Neuropsychological effects of shunting in iNPH – determining major and minor responses
Wallin et al. Fluids and Barriers of the CNS
Neuropsychological effects of shunting in iNPH - determining major and minor responses
Maria Wallin 0
Mats Tullberg 0
Carsten Wikkelsö 0
Per Hellström 0
0 Institute of neuroscience and physiology , Sweden
iNPH is characterized by a wide range of
neuropsychological deficits. The severity of impairment is associated
with that of gait, balance and continence disturbances,
and correlations between results on disparate
neuropsychological tests are far stronger than among healthy; a
dedifferentiation of functions.
Following surgery, performance at group level, is
significantly improved and remains stable for at least the
first year of treatment. Importantly, however, shunted
iNPH patients still perform well below normal levels.
The magnitude of change varies substantially, some
patients showing only modest advances or even further
deterioration, whereas others show considerable
improvements on the majority or all administered tests.
In this study we compared patients belonging to these
two extremes, aiming to predict neuropsychological
benefits of surgery.
Consecutive iNPH patients (N=235) underwent pre- and
postoperative assessments of learning (Rey Auditory
Verbal Learning test; RAVLT), dexterity (Grooved pegboard),
basic processing speed (Stroop, color naming task) and
executive control (Stroop, interference task). For each test
the patients were divided into four groups (Q1-Q4)
according to the quartile limits of the distributions of
Reliable Change Indices (RCIs). Q1 and Q4, i.e. the least and
the most improved, were compared with regard to
preoperative characteristics pertaining to demography, other
iNPH manifestations and other findings in neurological
and physiotherapeutic examinations, and CSF dynamics.
For each set of analyses they were also compared with
regard to the changes (RCI scores) and postoperative
performances on the remaining three tests.
Patients who showed substantial positive changes in one
neuropsychological function did so in the others as well,
and vice versa. For learning and dexterity, neither
demographic, nor clinical or CSF dynamics predicted changes
following treatment. In the group who showed the greatest
improvement of basic processing speed, preoperative gait
disorders were more severe, and paratonia was more
frequent than among the least improved. Those with greatest
positive changes in executive control also had more severe
gait disorders and more frequent paratonia, and, in
addition, more marked problems with turning, balance and
continence, and a lower general intellectual level.
Neuropsychological improvement following shunt
treatment is consistent across functions. Statistically reliable
and meaningful changes in learning and dexterity can not
be predicted from demography, severity in other iNPH
symptoms or CSF dynamics. Changes of basic processing
speed and executive control, however, do appear possible
to foresee on the basis of preoperative findings.