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Measurements in Idiopathic Normal Pressure Hydrocephalus: Computerized neuropsychological test battery and intracranial pulse waves
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.ORCID iD: 0000-0002-9099-0348
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Idiopathic Normal Pressure Hydrocephalus (INPH) is a condition affecting gait, cognition and continence. Radiological examination reveals enlarged ventricles of the brain. A shunt that drains CSF from the ventricles to the abdomen often improves the symptoms. Much research on INPH has been focused on identifying tests that predict the outcome after shunt surgery. As part of this quest, there are attempts to find measurement methods of intracranial parameters that are valid, reliable, tolerable and safe for patients.

Today's technologies for intracranial pressure (ICP) measurement are invasive, often requiring a burr-hole in the skull. Recently, a method for non-invasive ICP measurements was suggested: the Pulsatile Index (PI) calculated from transcranial Doppler data assessed from the middle cerebral artery. In this thesis the relation between PI and ICP was explored in INPH patients during controlled ICP regulation by lumbar infusion. The confidence interval for predicted ICP, based on measured PI was too large for the method to be of clinical utility.

In the quest for better predictive tests for shunt success in INPH, recent studies have shown promising results with criteria based on cardiac related ICP wave amplitudes. The brain ventricular system, and the fluid surrounding the spinal cord are in contact. In this thesis it was shown that ICP waves could be measured via lumbar subarachnoid space, with a slight underestimation.

One of the cardinal symptoms of hydrocephalus is cognitive impairment. Neuropsychological studies have demonstrated cognitive tests that are impaired and improve after shunt surgery in INPH patients. However, there is currently no standardized test battery and different studies use different tests. In response, in this thesis a fully automated computerized neuropsychological test battery was developed. The validity, reliability, responsiveness to improvement after shunt surgery and feasibility for testing INPH patients was demonstrated. It was also demonstrated that INPH patients were impaired in all subtests, compared to healthy elderly. 

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2014. , 67 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1689
Keyword [en]
Hydrocephalus, Normal Pressure; Neuropsychological tests; Neuropsychology; Reliability and validity; Software; Dementia; intracranial pressure; spinal puncture; cerebrospinal fluid pressure; pulse pressure waves; Blood flow velocity; Middle cerebral artery; Pulsatility index
National Category
Medical and Health Sciences
Research subject
Neurology
Identifiers
URN: urn:nbn:se:umu:diva-96195ISBN: 978-91-7601-155-3 (print)OAI: oai:DiVA.org:umu-96195DiVA: diva2:762579
Public defence
2014-12-05, Sal E04 Unod R1, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2014-11-14 Created: 2014-11-12 Last updated: 2015-10-01Bibliographically approved
List of papers
1. Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.
Open this publication in new window or tab >>Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.
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2010 (English)In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 66, no 6, 1050-1057 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Transcranial Doppler sonography (TCD) assessment of intracranial blood flow velocity has been suggested to accurately determine intracranial pressure (ICP). OBJECTIVE: We attempted to validate this method in patients with communicating cerebrospinal fluid systems using predetermined pressure levels. METHODS: Ten patients underwent a lumbar infusion test, applying 4 to 5 preset ICP levels. On each level, the pulsatility index (PI) in the middle cerebral artery was determined by measuring the blood flow velocity using TCD. ICP was simultaneously measured with an intraparenchymal sensor. ICP and PI were compared using correlation analysis. For further understanding of the ICP-PI relationship, a mathematical model of the intracranial dynamics was simulated using a computer. RESULTS: The ICP-PI regression equation was based on data from 8 patients. For 2 patients, no audible Doppler signal was obtained. The equation was ICP = 23*PI + 14 (R = 0.22, P < .01, N = 35). The 95% confidence interval for a mean ICP of 20 mm Hg was -3.8 to 43.8 mm Hg. Individually, the regression coefficients varied from 42 to 90 and the offsets from -32 to +3. The mathematical simulations suggest that variations in vessel compliance, autoregulation, and arterial pressure have a serious effect on the ICP-PI relationship. CONCLUSIONS: The in vivo results show that PI is not a reliable predictor of ICP. Mathematical simulations indicate that this is caused by variations in physiological parameters.

