1
|
Cerebral autoregulation assessed by near-infrared spectroscopy: validation using transcranial Doppler in patients with controlled hypertension, cognitive impairment and controls. Eur J Appl Physiol 2021; 121:2165-2176. [PMID: 33860383 PMCID: PMC8260523 DOI: 10.1007/s00421-021-04681-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 04/02/2021] [Indexed: 01/05/2023]
Abstract
PURPOSE Cerebral autoregulation (CA) aims to attenuate the effects of blood pressure variation on cerebral blood flow. This study assessed the criterion validity of CA derived from near-infrared spectroscopy (NIRS) as an alternative for Transcranial Doppler (TCD). METHODS Measurements of continuous blood pressure (BP), oxygenated hemoglobin (O2Hb) using NIRS and cerebral blood flow velocity (CBFV) using TCD (gold standard) were performed in 82 controls, 27 patients with hypertension and 94 cognitively impaired patients during supine rest (all individuals) and repeated sit to stand transitions (cognitively impaired patients). The BP-CBFV and BP-O2Hb transfer function phase shifts (TFφ) were computed as CA measures. Spearman correlations (ρ) and Bland Altman limits of agreement (BAloa) between NIRS- and TCD-derived CA measures were computed. BAloa separation < 50° was considered a high absolute agreement. RESULTS NIRS- and TCD-derived CA estimates were significantly correlated during supine rest (ρ = 0.22-0.30, N = 111-120) and repeated sit-to-stand transitions (ρ = 0.46-0.61, N = 19-32). BAloa separation ranged between 87° and 112° (supine rest) and 65°-77° (repeated sit to stand transitions). CONCLUSION Criterion validity of NIRS-derived CA measures allows for comparison between groups but was insufficient for clinical application in individuals.
Collapse
|
2
|
El Mekabaty A, Gottschalk A, Moghekar A, Obusez E, Khan M, Chung C, Spiotta A, Luciano MG, Hui FK. General Anesthesia Alters Intracranial Venous Pressures During Transverse Sinus Stenting. World Neurosurg 2020; 138:e712-e717. [PMID: 32194272 DOI: 10.1016/j.wneu.2020.03.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/06/2020] [Accepted: 03/07/2020] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Pressure gradients across venous stenosis are used as a marker for physiologically significant narrowing in idiopathic intracranial hypertension. Performing such measurements under conscious sedation (CS) more likely reflects physiologic conditions, but can be uncomfortable, leading some operators to perform measurement under general anesthesia (GA), though this may not be equivalent. METHODS We performed a retrospective analysis of patients who received endovascular transverse sinus stenting due to idiopathic intracranial hypertension between August 2013 and May 2017. Patients' demographics and anesthetic parameters were collected along with venous pressure measurements. RESULTS We identified 15 patients (14 women). The mean (SD) age was 30.5 (9.0) years and the mean body mass index (SD) was 39.5 (9.6) kg/m2. After measurements during CS, GA was induced with propofol and maintained with a volatile anesthetic. The median [IQR; range] transverse sinus pressure gradient under CS was 18 [12, 25; 6-38] mmHg compared with 14 [8, 21; 3-26] mm Hg under GA. The median [IQR; range] pressure gradient change after initiation of GA was -3 [-12, 0; -22 to 9] mm Hg (P = 0.014). After correction for increases in internal jugular vein pressures associated with assumption of GA, the median [IQR; range] gradient change was -11 [-12.5, -5; -22 to 0] mm Hg (P < 0.001). CONCLUSIONS The transition from CS to GA results in clinically meaningful reductions in transverse sinus gradients in idiopathic intracranial hypertension. Correction for increases in the internal jugular vein pressures reveals even more dramatic reductions in transverse sinus gradients.
Collapse
Affiliation(s)
- Amgad El Mekabaty
- Department of Radiology, The Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Allan Gottschalk
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Hospital, Baltimore, Maryland, USA; Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Abhay Moghekar
- Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Emmanuel Obusez
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Majid Khan
- Department of Radiology, The Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Charlotte Chung
- Department of Radiology, Emory University Hospital, Atlanta, Georgia, USA
| | - Alejandro Spiotta
- Department of Neurosurgery, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Mark G Luciano
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Ferdinand K Hui
- Department of Radiology, The Johns Hopkins Hospital, Baltimore, Maryland, USA.
