| 1. |
- Andersson, Nina, et al.
(författare)
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Dependency of cerebrospinal fluid outflow resistance on intracranial pressure
- 2008
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Ingår i: Journal of Neurosurgery. - 0022-3085 .- 1933-0693. ; 109:5, s. 918-922
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT: The outflow resistance (Rout) of the cerebrospinal fluid (CSF) system has generally been accepted by most investigators as independent of intracranial pressure (ICP), but there are also those claiming that it is not. The general belief is that this question has been investigated numerous times in the past, but few studies have actually been specifically aimed at looking at this relationship, and no study has been able to provide scientific evidence to elucidate fully this fundamental and important issue. The objective of this study was to investigate the relationship between ICP and CSF outflow in 30 patients investigated for idiopathic normal-pressure hydrocephalus. METHODS: Lumbar infusion tests with constant pressure levels were performed, and ICP and corresponding flow were measured on 6 pressure levels for each patient. All data were standardized for comparison. RESULTS: In the range of moderate increases from baseline pressure (approximately 5-12 mm Hg, mean baseline pressure 11.7 mm Hg), the assumption of a pressure-independent Rout was confirmed (p = 0.5). However, when the pressure increment from baseline pressure was larger (approximately 15-22 mm Hg), the relationship had a nonlinear tendency (p < 0.05). CONCLUSIONS: The results of this study support the classic textbook theory of a pressure-independent Rout in the normal ICP range, where the CSF system is commonly operating. However, the theory might have to be questioned in regions where ICP exceeds baseline pressure by too much.
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| 2. |
- Andisheh, Bahram, 1967-, et al.
(författare)
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Clinical and radiobiological advantages of single-dose stereotactic light-ion radiation therapy for large intracranial arteriovenous malformations. Technical note
- 2009
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Ingår i: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 111:5, s. 919-926
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT:Radiation treatment of large arteriovenous malformations (AVMs) remains difficult and not very effective, even though seemingly promising methods such as staged volume treatments have been proposed by some radiation treatment centers. In symptomatic patients harboring large intracranial AVMs not amenable to embolization or resection, single-session high-dose stereotactic radiation therapy is a viable option, and the special characteristics of high-ionization-density light-ion beams offer several treatment advantages over photon and proton beams. These advantages include a more favorable depth-dose distribution in tissue, an almost negligible lateral scatter of the beam, a sharper penumbra, a steep dose falloff beyond the Bragg peak, and a higher probability of vascular response due to high ionization density and associated induction of endothelial cell proliferation and/or apoptosis. Carbon ions were recently shown to be an effective treatment for skull-base tumors. Bearing that in mind, the authors postulate that the unique physical and biological characteristics of light-ion beams should convey considerable clinical advantages in the treatment of large AVMs. In the present meta-analysis the authors present a comparison between light-ion beam therapy and more conventional modalities of radiation treatment with respect to these lesions.METHODS:Dose-volume histograms and data on peripheral radiation doses for treatment of large AVMs were collected from various radiation treatment centers. Dose-response parameters were then derived by applying a maximum likelihood fitting of a binomial model to these data. The present binomial model was needed because the effective number of crucial blood vessels in AVMs (the number of vessels that must be obliterated to effect a cure, such as large fistulous nidus vessels) is low, making the Poisson model less suitable. In this study the authors also focused on radiobiological differences between various radiation treatments.RESULTS:Light-ion Bragg-peak dose delivery has the precision required for treating very large AVMs as well as for delivering extremely sharp, focused beams to irregular lesions. Stereotactic light-ion radiosurgery resulted in better angiographically defined obliteration rates, less white-matter necrosis, lower complication rates, and more favorable clinical outcomes. In addition, in patients treated by He ion beams, a sharper dose-response gradient was observed, probably due to a more homogeneous radiosensitivity of the AVM nidus to light-ion beam radiation than that seen when low-ionization-density radiation modalities, such as photons and protons, are used.CONCLUSIONS:Bragg-peak radiosurgery can be recommended for most large and irregular AVMs and for the treatment of lesions located in front of or adjacent to sensitive and functionally important brain structures. The unique physical and biological characteristics of light-ion beams are of considerable advantage for the treatment of AVMs: the densely ionizing beams of light ions create a better dose and biological effect distribution than conventional radiation modalities such as photons and protons. Using light ions, greater flexibility can be achieved while avoiding healthy critical structures such as diencephalic and brainstem nuclei and tracts. Treatment with the light ion He or Li is more suitable for AVMs
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| 3. |
- Ansar, Saema, et al.