Keyword
Blood flow velocity, hydrocephalus, intracranial pressure, middle cerebral artery, pulsatility indix
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-34863 (URN)10.1227/01.NEU.0000369519.35932.F2 (DOI)000278006200018 ()20495421 (PubMedID)
Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved
2. In Reply
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2010 (English)In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 67, no 6, 1864- p.Article in journal, Letter (Other (popular science, discussion, etc.)) Published
National Category
Medical and Health Sciences
Research subject
Neurology
Identifiers
urn:nbn:se:umu:diva-96193 (URN)10.1227/NEU.0b013e3181fdbf39 (DOI)
Available from: 2014-11-12 Created: 2014-11-12 Last updated: 2017-12-05
3. Intracranial Pressure and Pulsatility Index:  
Open this publication in new window or tab >>Intracranial Pressure and Pulsatility Index:  
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2011 (English)In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 69, no 4, E1033-E1034 p.Article in journal (Refereed) Published
Keyword
intracranial pressure, transcranial Doppler ultrasound
Identifiers
urn:nbn:se:umu:diva-45852 (URN)10.1227/NEU.0b013e31822999b7 (DOI)21694654 (PubMedID)
Available from: 2011-08-18 Created: 2011-08-18 Last updated: 2017-12-08Bibliographically approved
4. Are intracranial pressure wave amplitudes measurable through lumbar puncture?
Open this publication in new window or tab >>Are intracranial pressure wave amplitudes measurable through lumbar puncture?
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2013 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 127, no 4, 233-241 p.Article in journal (Refereed) Published
Abstract [en]

 Objective The aim of this study was to investigate whether pulsations measured in the brain correspond to those measured in lumbar space, and subsequently whether lumbar punctures could replace invasive recordings. Methods In ten patients with normal pressure hydrocephalus, simultaneous recordings of the intracranial pressure (ICP; intraparenchymal) and lumbar pressure (LP; cerebrospinal fluid pressure) were performed. During registration, pressure was altered between resting pressure and 45mmHg using an infusion test. Data were analyzed regarding pulsations (i.e., amplitudes). Also, the pressure sensors were compared in a bench test. Results The correlation between intracranial and lumbar amplitudes was 0.98. At resting pressure, and moderately elevated ICP, intracranial pulse amplitudes exceeded that of lumbar space with about 0.9mmHg. At the highest ICP, the difference changed to 0.2mmHg. The bench test showed that the agreement of sensor readings was good at resting pressure, but reduced at higher amplitudes. Conclusions Compared to intracranial registrations, amplitudes measured through lumbar puncture were slightly attenuated. The bench test showed that differences were not attributable to dissimilarities of the sensor systems. A lumbar pressure amplitude measurement is an alternative to ICP recording, but the thresholds for what should be interpreted as elevated amplitudes need to be adjusted.

Keyword
intracranial pressure, spinal puncture, cerebrospinal fluid pressure, hydrocephalus, normal pressure, pulse pressure waves
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-68250 (URN)10.1111/j.1600-0404.2012.01701.x (DOI)000316215900004 ()
Available from: 2013-04-18 Created: 2013-04-15 Last updated: 2017-12-06Bibliographically approved
5. A computerized neuropsychological test battery designed for idiopathic normal pressure hydrocephalus
Open this publication in new window or tab >>A computerized neuropsychological test battery designed for idiopathic normal pressure hydrocephalus
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2014 (English)In: Fluids and Barriers of the CNS, ISSN 2045-8118, E-ISSN 2045-8118, Vol. 11, 22Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: A tool for standardized and repeated neuropsychological assessments in patients with idiopathic normal pressure hydrocephalus (INPH) is needed. The objective of this study was to develop a computerized neuropsychological test battery designed for INPH and to evaluate its reliability, validity and patient's ability to complete the tests.

