This study prospectively analyzed 43 patients with idiopathic normal pressure hydrocephalus (INPH) who were randomized to either a flow-regulated (FR) or differential pressure (DP) shunt valve. Both groups showed improvement on the Neuropsychological Assessment Battery (NAB) and Berg Balance Scale at 6 and 12 months post-operation compared to baseline. The FR group demonstrated more striking improvement at 6 months on the NAB and Berg Balance Scale. The DP group experienced a higher rate of subdural hematomas, most of which were managed with shunt reprogramming. Both valve types were effective in treating INPH, but the FR valve showed earlier improvement and fewer complications.

1. Flow-regulated vs Pressure-regulated shunts: A Prospective Analysis in Patients with Idiopathic Normal
Pressure Hydrocephalus
Phillip G. St. Louis MD; Jennifer Clements
Associates in Neurosurgery
Introduction
Guidelines for treatment of
Idiopathic Normal Pressure
(INPH)indicate ventriculoperitoneal
shunt placement as an effective
intervention. Current literature
comparing Differential Pressure
(DP) versus Flow Regulated (FR)
Valves for is lacking. This
prospective study evaluates one
year outcome data of 43 patients
randomized to either a DP or FR
valve.
Methods
All patients completed pre-operative
and post-operative evaluations to
assess hallmark indicators of INPH
such as magnetic gait (BERG
Balance Scale), cognitive
dysfunction (Neuropsychological
Assessment Battery [NAB]), and
ventriculomegaly (MRI/CT).
Patients who consented were then
randomized to a DP or FR valve.
Results
Baseline testing of the DP Group
(N=22) was NAB: 78.16 and BERG
34.2. Significant improvement was
demonstrated at 6 and 12 months
post-operatively with NAB: 86.5 and
87.75, and BERG 43.06,44.17
scores.
Baseline testing for the FR Group
(N=21) was NAB: 77.4 and BERG:
39. Improvement was noted at 6
and 12 months post operatively with
NAB: 86.25 and 89.17. There was a
slight decrease in the 6 and 12
month BERG: 47.2 and 46.11
scores. There were no shunt
infections. There was one subdural
hematoma in the FR Group requiring
surgical intervention in the
immediate post-operative period,
and 3 subdural hematomas in the
DP Group requiring 1 surgical
intervention. The number of follow
up appointments was slightly
increased in the DP Group, which
was primarily related to patients who
required shunt reprogramming.
Conclusions
Both shunt systems appear to be
effective in treatment of INPH.
Improvement was noted in both NAB
and BERG at 6 and 12 months post-
operatively when compared to
baseline. There was a distinct trend
of more striking improvement at 6
months in the FR Group. A
significantly higher incidence of
subdural hematomas was
demonstrated in the DP Group, most
of which were successfully managed
by shunt reprogramming.
Learning Objectives
Patients with Flow Regulated Valves
demonstrated a more striking
improvement at 6 months. Patients
with Differential Pressure Valves
experienced a larger incidence of
subdural hematomas, however most
of which were managed by shunt
reprogramming. Both groups
demonstrated overall improvement
when compared to baseline
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BERG Balance Scale
NAB

2. BERG Balance Scale

3. NAB