(författare)
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Equal contribution of increased intracranial pressure and subarachnoid blood to cerebral blood flow reduction and receptor upregulation after subarachnoid hemorrhage.
- 2009
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Ingår i: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 111, s. 978-987
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Tidskriftsartikel (refereegranskat)abstract
- Object Cerebral ischemia remains the key cause of disability and death in the late phase after subarachnoid hemorrhage (SAH), and its pathogenesis is still poorly understood. The purpose of this study was to examine whether the change in intracranial pressure or the extravasated blood causes the late cerebral ischemia and the upregulation of receptors or the cerebral vasoconstriction observed following SAH. Methods Rats were allocated to 1 of 3 experimental conditions: 1) cisternal injection of 250 mul blood (SAH Group), 2) cisternal injection of 250 mul NaCl (Saline Group), or 3) the same procedure but without fluid injection (Sham Group). Two days after the procedure, the basilar and middle cerebral arteries were harvested, and contractile responses to endothelin (ET)-1 and 5-carboxamidotryptamine (5-CT) were investigated by means of myography. In addition, real-time polymerase chain reaction was used to determine the mRNA levels for ET(A), ET(B), and 5-HT(1) receptors. Regional and global cerebral blood flow (CBF) were quantified by means of an autoradiographic technique. Results Compared with the sham condition, both SAH and saline injection resulted in significantly enhanced contraction of cerebral arteries in response to ET-1 and 5-CT. Regional and global CBF were reduced both in the Saline and SAH groups compared with the Sham Group. The mRNA levels for ET(B) and 5-HT(1B) receptors were upregulated after SAH and saline injection compared with the sham procedure. The effects in all parameters were more pronounced for SAH than for saline injection. Conclusions This study revealed that both the elevation of intracranial pressure and subarachnoid blood per se contribute approximately equally to the late CBF reductions and receptor upregulation following SAH.
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| 4. |
- Arnell, Kai, et al.
(författare)
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Treatment of cerebrospinal fluid shunt infections in children using systemic and intraventricular antibiotic therapy in combination with externalization of the ventricular catheter : efficacy in 34 consecutively treated infections
- 2007
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Ingår i: Journal of Neurosurgery. - 0022-3085 .- 1933-0693. ; 107:3, s. 213-219
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT: There are no randomized studies comparing the efficacy of different antibiotic regimens for the treatment of cerebrospinal fluid (CSF) shunt infections, and in the studies that have been reported, efficacy data are limited. The aim of this study was therefore to report the authors' experience using a specific protocol for the management of shunt infections in children. Standard treatment included a two-stage procedure involving externalization of the ventricular catheter in combination with intraventricular and systemic administration of antibiotic medication followed by shunt replacement. Intraventricular treatment consisted of daily instillations of vancomycin or gentamicin with trough concentrations held at high levels of 7 to 17 mg/L for both antibiotic agents. METHODS: During a 13-year study period, the authors treated 34 consecutive intraventricular shunt infections in 30 children. Infections with coagulase-negative staphylococci predominated, and Gram-negative bacterial infection occurred in five children. Ten of the children were initially treated with intravenous antibiotic therapy for at least 3 days, but this treatment did not sterilize the CSF. After externalization of the ventricular catheter, high-dose intraventricular treatment was given for a median of 8 days (range 3-17 days) before shunt replacement. RESULTS: The CSF was found to be sterile (cultures were negative for bacteria) in one of three, seven of eight, 20 of 20, and six of six cases after 1, 2, 3, and more than 3 days' treatment, respectively. In no case was any subsequent culture positive after a negative result had been obtained. Clinical symptoms resolved in parallel with the sterilization of the CSF. There were no relapses or deaths during the 6-month follow-up period, and there have been none as of April 2007. CONCLUSIONS: Despite the ventricular catheter being left in place and the short duration of therapy, the treatment regimen described by the authors resulted in quick sterilization of the CSF, a low relapse rate, and survival of all patients in this series.