| |
Collapse
|
3
|
Regli L, Held MC, Anderson RE, Meyer FB. Nitric oxide synthase inhibition by L-NAME prevents brain acidosis during focal cerebral ischemia in rabbits. J Cereb Blood Flow Metab 1996; 16:988-95. [PMID: 8784244 DOI: 10.1097/00004647-199609000-00024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This experiment examined the effects of nitric oxide (NO) synthase inhibition on brain intracellular pH, regional cortical blood flow, and NADH fluorescence before and during 3 h of focal cerebral ischemia using in vivo fluorescence imaging. Thirty fasted rabbits under 1% halothane were divided into four treatment groups receiving N omega-nitro-L-arginine methyl ester (L-NAME) intravenously at 20 min prior to ischemia (0.1, 1, and 10 mg/kg and 1 mg/kg + 5 mg/kg L-arginine) and two control groups (nonischemic and ischemic). In ischemic controls, brain pH(i), declined to 6.73 +/- 0.03 at 30 min and remained acidotic through the remainder of the ischemic period. In the 0.1 mg/kg group, brain pH(i) fell after 30 min of ischemia to 6.76 +/- 0.05 (p < 0.05), but then improved progressively despite occlusion. In the 1 mg/kg group, brain pH(i), remained normal despite middle cerebral artery (MCA) occlusion. In the 10 mg/kg group and in the combined L-NAME + L-arginine group, pH(i) fell after 30 min of ischemia to 6.81 +/- 0.03 (p < 0.05) and remained acidotic. During occlusion, regional cortical blood flow dropped in a dose-dependent manner. After 3 h of ischemia, regional cortical blood flow was 33.9 +/- 10.9 and 25.1 +/- 8.9 ml/100 g/min at doses of 0.1 and 10.0 mg/kg, respectively, L-NAME treatment did not significantly alter the increased NADH fluorescence that accompanied occlusion. This study shows that L-NAME can prevent intracellular brain acidosis during focal cerebral ischemia independent from regional cortical blood flow changes. This experiment suggests that NO is involved in pH(i) regulation during focal cerebral ischemia.
Collapse
Affiliation(s)
- L Regli
- Thoralf M. Sundt Jr, M.D. Neurosurgical Research Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
| | | | | | | |
Collapse
|
4
|
Regli L, Anderson RE, Meyer FB. Effects of intermittent reperfusion on brain pHi, rCBF, and NADH during rabbit focal cerebral ischemia. Stroke 1995; 26:1444-51; discussion 1451-2. [PMID: 7631351 DOI: 10.1161/01.str.26.8.1444] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND AND PURPOSE The use of intermittent reperfusion versus straight occlusion during neurovascular procedures is controversial. This experiment studied the effects of intermittent reperfusion and single occlusion on intracellular brain pH (pHi), regional cerebral or cortical blood flow, and nicotinamide adenine dinucleotide (NADH) fluorescence during temporary focal ischemia. METHODS Twenty fasted rabbits under 1.0% halothane anesthesia were divided into four groups: (1) nonischemic controls, (2) 60 minutes of uninterrupted focal ischemia, (3) 2 x 30-minute periods of focal ischemia separated by a 5-minute reperfusion, and (4) 4 x 15-minute periods of focal ischemia separated by three 5-minute reperfusion periods. Focal ischemia was produced by occlusion of both the middle cerebral and ipsilateral anterior cerebral arteries. After the final occlusion, there was a 3-hour reperfusion period in all groups. Regional cerebral and cortical blood flow, brain pHi, and NADH fluorescence were measured with in vivo panoramic fluorescence imaging. RESULTS During occlusion, regional cerebral and cortical blood flows and NADH fluorescence values were not different among the groups. Brain pHi was significantly lower in the 4 x 15-minute group compared with the 1 x 60-minute group (6.57 +/- 0.02 versus 6.73 +/- 0.06; P < .03) but not significant when compared with the 2 x 30-minute group. During the short reperfusion periods, all parameters returned to normal except for NADH fluorescence levels, which remained elevated. During the postischemic final reperfusion period, there was a mild brain alkalosis of approximately 7.1 in all groups. There were no significant differences in NADH fluorescence among groups during the final reperfusion. Regional cerebral and cortical blood flow returned to near normal values in all groups. CONCLUSIONS This study demonstrates that intermittent reperfusion during temporary focal ischemia has different effects on the intracytoplasmic and the intramitochondrial compartments: worsening of brain cytoplasmic pHi but no significant differences in the oxidation/reduction level of mitochondrial NADH.
