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Qvarlander, Sara, Teknisk doktor
Publications (10 of 20) Show all publications
Holmlund, P., Qvarlander, S., Malm, J. & Eklund, A. (2019). Can pulsatile CSF flow across the cerebral aqueduct cause ventriculomegaly?: A prospective study of patients with communicating hydrocephalus.. Fluids and Barriers of the CNS, 16(1), Article ID 40.
Open this publication in new window or tab >>Can pulsatile CSF flow across the cerebral aqueduct cause ventriculomegaly?: A prospective study of patients with communicating hydrocephalus.
2019 (English)In: Fluids and Barriers of the CNS, ISSN 2045-8118, E-ISSN 2045-8118, Vol. 16, no 1, article id 40Article in journal (Refereed) Published
Abstract [en]

Background: Communicating hydrocephalus is a disease where the cerebral ventricles are enlarged. It is characterized by the absence of detectable cerebrospinal fluid (CSF) outflow obstructions and often with increased CSF pulsatility measured in the cerebral aqueduct (CA). We hypothesize that the cardiac-related pulsatile flow over the CA, with fast systolic outflow and slow diastolic inflow, can generate net pressure effects that could source the ventriculomegaly in these patients. This would require a non-zero cardiac cycle averaged net pressure difference (ΔPnet) over the CA, with higher average pressure in the lateral and third ventricles.

Methods: We tested the hypothesis by calculating ΔPnet across the CA using computational fluid dynamics based on prospectively collected high-resolution structural (FIESTA-C, resolution 0.39 × 0.39 × 0.3 mm3) and velocimetric (2D-PCMRI, in-plane resolution 0.35 × 0.35 mm2) MRI-data from 30 patients investigated for communicating hydrocephalus.

Results: The ΔPnet due to CSF pulsations was non-zero for the study group (p = 0.03) with a magnitude of 0.2 ± 0.4 Pa (0.001 ± 0.003 mmHg), with higher pressure in the third ventricle. The maximum pressure difference over the cardiac cycle ΔPmax was 20.3 ± 11.8 Pa and occurred during systole. A generalized linear model verified an association between ΔPnet and CA cross-sectional area (p = 0.01) and flow asymmetry, described by the ratio of maximum inflow/outflow (p = 0.04), but not for aqueductal stroke volume (p = 0.35).

Conclusions: The results supported the hypothesis with respect to the direction of ΔPnet, although the magnitude was low. Thus, although the pulsations may generate a pressure difference across the CA it is likely too small to explain the ventriculomegaly in communicating hydrocephalus.

Place, publisher, year, edition, pages
BioMed Central, 2019
Keywords
Communicating hydrocephalus, computational fluid dynamics, cerebrospinal fluid pressure, brain imaging, cerebral aqueduct
National Category
Medical Engineering
Identifiers
urn:nbn:se:umu:diva-157029 (URN)10.1186/s12987-019-0159-0 (DOI)000504082400001 ()31865917 (PubMedID)
Funder
Swedish National Space BoardSwedish Research Council, grant 2015-05616Swedish Heart Lung Foundation, grant 20140592
Note

Originally included in thesis in manuscript form

Available from: 2019-03-06 Created: 2019-03-06 Last updated: 2020-01-09Bibliographically approved
Jacobsson, J., Qvarlander, S., Eklund, A. & Malm, J. (2019). Comparison of the CSF dynamics between patients with idiopathic normal pressure hydrocephalus and healthy volunteers. Journal of Neurosurgery, 131(4), 1018-1023
Open this publication in new window or tab >>Comparison of the CSF dynamics between patients with idiopathic normal pressure hydrocephalus and healthy volunteers
2019 (English)In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 131, no 4, p. 1018-1023Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: Intracranial pressure (ICP), outflow resistance (Rout), and amplitude of cardiac-related ICP pulsations (AMPs) are established parameters to describe the CSF hydrodynamic system and are assumed, but not confirmed, to be disturbed in idiopathic normal pressure hydrocephalus (INPH). The aim of this study was to compare the CSF hydrodynamic profile between patients with INPH and healthy volunteers.

