Combined systemic thrombolysis with alteplase and early hyperbaric oxygen therapy in experimental embolic stroke in rats: relationship to functional outcome and reduction of structural damage.

INTRODUCTION: The only causal therapy in ischemic stroke is thrombolysis with recombinant tissue plasminogen activator (rtPA), but it is feasible only for few patients, and new therapies are needed. This study investigates the effects of systemic thrombolysis with rtPA combined with hyperbaric oxygen therapy (HBOT) in embolic stroke in rats. METHODS: In 22 male Wistar rats, an embolic ischemic stroke was induced. The animals were randomized to one of four groups: control, thrombolysis alone, HBOT sequential or HBOT parallel with thrombolysis. HBOT (2.4 ATA, 1 h) started 45 min (sequential) or 120 min (parallel) after stroke. rtPA was given intravenously 120 min after stroke onset. Functional tests were performed after stroke induction and after treatment. After 6 h infarct volume and intracerebral hemorrhagic complications were assessed. RESULTS: Compared to the control group only the combination of HBOT and thrombolysis significantly improved the functional outcome (p=0.03) and reduced the infarct volume (p=0.01), whereas thrombolysis alone did not show a significant benefit. In all treatment groups there was a trend towards fewer hemorrhagic transformations. CONCLUSION: Hyperbaric oxygen in combination with thrombolysis shows neuroprotection in acute ischemic stroke in rats by reducing infarct volume and improving functional outcome in the early poststroke period.

Prophylactic, endovascularly based, long-term normothermia in ICU patients with severe cerebrovascular disease: bicenter prospective, randomized trial.

BACKGROUND AND PURPOSE: We sought to study the effectiveness and safety of endovascular cooling to maintain prophylactic normothermia in comparison with standardized, stepwise, escalating fever management to reduce fever burden in patients with severe cerebrovascular disease. METHODS: This study was a prospective, randomized, controlled trial with a blinded neurologic outcome evaluation comparison between prophylactic, catheter-based normothermia (CoolGard; ie, body core temperature 36.5 degrees C) and conventional, stepwise fever management with anti-inflammatory drugs and surface cooling. Patients admitted to 1 of the 2 neurointensive care units were eligible for study inclusion when they had a (1) spontaneous subarachnoid hemorrhage with Hunt & Hess grade between 3 and 5, (2) spontaneous intracerebral hemorrhage with a Glasgow Coma Scale score or=15. RESULTS: A total of 102 patients (56 female) were enrolled during a 3.5-year period. Fifty percent had a spontaneous subarachnoid hemorrhage, 40% had a spontaneous intracerebral hemorrhage, and 10% had a complicated cerebral infarction. Overall median total fever burden during the course of treatment was 0.0 degrees C hour and 4.3 degrees C hours in the catheter and conventional groups, respectively (P<0.0001). Prophylactic normothermia did not lead to an increase in the number of patients who experienced a major adverse event. No significant difference was found in mortality and neurologic long-term follow-up. CONCLUSIONS: Long-term, catheter-based, prophylactic normothermia significantly reduces fever burden in neurointensive care unit patients with severe cerebrovascular disease and is not associated with increased major adverse events.

Protective effect of hyperbaric oxygen therapy on experimental brain contusions.

BACKGROUND: We evaluated the effect of hyperbaric oxygen therapy (HBO) on experimental brain contusions in rats using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Ten Sprague-Dawley rats were investigated at 24 h and 72 h after controlled cortical impact injury. One hour after trauma, 5 rats were treated for 60 min with 100% oxygen at 2.5 absolute atmosphere (ATA), 5 were kept at normobaric room air. MRI was performed longitudinally at 24 h and 72 h after injury. Lesion volume was determined in T2 weighted MRI scans. Relative apparent diffusion coefficient (ADC) changes were calculated in comparison to the contralateral side. RESULTS: Following HBO, T2 lesion volume was smaller at 24 h versus controls (63.1 +/- 16.5 mm3 vs. 87.4 +/- 13.8 mm3, p < 0.05), and decreased further at 72 h (46.8 +/- 17.8 mm3 vs. 92.5 +/- 13.1 mm3, p < 0.01). At 24 h, the mean relative ADC change in the lesion area decreased from + 26.8 +/- 2.3% in controls to + 2.3 +/- 12.2% in HBO animals (p < 0.01). At 72 h, the HBO effect on relative ADC values was less when compared to 24 h. DISCUSSION: A 60-minute exposure to hyperbaric oxygen starting 1 h after impact injury significantly attenuated lesion growth and relative increase of ADC values within the contused area for up to 72 h. Thus, a "single-shot" HBO treatment seems to have long-lasting neuroprotective effects on the contused brain and its penumbra.

