Hyperthermia is a surrogate marker of inflammation-mediated cause of brain damage in acute ischaemic stroke

Impact of fever on the outcome non-anoxic acute brain injury patients: a systematic review and meta-analysis

BACKGROUND

Fever is a common condition in intensive care unit (ICU) patients, with an incidence between 30 and 50% in non-neurological ICU patients and up to 70-90% in neurological ICU patients. We aim to perform systematic review and meta-analysis of current literature to assess impact of fever on neurological outcomes and mortality of acute brain injury patients.

METHODS

We searched PubMed/Medline, Scopus and Embase databases following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and we included both retrospective and prospective observational studies, interventional studies, and randomized clinical trials that had data on body temperature and fever during ICU admission. The primary endpoints were neurological outcome and mortality at any time. Secondary outcomes included: early neurological deterioration, delayed cerebral ischemia (DCI, only for patients with subarachnoid hemorrhage), large infarct or hemorrhage size, hemorrhagic transformation (only for patients with ischemic stroke). This study was registered in PROSPERO (CRD42020155903).

RESULTS

180 studies from 14692 records identified after the initial search were included in the final analysis, for a total of 460,825 patients. Fever was associated with an increased probability of unfavorable neurological outcome (pooled OR 2.37 [95% CI 2.08-2.71], I2:92%), death (pooled OR 1.31 [95% CI 1.28-1.34], I2:93%), neurological deterioration (pooled OR 1.10 [95% CI 1.05-1.15]), risk of DCI (pooled OR 1.96 [95% CI 1.73-2.22]), large infarct size (pooled OR 2.94 [95% CI 2.90-2.98]) and hemorrhagic transformation (pooled OR 1.63 [95% CI 1.34-1.97]) and large hemorrhagic volume (pooled OR 2.38 [95% CI 1.94-2.93]).

CONCLUSION

Fever was associated with poor neurological outcomes and mortality in patients with acute brain injury. Whether normothermia should be targeted in the management of all neuro critically ill patients warrants specific research.

Clinical experience with bromocriptine for central hyperthermia after brain insult

INTRODUCTION

Bromocriptine is a dopamine receptor agonist used for central hyperthermia with limited data. We describe our single-center experience utilizing bromocriptine for central hyperthermia, including the population treated, most common dosing regimens, adverse events, and discontinuation reasons.

METHODS

A retrospective study was conducted screening patients who were admitted to intensive care units for acute neurological insults and administered bromocriptine for central hyperthermia between April 2016 and September 2022. Baseline characteristics, disease severity markers, and bromocriptine doses were collected. Body temperatures prior to the first dose of bromocriptine, at the time of dose, and after each dose were recorded. Co-administration of additional hyperthermia management therapies was noted.

RESULTS

Thirty patients were included. The most common diagnosis was traumatic brain injury (TBI) (N = 14). The most common reason for discontinuation was resolution of indication (N = 14). Discontinuation due to mild adverse effects occurred in four patients; hepatotoxicity was the most common. There was a paired mean difference of -0.37°C (p = 0.005) between temperatures before and after bromocriptine initiation.

CONCLUSION

Bromocriptine is a potential therapy for the management of central hyperthermia in patients with severe acute neurologic insults who have failed other therapies. Bromocriptine was well tolerated and associated with a low incidence of adverse events.

Body temperature in the acute phase and clinical outcomes after acute ischemic stroke

BACKGROUND

This study aimed to examine whether post-stroke early body temperature is associated with neurological damage in the acute phase and functional outcomes at three months.

METHODS

We included 7,177 patients with acute ischemic stroke within 24 h of onset. Axillary temperature was measured daily in the morning for seven days. Mean body temperature was grouped into five quintiles (Q1: 35.1‒36.5°C, Q2: 36.5‒36.7°C, Q3: 36.7‒36.8°C, Q4: 36.8‒37.1°C, and Q5: 37.1‒39.1°C). Clinical outcomes included neurological improvement during hospitalization and poor functional outcome (modified Rankin scale score, 3-6) at three months. A logistic regression analysis was performed to evaluate the association between body temperature and clinical outcomes.