METHODS: Sixty-two consecutive INPH patients (mean age 74 years) and 40 healthy volunteers (mean age 70 years) were included. Diagnosis was made by two independent neurologists who assessed patients’ history, neurological status, and MRI studies. A CSF dynamic investigation through the lumbar route was performed: ICP and other CSF dynamic variables were blinded to the neurologists during the diagnostic process and were not used for establishing the diagnosis of INPH.

RESULTS: Rout was significantly higher in INPH (Rout 17.1 vs 11.1; p < 0.001), though a substantial number of INPH subjects had normal Rout. There were no differences between INPH patients and controls regarding ICP (mean 11.5 mm Hg). At resting pressure, there was a trend that AMP in INPH was increased (2.4 vs 2.0 mm Hg; p = 0.109). The relationship between AMP and ICP was that they shared the same slope, but the curve was significantly shifted to the left for INPH (reduced P0 [p < 0.05]; i.e., higher AMP for the same ICP).

CONCLUSIONS: This study established that the CSF dynamic profile of INPH deviates from that of healthy volunteers and that INPH should thus be regarded as a disease in which intracranial hydrodynamics are part of the pathophysiology.

Clinical trial registration no.: NCT01188382 (clinicaltrials.gov)

Place, publisher, year, edition, pages
American Association of Neurological Surgeons, 2019
Keywords
normal pressure hydrocephalus, gait disorders, cerebrospinal fluid, dementia, intracranial pressure, pulsatility
Identifiers
urn:nbn:se:umu:diva-164993 (URN)10.3171/2018.5.JNS173170 (DOI)000490249600005 ()30497143 (PubMedID)
Funder
Swedish Research Council, 2015-05616
Available from: 2019-11-08 Created: 2019-11-08 Last updated: 2019-11-08Bibliographically approved
Kristiansen, M., Linden, C., Qvarlander, S., Wåhlin, A., Ambarki, K., Hallberg, P., . . . Jóhannesson, G. (2018). Blood flow rate of ophthalmic artery in patients with normal tension glaucoma and healthy controls. Paper presented at Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), APR 29-MAY 03, 2018, Honolulu, HI. Investigative Ophthalmology and Visual Science, 59(9)
Open this publication in new window or tab >>Blood flow rate of ophthalmic artery in patients with normal tension glaucoma and healthy controls
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2018 (English)In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Purpose: To determine the blood flow rate of the ophthalmic artery (OA) in patients with Normal Tension Glaucoma (NTG) compared to age-matched healthy controls using phase-contrast magnetic resonance imaging (PCMRI).

Methods: Seventeen patients with treated NTG (11 female; mean age: 70±9 years) and 16 age-matched healthy controls (10 female; mean age: 71±9 years) underwent PCMRI using a 3-Tesla scanner as well as ophthalmological examinations including visual acuity, Goldmann Applanation Tonometry, Humphrey perimetry and fundoscopy. Ophthalmic blood flow was acquired using a 2D PCMRI sequence set to a spatial resolution of 0.35mm/pixel. Mean flow rate and cross-sectional area was calculated using Segment Software. The eye with the most severe glaucomatous damage classified by visual field index (VFI) was chosen for comparison. The primary outcome was blood flow rate of OA.

Results: The mean VFI was 41% ± 26 (mean±SD) for the worse NTG eyes. The intraocular pressure was 13.6±2.6 mmHg for NTG eyes and 13.8±2.1 mmHg for control eyes. The blood flow rate in the NTG group was 9.6±3.7 ml/min compared to 11.8±5.5 ml/min in the control group. The area was 1.7±0.3 mm2 and 2.0±0.6 mm2 respectively. No statistical significance was found between NTG and the control group regarding blood flow rate (p=0.07) or OA area (p=0.12).

Conclusions: Despite OA being an anastomosis between the intracranial and extracranial circulation, possibly generating an eye unrelated variability in blood flow, we found a trend level reduction of approximately 2 ml/min in NTG. The finding warrants blood flow rate analysis of smaller arteries specifically supplying the eye, e.g. the central retinal artery.