Evidence-Based Critical Care of Intracerebral Hemorrhage: An Overview.

Outcome of intracerebral hemorrhage (ICH) is still poor and siginificantly influenced by complications during the acute phase, so optimized neurocritical care is crucial. Vital parameters, neurological status and laboratory values of ICH-patient should be monitored very closely with special attention on blood pressure and intracranial pressure. Systolic blood pressure should be kept <140 mm Hg and intracranial pressure <20 mm Hg. Administration of hemostatic agents in spontaneous ICH without intake of anticoagulants is actually not recommended out of clinical trials. Neurosurgical treatment of ICH is still an individual decision. Patients with a higher level of consciousness may profit from an early operation.

Autonomic reactions and peri-interventional alterations in body weight as potential supplementary outcome parameters for thromboembolic stroke in rats.

BACKGROUND: Since several neuroprotectives failed to reproduce promising preclinical results under clinical conditions, efforts emerged to implement clinically relevant endpoints in animal stroke studies. Thereby, insufficient attention was given on autonomic reactions due to experimental stroke, although clinical trials reported on high functional and prognostic impact. This study focused on autonomic consequences and body weight changes in a translational relevant stroke model and investigated interrelations to different outcome measurements. METHODS: Forty-eight rats underwent thromboembolic middle cerebral artery occlusion (MCAO) while recording heart rate (HR) and mean arterial pressure (MAP). After assessing early functional impairment (Menzies score), animals were assigned to control procedure or potentially neuroprotective treatment with normobaric (NBO) or hyperbaric oxygen (HBO). Four or 24 hours after ischemia onset, functional impairment was re-assessed and FITC-albumin administered intravenously obtaining leakage-related blood-brain barrier (BBB) impairment. Body weight was documented prior to MCAO and 4 or 24 hours after ischemia onset. RESULTS: During MCAO, HR was found to increase significantly while MAP decreased. The amount of changes in HR was positively correlated with early functional impairment (P = 0.001): Severely affected animals provided an increase of 15.2 compared to 0.8 beats/minute in rats with low impairment (P = 0.048). Regarding body weight, a decrease of 9.4% within 24 hours after MCAO occurred, but treatment-specific alterations showed no significant correlations with respective functional or BBB impairment. CONCLUSIONS: Future studies should routinely include autonomic parameters to allow inter-group comparisons and better understanding of autonomic reactions due to experimental stroke. Prospectively, autonomic consequences might represent a useful outcome parameter enhancing the methodological spectrum of preclinical stroke studies.

Long-lasting neuronal loss following experimental focal cerebral ischemia is not affected by combined administration of tissue plasminogen activator and hyperbaric oxygen.

Acute focal cerebral ischemia and consecutive energy failure are accompanied by neuronal death in regions with impaired cerebral blood flow. Several translational attempts of potential neuroprotective agents have failed, hence extended perspectives are required regarding the regional differences of neuronal impairment and glial involvement by using clinically relevant stroke models. This study aimed on neuronal loss following experimental focal cerebral ischemia, considering tissue plasminogen activator (tPA) as established treatment in stroke and hyperbaric oxygenation (HBO) as potential neuroprotective co-treatment. Wistar rats were subjected to embolic middle cerebral artery occlusion and underwent either treatment with tPA only, combined tPA+HBO, or no treatment. Neuronal impairment was assessed by Neuronal Nuclei (NeuN) staining in 4 ischemia-related areas and at 4 different time points after stroke induction (24hours, 7, 14 and 28 days). Additionally, spatial relationships between neuronal loss and gliosis were revealed by triple fluorescence staining of neurons, astrocytes and microglia, comparing the ipsi- and contra-lesional hemisphere. Analyzing the ischemic injury in general, a shell-like distribution of neuronal damage was observed, starting in the ischemic core and diminishing over the general ischemic area to the ischemic border zone and the primary non-affected area. This pattern remained detectable up to 4weeks after ischemia induction. Surprisingly, tPA and tPA+HBO did not markedly affect the post-ischemic course of neuronal impairment. Further studies are needed to investigate the effects of treatment with tPA or potential neuroprotective agents on neuronal integrity, with emphasis on the separation of intact neurons from those undergoing apoptosis or necrosis.

Long-term functional and neurological outcome after simultaneous treatment with tissue-plasminogen activator and hyperbaric oxygen in early phase of embolic stroke in rats.

