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Idiopathic Normal Pressure Hydrocephalus: Cerebrospinal Fluid Tap Test and Magnetic Resonance Imaging as Preoperative Prognostic Investigations
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Idiopathic normal pressure hydrocephalus (iNPH) is a condition with dilated cerebral ventricles but intracranial pressure within normal limits. The symptoms of gait impairment, cognitive decline and urinary incontinence develop gradually. Treatment with shunt insertion results in improvement in eight out of ten patients.

The cerebrospinal fluid tap test (CSF TT) and preoperative magnetic resonance imaging (MRI) are methods used to select patients who may benefit from shunt surgery, but they are performed and interpreted differently in different centers throughout the world. The aim of this thesis was to evaluate the performance of the CSF TT and the underlying mechanisms of improvement in gait function after CSF removal, and to investigate the prognostic value of preoperative MRI scans.

Improvement in gait and changes in cerebral blood flow (CBF) after a CSF TT were investigated in two prospective studies that included 39 and 20 patients, respectively. Gait assessment and perfusion MRI were done before and several times during the first 24 hours after a CSF TT. Perfusion was investigated with pseudo-continuous arterial spin labeling. At the group level, gait function was significantly improved at all investigation times, but only one-third of individual CSF TT responders were improved at all investigation times. In patients with increased CBF in lateral and frontal white matter after the CSF TT, gait function improved more than it did in patients with decreased CBF in these regions. However, in the whole sample, there was no significant increase in CBF after CSF removal.

Preoperative MRI scans were retrospectively evaluated in 109 patients with iNPH who had undergone shunt surgery. The callosal angle was smaller in shunt responders compared with non-responders. The following findings showed the highest association with a positive outcome after shunting: a small callosal angle, wide temporal horns, and occurrence of disproportionally enlarged subarachnoid space hydrocephalus.

In conclusion, CBF in white matter close to the lateral ventricles may play a role in the reversibility of symptoms after CSF removal in patients with iNPH. The CSF TT should be reevaluated if the patient does not initially improve, and preoperative MRI investigations can add prognostic information regarding the selection of shunt candidates.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. , 98 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1001
Keyword [en]
normal pressure hydrocephalus, NPH, cerebrospinal fluid disorders, dementia, MRI, CSF tap test, CBF, ASL
National Category
Neurology
Research subject
Neurology; Neurosurgery; Radiology
Identifiers
URN: urn:nbn:se:uu:diva-222779ISBN: 978-91-554-8958-8 (print)OAI: oai:DiVA.org:uu-222779DiVA: diva2:713530
Public defence
2014-06-09, Gunnesalen, Akademiska sjukhuset, ing 10, 751 85, Uppsala, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2014-05-19 Created: 2014-04-14 Last updated: 2014-06-30
List of papers
1. The CSF tap test in normal pressure hydrocephalus: evaluation time, reliability and the influence of pain
Open this publication in new window or tab >>The CSF tap test in normal pressure hydrocephalus: evaluation time, reliability and the influence of pain
2012 (English)In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 19, no 2, 271-276 p.Article in journal (Refereed) Published
Abstract [en]

Background:  The cerebrospinal fluid tap test (TT) is a diagnostic tool used to select patients with idiopathic normal pressure hydrocephalus (iNPH) for shunt surgery. The procedure and the evaluation of the TT vary between centres. We aimed to describe the evaluation time after the TT, to assess the variability between repeated measurements, the interrater agreement of the gait tests chosen and finally to investigate whether pain affects the gait performance post-TT.

Methods:  Forty patients (21 men and 19 women) under evaluation for iNPH underwent a TT. Standardized gait analyses were performed before and 2, 4, 6, 8 and 24 h after the TT and repeated twice on every occasion. Independent of each other, two investigators evaluated the quality of gait. At each assessment time, the patients graded headache and back pain on a visual analogue scale.

Results:  Twenty-seven patients (15 men and 12 women) responded to TT. Improvements in gait speed and number of steps were significant at every assessment time post-TT. The variability between two measurements was low (Intra class correlation coefficient = 0.97), and the inter-rater agreement was good with a κ = 0.74. Pain correlated negatively with improvement in gait speed (r = -0.40, P < 0.05).

Conclusions:  We suggest that the TT can be evaluated at any time within the first 24 h and should be repeated if the patient does not initially improve. Gait analysis appears reliable between two evaluators. Further, it is indicated that post-lumbar puncture pain negatively affects the gait and should be minimized.