RESULTS

The patient's mean (SD) age was 70.6 (12.3) years, and 35.7% of patients were women. Mean body temperature was significantly associated with less neurological improvement from Q2 (odds ratios [95% confidence interval], 0.77 [0.65-0.99] vs. Q1) to Q5 (0.33 [0.28-0.40], P for trend <0.001) even after adjusting for potential confounders, including baseline neurological severity, C-reactive protein levels, and post-stroke acute infections. The multivariable-adjusted risk of poor functional outcome linearly increased from Q2 (1.36 [1.03-1.79]) to Q5 (6.44 [5.19-8.96], P for trend <0.001). These associations were maintained even in the analyses excluding patients with acute infectious diseases. Multivariable-adjusted risk of poor functional outcome was higher in patients with early body temperature elevation on days 1-3 and with longer duration with body temperature >37.0°C.

CONCLUSIONS

Post-stroke early high body temperature is independently associated with unfavorable outcomes following acute ischemic stroke.

Near Infrared Emissive Lanthanide Luminescence Nanoparticle Used in Early Diagnosis and Brain Temperature Detection for Ischemic Stroke

Ischemic stroke (IS) is one of the most dangerous medical conditions resulting in high mortality and morbidity. The increased brain temperature after IS is closely related to prognosis, making it highly significant for the early diagnosis and the progression evaluation of IS. Herein, a temperature-responsive near infrared (NIR) emissive lanthanide luminescence nanoparticle is developed for the early diagnosis and brain temperature detection of IS. After intravenous injection, the nanoparticles can pass through the damaged blood-brain barrier of the ischemic region, allowing the extravasation and enrichment of nanoparticles into the ischemic brain tissue. The NIR luminescence signals of the nanoparticles are used not only to judge the location and severity of the cerebral ischemic injury but also to report the brain temperature variation in the ischemic area through a visualized way. The results show that the designed nanoparticles can be used for the early diagnosis of ischemic stroke and minimally invasive temperature detection of cerebral ischemic tissues in transient middle cerebral artery occlusion mice model, which is expected to make the clinical diagnosis of ischemic stroke more rapid and convenient, more accurately evaluate the state of brain injury in stroke patients and also guide stroke hypothermia treatment.

Influence of Temperature Chronobiology on Stroke Outcome

The circadian system regulates numerous physiological variables, including body temperature. Additionally, a circadian patter has been described in stroke onset. Considering this, we hypothesised that the chronobiology of temperature may have an impact on stroke onset and functional outcomes. We also studied the variation of blood biomarkers according to stroke onset time. This is a retrospective observational study. Of the patients included, 2763 had a stroke between midnight and 8:00 h; 1571 between 8:00-14:00 h; and 655 between 14:00 h and midnight. Axillary temperature was measured at admission. At this time, blood samples were collected for biomarker analysis (TNF-α, IL-1β, IL-6, IL-10, and glutamate). Temperature was higher in patients admitted from 8:00 h to midnight (p < 0.0001). However, the percentage of poor outcome at 3 months was highest in patients from midnight to 8:00 h (57.7%, p < 0.001). The association between temperature and mortality was highest during night time (OR: 2.79; CI 95%: 2.36-3.28; p < 0.001). These patients exhibited high glutamate (220.2 ± 140.2 µM), IL-6 (32.8 ± 14.3 pg/mL) and low IL-10 (9.7 ± 14.3 pg/mL) levels. Therefore, temperature chronobiology could have a significant impact on stroke onset and functional outcome. Superficial body hyperthermia during sleep seems to be more dangerous than during wakefulness. Further studies will be necessary to confirm our data.

A Novel Non-Invasive Thermometer for Continuous Core Body Temperature: Comparison with Tympanic Temperature in an Acute Stroke Clinical Setting

There is a growing research interest in wireless non-invasive solutions for core temperature estimation and their application in clinical settings. This study aimed to investigate the use of a novel wireless non-invasive heat flux-based thermometer in acute stroke patients admitted to a stroke unit and compare the measurements with the currently used infrared (IR) tympanic temperature readings. The study encompassed 30 acute ischemic stroke patients who underwent continuous measurement (Tcore) with the novel wearable non-invasive CORE device. Paired measurements of Tcore and tympanic temperature (Ttym) by using a standard IR-device were performed 3−5 times/day, yielding a total of 305 measurements. The predicted core temperatures (Tcore) were significantly correlated with Ttym (r = 0.89, p < 0.001). The comparison of the Tcore and Ttym measurements by Bland−Altman analysis showed a good agreement between them, with a low mean difference of 0.11 ± 0.34 °C, and no proportional bias was observed (B = −0.003, p = 0.923). The Tcore measurements correctly predicted the presence or absence of Ttym hyperthermia or fever in 94.1% and 97.4% of cases, respectively. Temperature monitoring with a novel wireless non-invasive heat flux-based thermometer could be a reliable alternative to the Ttym method for assessing core temperature in acute ischemic stroke patients.