METHODS: Based on a structured review of the literature on neuropsychological testing in INPH, the eight tests most sensitive to the INPH cognitive profile were implemented in a computerized format. The Geriatric Depression Scale (GDS) was also included. Tests were presented on a touch-screen monitor, with animated instructions and speaker sound. The battery was evaluated with the following cohorts: A. Test-retest reliability, 44 healthy elderly; B. Validity against standard pen and pencil testing, 28 patients with various cognitive impairments; C. Ability to complete test battery, defined as completion of at least seven of the eight tests, 40 investigated for INPH.

RESULTS: A. All except the figure copy test showed good test-retest reliability, r = 0.67-0.90; B. A high correlation was seen between conventional and computerized tests (r = 0.66-0.85) except for delayed recognition and figure copy task; C. Seventy-eight percent completed the computerized battery; Patients diagnosed with INPH (n = 26) performed worse on all tests, including depression score, compared to healthy controls.

CONCLUSIONS: A new computerized neuropsychological test battery designed for patients with communicating hydrocephalus and INPH was introduced. Its reliability, validity for general cognitive impairment and completion rate for INPH was promising. After exclusion of the figure copy task, the battery is ready for clinical evaluation and as a next step we suggest validation for INPH and a comparison before and after shunt surgery.

TRIAL REGISTRATION: ClinicalTrials.org NCT01265251.

Keyword
Dementia, Hydrocephalus, Normal pressure, Neuropsychological tests, Neuropsychology, Reliability and validity, Software
National Category
Psychiatry Neurology
Research subject
Neurology
Identifiers
urn:nbn:se:umu:diva-96190 (URN)10.1186/2045-8118-11-22 (DOI)25279138 (PubMedID)
Available from: 2014-11-12 Created: 2014-11-12 Last updated: 2017-12-05Bibliographically approved
6. The Computerized General Neuropsychological INPH Test (CoGNIT) revealed improvement in Idiopathic Normal Pressure Hydrocephalus (INPH) after shunt surgery
Open this publication in new window or tab >>The Computerized General Neuropsychological INPH Test (CoGNIT) revealed improvement in Idiopathic Normal Pressure Hydrocephalus (INPH) after shunt surgery
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background

We have developed the COmputerized General Neuropsychological INPH Test (CoGNIT) dedicated for patients with idiopathic normal pressure hydrocephalus (INPH). Previously, validity and reliability of included tests have been established. The aim was to evaluate the battery’s sensitivity to detect cognitive changes after shunt surgery in INPH patients.

Methods

Preoperatively, thirty-one INPH patients were given CoGNIT, which includes tests assessing memory, executive functions, attention, manual dexterity and psychomotor speed. CoGNIT also includes the Geriatric Depression Scale (GDS). Re-examination was done four months after shunt surgery. Scores and test completion were examined and compared to healthy elderly (n=44).

Results

Preoperative INPH test results were significantly lower in all tests compared to healthy. Improvements after shunt surgery were seen in all cognitive domains: memory (Ten-word list test, p<0,01), executive functions (Stroop incongruent, (p<0.05), attention (Two choice reaction test, p<0.01), psychomotor speed (Stroop congruent, p<0.05) and manual dexterity (Four- finger tapping, p<0.01). No ceiling effects were observed. Depressive symptoms were more common in INPH versus healthy and did not change postoperatively. Preoperatively 81 % of INPH patients completed at least eight of the nine included test.

Conclusions

CoGNIT is sensitive to cognitive impairment and to investigate changes after shunt surgery in INPH. Completion rates are good. CoGNIT has a potential to be useful in the cognitive assessment of INPH. 

National Category
Medical and Health Sciences
Research subject
Neurology
Identifiers
urn:nbn:se:umu:diva-96194 (URN)
Available from: 2014-11-12 Created: 2014-11-12 Last updated: 2014-11-13

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