Change search
ReferencesLink to record
Permanent link

Direct link
The pulsatility curve: the relationship between mean intracranial pressure and pulsation amplitude
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.ORCID iD: 0000-0001-6451-1940
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
2010 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 31, no 11, 1517-1528 p.Article in journal (Refereed) Published
Abstract [en]

The amplitude of cardiac-related pulsations in intracranial pressure has recently been suggested as useful for selecting patients for shunt surgery in hydrocephalus. To better understand how shunting affects these pulsations, we aim to model the relationship between mean pressure and pulsation amplitude in a wide range, including low pressures typically found after shunt surgery. Twenty-five patients with probable idiopathic normal pressure hydrocephalus were examined with lumbar constant pressure infusion investigations including drainage of cerebrospinal fluid. Mean pressure and pulsation amplitude were determined for consecutive 1.5 s intervals, starting at peak pressure (ca 35 mmHg), after infusion, continuing during spontaneous return to baseline and drainage to 0 mmHg. The amplitude versus pressure relationship revealed a linear phase at higher pressures (14-32 mmHg, lack of fit test: p = 0.79), a transitional phase and an essentially constant phase at low pressures (0-10 mmHg, slope = -0.02, lack of fit test: p = 0.88). Individual patients' baseline values were found in all three phases. The model and methodology presented in this paper can be used to preoperatively identify patients with potential for postoperative amplitude decrease and to predict how much the amplitude can be reduced.

Place, publisher, year, edition, pages
2010. Vol. 31, no 11, 1517-1528 p.
Keyword [en]
normal pressure hydrocephalus, pulse pressure, amplitudes, cerebrospinal fluid pressure, intracranial pressure, infusion test, arterial pulsaations
National Category
Medical Engineering Neurology
Research subject
URN: urn:nbn:se:umu:diva-37363DOI: 10.1088/0967-3334/31/11/008ISI: 000283491900011PubMedID: 20938063OAI: diva2:359701
Available from: 2010-10-29 Created: 2010-10-28 Last updated: 2015-10-01Bibliographically approved
In thesis
1. Analysis of ICP pulsatility and CSF dynamics: the pulsatility curve and effects of postural changes, with implications for idiopathic normal pressure hydrocephalus
Open this publication in new window or tab >>Analysis of ICP pulsatility and CSF dynamics: the pulsatility curve and effects of postural changes, with implications for idiopathic normal pressure hydrocephalus
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Analys av ICP-pulsationer och CSF-dynamik : pulsationskurvan och effekter av ändrad kroppsposition, med implikationer för idiopatisk normaltryckshydrocefalus
Abstract [en]

The volume defined by the rigid cranium is shared by the brain, blood and cerebrospinal fluid (CSF). With every heartbeat the arterial blood volume briefly increases and venous blood and CSF are forced out of the cranium, leading to pulsatility in CSF flow and intracranial pressure (ICP). Altered CSF pulsatility has been linked to idiopathic normal pressure hydrocephalus (INPH), which involves enlarged cerebral ventricles and symptoms of gait/balance disturbance, cognitive decline and urinary incontinence that may be improved by implantation of a shunt. The overall aim of this thesis was to investigate the fluid dynamics of the CSF system, with a focus on pulsatility, and how they relate to INPH pathophysiology and treatment.

Mathematical modelling was applied to data from infusion tests, where the ICP response to CSF volume manipulation is measured, to analyse the relationship between mean ICP and ICP pulse amplitude (AMP) before and after shunt surgery in INPH (paper I-II). The observed relationship, designated the pulsatility curve, was found to be constant at low ICP and linear at high ICP, corresponding to a shift from constant to ICP dependent compliance (paper I). Shunt surgery did not affect the pulsatility curve, but shifted baseline ICP and AMP along the curve towards lower values. Patients who improved in gait after surgery had significantly larger AMP reduction than those who did not, while ICP reduction was similar, suggesting that improving patients had baseline ICP in the linear zone of the curve before surgery. Use of this phenomenon for outcome prediction was promising (paper II). The fluid dynamics of an empirically derived pulsatility-based predictive infusion test for INPH was also investigated, with results showing strong influence from compliance (paper III).

Clinical ICP data at different body postures was used to evaluate three models describing postural effects on ICP. ICP decreased in upright positions, whereas AMP increased. The model describing the postural effects based on hydrostatic changes in the venous system, including effects of collapse of the jugular veins in the upright position, accurately predicted the measured ICP (paper IV).

Cerebral blood flow and CSF flow in the aqueduct and at the cervical level was measured with phase contrast magnetic resonance imaging, and compared between healthy elderly and INPH (paper V). Cerebral blood flow and CSF flow at the cervical level were similar in INPH patients and healthy elderly, whereas aqueductal CSF flow differed significantly. The pulsatility in the aqueduct flow was increased, and there was more variation in the net flow in INPH, but the mean net flow was normal, i.e. directed from the ventricles to the subarachnoid space (paper V).

In conclusion, this thesis introduced the concept of pulsatility curve analysis, and provided evidence that pulsatility and compliance are important aspects for successful shunt treatment and outcome prediction in INPH. It was further confirmed that enhanced pulsatility of aqueduct CSF flow was the most distinct effect of INPH pathophysiology on cerebral blood flow and CSF flow. A new model describing postural and hydrostatic effects on ICP was presented, and the feasibility and potential importance of measuring ICP in the upright position in INPH was demonstrated. 

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2013. 79 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1613
Cerebrospinal fluid, CSF dynamics, Intracranial pressure, Pulse pressure, Normal pressure hydrocephalus, Posture, Predictive tests, Mathematical modelling, Magnetic resonance imaging, Infusion tests
National Category
Medical Engineering
urn:nbn:se:umu:diva-82784 (URN)978-91-7459-762-2 (ISBN)
Public defence
2013-12-06, Hörsal E 04, Unod R1, Norrlands Universitetssjukhus, Umeå, 13:00 (English)
Swedish Research Council, 221-2011-5216Swedish Research Council, VR3011-2006-7551Vinnova, VR3011-2006-7551Swedish Foundation for Strategic Research , VR3011-2006-7551


European Union, ERDF: Objective 2, Northern Sweden (grant no. 158715-CMTF). 

Available from: 2013-11-15 Created: 2013-11-11 Last updated: 2015-10-01Bibliographically approved

Open Access in DiVA

fulltext(310 kB)139 downloads
File information
File name FULLTEXT02.pdfFile size 310 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Qvarlander, SaraMalm, JanEklund, Anders
By organisation
Radiation PhysicsNeurology
In the same journal
Physiological Measurement
Medical EngineeringNeurology

Search outside of DiVA

GoogleGoogle Scholar
Total: 139 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 78 hits
ReferencesLink to record
Permanent link

Direct link