The goal of this observational study is to evaluate the role of DTI-ALPS in the diagnostic and therapeutic management of NPH

The main questions it aims to answer are:

• Whether the glymphatic system (GS) is actually impaired in NPH
• Whether DTI-ALPS index can predict the positive response to tap test (TT) and to ventriculo-peritoneal shunt (VPS) surgery.

A healthy control group of patients (HC group) matched for age with the study group, will undergo MR with DTI-ALPS study

Enrolled patients followed a diagnostic-therapeutic pathway, consisting of the following steps:

• t0: MR with DTI-ALPS study;
• t1 (within 7 days from T0): clinical and neurosurgical assessment with NPH-specific rating scales (detailed below) before and after a lumbar TT, including measurements of opening pressure, drainage of 40-50 mL of CSF and collection of samples for neurodegenerative biomarkers (β-Amyloid 40, 42 total and P-Tau) quantification. An MR with DTI-ALPS study within 6 hours from TT;
• t2 (within 3 months from T1): patients with a positive TT response (included responders, IR group) underwent VPS surgery, with CSF samples collected for the same neurodegenerative biomarkers (β-Amyloid 40, 42 total and P-Tau);
• t3 (three months after surgery, IR group only): clinical and neurosurgical evaluation using NPH-specific rating scales to classify patients as improved, unchanged, or worsened compared to their preoperative condition; MR with DTI-ALPS study.

Suspected NPH patients according to the following:

Inclusion Criteria:

• clinical and radiological diagnosis of probable NPH according to existing guidelines
• age of over 50 years

Exclusion Criteria:

• inability to undergo MR
• diagnosis of any other neurological pathology, particularly neurodegenerative or neuroinflammatory
• previous neurosurgical interventions on the brain of any type.
• inability to undergo general anaesthesia

Patients affected by normal pressure hydrocephalus