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Malm, Jan
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Dunås, T., Wåhlin, A., Zarrinkoob, L., Malm, J. & Eklund, A. (2019). 4D flow MRI: automatic assessment of blood flow in cerebral arteries. Biomedical Physics & Engineering Express, 5(1), Article ID 015003.
Open this publication in new window or tab >>4D flow MRI: automatic assessment of blood flow in cerebral arteries
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2019 (English)In: Biomedical Physics & Engineering Express, ISSN 2057-1976, Vol. 5, no 1, article id 015003Article in journal (Refereed) Published
Abstract [en]

Objective: With a 10-minute 4D flow MRI scan, the distribution of blood flow to individual arteries throughout the brain can be analyzed. This technique has potential to become a biomarker for treatment decisions, and to predict prognosis after stroke. To efficiently analyze and model the large dataset in clinical practice, automatization is needed. We hypothesized that identification of selected arterial regions using an atlas with a priori probability information on their spatial distribution can provide standardized measurements of blood flow in the main cerebral arteries.

Approach: A new method for automatic placement of measurement locations in 4D flow MRI was developed based on an existing atlas-based method for arterial labeling, by defining specific regions of interest within the corresponding arterial atlas. The suggested method was evaluated on 38 subjects with carotid artery stenosis, by comparing measurements of blood flow rate at automatically selected locations to reference measurements at manually selected locations.

Main results: Automatic and reference measurement ranged from 10 to 580 ml min−1 and were highly correlated (r = 0.99) with a mean flow difference of 0.61 ± 10.7 ml min−1 (p = 0.21). Out of the 559 arterial segments in the manual reference, 489 were correctly labeled, yielding a sensitivity of 88%, a specificity of 85%, and a labeling accuracy of 87%.

Significance: This study confirms that atlas-based labeling of 4D flow MRI data is suitable for efficient flow quantification in the major cerebral arteries. The suggested method improves the feasibility of analyzing cerebral 4D flow data, and fills a gap necessary for implementation in clinical use.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2019
Keywords
cerebral arteries, hemodynamics, carotid stenosis, magnetic resonance imaging, circle of willis, cerebrovascular circulation
National Category
Medical Image Processing
Identifiers
urn:nbn:se:umu:diva-147254 (URN)10.1088/2057-1976/aae8d1 (DOI)000457627700003 ()
Funder
Swedish Research Council, 2015-05616Swedish Heart Lung Foundation, 20110383, 20140592
Note

Originally included in thesis in manuscript form

Available from: 2018-04-30 Created: 2018-04-30 Last updated: 2019-03-04Bibliographically approved
Dunås, T., Holmgren, M., Wåhlin, A., Malm, J. & Eklund, A. (2019). Accuracy of blood flow assessment in cerebral arteries with 4D flow MRI: Evaluation with three segmentation methods. Journal of Magnetic Resonance Imaging, 50(2), 511-518
Open this publication in new window or tab >>Accuracy of blood flow assessment in cerebral arteries with 4D flow MRI: Evaluation with three segmentation methods
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2019 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 50, no 2, p. 511-518Article in journal (Refereed) Published
Abstract [en]

Background: Accelerated 4D flow MRI allows for high‐resolution velocity measurements with whole‐brain coverage. Such scans are increasingly used to calculate flow rates of individual arteries in the vascular tree, but detailed information about the accuracy and precision in relation to different postprocessing options is lacking.

Purpose: To evaluate and optimize three proposed segmentation methods and determine the accuracy of in vivo 4D flow MRI blood flow rate assessments in major cerebral arteries, with high‐resolution 2D PCMRI as a reference.

Study Type: Prospective.

Subjects: Thirty‐five subjects (20 women, 79 ± 5 years, range 70–91 years).

Field Strength/Sequence: 4D flow MRI with PC‐VIPR and 2D PCMRI acquired with a 3 T scanner.

Assessment: We compared blood flow rates measured with 4D flow MRI, to the reference, in nine main cerebral arteries. Lumen segmentation in the 4D flow MRI was performed with k‐means clustering using four different input datasets, and with two types of thresholding methods. The threshold was defined as a percentage of the maximum intensity value in the complex difference image. Local and global thresholding approaches were used, with evaluated thresholds from 6–26%.

Statistical Tests: Paired t‐test, F‐test, linear correlation (P < 0.05 was considered significant) along with intraclass correlation (ICC).

