Acetazolamide Trial in Normal Pressure Hydrocephalus

Study Overview
=================
Brief Summary
-----------------
A pharmacological treatment to patients with normal pressure hydrocephalus (NPH) is missing. The aim is to investigate if acetazolamide given to patients with NPH improves gait function and study the pathophysiological mechanisms leading to reduced symptoms. Patients will be randomized to acetazolamide or placebo and duration of treatment will be from diagnosis to the day of shunt surgery. Target dose is 500 mg/day. Study design is a double-blind randomized controlled trial and the plan is to include 42-50 patients. The study is investigator-initiated without financial sponsorship from the industry.

Detailed Description
-----------------
Background: The only available treatment for normal pressure hydrocephalus (NPH) is implantation of a neurosurgical shunt system that reduces symptoms in two out of three cases. Postoperative complications are common, causing reoperations in 20-30% within the first years after surgery. A pharmacological treatment is missing. In three previous studies, acetazolamide, a reversible inhibitor of the carbonic anhydrase enzyme, was used as treatment off-label. In the first of these studies, 15 patients with NPH were treated with doses 250-500 mg/day and 10 patients improved (Aimard G et. al.). The second study was a case report of one patient with NPH who improved after receiving the dose 500 mg/day (Garcia-Gasco P et. al.). The most recent study used doses of 125-375 mg/day and included 8 patients of whom 5 improved. Furthermore, the last study reported a reduction of the periventricular edema that is often present in the white matter close to the lateral ventricles in patients with NPH (Alperin N et. al.). These three studies were open label with no blinding or control group. Study design: Study design is a double-blind randomized placebo-controlled trial. The study is investigator-initiated without financial sponsorship from the industry. The plan is to consecutively include 42-50 patients with NPH. Patients will be randomized to acetazolamide or placebo and take the study drug from diagnosis (baseline) to admission for shunt surgery. Waiting time for shunt surgery at the center of the study is approximately 4-8 months at the moment. The dose will be titrated to 250 mg x 2 during 4-6 weeks. Two phone visits with a study nurse and routine blood samples are controlled during the titration phase to rule out side effects. Evaluations of clinical symptoms and blood samples for blood biomarkers are collected at baseline, after 3 months and when the study drug is stopped. Lumbar cerebrospinal fluid (CSF) is collected at baseline and intraventricular CSF is collected during shunt surgery. All patients are investigated after shunt surgery, 3 months postoperatively with evaluation of symptoms and blood samples. Blood- and CSF samples are stored in a biobank. In a subgroup of 24-26 patients, an MRI of the brain is performed before the start of study drug and after 3 months. In this subgroup also assessments of symptoms and blood samples for analysis of plasma biomarkers will be collected in connection with the MRI scans.

Official Title
-----------------
Double-blind Randomized Acetazolamide Trial in Normal Pressure Hydrocephalus

Conditions
-----------------
Idiopathic Normal Pressure Hydrocephalus (INPH)

Intervention / Treatment
-----------------
* Drug: Acetazolamide
* Drug: Placebo


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Diagnosis of idiopathic normal pressure hydrocephalus according to international guidelines Age ≥ 50 years and ≤ 82 years Cognitive function with Mini-Mental State Examination > 20 points or cognitive domain of iNPH scale ≥ 30 points. MRI image characteristic of normal pressure hydrocephalus, defined as callosal angle < 90 degrees and dilated lateral ventricles or pattern of disproportionately enlarged subarachnoid space hydrocephalus (DESH). Signed informed consent form Exclusion Criteria: Exclusion criteria for MRI examination Participation in another medical trial Other disease likely to impact the symptoms of the patient Wheelchair user or unable to walk without support Reduced kidney function with GFR < 50 Reduced liver function (increased INR or alanine transaminase concentrations in plasma elevated more than 1.5 times reference values) Known heart failure Low concentrations of electrolytes in blood plasma that, according to the investigator, prevents participation in the study Angle-closure glaucoma Allergy to acetazolamide, sulfonamides, or sulfonamide derivatives Treatment with phenytoin, valproate, carbamazepine, lithium, oral anticoagulants, thiazide-diuretics, or acetylsalicylic acid > 100 mg/day Inability to swallow capsules of the same size as the investigational medicinal products (will be tested using empty capsules when the patient is asked to participate in the study) Average walking time for the three walking tests < 10.5 seconds for men and < 11.5 seconds for women. Average walking time for the three walking tests > 50 seconds Inability to comply with the study treatment independently, and a concurrent lack of individuals to help the patient comply with the treatment during the study period Fertile woman without highly effective contraception. A Fertile woman will be tested with pregnancy test before inclusion is possible.