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| 5. |
- Forander, P, et al.
(författare)
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Combination of microsurgery and Gamma Knife surgery for the treatment of intracranial chondrosarcomas
- 2006
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Ingår i: Journal of neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 105105 Suppl, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- Intracranial chondrosarcomas have a high risk of recurrence after surgery. This retrospective study of patients with intracranial chondrosarcoma was conducted to determine the long-term results of microsurgery followed by Gamma Knife surgery (GKS) for residual tumor or recurrence.MethodsThe authors treated nine patients whose median age was 36 years. Seven patients had low-grade chondrosarcomas (LGCSs), whereas mesenchymal chondrosarcomas (MCSs) were diagnosed in two. Radiosurgery was performed in eight patients, whereas one patient declined further surgical intervention and tumor-volume reduction necessary for the GKS.The patients were followed up for 15 to 173 months (median 108 months) after diagnosis and 3 to 166 months (median 88 months) after GKS. Seven patients had residual tumor tissue after microsurgery, and two operations appeared radical. In the two latter cases, tumors recurred after 25 and 45 months. Thus, definite tumor control was not achieved after surgery alone in any patient, whereas the addition of radiosurgery allowed tumor control in all six patients with LGCSs. Two of these patients experienced an initial tumor regrowth after GKS; in both cases the recurrences were outside the prescribed radiation field. The patients underwent repeated GKS, and subsequent tumor control was observed. An MCS was diagnosed in the remaining two patients. Complications after microsurgery included diplopia, facial numbness, and paresis. After GKS, one patient had radiation necrosis, which required microsurgery, and two patients had new cranial nerve palsies.Conclusions Tumor control after microsurgery alone was not achieved in any patient, whereas adjuvant radiosurgery provided local tumor control in six of eight GKS-treated patients. Tumor control was not achieved in the two patients with MCS. Similar to other treatments for intracranial chondrosarcoma, morbidity after micro- and radiosurgical combination therapy was high and included severe cranial nerve palsies.
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| 6. |
- Hillman, Jan, 1952-, et al.
(författare)
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Variations in the response of interleukins in neurosurgical intensive care patients monitored using intracerebral microdialysis
- 2007
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Ingår i: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 106:5, s. 820-825
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Tidskriftsartikel (refereegranskat)abstract
- Object. The aim of this study was to make a preliminary evaluation of whether microdialysis monitoring of cytokines and other proteins in severely diseased neurosurgical patients has the potential of adding significant information to optimize care, thus broadening the understanding of the function of these molecules in brain injury. Methods. Paired intracerebral microdialysis catheters with high-cutoff membranes were inserted in 14 comatose patients who had been treated in a neurosurgical intensive care unit following subarachnoidal hemorrhage or traumatic brain injury. Samples were collected every 6 hours (for up to 7 days) and were analyzed at bedside for routine metabolites and later in the laboratory for interleukin (IL)-1 and IL-6, in two patients, vascular endothelial growth factor and cathepsin-D were also checked. Aggregated microprobe data gave rough estimations of profound focal cytokine responses related to morphological tissue injury and to anaerobic metabolism that were not evident from the concomitantly collected cerebrospinal fluid data. Data regarding tissue with no macroscopic evidence of injury demonstrated that IL release not only is elicited in severely compromised tissue but also may be a general phenomenon in brains subjected to stress. Macroscopic tissue injury was strongly linked to IL-6 but not IL-1b activation. Furthermore, IL release seems to be stimulated by local ischemia. The basal tissue concentration level of IL-1b was estimated in the range of 10 to 150 pg/ml, for IL-6, the corresponding figure was 1000 to 20,000 pg/ml. Conclusions. Data in the present study indicate that catheters with high-cutoff membranes have the potential of expanding microdialysis to the study of protein chemistry as a routine bedside method in neurointensive care.