Results: With the thresholding methods, the lowest average flow difference was obtained for 20% local (0.02 ± 15.0 ml/min, ICC = 0.97, n = 310) or 10% global (0.08 ± 17.3 ml/min, ICC = 0.97, n = 310) thresholding with a significant lower standard deviation for local (F‐test, P = 0.01). For all clustering methods, we found a large systematic underestimation of flow compared with 2D PCMRI (16.1–22.3 ml/min).

Data Conclusion: A locally adapted threshold value gives a more stable result compared with a globally fixed threshold. 4D flow with the proposed segmentation method has the potential to become a useful reliable clinical tool for assessment of blood flow in the major cerebral arteries.

Level of Evidence: 2

Technical Efficacy: Stage 2

Keywords
magnetic resonance imaging, cerebral arteries, phase‐contrast MRI, 4D flow MRI, cerebral blood flow, Circle of Willis
National Category
Medical Image Processing
Identifiers
urn:nbn:se:umu:diva-147255 (URN)10.1002/jmri.26641 (DOI)000475681600017 ()30637846 (PubMedID)2-s2.0-85059966858 (Scopus ID)
Funder
Swedish Research Council, 2015–05616; 2017-04949Swedish Heart Lung Foundation, 20140592
Note

Originally included in thesis in manuscript form with title "Blood flow assessment in cerebral arteries with 4D flow MRI, concordance with 2D PCMRI"

Available from: 2018-04-30 Created: 2018-04-30 Last updated: 2019-08-12Bibliographically approved
Zarrinkoob, L., Wåhlin, A., Ambarki, K., Birgander, R., Eklund, A. & Malm, J. (2019). Blood flow lateralization and collateral compensatory mechanisms in patients with carotid artery stenosis. Stroke, 50(5), 1081-1088
Open this publication in new window or tab >>Blood flow lateralization and collateral compensatory mechanisms in patients with carotid artery stenosis
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2019 (English)In: Stroke, ISSN 0039-2499, E-ISSN 1524-4628, Vol. 50, no 5, p. 1081-1088Article in journal (Refereed) Published
Abstract [en]

Background and Purpose: Four-dimensional phase-contrast magnetic resonance imaging enables quantification of blood flow rate (BFR; mL/min) in multiple cerebral arteries simultaneously, making it a promising technique for hemodynamic investigation in patients with stroke. The aim of this study was to quantify the hemodynamic disturbance and the compensatory pattern of collateral flow in patients with symptomatic carotid stenosis.

Methods: Thirty-eight patients (mean, 72 years; 27 men) with symptomatic carotid stenosis (>/=50%) or occlusion were investigated using 4-dimensional phase-contrast magnetic resonance imaging. For each patient, BFR was measured in 19 arteries/locations. The ipsilateral side to the symptomatic carotid stenosis was compared with the contralateral side.

Results: Internal carotid artery BFR was lower on the ipsilateral side (134+/-87 versus 261+/-95 mL/min; P<0.001). BFR in anterior cerebral artery (A1 segment) was lower on ipsilateral side (35+/-58 versus 119+/-72 mL/min; P<0.001). Anterior cerebral artery territory bilaterally was primarily supplied by contralateral internal carotid artery. The ipsilateral internal carotid artery mainly supplied the ipsilateral middle cerebral artery (MCA) territory. MCA was also supplied by a reversed BFR found in the ophthalmic and the posterior communicating artery routes on the ipsilateral side (-5+/-28 versus 10+/-28 mL/min, P=0.001, and -2+/-12 versus 6+/-6 mL/min, P=0.03, respectively). Despite these compensations, BFR in MCA was lower on the ipsilateral side, and this laterality was more pronounced in patients with severe carotid stenosis (>/=70%). Although comparing ipsilateral MCA BFR between stenosis groups (<70% and >/=70%), there was no difference ( P=0.95).

Conclusions: With a novel approach using 4-dimensional phase-contrast magnetic resonance imaging, we could simultaneously quantify and rank the importance of collateral routes in patients with carotid stenosis. An important observation was that contralateral internal carotid artery mainly secured the bilateral anterior cerebral artery territory. Because of the collateral recruitment, compromised BFR in MCA is not necessarily related to the degree of carotid stenosis. These findings highlight the importance of simultaneous investigation of the hemodynamics of the entire cerebral arterial tree.

