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Assessing Hydrocephalus Patients
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¹Jason A. Albano, M.S., Tracie M. Umaki, M.A.,
James F. Sanders, M.A.,²Philip K. Mothersead, Ph.D.
¹Forest Institute of Professional Psychology,
Springfield, Missouri ²St. John’s Hospital, Neuropsychology &
Rehabilitation, Springfield, Missouri.
The Repeatable Battery for Assessment of Neuropsychological Status (RBANS)
was utilized to assess neurocognitive functioning in six individuals
diagnosed with normal pressure hydrocephalus (NPH).
Current literature indicates a lack of
reliable measures that can be used in a repetitive assessment of cognitive
performance in NPH patients; therefore this preliminary study evaluated the
utility of the RBANS as a measure for assessing neurocognitive changes after
a three-day continuous cerebral spinal fluid (CSF) lumbar drain procedure.
Participants were evaluated pre-post lumbar drain and a Reliable Change
Index (RCI) was calculated for each RBANS domain to determine if significant
changes occurred. Three of the five patients demonstrated significant change
on the Immediate Memory and Delayed Memory Indices. Only one patient
demonstrated significant change on the Total Scale score.
Implications of these findings, precautionary
guidelines, and directions for future work are discussed regarding the
utilization of the RBANS as a measure of neurocognitive change with NPH
patients undergoing CSF lumbar drain protocols.
A review of current literature indicates a lack of reliable measures
available for use in repeated assessment of cognitive performance with NPH
patients undergoing continuous lumbar drain (CLD) protocols for
consideration of ventriculoperitoneal (VP) shunt surgery. The prevalence of
NPH is estimated to be approximately 5% of all dementia patients and
represents a treatable dementia syndrome.
Although there are classic symptoms
associated with NPH, including gait apraxia, urinary incontinence and
dementia, as well as CT or MRI findings of enlarged ventricles, the
challenge remains of identifying the proportional contribution to the
patient’s symptoms from hydrocephalus versus other disorders. The more
symptoms that can be attributed to hydrocephalus, the greater likelihood
that VP shunt surgery will be successful in relieving symptoms.
Consequently, continuous lumbar drains (CLDs)
of cerebral spinal fluid (CSF) are employed to slowly remove CSF over a
three day period of time, imitating what a VP shunt would accomplish and
demonstrating whether this procedure would produce significant improvement
in gait and cognitive ability. If no improvement is evident with re-testing
of gait and cognitive abilities after the CSF drain, then shunt surgery is
unlikely to be successful. This protocol requires a brief, reliable,
repeated assessment of cognitive skills.
Although there is often a dramatic
improvement in gait after VP shunt surgery, dementia reversal is less common
and a major factor limiting NPH shunt success (Goodman & Meyer, 2001).
Inadequate patient selection criteria and incomplete preoperative
assessments likely contribute to poor surgery outcomes. The adoption of a
CLD protocol with reliable assessment of pre-post cognitive changes would
help to improve the selection of surgery candidates and better predict
post-surgical outcomes.
This preliminary study evaluated the utility
of the Repeatable Battery for Assessment of Neuropsychological Status (RBANS)
as a measure for repeated assessment of neurocognitive changes pre-post CLD.
The RBANS was utilized to assess neurocognitive functioning in six
individuals diagnosed with NPH. Participants were evaluated pre-post
continuous lumbar drain of CSF over a three-day period. The Reliable Change
Index (RCI) and 90% confidence intervals were calculated for each RBANS
domain to determine if significant differences occurred as a result of the
CLD procedure. The sensitivity of a brief neuropsychological measure in
detecting significant neurocognitive changes related to CLD may provide a
clinically useful means of predicting suitability for subsequent VP shunt
surgery.
Six hospitalized patients ranging from 61 to 75 years of age with confirmed
diagnoses of NPH were initially included in this study. One patient was
subsequently disqualified due to the presence of a severe chronic mood
disorder present at the time of testing. The remaining patients were
Caucasian and consisted of four males and one female with a mean age of 68.5
and mean educational level of 11.4 years (6-16 years).
NPH patients underwent slow continuous lumbar drain of CSF over a three-day
period performed under the direction of a neurosurgeon. This procedure was
utilized to determine the suitability of these patients for placement of a
VP shunt. A RCI was calculated to determine if significant change occurred
in each patient’s RBANS Index scores from pre-post testing sessions. The RCI
is a statistical method for evaluating clinically significant changes on an
individual level and as noted by Johnson et al. (2006), may be particularly
useful for individuals with central nervous system conditions. Utilizing
pretest (X1) and post-test (X2) scores, RCI analyses account for the
standard error evidenced in test and retest performance on a given measure (Sdiff),
evaluating whether changes post intervention are statistically significant
and truly a result of the intervention. For the purposes of this study, RCIs
were calculated utilizing a 90% confidence interval. Thus, RCI scores are
said to represent clinically significant change at the .10 level when they
exceed one and one half standard deviations on a normal z distribution (i.e.
+/ – 1.654).
Table 1 shows RBANS pre-post index
scores, differences and RCI results for five patients in this study. Also,
90% confidence intervals were calculated for each index score. Positive
improvement in cognitive performance was less impressive than change with
balance and gait, but was evident with three patients on Immediate Memory
(S2, S4, S5), one subject (S3) on Visual/Constructional Ability and one
subject (S5) on Delayed Memory.
Only one subject (S3) demonstrated positive
change on the Total Scale score. Significant negative changes were also
noted, especially with Delayed Memory (S1, S4). Four patients in this study
were considered to be good candidates for VP shunt surgery due to
improvement with gait as well as other criteria, and did undergo subsequent
surgery.
The primary focus of this preliminary study was to evaluate the RBANS as a
sensitive measure for detecting clinically significant neurocognitive change
pre-post CLD. Three patients did demonstrate positive improvement on the
Immediate Memory Index of the RBANS. Surprisingly, two patients exhibited a
significant decline in Delayed Memory.
The lack of significant change with other
index scores may reflect the brief three-day time frame before retesting,
and the small sample size. One study utilizing cognitive measures
demonstrated improvement in memory and psychomotor speed when cognitive
abilities were reassessed 6-12 months after shunt surgery (Duinkerke,
Williams, Rigamonti & Hillis, 2004) but did not utilize RCIs to determine
significant change. More generalized cognitive changes may not be evident
until VP shunt surgery has been completed and adequate time has elapsed.
Follow-up of patients demonstrating
significant decline in post CLD RBANS performance is also needed to
determine long-term outcomes. By conducting pre-post CLD cognitive testing
as well as postoperative follow-up assessments, greater predictive power of
select RBANS Index Scores can be identified.
Although NPH is commonly referred to as a
treatable form of dementia, cognitive deficits are only one part of the
syndrome and often do not improve with shunt surgery (Verrees & Selman,
2004). Future longitudinal research using larger samples of individuals
undergoing the CLD protocol will help determine the predictive power of the
RBANS in selecting appropriate candidates for VP shunt surgery and thereby
improving surgery outcome.
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