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| 7. |
- Howells, Tim, et al.
(författare)
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Pressure reactivity as a guide in the treatment of cerebral perfusion pressure in patients with brain trauma
- 2005
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Ingår i: Journal of Neurosurgery. - 0022-3085 .- 1933-0693. ; 102:2, s. 311-317
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT: The aim of this study was to compare the effects of two different treatment protocols on physiological characteristics and outcome in patients with brain trauma. One protocol was primarily oriented toward reducing intracranial pressure (ICP), and the other primarily on maintaining cerebral perfusion pressure (CPP).METHODS: A series of 67 patients in Uppsala were treated according to a protocol aimed at keeping ICP less than 20 mm Hg and, as a secondary target, CPP at approximately 60 mm Hg. Another series of 64 patients in Edinburgh were treated according to a protocol aimed primarily at maintaining CPP greater than 70 mm Hg and, secondarily, ICP less than 25 mm Hg for the first 24 hours and 30 mm Hg subsequently. The ICP and CPP insults were assessed as the percentage of monitoring time that ICP was greater than or equal to 20 mm Hg and CPP less than 60 mm Hg, respectively. Pressure reactivity in each patient was assessed based on the slope of the regression line relating mean arterial blood pressure (MABP) to ICP. Outcome was analyzed at 6 months according to the Glasgow Outcome Scale (GOS). The prognostic value of secondary insults and pressure reactivity was determined using linear methods and a neural network. In patients treated according to the CPP-oriented protocol, even short durations of CPP insults were strong predictors of death. In patients treated according to the ICP-oriented protocol, even long durations of CPP insult-mostly in the range of 50 to 60 mm Hg--were significant predictors of favorable outcome (GOS Score 4 or 5). Among those who had undergone ICP-oriented treatment, pressure-passive patients (MABP/ICP slope > or = 0.13) had a better outcome. Among those who had undergone CPP-oriented treatment, the more pressure-active (MABP/ICP slope < 0.13) patients had a better outcome.CONCLUSION: Based on data from this study, the authors concluded that ICP-oriented therapy should be used in patients whose slope of the MABP/ICP regression line is at least 0.13, that is, in pressure-passive patients. If the slope is less than 0.13, then hypertensive CPP therapy is likely to produce a better outcome.
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| 8. |
- Karlsson, B, et al.
(författare)
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Calculation of isoeffective doses and the alpha/beta value by comparing results following radiosurgery and radiotherapy for arteriovenous malformations of the brain
- 2006
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Ingår i: Journal of neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 105105 Suppl, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- The authors sought to assess the relationship between obliteration rate and different dose parameters following fractionated radiotherapy for arteriovenous malformations (AVMs). A comparison of the results of radiosurgery and radiotherapy for AVMs was made to calculate the best fit α/β value, which would then be used as a model for predicting the treatment outcome, independent of the number of fractions applied.MethodsData from 1453 patients were analyzed: 1154 treated with radiosurgery and 300 with fractionated radiotherapy. The relationships between dose and obliteration rate after 3 years were calculated, and the best fit curve to the empirical results was defined. The higher the dose per fraction, biologically effective dose, and the lower the total dose, the higher the obliteration rate. The isoeffective doses when comparing radiotherapy and radiosurgery independent of the α/β value could not be defined. The dose per fraction had the best predictive value, independent of the number of fractions.Conclusions Dose per fraction seems to be the decisive parameter for the treatment response following both radiotherapy and radiosurgery. A larger number of fractions did not increase the obliteration rate. The data indicate that higher doses per fraction should be used when irradiating AVMs.
