A Study Comparing Shunt Placement Versus Endoscopic Third Ventriculostomy in the Treatment of Hydrocephalus

The management of normal pressure hydrocephalus (NPH) is challenging due to diagnostic
uncertainties and high treatment risks. To date, there are no evidence-based treatment
standards for this disorder. Our long-term goal is to improve the outcome of NPH improving
our understanding of cerebrospinal fluid (CSF) hydrodynamics. The Specific Aims are to 1)
determine the value of a high volume tap test, and 2) determine whether intracranial
hemo/hydrodynamic variables, measured before a shunt operation, support the tuned-dynamic
absorber model of intracranial pressure dynamics.

The study's Aim relates to modeling the complex hydro- and hemodynamics of intracranial
physiology-pathology. We hypothesize that current hydrocephalus models are over-simplistic
and that shunt-induced hydrodynamics are better modeled based on ICP waveform
characteristics and the application of novel dynamic models. Much of the data for this Aim
will be passively recorded during the routine care of the patient. In essence, we are only
adding noninvasive MRI studies and TCD (transcranial Doppler) studies.

The experimental methodology is aimed at altering the intracranial compartment compliance by
placing the patient in various positions so that these phase differences can be detected.
The simplest way to alter intracranial compliance is to make postural changes. When a
patient is in the Trendelenburg position, venous outflow out of the brain is hindered
resulting in an increase in ICP and presumably a reduction in compliance. Conversely,
raising the head of bed to 60 degrees will result in the opposite effect. The second
mechanism of altering compliance (and ICP) will occur as a result of treating the
hydrocephalus with a CSF shunt. Because we are able to study hydrocephalus patients prior to
shunting as part of their diagnostic workup, we create a new state with the shunt that will
allow us to further characterize the intracranial system.

Inclusion Criteria:

- Findings of gait/balance disturbance must be present, plus at least one other area of
impairment in cognition, urinary symptoms or both

- Minimum duration of symptoms of at least three months, progression over time, and no
other neurological, psychiatric or general medical conditions that are sufficient to
explain the presenting symptoms

- MRI or CT performed after onset of symptoms must show evidence of ventricular
enlargement (Evan's index > 0.3) not entirely attributable to cerebral atrophy or
congenital enlargement

- Criteria for shunt placement: we place greatest emphasis on the results of the
temporary CSF drainage trial. Patients who experience a temporary improvement in
neurological function (gait, bladder control, and/or cognition) are offered a shunt
operation. For patients in whom the CSF drainage results were equivocal, then other
factors such as elevated baseline ICP and/or high Rout will also be considered for a
shunt under these circumstances

Exclusion Criteria:

- Age < 40

- Fixed musculoskeletal deformities that will exclude gait improvement

- Advanced dementia

- Inability to obtain an MRI study

- General medical conditions in which operative risks are excessive

- Patients taking Warfarin (Coumadin) will be excluded