Association between hyperpyrexia and poststroke outcomes in patients with recanalization after mechanical thrombectomy: a retrospective cohort study

BACKGROUND

Limited data are available for evaluating the relationship between the prognosis and body temperature (BT) in patients treated with mechanical thrombectomy (MT), especially in those with successful recanalization. We aimed to explore the prognostic value of BT in predicting outcomes of stroke recovery at 3 months poststroke.

METHODS

We retrospectively analyzed the relationship among BT levels as a continuous variable, with fever (BT ≥ 37.5℃) as a binary variable, and obtained several outcomes of interest. Subjects were stratified according to successful recanalization (thrombolysis in cerebral infarction scores of 2b-3) following MT. Functional independence was defined as a modified Rankin scale (mRS) score of 0-2.

RESULTS

In total, 258 patients were included. The proportion of patients with functional independence was significantly lower among patients with BT ≥ 37.5℃ than among those with BT < 37.5 °C (45.3 % versus 23.0 %; P < 0.001). In the multivariate analysis, hyperpyrexia (especially BT ≥ 38 °C) was significantly associated with poor 3-month outcomes in patients treated with MT. Subgroup analysis was conducted by comparing the successful recanalization group with the non-recanalization group, showing that BT ≥ 37.5 °C was associated with a significantly lower proportion of functional independence in the recanalized patients. Besides, the Kaplan-Meier model showed that the fever group had significantly lower survival rates than the non-fever group during the 3-month follow-up.

CONCLUSIONS

In patients treated with MT, hyperpyrexia is an independent predictor of poststroke outcomes at 3 months, particularly in those with successful recanalization.

Neurological Instability in Ischemic Stroke: Relation with Outcome, Latency Time, and Molecular Markers

The National Institutes of Health Stroke Scale (NIHSS) is commonly used to evaluate stroke neurological deficits and to predict the patient’s outcome. Neurological instability (NI), defined as the variation of the NIHSS in the first 48 h, is a simple clinical metric that reflects dynamic changes in the area of the brain affected by the ischemia. We hypothesize that NI may represent areas of cerebral instability known as penumbra, which could expand or reduce brain injury and its associated neurological sequels. In this work, our aim was to analyze the association of NI with the functional outcome at 3 months and to study clinical biomarkers associated to NI as surrogate biomarkers of ischemic and inflammatory penumbrae in ischemic stroke (IS) patients. We included 663 IS patients in a retrospective observational study. Neutral NI was defined as a variation in the NI scale between − 5 and 5% (37.1%). Positive NI is attributed to patients with an improvement of > 5% NI after 48 h (48.9%), while negative NI is assigned to patients values lower than − 5% (14.0%). Poor outcome was assigned to patients with mRS ≥ 3 at 3 months. We observed an inverse association of poor outcome with positive NI (OR, 0.35; 95%CI, 0.18–0.67; p = 0.002) and a direct association with negative NI (OR, 6.30; 95%CI, 2.12–18.65; p = 0.001). Negative NI showed a higher association with poor outcome than most clinical markers. Regarding good functional outcome, positive NI was the marker with the higher association (19.31; CI 95%, 9.03–41.28; p < 0.0001) and with the highest percentage of identified patients with good functional outcome (17.6%). Patients with negative NI have higher glutamate levels compared with patients with neutral and positive NI (p < 0.0001). IL6 levels are significantly lower in patients with positive NI compared with neutral NI (p < 0.0001), while patients with negative NI showed the highest IL6 values (p < 0.0001). High glutamate levels were associated with negative NI at short latency times, decreasing at higher latency times. An opposite trend was observed for inflammation, and IL6 levels were similar in patients with positive and negative NI in the first 6 h and then higher in patients with negative NI. These results support NI as a prognosis factor in IS and the hypothesis of the existence of a delayed inflammatory penumbra, opening up the possibility of extending the therapeutic window for IS.

