CPT-3 in Normal Pressure Hydrocephalus
CPT-3 in Normal Pressure Hydrocephalus
The study will collect prospective cohort data of individuals that are undergoing routine
 clinical care for suspected idiopathic Normal Pressure Hydrocephalus (NPH). The
 administration of the Conner's Continual Performance Test - version 3 (CPT-3), an automated
 14-minute computerized measure of reaction-time and sustained attention, will be added to the
 current neurocognitive screen being used (i.e., the Montreal Cognitive Assessment, MoCA)
 along with gait assessment. Patients will undergo pre-tap testing on the morning of their
 large volume Lumbar Puncture (CSF-TT). These patients will receive post-tap CPT-3 and MoCA
 testing one-to-three hours post-tap, and again at 2-3 days post-CSF-TT, during the follow-up
 appointment in clinic.

 The standard NPH quantitative assessment methods of MoCA and gait evaluation will continue to
 be collected. For those patients that ultimately undergo ventricular shunt placement, the
 CPT-3 will be administered at their post-operative follow-up appointment (~3 months
 post-operation). The results of CPT-3 will not factor into consideration for shunt candidacy.
Normal pressure hydrocephalus (NPH) is a syndrome involving the clinical triad of gait
 disturbance, urinary incontinence, and cognitive dysfunction, in the context of ventricular
 enlargement out of proportion to parenchymal atrophy with normal intracranial pressure.

 In the 1980's, a protocol for quantitative measurement of symptom response to large volume
 CSF tap (40-50ml) was developed, as a method for evaluating suitability for undergoing
 ventricular shunting surgery. A 2016 systematic review of the literature noted heterogeneous
 findings within the eight prospective cohort studies that were included in analysis, but
 concluded that there appeared to be support for the CSF-TT as a rule-in screen for response
 to shunt placement.

 Unfortunately, no extant literature has analyzed the independent predictive power of a
 clinically significant reaction time improvement in response to CSF-TT (widely defined across
 the literature as 5% improvement) to subsequent response to ventricular shunting. This
 frustrates an a priori power analysis. However, a rough estimate was calculated based on data
 presented within one of the aforementioned reviewed studies that identified an improvement in
 reaction time in response to CSF-TT, as well as an improvement in reaction time to subsequent
 shunting.

 The authors reported that 17 of 68 (25%) of the patients were labeled as positive-responders
 to CSF-TT, defined as meeting at least 2 of the following criteria: 1) 5% improvement in
 reaction time, 2) 5% improvement in gait (time or steps), 3) 25% improvement on visuospatial
 recall task, 4) 25% improvement on visuospatial recognition task. Of those 17 positive
 responders, 16 (94%) met the same positive-response criteria, post-shunting. If we use a 50%
 response rate as a proportion null hypothesis, this gives us a z-statistic = 3.63, or f2 =
 3.71. G*Power analysis, for a 4-predictor regression (i.e., the aforementioned indicators
 used), estimates a necessary sample size of 16. The primary limitation of this approach is
 that it is unclear which of the 2+ positive response criteria were met. However, review of
 the pre- versus post-shunting data suggests reaction time was significantly improved
 (p<0.001; Cohen's d = 0.399), suggesting it is reasonable to infer the domain was favorably
 impacted by the temporary effects of a CSF-TT.

 Patients will undergo pre-tap testing on the morning of their CSF-TT. The administration of
 the Conners Continual Performance Test - version 3 (CPT-3), an automated 14-minute
 computerized measure of reaction-time and sustained attention, will be added to the current
 neurocognitive screen being used (i.e., the Montreal Cognitive Assessment, MoCA). The current
 CSF-TT protocol's quantitative methods for measuring urinary incontinence and gait will
 continue to be collected. These patients will receive post-tap CPT-3 and MoCA testing
 one-to-three hours post-tap, and again at 2-3 days post-CSF-TT, during the follow-up
 appointment with Neurosurgery. For those that undergo ventricular shunt placement, the CPT-3
 will be administered at their post-operative follow-up appointment (~3 months
 post-operation).
Inclusion Criteria:

 -  patients being referred for CSF tap test as part of routine clinical assessment of
 idiopathic Normal Pressure Hydrocephalus by their medical provider

 -  adults older than 18 years old

 Exclusion Criteria:

 -  premorbid neurodegenerative disease (e.g. Alzheimer's Disease, Frontotemproal
 Dementia, Parkinson's Disease)

 -  serious acquired brain injury such as moderate to severe traumatic brain injury, large
 ischemic strokes

 -  seizure disorders

 -  serious neuropsychiatric disease (e.g. schizophrenia, bipolar disorder, major
 depressive disorder, active alcohol or drug abuse)

 -  untreated vitamin deficiencies (B12, Wernicke-Korsakoff Syndrome)