Place, publisher, year, edition, pages
Philadelphia: Lippincott Williams & Wilkins, 2019
Keywords
carotid stenosis, circle of Willis, humans, magnetic resonance imaging, cine, middle cerebral artery
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-158003 (URN)10.1161/STROKEAHA.119.024757 (DOI)000469350000029 ()30943887 (PubMedID)
Funder
Swedish Research Council, 2015-05616Swedish Research Council, 2017-04949Västerbotten County CouncilSwedish Heart Lung Foundation, 20140592
Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-06-17Bibliographically approved
Wåhlin, A., Fordell, H., Ekman, U., Lenfeldt, N. & Malm, J. (2019). Rehabilitation in chronic spatial neglect strengthens resting-state connectivity. Acta Neurologica Scandinavica, 139(3), 254-259
Open this publication in new window or tab >>Rehabilitation in chronic spatial neglect strengthens resting-state connectivity
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2019 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 139, no 3, p. 254-259Article in journal (Refereed) Published
Abstract [en]

Objectives: Rehabilitation of patients with chronic visuospatial neglect is underexplored, and little is known about neural mechanisms that can be exploited to promote recovery. In this study, we present data on resting-state functional connectivity within the dorsal attention network (DAN) in chronic neglect patients as they underwent training in a virtual reality (VR) environment that improved left-side awareness.

Methods: The study included 13 patients with visuospatial neglect persisting more than six months after a right-sided stroke. The patients underwent resting-state functional magnetic resonance imaging (fMRI). Scans were collected at baseline and after five weeks of intense training. We specifically examined resting-state functional connectivity within the DAN. In addition, using spatial concordance correlation, we compared changes in the spatial topology of the DAN with that of other networks.

Results: We found a longitudinal increase in interhemispheric functional connectivity between the right frontal eye field and the left intraparietal sulcus following training (before: 0.33 +/- 0.17 [mean +/- SD]; after: 0.45 +/- 0.13; P = 0.004). The spatial concordance analyses indicated that training influenced the DAN connectivity more than any of the other networks.

Conclusion: Intense VR training that improved left-sided awareness in chronic stroke patients also increased sporadic interhemispheric functional connectivity within the DAN. Specifically, a region responsible for saccadic eye movement to the left became more integrated with the left posterior parietal cortex. These results highlight a mechanism that should be exploited in the training of patients with chronic visuospatial neglect.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
cognitive rehabilitation, functional magnetic resonance imaging, neuronal plasticity, spatial neglect, virtual reality
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-156864 (URN)10.1111/ane.13048 (DOI)000458682700006 ()30427058 (PubMedID)
Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Westlund, A., Holmlund, P., Johansson, E., Malm, J. & Eklund, A. (2019). Semi-automatic method for segmentation of the internal jugular vein in ultrasound movies evaluated at different body postures. Biomedical Physics & Engineering Express, 5(4), Article ID 045034.
Open this publication in new window or tab >>Semi-automatic method for segmentation of the internal jugular vein in ultrasound movies evaluated at different body postures
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2019 (English)In: Biomedical Physics & Engineering Express, E-ISSN 2057-1976, Vol. 5, no 4, article id 045034Article in journal (Refereed) Published
Abstract [en]

Objective: The collapse of the internal jugular vein (IJV) regulates intracranial pressure (ICP) in upright body positions. The cross-section area (CSA) is therefore of interest when studying the effects of postural changes in various neurological diseases. We have developed a semi-automatic segmentation method, which tracks the CSA of the IJV in ultrasound movies, and evaluated its performance in three body positions (supine, 16°, 71°). Approach: The proposed method utilized post-processing image filtering combined with a modified snake active contour algorithm. The ultrasound movies were retrospectively analysed (n = 231, 3s, 28 fps) based on previously collected data from 17 healthy volunteers. The computed CSAs (CA) from the segmentation method were compared to manually segmented CSAs (MA) in two frames per movie. Tracking performance were evaluated by visual inspection. Main results: In the supine position, 100% of the ultrasound movies were tracked successfully, and the mean of CA-MA was −4.4 ± 6.9 mm2 (MA, 88.4 ± 50.5 mm2). The most challenging movies occurred in upright body posture where tracking success rate was 90% and mean of CA-MA was −1.4 ± 2.2 mm2 (MA, 12.0 ± 11.1 mm2). The semi-automatic segmentations took 55 s to perform on average (per movie) compared to manual segmentations which took 50 min. Significance: Segmentations made by the proposed method were comparable to manual segmentations in all tilt-angles, however much faster. Efficient and accurate tracking of the CSA of the IJV, with respect to postural changes, could help furthering our understanding of how IJV-biomechanics relates to regulation of intracranial pressure in different neurological diseases and physiological states.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2019
Keywords
posture, intracranial pressure, ultrasound, jugular veins, computer-assisted image analysis
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-161912 (URN)10.1088/2057-1976/ab285e (DOI)000475798800001 ()
Available from: 2019-08-07 Created: 2019-08-07 Last updated: 2019-08-07Bibliographically approved
Sandvig, A., Arnell, K., Malm, J., Eklund, A. & Koskinen, L.-O. D. (2018). Analysis of Codman microcerebrospinal fluid shunt. Brain and Behavior, 8(10), Article ID e01002.
Open this publication in new window or tab >>Analysis of Codman microcerebrospinal fluid shunt
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2018 (English)In: Brain and Behavior, ISSN 2162-3279, E-ISSN 2162-3279, Vol. 8, no 10, article id e01002Article in journal (Refereed) Published
Abstract [en]