Ages Eligible for Study
-----------------
Minimum Age: 50 Years
Maximum Age: 82 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Double-blind randomized trial.
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Acetazolamide<br>Acetazolamide (active) | Drug: Acetazolamide<br>* Target dose: 500 mg / day<br>* Other names: Diamox;|
| Placebo Comparator: Placebo<br>Placebo | Drug: Placebo<br>* Placebo<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportional change in gait function | Gait function is determined by one variable that is calculated as the mean time and number of steps of three different gait tests: 10 meter walking in self chosen speed, timed up and go test (TUG) and 3 m walking backwards. The two fastest attempts of three attempts for each test are documented. The mean time and number of steps of the two fastest attempts for the three tests are calculated to a single variable and the proportional difference between study visits is used as the primary outcome variable. | Change from baseline gait function immediately after intervention (at time of shunt surgery) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in idiopathic normal pressure hydrocephalus (iNPH) scale | Swedish idiopathic normal pressure hydrocephalus (iNPH) scale that is a combination of subscales for gait, balance, cognition and continence. Minimum value is 0 and maximum value is 100. High values indicate better function. | Change from baseline iNPH-scale score immediately after intervention (at time of shunt surgery) | 
| Change in volume of periventricular hyperintensities | Measured using volumetric MRI | Change from baseline at 3 months | 
| Change in cerebral blood perfusion | Measured using pseudo continuous arterial spin labeling (MRI perfusion) | Change from baseline at 3 months | 
| Change in quantified CSF flow in cerebral aqueduct | Measured using phase contrast MRI | Change from baseline at 3 months | 
| Change in parenchymal water content | Measured using Synthetic MRI | Change from baseline at 3 months | 
| Change in cerebral myelin volume | Measured using Synthetic MRI | Change from baseline at 3 months | 
| Changes in plasma biomarkers | Change in plasma levels of neurofilament light chain protein, Total-tau, amyloid beta-42, glial fibrillary acidic protein will be measured using Quanterix (SIMOA). | Change from baseline immediately after intervention (at time of shunt surgery) | 
| Change in CSF biomarkers | CSF levels of neurofilament light chain protein, Total-tau, amyloid beta-42, glial fibrillary acidic protein will be measured using Quanterix (SIMOA). | Change from baseline immediately after intervention (at time of shunt surgery) | 
| Changes in plasma and CSF proteins | Semi-quantified levels of approximately 200 proteins are measured with proximity extension assay (Neurology panel and Neuro exploratory panel, Olink.com). | Change from baseline immediately after intervention (at time of shunt surgery) | 
| Patients self reported assessment of symptoms | Gait, cognition, continence, balance, activities of daily life and quality of life is rated by patients on a questionnaire using 4-level scales. | Change from baseline immediately after intervention (at time of shunt surgery) | 
| Change in Euro-Quality of Life-5 dimension-5L (EQ-5D-5L) descriptive system | Measured using EQ-5D-5L using the descriptive system. | Change from baseline EQ-5D-5L score immediately after intervention (at time of shunt surgery) | 
| Change in Euro-Quality of Life-5 dimension-5L (EQ-5D-5L) VAS | Measured using the visual analogue scale (VAS) in EQ-5D-5L. | Change from baseline EQ-5D-5L score immediately after intervention (at time of shunt surgery) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
RCT, normal pressure hydrocephalus, iNPH, Acetazolamide, Diamox