Place, publisher, year, edition, pages
The Association for Research in Vision and Ophthalmology, 2018
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-152420 (URN)000442932805099 ()
Conference
Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), APR 29-MAY 03, 2018, Honolulu, HI
Funder
Swedish Society for Medical Research (SSMF)The Swedish Medical Association
Available from: 2018-10-05 Created: 2018-10-05 Last updated: 2018-10-08Bibliographically approved
Lindén, C., Qvarlander, S., Jóhannesson, G., Johansson, E., Östlund, F., Malm, J. & Eklund, A. (2018). Normal-Tension Glaucoma Has Normal Intracranial Pressure: A Prospective Study of Intracranial Pressure and Intraocular Pressure in Different Body Positions. Ophthalmology (Rochester, Minn.), 125(3), 361-368
Open this publication in new window or tab >>Normal-Tension Glaucoma Has Normal Intracranial Pressure: A Prospective Study of Intracranial Pressure and Intraocular Pressure in Different Body Positions
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2018 (English)In: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, no 3, p. 361-368Article in journal (Refereed) Published
Abstract [en]

PURPOSE: To test the hypothesis that normal-tension glaucoma (NTG) is caused by an increased pressure difference across the lamina cribrosa (LC) related to a low intracranial pressure (ICP).

DESIGN: Prospective case-control study.

PARTICIPANTS: Thirteen NTG patients (9 women; median 71 [range: 56-83] years) were recruited for investigation with the same protocol as 11 healthy volunteers (8 women; 47 [30-59] years). A larger control group (n = 51; 30 women; 68 [30-81] years) was used only for ICP comparison in supine position.

METHODS: ICP and intraocular pressure (IOP) were simultaneously measured in supine, sitting, and 9° head-down tilt (HDT) positions. Trans-lamina cribrosa pressure difference (TLCPD) was calculated using ICP and IOP together with geometric distances estimated from magnetic resonance imaging to adjust for hydrostatic effects.

MAIN OUTCOME MEASURES: ICP, IOP, and TLCPD in different body positions.

RESULTS: Between NTG patients and healthy volunteers, there were no differences in ICP, IOP, or TLCPD in supine, sitting, or HDT (P ≥ 0.11), except for IOP in HDT (P = 0.04). There was no correlation between visual field defect and TLCPD, IOP, or ICP and in any body position (P ≥ 0.39). Mean ICP in supine was 10.3 mmHg (SD = 2.7) in the NTG group (n = 13) and 11.3 (2.2) mmHg in the larger control group (n = 51) (P = 0.24).

CONCLUSIONS: There was no evidence of reduced ICP in NTG patients as compared with healthy controls, either in supine or in upright position. Consequently, the hypothesis that NTG is caused by an elevated TLCPD from low ICP was not supported.

National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-142423 (URN)10.1016/j.ophtha.2017.09.022 (DOI)000425377300015 ()29096996 (PubMedID)
Funder
Swedish Research Council, 2015-05616
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-06-21Bibliographically approved
Lindén, C., Qvarlander, S., Jóhannesson, G., Johansson, E., Östlund, F., Malm, J. & Eklund, A. (2018). Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY [Letter to the editor]. Ophthalmology (Rochester, Minn.), 125(6), e43-e44
Open this publication in new window or tab >>Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY
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2018 (English)In: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, no 6, p. e43-e44Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-148825 (URN)10.1016/j.ophtha.2018.01.006 (DOI)000432371600007 ()29784104 (PubMedID)
Note

Refers to: Baartman B, Sudhagoni R, Swan R, Greenwood M, Berdahl, J. Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) DOI: 10.1016/j.ophtha.2017.09.022

Available from: 2018-06-21 Created: 2018-06-21 Last updated: 2018-11-06Bibliographically approved
Lindén, C., Qvarlander, S., Jóhannesson, G., Johansson, E., Östlund, F., Malm, J. & Eklund, A. (2018). Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY [Letter to the editor]. Ophthalmology (Rochester, Minn.), 125(10), E74-E75
Open this publication in new window or tab >>Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY
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2018 (English)In: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, no 10, p. E74-E75Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-152382 (URN)10.1016/j.ophtha.2018.04.028 (DOI)000445012100008 ()30243346 (PubMedID)
Note

Refers to: Baartman B, Sudhagoni R, Swan R, Greenwood M, Berdahl, J. Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) DOI: 10.1016/j.ophtha.2017.09.022

Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2019-11-25Bibliographically approved
Holmlund, P., Eklund, A., Koskinen, L.-O. D., Johansson, E., Sundström, N., Malm, J. & Qvarlander, S. (2018). Venous collapse regulates intracranial pressure in upright body positions. American Journal of Physiology. Regulatory Integrative and Comparative Physiology, 314(3), R377-R385
Open this publication in new window or tab >>Venous collapse regulates intracranial pressure in upright body positions
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2018 (English)In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 314, no 3, p. R377-R385Article in journal (Refereed) Published
Abstract [en]

Recent interest in intracranial pressure (ICP) in the upright posture has revealed that the mechanisms regulating postural changes in ICP are not fully understood. We have suggested an explanatory model where the postural changes in ICP depend on well-established hydrostatic effects in the venous system and where these effects are interrupted by collapse of the internal jugular veins (IJVs) in more upright positions. The aim of this study was to investigate this relationship by simultaneous invasive measurements of ICP, venous pressure and IJV collapse in healthy volunteers. ICP (monitored via the lumbar route), central venous pressure (PICC-line) and IJV cross-sectional area (ultrasound) were measured in 11 healthy volunteers (47±10 years) in seven positions, from supine to sitting (0°-69°). Venous pressure and anatomical distances were used to predict ICP in accordance with the explanatory model, and IJV area was used to assess IJV collapse. The hypothesis was tested by comparing measured ICP to predicted ICP. Our model accurately described the general behavior of the observed postural ICP changes (mean difference: -0.03±2.7 mmHg). No difference was found between predicted and measured ICP for any tilt-angle (p-values: 0.65 - 0.94). The results support the hypothesis that postural ICP changes are governed by hydrostatic effects in the venous system and IJV collapse. This improved understanding of the postural ICP regulation may have important implications for the development of better treatments for neurological and neurosurgical conditions affecting ICP.

Place, publisher, year, edition, pages
American Physiological Society, 2018
Keywords
Intracranial pressure, healthy volunteers, hydrocephalus, posture, venous pressure
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-142424 (URN)10.1152/ajpregu.00291.2017 (DOI)000426326500006 ()29118021 (PubMedID)
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2019-03-06Bibliographically approved
Qvarlander, S., Ambarki, K., Wåhlin, A., Jacobsson, J., Birgander, R., Malm, J. & Eklund, A. (2017). Cerebrospinal fluid and blood flow patterns in idiopathic normal pressure hydrocephalus. Acta Neurologica Scandinavica, 135(5), 576-584
Open this publication in new window or tab >>Cerebrospinal fluid and blood flow patterns in idiopathic normal pressure hydrocephalus
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2017 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 135, no 5, p. 576-584Article in journal (Refereed) Published
Abstract [en]

Objectives: Increased aqueduct cerebrospinal fluid (CSF) flow pulsatility and, recently, a reversed CSF flow in the aqueduct have been suggested as hallmarks of idiopathic normal pressure hydrocephalus (INPH). However, these findings have not been adequately confirmed. Our objective was to investigate the flow of blood and CSF in INPH, as compared to healthy elderly, in order to clarify which flow parameters are related to the INPH pathophysiology.

Materials and Methods: Sixteen INPH patients (73 years) and 35 healthy subjects (72 years) underwent phase-contrast magnetic resonance imaging (MRI). Measurements included aqueduct and cervical CSF flow, total arterial inflow (tCBF; i.e. carotid + vertebral arteries), and internal jugular vein flow. Flow pulsatility, net flow, and flow delays were compared (multiple linear regression, correcting for sex and age).

Results: Aqueduct stroke volume was higher in INPH than healthy (148±95 vs 90±50 mL, P<.05). Net aqueduct CSF flow was similar in magnitude and direction. The cervical CSF stroke volume was lower (P<.05). The internal carotid artery net flow was lower in INPH (P<.05), although tCBF was not. No differences were found in internal jugular vein flow or flow delays.