Introduction: Ventriculo-peritoneal cerebrospinal fluid (CSF) shunt is the most common method of treating pediatric hydrocephalus. The Codman microadjustable valve (CMAV) is a CSF shunt constructed for children. The objective of the study was (a) to analyze complications after insertion of a CMAV shunt in hydrocephalic children, (b)to analyze complications after replacing a CMAV by an adult-type Codman Hakim adjustable valve shunt (CHAV), and to (c) analyze the in vitro characteristics of the CMAV shunt and correlate the findings with the clinical performance of the shunt.

Methods: A retrospective study analyzed a cohort of hydrocephalic children who had received a CMAV shunt and later replaced by a CHAV shunt. We report on the complications that resulted from replacing the CMAV with the CHAV. We tested six CMAV shunts with or without an antisiphon device (ASD) in which opening pressure, resistance, sensitivity to abdominal pressure, ASD position dependency, and function were determined. The test results were correlated with the clinical performance of the shunt in the retrospective study.

Results: Thirty-seven children (19 boys, 18 girls) were identified. Within the first month after shunt placement, a total of 10 patients (27%) developed complications including infections, hygromas, and shunt dysfunction. Shunt survival varied from 1week to 145 months. Over the 10-year follow-up period, 13 children had their shunts replaced, six of them with a CHAV without any further complications. A bench test of the CMAV was done to test whether the opening pressure was in agreement with the manufacturer's specifications. Our results were generally in agreement with specifications stated by the manufacturer.

Conclusion: Replacing a CMAV with a CHAV was well tolerated by the patients. Bench test results were generally in agreement with manufacturers specifications. Replacing a CMAV with a CHAV in pediatric hydrocephalus patients can be accomplished safely.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
cerebrospinal fluid, clinical retrospective study
National Category
Pediatrics
Identifiers
urn:nbn:se:umu:diva-153130 (URN)10.1002/brb3.1002 (DOI)000447544700001 ()30207083 (PubMedID)2-s2.0-85053399281 (Scopus ID)
Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2018-11-09Bibliographically approved
Larsson, J., Israelsson, H., Eklund, A. & Malm, J. (2018). Epilepsy, headache, and abdominal pain after shunt surgery for idiopathic normal pressure hydrocephalus: the INPH-CRasH study. Journal of Neurosurgery, 128(6), 1674-1683
Open this publication in new window or tab >>Epilepsy, headache, and abdominal pain after shunt surgery for idiopathic normal pressure hydrocephalus: the INPH-CRasH study
2018 (English)In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 128, no 6, p. 1674-1683Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE Adverse events related to shunt surgery are common and might have a negative effect on outcome in patients with idiopathic normal pressure hydrocephalus (INPH). The authors' objectives were to establish the frequencies of epilepsy, headache, and abdominal pain and determine their impact on patient quality of life (QOL), in long-term follow-up after shunt surgery for INPH.

METHODS One hundred seventy-six shunt-treated patients with INPH (mean age 74 years) and 368 age- and sex-matched controls from the population were included. The mean follow-up time after surgery was 21 months (range 6-45 months). Each participant answered a questionnaire regarding present frequency and severity of headache and abdominal pain. Confirmed diagnoses of epilepsy and all prescriptions for antiepileptic drugs (AEDs) before and after shunt surgery for INPH were gathered from national registries. Equivalent presurgical and postsurgical time periods were constructed for the controls based on the date of surgery (the division date for controls is referred to as virtual surgery). All registry data covered a mean period of 6 years (range 3-8 years) before surgery/virtual surgery and 4 years (range 2-6 years) after surgery/virtual surgery. Provoked epileptic seizures were excluded. Patient QOL was assessed with the EuroQoL 5-dimension 5-level instrument.

