Baseline neuropsychological profile and cognitive response to cerebrospinal fluid shunting for idiopathic normal pressure hydrocephalus.

OBJECTIVE

To evaluate neurocognitive changes and predict neurocognitive outcome after ventriculoperitoneal shunting for idiopathic normal pressure hydrocephalus (INPH).

BACKGROUND

Reports of neurocognitive response to shunting have been variable and studies that predict cognitive outcomes after shunting are limited. We reviewed our experience with cognitive outcomes for INPH patients who were selected for shunting based on abnormal cerebrospinal fluid (CSF) pressure monitoring and positive response in any of the NPH symptoms following large volume CSF drainage.

METHODS

Forty-two INPH patients underwent neurocognitive testing and Folstein Mini-Mental State Examination (MMSE) prior to shunting. Neurocognitive testing or MMSEwere performed at least 3 months after shunt insertion. Significant improvement in a neurocognitive subtest was defined as improvement by one standard deviation (1 SD) for the patient's age, sex and education level. Significant improvement in overall neurocognitive outcome was defined as a 4-point improvement in MMSE or improvement by 1 SD in 50% of the administered neurocognitive subtests. Nonparametric tests were used to assess changes. Predictors of outcome were assessed via logistic regression analysis.

RESULTS

Twenty-two patients (52.3%) showed overall neurocognitive improvement, and significant improvement was seen in tests of verbal memory and psychomotor speed. Predictive analysis showed that patients scoring more than 1 SD below mean at baseline on verbal memory immediate recall were fourfold less likely to show overall cognitive improvement, and sixfold less likely if also associated with visuoconstructional deficit or executive dysfunction. Verbal memory scores at baseline were higher in patients who showed overall cognitive improvement.

CONCLUSIONS

Shunting INPH patients on the basis of CSF pressure monitoring and drainage response shows a significant rate of cognitive improvement, and baseline neurocognitive test scores may distinguish patients likely to respond to shunt surgery from those who will not.