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- Behrens, Anders, et al.
(author)
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Are intracranial pressure wave amplitudes measurable through lumbar puncture?
- 2013
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In: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 127:4, s. 233-241
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Journal article (peer-reviewed)abstract
- 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.
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| 2. |
- Behrens, Anders, et al.
(author)
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In Reply
- 2010
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In: Neurosurgery. - 0148-396X .- 1524-4040. ; 67:6, s. 1864-
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Journal article (pop. science, debate, etc.)
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| 3. |
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| 4. |
- Behrens, Anders, 1979-
(author)
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Measurements in Idiopathic Normal Pressure Hydrocephalus : Computerized neuropsychological test battery and intracranial pulse waves
- 2014
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Doctoral thesis (other academic/artistic)abstract
- 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.
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| 5. |
- Behrens, Anders, et al.
(author)
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Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.
- 2010
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In: Neurosurgery. - 0148-396X .- 1524-4040. ; 66:6, s. 1050-1057
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Journal article (peer-reviewed)abstract
- 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.
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| 7. |
- Bäckström, David C, M.D. 1978-, et al.
(author)
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NfL as a biomarker for neurodegeneration and survival in Parkinson disease
- 2020
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In: Neurology. - : Wolters Kluwer. - 0028-3878 .- 1526-632X. ; 95:7, s. e827-e838
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To determine whether neurofilament light chain protein in CSF (cNfL), a sensitive biomarker of neuroaxonal damage, reflects disease severity or can predict survival in Parkinson disease (PD).METHODS: We investigated whether disease severity, phenotype, or survival in patients with new-onset PD correlates with cNfL concentrations around the time of diagnosis in the population-based New Parkinsonism in Umeå (NYPUM) study cohort (n = 99). A second, larger new-onset PD cohort (n = 194) was used for independent validation. Association of brain pathology with the cNfL concentration was examined with striatal dopamine transporter imaging and repeated diffusion tensor imaging at baseline and 1 and 3 years.RESULTS: Higher cNfL in the early phase of PD was associated with greater severity of all cardinal motor symptoms except tremor in both cohorts and with shorter survival and impaired olfaction. cNfL concentrations above the median of 903 ng/L conferred an overall 5.8 times increased hazard of death during follow-up. After adjustment for age and sex, higher cNfL correlated with striatal dopamine transporter uptake deficits and lower fractional anisotropy in diffusion tensor imaging of several axonal tracts.CONCLUSIONS: cNfL shows usefulness as a biomarker of disease severity and to predict survival in PD. The present results indicate that the cNfL concentration reflects the intensity of the neurodegenerative process, which could be important in future clinical trials.CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that in patients with PD, cNfL concentrations are associated with more severe disease and shorter survival.
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| 8. |
- Bäckström, David C, M.D. 1978-
(author)
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The biology of cognitive decline and reduced survival in Parkinson disease : prognostic factors in a population-based cohort
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Parkinson disease (PD) is a progressive neurodegenerative disease that affects about 1% of the population over 60 years. The cardinal symptoms are motor disabilities but cognitive decline is also common. About 50% of all persons with PD develop dementia within 10 years after disease onset. Dementia in PD account for high social costs and has large, negative effects on quality of life. Aims. The aim of the study was to investigate clinical, neurobiological and genetic factors of importance for progression and for the prognosis in PD and parkinsonism. First, we aimed to describe mortality and risk factors for death, including possible associations with cognitive dysfunction, in patients with idiopathic parkinsonism. Second, we aimed to study if biomarkers in the cerebrospinal fluid (CSF) are useful for the diagnosis of different forms of idiopathic parkinsonism and prediction of cognitive decline in PD. Methods. A population-based cohort consisting of patients with new-onset, idiopathic parkinsonism was studied prospectively. After screening in a catchment area of ~142 000 inhabitants in Sweden, 182 patients with parkinsonism were included. The patients were investigated comprehensively, including neuropsychological testing, multimodal neuroimaging and genetic and biosample analyses. During follow up, 143 patients were diagnosed with PD, 13 with multiple system atrophy (MSA), and 18 with progressive supranuclear palsy (PSP). A total of 109 patients died. Results. Patients with MSA and PSP had the shortest life expectancy. PD patients who presented with normal cognitive function had a largely normal life expectancy. In contrast, the mortality was increased in PD patients with cognitive impairment, freezing of gait, hyposmia, and mildly elevated leukocytes in the CSF. Of importance for the prognosis, patients with PD with an early CSF pattern of high Neurofilament light protein, low β-amyloid, and high heart fatty acid binding protein had an 11.8 times increased risk of developing PD dementia (95% CI 3.3-42.1, p <0.001), compared with PD patients with a more ”normal” CSF pattern. Variation in genes associated with dopamine function was also associated with some effects on cognitive functions in PD. Conclusions. PD subtypes, for instance the subtype characterized by cognitive decline, have distinguishing clinical, neurochemical and neurobiological traits, which are of importance for the prognosis and the survival. An early CSF analysis is useful for predicting cognitive decline. The finding of a low-grade immune reaction in the CSF of patients with PD may have clinical implications. In clinical practice, CSF biomarkers could be useful for improving diagnosis and prognostication.
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| 9. |
- Ekman, Urban, et al.
(author)
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Increase of frontal neuronal activity in chronic neglect after training in virtual reality
- 2018
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In: Acta Neurologica Scandinavica. - : John Wiley & Sons. - 0001-6314 .- 1600-0404. ; 138:4, s. 284-292
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Journal article (peer-reviewed)abstract
- 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.
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