Collapse
Affiliation(s)
- L Regli
- Thoralf M. Sundt Jr Neurosurgical Research Laboratory, Mayo Clinic, Rochester, Minn 55905, USA
| | | | | |
Collapse
|
5
|
Young WL, Freymond D, Ravussin P. [Is there still a place for routine deep hypocapnia in intracranial surgery?]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 1995; 14:70-6. [PMID: 7677290 DOI: 10.1016/s0750-7658(05)80153-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Deliberate hypocapnia during the anaesthetic management of the patient undergoing craniotomy has become an accepted standard of care. However there has been a resurgence of interest, in how hypocapnia should be applied in intra- and extra-operative settings. There are three possible therapeutic effects of hypocapnia, namely, (a) reduction of brain bulk through a reduction in cerebral blood volume, with a decrease cerebral blood flow; (b) developing an "inverse steal" by redistribution of blood from normal to ischaemic regions and (c) acting to offset cerebral acidosis by increasing pH in the extracellular space. In anaesthetic intraoperative practice, hypocapnia is used as a specific treatment of, or prophylaxis against, intracranial hypertension during induction of anaesthesia and the period before dural exposure. More commonly, hypocapnia is used for intraoperative brain relaxation (intracranial pressure = 0). Severe hypocapnia (< 20 mmHg) may result in cerebral production of lactate; however no studies have shown that a Paco2 in the range of 23-28 mmHg has deleterious effects. Recent studies in head-injured patients suggest that routine long-term hyperventilation, without an objective index of cerebral flow/metabolism coupling, may place the brain at risk for adverse outcome. The few data available for intraoperative management suggest that Paco2 figures of 30-35 mmHg result in acceptable operating conditions. Unless otherwise specifically indicated by surgical conditions or cerebral flow/metabolism coupling (e.g. jugular O2 saturation), routine application of profound (Paco2 < 28-30 mmHg) hyperventilation should probably be avoided and its use needs reevaluation.
Collapse
Affiliation(s)
- W L Young
- College of Physicians & Surgeons of Columbia University, New York, USA
| | | | | |
Collapse
|
6
|
Kirkpatrick PJ, Bucknall R, Naylor P, Rudman S, Strong AJ. Digital imaging of umbelliferone clearance: a method for repeated measurements of cerebral cortical blood flow with high temporal and spatial resolution. J Cereb Blood Flow Metab 1994; 14:1062-9. [PMID: 7929649 DOI: 10.1038/jcbfm.1994.139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have developed a procedure for digital imaging of the exposed cerebral cortex during elution of a fluorescent dye. This avoids disturbing the cortex and has provided a method for the repeated estimation of regional CBF (rCBF) with a high topographical resolution. Under varying conditions of MABP and arterial blood gases, grey-level images of the exposed cortex irradiated with ultraviolet light (340 or 370 nm) were digitised (8 bits) at 15-s intervals after the injection of 1-2 ml of saturated umbelliferone solution into the lingual or external carotid artery of anaesthetised cats and rabbits. Specifically designed software allowed (a) regions of interest (ROIs) in the exposed cortex to be defined that were automatically applied to the sequence of images in a selected clearance and (b) solution of the initial slope equation for rCBF from the decay in grey-level fluorescence by exponential regression. Separate software that solved the equation at the level of a single pixel allowed a pseudocolour map of cortical rCBF to be generated. The factors affecting the resolution of this technique have been identified and quantified. Thus consistent and reproducible results were obtained provided that the fluorescence enhancement exceeded 20 grey levels and the r2 coefficient for regression was 90% or above. Mean rCBF values of 99.5 [95% confidence interval (CI), 89.4-110] ml 100 g-1 min-1 were obtained for rabbits (N = 12; mean MABP = 75.2; mean PaCO2 = 32.9; PaO2 = 111.8; pH 7.38) and 65.1 (95% CI, 55.1-75.1) ml 100 g-1 min-1 for cats (N = 8; mean MABP = 92.8; PaCO2 = 31.5; PaO2 = 114.6, pH 7.40).(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- P J Kirkpatrick
- University Department of Neurosurgery, Addenbrookes Hospital, Cambridge, England
| | | | | | | | | |
Collapse
|
7
|