The combination of hyperbaric oxygen therapy (HBO) and recombinant tissue-plasminogen activator (tPA) is of interest in the treatment of acute ischemic stroke with a view to combine positive effects of both strategies. We investigated neurological and functional outcome after early treatment with HBO additional to tPA in ischemic stroke. Focal cerebral ischemia was induced using an embolic stroke model in 87 male Wistar rats. Animals were randomized to therapy with tPA+HBO, tPA alone, or control. Menzies score, Beam walk, and the Corner test were assessed for a period of 4 weeks following ischemia. Within the first 24 h neurological deficits improved in all groups but most pronounced in animals treated with tPA+HBO. Thereafter, a deterioration of neurological deficits occurred in the tPA+HBO group with significant differences at day 7, 8, 18, and 24 (P<0.05). Surprisingly, Beam walk and Corner test results did not differ significantly between all groups. This first report of early simultaneous treatment with tPA and HBO in experimental embolic stroke with 4-week follow-up confirms previous studies reporting positive effects of HBO shortly after the ischemia. Following the acute phase, combined tPA and HBO resulted in deterioration of neurological deficits without affecting functional recovery. Future studies should focus on interactions of tPA and HBO on molecular level leading to delayed damage to brain tissue at risk.

Neuroprotective effect of hyperbaric oxygen therapy monitored by MR-imaging after embolic stroke in rats.

The potential neuroprotective effects of hyperbaric oxygen (HBO) were tested in an embolic model of focal cerebral ischemia with partially spontaneous reperfusion. Rats (n = 10) were subjected to embolic middle cerebral artery occlusion (MCAO) and diffusion weighted MRI (DWI) was performed at baseline, 1, 3, and 6 h after MCAO to determine the ADC viability threshold yielding the lesion volumes that best approximated the 2,3,5-triphenyltetrazolium chloride (TTC) infarct volumes at 24 h (experiment 1). For assessment of neuroprotective effects, rats were treated with 100% oxygen at 2.5 atmospheres absolute (ATA, n = 15) or normobaric room air (n = 15) for 60 min beginning 180 min after MCAO (experiment 2). DWI-, perfusion (PWI)- and T2-weighted MRI (T2WI) started within 0.5 h after MCAO and was continued 5 h, 24 h (PWI and T2WI only), and 168 h (T2WI only). Infarct volume was calculated based on TTC-staining at 24 h (experiment 1) or 168 h (experiment 2) post-MCAO. ADC-lesion evolution was maximal between 3 and 6 h. In experiment 2, the relative regional cerebral blood volume (rCBV) of both groups showed similar incomplete spontaneous reperfusion in the ischemic core. HBO reduced infarct volume to 145.3 +/- 39.6 mm3 vs. 202.5 +/- 58.3 mm3 (control, P = 0.029). As shown by MRI and TTC, HBO treatment demonstrated significant neuroprotection at 5 h after embolic focal cerebral ischemia that lasted for 168 h.

Reduced infarct volume and differential effects on glial cell activation after hyperbaric oxygen treatment in rat permanent focal cerebral ischaemia.

Permanent middle cerebral artery occlusion (MCAO) causes neurodegeneration and a robust activation of glial cells primarily in sensorimotor brain regions of rats. It has been shown that hyperbaric oxygen (HBO) increases oxygen supply to ischaemic areas and reduces neuronal cell loss. The effects of HBO treatment on microgliosis and astrogliosis in permanent cerebral ischaemia have not been addressed so far, but might be critical for neurodegeneration and neuroprotection, respectively. Therefore, we used spontaneously hypertensive rats with permanent MCAO to investigate the time window to start HBO and to compare the effects of different HBO treatment frequencies on infarct volume and on differences with regard to microgliosis and astrogliosis. Seven days after MCAO the infarct volume was calculated from Nissl-stained brain sections by image analysis. HBO significantly decreased the infarct volume when used as early as 15, 90 or 180 min post-MCAO by 24%, 16% and 13%, respectively, in the single-treatment group. Repetitive HBO treatment (first HBO session 90 min after MCAO) was not effective. Microglial cells and astrocytes were detected by cytochemical fluorescent labelling and confocal laser scanning microscopy. In the single-treatment group we observed significantly higher astrocyte immunoreactivity but decreased microglial density in the peri-infarct region. These effects of HBO treatment on glial cells were not present in rats where HBO did not reduce the infarct volume (360 min after MCAO). Our data indicate that HBO-induced suppression of microgliosis and aggravated response of astrocytes might contribute to the reported beneficial effects of early HBO treatment in cerebral ischaemia.