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| 9. |
- Marklund, Niklas, et al.
(författare)
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Cognitive outcome following brain injury and treatment with an inhibitor of Nogo-A in association with an attenuated downregulation of hippocampal growth-associated protein-43 expression
- 2007
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Ingår i: Journal of Neurosurgery. - 0022-3085 .- 1933-0693. ; 107:4, s. 844-853
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Tidskriftsartikel (refereegranskat)abstract
- Object. Central nervous system axons regenerate poorly after traumatic brain injury (TBI), partly due to inhibitors such as the protein Nogo-A present in myelin. The authors evaluated the efficacy of anti-Nogo-A monoclonal antibody (mAb) 7B 12 administration on the neurobehavioral and cognitive outcome of rats following lateral fluid-percussion brain injury, characterized the penetration of the 7B 12 or control antibodies into target brain regions, and evaluated the effects of Nogo-A inhibition on hemispheric tissue loss and sprouting of uninjured motor tracts in the cervical cord. To elucidate a potential molecular response to Nogo-A inhibition, we evaluated the effects of 7B 12 on hippocampal GAP-43 expression. Methods. Beginning 24 hours after lateral fluid-percussion brain injury or sham injury in rats, the mAb 7B12 or control antibody was infused intracerebroventricularly over 14 days, and behavior was assessed over 4 weeks. Results. Immunoreactivity for 7B 12 or immunoglobulin G was detected in widespread brain regions at 1 and 3 weeks postinjury. The brain-injured animals treated with 7B12 showed improvement in cognitive function (p < 0.05) at 4 weeks but no improvement in neurological motor function from 1 to 4 weeks postinjury compared with brain-injured, vehicle-treated controls. The enhanced cognitive function following inhibition of Nogo-A was correlated with an attenuated postinjury downregulation of hippocampal GAP-43 expression (p < 0.05). Conclusions. Increased GAP-43 expression may be a novel molecular mechanism of the enhanced cognitive recovery mediated by Nogo-A inhibition after TBI in rats.
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| 10. |
- Marklund, Niklas, et al.
(författare)
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Monitoring of brain interstitial total tau and beta amyloid proteins by microdialysis in patients with traumatic brain injury.
- 2009
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Ingår i: Journal of neurosurgery. - 0022-3085 .- 1933-0693. ; 110:6, s. 1227-37
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT: Damage to axons contributes to postinjury disabilities and is commonly observed following traumatic brain injury (TBI). Traumatic brain injury is an important environmental risk factor for the development of Alzheimer disease (AD). In the present feasibility study, the aim was to use intracerebral microdialysis catheters with a high molecular cutoff membrane (100 kD) to harvest interstitial total tau (T-tau) and amyloid beta 1-42 (Abeta42) proteins, which are important biomarkers for axonal injury and for AD, following moderate-to-severe TBI.METHODS: Eight patients (5 men and 3 women) were included in the study; 5 of the patients had a focal/mixed TBI and 3 had a diffuse axonal injury (DAI). Following the bedside analysis of the routinely measured energy metabolic markers (that is, glucose, lactate/pyruvate ratio, glycerol, and glutamate), the remaining dialysate was pooled and two 12-hour samples per day were used to analyze T-tau and Abeta42 by enzyme-linked immunosorbent assay from Day 1 up to 8 days postinjury.RESULTS: The results show high levels of interstitial T-tau and Abeta42 postinjury. Patients with a predominantly focal lesion had higher interstitial T-tau levels than in the DAI group from Days 1 to 3 postinjury (p < 0.05). In contrast, patients with DAI had consistently higher Abeta42 levels when compared with patients with focal injury.CONCLUSIONS: These results suggest that monitoring of interstitial T-tau and Abeta42 by using microdialysis may be an important tool when evaluating the presence and role of axonal injury following TBI.
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