Tomlinson FH, Anderson RE, Meyer FB. Acidic foci within the ischemic penumbra of the New Zealand white rabbit. Stroke 1993; 24:2030-9; discussion 2040. [PMID: 8248985 DOI: 10.1161/01.str.24.12.2030] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND AND PURPOSE In vivo panoramic imaging of reduced nicotinamide adenine dinucleotide (NADH), intracellular brain pH (pHi), and cortical blood flow was used to characterize the ischemic penumbra during focal ischemia. During global ischemia, hypoxia, and status epilepticus, the development of cortical acidic foci has been observed. The hypothesis tested was that during focal ischemia, acidic foci develop, which may lead to recruitment of the ischemic penumbra into infarction. METHODS Five fasted New Zealand White rabbits underwent middle cerebral artery (MCA) occlusion under 1.5% halothane anesthesia through a retro-orbital approach, and five animals served as controls. Brain pHi and cerebral blood flow were measured with in vivo umbelliferone fluorescence. RESULTS Baseline brain pHi was 6.98 +/- 0.05, whereas cortical blood flow and NADH fluorescence measured 52.2 +/- 8.7 mL/100 g per minute and 35.5 +/- 3.7 gray-scale units, respectively. Fifteen minutes after MCA occlusion, overall brain pHi and cortical blood flow of the ischemic penumbra measured 6.61 +/- 0.06 and 31.9 +/- 9.2 mL/100 g per minute. Over 3 hours there was normalization of pHi in the majority of the penumbra due to increases in cortical blood flow. Within the ischemic penumbra acidic foci developed with an initial pHi of 6.35 +/- 0.09 and cortical blood flow of 18.0 +/- 5.7 mL/100 g per minute. These foci remained acidic with increased NADH fluorescence despite being surrounded by cortex that was recovering from ischemia. On light microscopy, these acidic foci had a mixed pattern of neuronal injury. CONCLUSIONS Within the ischemic penumbra, acidic foci develop that do not follow a vascular distribution and have microscopic evidence of ischemic neuronal injury. This suggests that there is a cortical selective vulnerability regarding pHi regulation and these acidic foci may lead to recruitment of the ischemic penumbra into infarction.
Collapse
Affiliation(s)
- F H Tomlinson
- Neurosurgical Research Laboratory, Mayo Graduate School of Medicine, Rochester, Minn
| | | | | |
Collapse
|
8
|
Tomlinson FH, Anderson RE, Meyer FB. Brain pHi, cerebral blood flow, and NADH fluorescence during severe incomplete global ischemia in rabbits. Stroke 1993; 24:435-43. [PMID: 8446980 DOI: 10.1161/01.str.24.3.435] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND AND PURPOSE The aim of this experiment was to study the serial changes in brain intracellular pH, cerebral blood flow, and the oxidation/reduction level of intramitochondrial nicotinamide adenine dinucleotide fluorescence across the cortical surface during severe incomplete global ischemia. METHODS Reduced nicotinamide adenine dinucleotide fluorescence and brain intracellular pH using the pH-sensitive indicator umbelliferone were measured with in vivo panoramic fluorescence imaging of the cortical surface. Cerebral blood flow was measured with the clearance of both umbelliferone and xenon-133. Fifteen minutes of severe incomplete global ischemia was produced by temporary occlusion of the innominate, left carotid, and subclavian arteries in five fasted New Zealand White rabbits. RESULTS Baseline brain intracellular pH was homogeneous over the exposed cortex, measuring 7.00 +/- 0.02, while cerebral blood flow was 48.0 +/- 2.6 ml/100 g/min. During 15 minutes of ischemia, cerebral blood flow measured 6.3 +/- 1.8 ml/100 g/min and brain pH declined to 6.61 +/- 0.02 (p < 0.005); in addition, there were acidotic foci with pH measuring 6.40 +/- 0.10. During reperfusion, there was an initial normalization of brain intracellular pH without an alkaline shift followed by a recurrent cortical acidosis of pH 6.88 +/- 0.06. There was a heterogeneous pattern of fluorescence that increased significantly following 60 minutes of reperfusion, coinciding with a postischemic hypoperfusion. The hypoperfusion was a uniform reduction in cerebral blood flow over the brain's surface, with reductions of 42.5% and 44.2% at 30 and 45 minutes, respectively. CONCLUSIONS During incomplete global ischemia there is a heterogeneous pattern of brain intracellular pH and reduced nicotinamide adenine dinucleotide changes that do not correlate with changes in cortical blood flow. The acidotic foci that were approximately 0.2 pH units more acidotic than the surrounding cortex may be the result of continued glucose delivery under anaerobic conditions. The degree of reduced nicotinamide adenine dinucleotide fluorescence suggests that the cortex is most vulnerable to metabolic failure after 60 minutes of reperfusion following severe incomplete global ischemia. The heterogeneous pattern of brain intracellular pH and reduced nicotinamide adenine dinucleotide changes suggest that there may be a selective vulnerability of cortical tissue to an ischemic challenge.
