Affiliations: Johns Hopkins University, School of Medicine,
Baltimore, MD, USA
Note: [] Address for correspondence: Michael A. Williams, MD, FAAN,
LifeBridge Health Brain & Spine Institute, Sinai Hospital, 5051 Greenspring
Avenue, Baltimore, MD 21209, USA. Tel.: +1 410 601 1900; Fax: +1 410 601 1901;
E-mail: [email protected]
Abstract: Studies of the cognitive outcome after shunt insertion for treatment
of Normal Pressure Hydrocephalus have reported widely mixed results. We
prospectively studied performance of 60 patients with Normal Pressure
Hydrocephalus on a comprehensive battery of neuropsychological tests before and
after shunt surgery to determine which cognitive functions improve with shunt
insertion. We also administered a subset of cognitive tests before and after
temporary controlled drainage of cerebrospinal fluid to determine if change on
this brief subset of tests after drainage could predict which patients would
show cognitive improvement three to six months after shunt insertion. There was
a significant improvement in learning, retention, and delayed recall of verbal
memory three to six months after surgery (using paired t-tests). The majority
(74%) of patients showed significant improvement (by at least one standard
deviation) on at least one of the memory tests. Absence of improvement on
verbal memory after temporary drainage of cerebrospinal fluid had a high
negative predictive value for improvement on memory tests at 3–6 months
after surgery (96%; p=0.0005). Also, the magnitude of improvement from Baseline
to Post-Drainage on few specific tests of learning and recall significantly
predicted the magnitude of improvement after shunt surgery on the same tests
(r^{2}=0.32–0.58; p=0.04–0.001). Results
indicate that testing before and after temporary drainage may be useful in
predicting which patients are less likely to improve in memory with
shunting.
