characterized by impaired cerebrospinal fluid dynamics.
• Glymphatic system dysfunction is increasingly recognized as a contributing factor in various neurological disorders.
• Non-invasive imaging techniques are crucial for evaluating brain function in NPH patients.

Purpose of the Study:

• To assess glymphatic activity in NPH patients using the Diffusion Tensor Image-Analysis aLong the Perivascular Space (DTI-ALPS) method.
• To determine the feasibility of using non-invasive MRI for evaluating glymphatic function in NPH.
• To correlate DTI-ALPS findings with clinical parameters and treatment response.

Main Methods:

• 16 NPH patients and 16 age/sex-matched controls underwent 3T DTI-MRI.
• The ALPS-index, quantifying water diffusion along the perivascular space, was calculated.
• Inter-observer agreement was assessed, and group differences were analyzed using Mann-Whitney and correlation analyses.

Main Results:

• Excellent inter-observer agreement was achieved for diffusivity and ALPS-index measurements.
• NPH patients exhibited significantly lower diffusivity and ALPS-index compared to controls (P < 0.0001).
• Lower ALPS-index correlated with poor treatment response and was positively associated with the callosal angle (r=0.82, P=0.0001).

Conclusions:

• The DTI-ALPS method is a valuable tool for identifying glymphatic dysfunction in NPH.
• This non-invasive MRI technique allows for individual quantification of glymphatic activity.
• DTI-ALPS shows potential for improving the diagnostic and prognostic evaluation of NPH.