Collapse
Affiliation(s)
- F H Tomlinson
- Department of Neurosurgery, Mayo Clinic, Rochester, MN 55905
| | | | | |
Collapse
|
9
|
Tomlinson FH, Anderson RE, Meyer FB. Effect of arterial blood pressure and serum glucose on brain intracellular pH, cerebral and cortical blood flow during status epilepticus in the white New Zealand rabbit. Epilepsy Res 1993; 14:123-37. [PMID: 8453950 DOI: 10.1016/0920-1211(93)90017-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Generalized seizures can induce both hypertension and hyperglycemia which may aggravate preexisting cerebral or medical conditions in patients. In vivo fluorescent imaging of regional cortical blood flow and brain intracellular pH (pHi) was performed in fasted New Zealand rabbits (n = 35) in which either mean arterial blood pressure (MABP) or serum glucose was the covaried factor during pentylenetetrazole induced status epilepticus under 1.5% inspired halothane. Baseline brain pHi and regional cortical blood flow were 7.02 +/- 0.02 and 51.1 +/- 1.7 ml/100 g/min, respectively. Following seizure induction, MABP increased to 105 mm Hg and brain pHi fell to 6.79 +/- 0.03 within 15 min and remained at this level for 1 h (P < 0.001). With normalization of MABP during ongoing seizures, there was no worsening in brain pHi despite a significant decrease in regional cortical blood flow. Hyperglycemia decreased pHi to 6.71 +/- 0.02 compared to 6.84 +/- 0.04 in normoglycemic animals (P < 0.001). Using pHi as a cerebral metabolic index, these data suggest that normalization of MABP does not increase metabolic injury while hyperglycemia does significantly worsen brain acidosis. Therefore, administration of glucose to patients with status epilepticus should be avoided unless there is documented hypoglycemia.
Collapse
Affiliation(s)
- F H Tomlinson
- Department of Neurosurgery, Mayo Clinic, Rochester, MN 55905
| | | | | |
Collapse
|
10
|
Tomlinson FH, Anderson RE, Meyer FB. Panoramic imaging of brain pHi and CBF during penicillin and metrazole induced status epilepticus. Epilepsy Res 1992; 13:49-58. [PMID: 1478198 DOI: 10.1016/0920-1211(92)90007-g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Using real-time in vivo umbelliferone fluorescent imaging, cortical intracellular brain pH (pHi) and cortical blood flow (CBF) were measured in New Zealand white rabbits during generalized seizures induced by intravenous metrazole or sodium penicillin. In the former, brain pHi declined from 7.04 +/- 0.07 to 6.78 +/- 0.07 within 15 min of generalized seizures and remained at this level for 1 h. In the penicillin group, pHi fell from 7.05 +/- 0.10 to 6.81 +/- 0.07 and also remained at this level over 60 min. This brain acidosis was uniform across the brain's surface. With the onset of status epilepticus there was a hyperemia which occurred in a heterogeneous pattern with blood flow appearing to be greater adjacent to cortical vasculature and slower in border zones between surface blood vessels. In the metrazole group, there was evidence of vasomotor paralysis with loss of autoregulation involving both cortical surface vasculature and penetrating arterioles with their capillary beds.
Collapse
Affiliation(s)
- F H Tomlinson
- Cerebral Vascular Research, Mayo Clinic, Rochester, MN 55905
| | | | | |
Collapse
|
11
|
Meyer FB, Anderson RE, Friedrich PF. MK-801 attenuates capillary bed compression and hypoperfusion following incomplete focal cerebral ischemia. J Cereb Blood Flow Metab 1990; 10:895-902. [PMID: 2211882 DOI: 10.1038/jcbfm.1990.146] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effects of the N-methyl-D-aspartate (NMDA) antagonist MK-801 on capillary beds and CBF following 1 h of transient incomplete focal cerebral ischemia were studied by examining 133Xe CBF, capillary diameter, and area of perfused vasculature. Capillary diameter increased from a control of 5.24 +/- 0.37 to 8.62 +/- 0.57 microns (p less than 0.001) and area of perfused vasculature from 20,943 +/- 1,151 to 30,442 +/- 1,691 microns2/x 10 magnification field (p less than 0.001) with MK-801 1.0 mg/kg administered 30 min prior to ischemia. After flow restoration in control animals, there was a relative hypoperfusion with eventual normalization of CBF over 60 min. Alternatively, in MK-801 1.0 mg/kg animals, there was rapid normalization of CBF upon flow restoration without the postischemic hypoperfusion observed in controls. On histological analysis, there was consistently less neuronal edema in MK-801-treated animals. These results support the hypothesis that hypoperfusion following incomplete focal cerebral ischemia may be due in part to NMDA-mediated cellular edema with subsequent extravascular capillary bed compression.