Conclusions: The typical flow of blood and CSF in INPH was mainly characterized by increased CSF pulsatility in the aqueduct and reduced cervical CSF pulsatility. The direction of mean net aqueduct CSF flow was from the third to the fourth ventricle. Our findings may reflect the altered distribution of intracranial CSF volume in INPH, although the causality of these relationships is unclear.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
aqueduct flow, cerebral blood flow, cerebrospinal fluid, dementia, normal pressure hydrocephalus, phase-contrast magnetic resonance imaging
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-131143 (URN)10.1111/ane.12636 (DOI)000400156400012 ()27388230 (PubMedID)
Funder
Swedish Research Council, 221-2011-5216
Available from: 2017-02-06 Created: 2017-02-06 Last updated: 2018-06-09Bibliographically approved
Holmlund, P., Johansson, E., Qvarlander, S., Wåhlin, A., Ambarki, K., Koskinen, L.-O. D., . . . Eklund, A. (2017). Human jugular vein collapse in the upright posture: implications for postural intracranial pressure regulation. Fluids and Barriers of the CNS, 14, Article ID 17.
Open this publication in new window or tab >>Human jugular vein collapse in the upright posture: implications for postural intracranial pressure regulation
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2017 (English)In: Fluids and Barriers of the CNS, ISSN 2045-8118, E-ISSN 2045-8118, Vol. 14, article id 17Article in journal (Refereed) Published
Abstract [en]

Background: Intracranial pressure (ICP) is directly related to cranial dural venous pressure (P-dural). In the upright posture, P-dural is affected by the collapse of the internal jugular veins (IJVs) but this regulation of the venous pressure has not been fully understood. A potential biomechanical description of this regulation involves a transmission of surrounding atmospheric pressure to the internal venous pressure of the collapsed IJVs. This can be accomplished if hydrostatic effects are cancelled by the viscous losses in these collapsed veins, resulting in specific IJV cross-sectional areas that can be predicted from flow velocity and vessel inclination. Methods: We evaluated this potential mechanism in vivo by comparing predicted area to measured IJV area in healthy subjects. Seventeen healthy volunteers (age 45 +/- 9 years) were examined using ultrasound to assess IJV area and flow velocity. Ultrasound measurements were performed in supine and sitting positions. Results: IJV area was 94.5 mm(2) in supine and decreased to 6.5 +/- 5.1 mm(2) in sitting position, which agreed with the predicted IJV area of 8.7 +/- 5.2 mm(2) (equivalence limit +/- 5 mm(2), one-sided t tests, p = 0.03, 33 IJVs). Conclusions: The agreement between predicted and measured IJV area in sitting supports the occurrence of a hydrostatic-viscous pressure balance in the IJVs, which would result in a constant pressure segment in these collapsed veins, corresponding to a zero transmural pressure. This balance could thus serve as the mechanism by which collapse of the IJVs regulates P-dural and consequently ICP in the upright posture.

Place, publisher, year, edition, pages
BioMed Central, 2017
Keywords
Jugular vein, Collapse, Intracranial pressure, Posture, Physiology
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-137632 (URN)10.1186/s12987-017-0065-2 (DOI)000403482600001 ()28623925 (PubMedID)
Available from: 2017-07-18 Created: 2017-07-18 Last updated: 2019-03-06Bibliographically approved
Holmlund, P., Johansson, E., Qvarlander, S., Wåhlin, A., Ambarki, K., Koskinen, L.-O. D., . . . Eklund, A. (2017). Jugular vein collapse in upright and its relation to intracranial pressure regulation. Paper presented at 28th International Symposium on Cerebral Blood Flow, Metabolism and Function / 13th International Conference on Quantification of Brain Function with PET, APR 01-04, 2017, Int Soc Cerebral Blood Flow & Metab, Berlin, GERMANY. Journal of Cerebral Blood Flow and Metabolism, 37, 297-297
Open this publication in new window or tab >>Jugular vein collapse in upright and its relation to intracranial pressure regulation
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2017 (English)In: Journal of Cerebral Blood Flow and Metabolism, ISSN 0271-678X, E-ISSN 1559-7016, Vol. 37, p. 297-297Article in journal, Meeting abstract (Refereed) Published
Place, publisher, year, edition, pages
SAGE PUBLICATIONS INC, 2017
National Category
Physiology Neurosciences
Identifiers
urn:nbn:se:umu:diva-136208 (URN)000400157400425 ()
Conference
28th International Symposium on Cerebral Blood Flow, Metabolism and Function / 13th International Conference on Quantification of Brain Function with PET, APR 01-04, 2017, Int Soc Cerebral Blood Flow & Metab, Berlin, GERMANY
Note

Supplement: 1 Meeting Abstract: PS03-082

Available from: 2017-07-03 Created: 2017-07-03 Last updated: 2019-05-20Bibliographically approved
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