National Category
Neurology
Research subject
Neurology
Identifiers
urn:nbn:se:uu:diva-159825 (URN)10.1111/j.1468-1331.2011.03486.x (DOI)000299255300018 ()21801282 (PubMedID)
Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2017-12-08Bibliographically approved
2. The callosal angle measured on MRI as a predictor of outcome in idiopathic normal-pressure hydrocephalus
Open this publication in new window or tab >>The callosal angle measured on MRI as a predictor of outcome in idiopathic normal-pressure hydrocephalus
2014 (English)In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 120, no 1, 178-184 p.Article in journal (Refereed) Published
Abstract [en]

Object

Different neuroimaging biomarkers have been studied to find a tool for prediction of response to CSF shunting in idiopathic normal-pressure hydrocephalus (iNPH). The callosal angle (CA) has been described as useful in discriminating iNPH from ventricular dilation secondary to atrophy. However, the usefulness of the CA as a prognostic tool for the selection of shunt candidates among patients with iNPH is unclear. The aim of this study was to compare the CA in shunt responders with that in nonresponders and clarify whether the CA can serve as a predictor of the outcome.

Methods

Preoperative MRI brain scans were evaluated in 109 patients who had undergone shunt surgery for iNPH during 2006-2010. Multiplanar reconstruction was performed interactively to obtain a coronal image through the posterior commissure, perpendicular to the anterior-posterior commissure plane. The CA was measured as the angle between the lateral ventricles on the coronal image. The patients were examined clinically before surgery and at 12 months postoperatively.

Results

Shunt responders had a significantly smaller mean preoperative CA compared with nonresponders: 59° (95% CI 56°-63°) versus 68° (95% CI 61°-75°) (p < 0.05). A CA cutoff value of 63° showed the best prognostic accuracy.

Conclusions

The preoperative CA is smaller in patients whose condition improves after shunt surgery and may be a useful tool in the selection of shunt candidates among patients with iNPH.

Place, publisher, year, edition, pages
http://thejns.org/action/showCoverGallery?journalCode=jns: , 2014
National Category
Medical and Health Sciences Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-208803 (URN)10.3171/2013.8.JNS13575 (DOI)000329087900027 ()24074491 (PubMedID)
Available from: 2013-10-08 Created: 2013-10-08 Last updated: 2017-12-06Bibliographically approved
3. Preoperative Prognostic Value of MRI Findings in 109 Patients with Idiopathic Normal Pressure Hydrocephalus
Open this publication in new window or tab >>Preoperative Prognostic Value of MRI Findings in 109 Patients with Idiopathic Normal Pressure Hydrocephalus
(English)Manuscript (preprint) (Other academic)
National Category
Neurology
Research subject
Neurology; Neurosurgery; Radiology
Identifiers
urn:nbn:se:uu:diva-222769 (URN)
Available from: 2014-04-14 Created: 2014-04-14 Last updated: 2014-06-30
4. Idiopathic normal pressure hydrocephalus: cerebral perfusion measured with pCASL before and repeatedly after CSF removal
Open this publication in new window or tab >>Idiopathic normal pressure hydrocephalus: cerebral perfusion measured with pCASL before and repeatedly after CSF removal
Show others...
2014 (English)In: Journal of Cerebral Blood Flow and Metabolism, ISSN 0271-678X, E-ISSN 1559-7016, Vol. 34, no 11, 1771-1778 p.Article in journal (Refereed) Published
Abstract [en]

Pseudo-continuous arterial, spin labeling (pCASL) measurements were performed in 20 patients with idiopathic normal pressure hydrocephalus (iNPH) to investigate whether cerebral blood flow (CBF) increases during the first 24 hours after a cerebrospinal fluid tap test (CSF TT). Five pCASL magnetic resonance imaging (MRI) scans were performed. Two scans were performed before removal of 40 mL CSF, and the other three at 30 minutes, 4 hours, and 24 hours, respectively after the CSF TT. Thirteen different regions of interest (ROIs) were manually drawn on coregistered MR images. In patients with increased CBF in lateral and frontal white matter after the CSF TT, gait function improved more than it did in patients with decreased CBF in these regions. However, in the whole sample, there was no significant increase in CBF after CSF removal compared with baseline investigations. The repeatability of CBF measurements at baseline was high, with intraclass correlation coefficients of 0.60 to 0.90 for different ROIs, but the median regional variability was in the range of 5% to 17%. Our results indicate that CBF in white matter close to the lateral ventricles plays a role in the reversibility of symptoms after CSF removal in patients with iNPH.

Keyword
arterial spin labeling, cerebral blood flow, cerebral perfusion, normal pressure hydrocephalus, pCASL, volumetry
National Category
Neurology
Research subject
Neurology; Neurosurgery; Radiology; Neuroscience
Identifiers
urn:nbn:se:uu:diva-222771 (URN)10.1038/jcbfm.2014.138 (DOI)000344428800005 ()25138210 (PubMedID)
Available from: 2014-04-14 Created: 2014-04-14 Last updated: 2017-12-05Bibliographically approved

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