Collapse
Affiliation(s)
- F B Meyer
- Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota 55905
| | | | | |
Collapse
|
12
|
Meyer FB, Anderson RE, Sundt TM. The novel dihydronaphthyridine Ca2+ channel blocker CI-951 improves CBF, brain pHi, and EEG recovery in focal cerebral ischemia. J Cereb Blood Flow Metab 1990; 10:97-103. [PMID: 2298840 DOI: 10.1038/jcbfm.1990.12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of the novel dihydronaphthyridine Ca2+ antagonist CI-951 on focal cerebral ischemia were assessed during MCA occlusion in 30 white New Zealand rabbits under 1.0% halothane anesthesia. In vivo brain pHi and focal CBF were measured with umbelliferone fluorescence. Baseline normocapnic brain pHi and CBF were 7.02 +/- 0.02 and 48.4 +/- 2.9 ml/100 g/min, respectively. In the severe ischemic regions, 15 min postocclusion brain pHi and CBF were 6.62 +/- 0.04 and 14.4 +/- 0.7 ml/100 g/min in controls vs. 6.60 +/- 0.02 and 12.9 +/- 2.3 ml/100 g/min, respectively, in animals destined to receive CI-951. Twenty minutes after MCA occlusion, CI-951 was administered at 0.5 microgram/kg/min and brain pHi and CBF were determined in both regions of severe and moderate ischemia for 4 h postocclusion. Control severe ischemic sites demonstrated no significant improvement in brain pHi and only mild increases in CBF over the next 4 h. CI-951 caused significant improvement in both of these parameters. Postocclusion 4 h brain pHi and CBF measured 6.69 +/- 0.04 and 18.5 +/- 3.2 ml/100 g/min in controls vs. 7.01 +/- 0.04 and 41.7 +/- 5.3 ml/100 g/min, respectively, in CI-951 animals (p less than 0.001). Similar improvements were observed in moderate ischemic sites. In animals that demonstrated postocclusion EEG attenuation, 75% of CI-951 animals had EEG recovery as compared to 18% in controls. CI-951 may be a useful therapeutic agent for focal cerebral ischemia if histological and outcome studies verify these data.
Collapse
Affiliation(s)
- F B Meyer
- Neurosurgical Cerebrovascular Research Center, Mayo Clinic, Rochester, MN 55903
| | | | | |
Collapse
|
13
|
Goldenberg G, Podreka I, Suess E, Deecke L. The cerebral localization of neuropsychological impairment in Alzheimer's disease: a SPECT study. J Neurol 1989; 236:131-8. [PMID: 2785163 DOI: 10.1007/bf00314327] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Twenty-three patients with a clinical diagnosis of Alzheimer's disease were examined with a set of neuropsychological tests and with 99mTc-hexamethyl-propyleneamineoxime (HMPAO) single photon emission computed tomography (SPECT). Correlations between test results and indices of regional HMPAO distribution were analysed by multidimensional scaling (MDS). Test results covaried positively with relative HMPAO uptake of frontal, inferior parietal and superior temporal regions but not, or in a negative way, with the remainder of the regions. When only positive correlations were analysed, MDS suggested two dimensions of organization: one was related to a dichotomy between frontal and temporo-parietal regions. The relationship of test results to this dimension was largely consistent with common neuropsychological knowledge. A second, less stringent dimension of organization opposed right and left hemisphere regions. The ordering of test results with respect to this dimension was only partly consistent with what is known about the lateralization of neuropsychological deficits from the study of localized brain lesions. The possibility is considered that these inconsistencies may reflect the effect of disproportionally severe involvement of extended cortical systems which modulates the sequels of localized brain damage.
Collapse
Affiliation(s)
- G Goldenberg
- Neurologische Universitätsklinik, Vienna, Austria
| | | | | | | |
Collapse
|
14
|
Meyer E, Thompson CJ, Marrett S, Hakim AM. Field of view for gamma ray detectors and extended radiation sources. J Cereb Blood Flow Metab 1988; 8:144-5. [PMID: 3339104 DOI: 10.1038/jcbfm.1988.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|