RESULTS Epilepsy was more common in shunt-treated patients with INPH than in controls (4.5% vs 1.1%, respectively; p = 0.023), as was treatment with AEDs (14.8% vs 7.3%, respectively; p = 0.010). No difference was found between the populations before surgery/virtual surgery (epilepsy, 2.3% [INPH] vs 1.1% [control], p = 0.280; AED treatment, 8.5% [INPH] vs 5.4% [control], p = 0.235). New-onset epilepsy and new AED treatment after surgery/virtual surgery were more common in INPH (epilepsy, 2.3% [INPH] vs 0.0% [control], p = 0.011; AED, 8.5% [INPH] vs 3.3% [control], p = 0.015). At follow-up, more patients with INPH than controls experienced headache several times per month or more often (36.1% vs 11.6%, respectively; p < 0.001). Patients with INPH and unilateral headache had more right-sided headaches than controls (p = 0.038). Postural headache was experienced by 16% (n = 27 of 169) of the patients with INPH. Twenty percent (n = 35) of the patients with INPH had persistent abdominal pain. Headache was not correlated to lower QOL. The study was underpowered to draw conclusions regarding QOL in patients with INPH who had epilepsy and abdominal pain, but the finding of no net difference in mean QOL indicates that no correlation between them existed.

CONCLUSIONS Epilepsy, headache, and abdominal pain are common in long-term follow-up in patients after shunt surgery for INPH and are more common among patients with INPH than in the general population. All adverse events, including mild and moderate ones, should be considered during postoperative follow-ups and in the development of new methods for shunt placement.

Place, publisher, year, edition, pages
Rolling Meadows: American association of neurological surgeons, 2018
Keywords
hydrocephalus, normal pressure, ventriculoperitoneal shunt, postoperative complications, headache, epilepsy, abdominal pain
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-139649 (URN)10.3171/2017.3.JNS162453 (DOI)000440653000010 ()28885121 (PubMedID)
Available from: 2017-09-19 Created: 2017-09-19 Last updated: 2018-11-30Bibliographically approved
Ekman, U., Fordell, H., Eriksson, J., Lenfeldt, N., Wåhlin, A., Eklund, A. & Malm, J. (2018). Increase of frontal neuronal activity in chronic neglect after training in virtual reality. Acta Neurologica Scandinavica, 138(4), 284-292
Open this publication in new window or tab >>Increase of frontal neuronal activity in chronic neglect after training in virtual reality
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2018 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 138, no 4, p. 284-292Article in journal (Refereed) Published
Abstract [en]

Objectives: A third of patients with stroke acquire spatial neglect associated with poor rehabilitation outcome. New effective rehabilitation interventions are needed. Scanning training combined with multisensory stimulation to enhance the rehabilitation effect is suggested. In accordance, we have designed a virtual-reality based scanning training that combines visual, audio and sensori-motor stimulation called RehAtt((R)). Effects were shown in behavioural tests and activity of daily living. Here, we use fMRI to evaluate the change in brain activity during Posners Cuing Task (attention task) after RehAtt((R)) intervention, in patients with chronic neglect.

Methods: Twelve patients (mean age=72.7years, SD=6.1) with chronic neglect (persistent symptoms >6months) performed the interventions 3 times/wk during 5weeks, in total 15hours. Training effects on brain activity were evaluated using fMRI task-evoked responses during the Posners cuing task before and after the intervention.

Results: Patients improved their performance in the Posner fMRI task. In addition, patients increased their task-evoked brain activity after the VR interventions in an extended network including pre-frontal and temporal cortex during attentional cueing, but showed no training effects during target presentations.

Conclusions: The current pilot study demonstrates that a novel multisensory VR intervention has the potential to benefit patients with chronic neglect in respect of behaviour and brain changes. Specifically, the fMRI results show that strategic processes (top-down control during attentional cuing) were enhanced by the intervention. The findings increase knowledge of the plasticity processes underlying positive rehabilitation effects from RehAtt((R)) in chronic neglect.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
cognitive rehabilitation, functional magnetic resonance imaging, neuronal plasticity, spatial neglect, virtual reality
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-152199 (URN)10.1111/ane.12955 (DOI)000443931400003 ()29770439 (PubMedID)
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2019-05-07Bibliographically 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
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