Temperature-Induced Changes in Reperfused Stroke: Inflammatory and Thrombolytic Biomarkers

Although hyperthermia is associated with poor outcomes in ischaemic stroke (IS), some studies indicate that high body temperature may benefit reperfusion therapies. We assessed the association of temperature with effective reperfusion (defined as a reduction of ≥8 points in the National Institute of Health Stroke Scale (NIHSS) within the first 24 h) and poor outcome (modified Rankin Scale (mRS) > 2) in 875 retrospectively-included IS patients. We also studied the influence of temperature on thrombolytic (cellular fibronectin (cFn); matrix metalloproteinase 9 (MMP-9)) and inflammatory biomarkers (tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6)) and their relationship with effective reperfusion. Our results showed that a higher temperature at 24 but not 6 h after stroke was associated with failed reperfusion (OR: 0.373, p = 0.001), poor outcome (OR: 2.190, p = 0.005) and higher IL-6 levels (OR: 0.958, p < 0.0001). Temperature at 6 h was associated with higher MMP-9 levels (R = 0.697; p < 0.0001) and effective reperfusion, although this last association disappeared after adjusting for confounding factors (OR: 1.178, p = 0.166). Our results suggest that body temperature > 37.5 °C at 24 h, but not at 6 h after stroke, is correlated with reperfusion failure, poor clinical outcome, and infarct size. Mild hyperthermia (36.5–37.5 °C) in the first 6 h window might benefit drug reperfusion therapies by promoting clot lysis.

Comparison of neuronal death and expression of TNF‑α and MCT4 in the gerbil hippocampal CA1 region induced by ischemia/reperfusion under hyperthermia to those under normothermia

Monocarboxylate transporter 4 (MCT4) is a high-capacity lactate transporter in cells and the alteration in MCT4 expression harms cellular survival. The present study investigated whether hypothermia affects tumor necrosis factor-α (TNF-α) and MCT4 immunoreactivity in the subfield cornu ammonis 1 (CA1) following cerebral ischemia/reperfusion (IR) in gerbils. Hypothermia was induced for 30 min before and during ischemia. It was found that IR-induced death of pyramidal neurons was markedly augmented and occurred faster under hyperthermia than under normothermia. TNF-α immunoreactivity in the pyramidal cells started to increase at 3 h after IR and peaked at 1 day after IR under normothermia. However, in hyperthermic control and sham operated gerbils, TNF-α immunoreactivity was significantly increased compared with the normothermic gerbils, and IR under hyperthermia caused a more rapid and significant increase in TNF-α immunoreactivity in pyramidal neurons than under normothermia. In addition, in the normothermic gerbils, MCT4 immunoreactivity began to decrease in pyramidal neurons from 3 h after IR and markedly increased at 1 and 2 days after IR. On the other hand, MCT4 immunoreactivity in pyramidal neurons of the hyperthermic gerbils was significantly increased from 3 h after IR, maintained until 1 day after IR and markedly decreased at 2 days after IR. These results indicate that acceleration of IR-induced neuronal death under hyperthermia might be closely associated with early alteration of TNF-α and MCT4 protein expression in the gerbil hippocampus after IR.

Protective effects of L-arginine on the intestinal epithelial barrier under heat stress conditions in rats and IEC-6 cell line

Heat stress (HS) and the associated restricted blood flow to the intestine have been proven to destroy intestinal integrity. Considering the beneficial properties of L-arginine on gut function, we investigated the protective effects of L-arginine on the intestine under HS conditions. In vivo, the serum cortisol level and the rectal temperature increased in response to HS. Under HS, the intestinal damage showed obvious morphological changes. Furthermore, HS decreased the mRNA and protein expression levels of Nurr1, ZO-1, occludin, claudin-6 and E-cadherin, increased the mRNA expression of NF-κB and IL-1β, and increased the protein expression of cleaved caspase-3. In contrast, L-arginine supplementation maintained intestinal integrity and increased the villus/crypt ratio. L-arginine also suppressed the expression of inflammation-related genes and the protein expression of cleaved caspase-3, whereas it upregulated the mRNA and protein expression of tight junction proteins and LC3B protein expression. In vitro, L-arginine attenuated HS-induced apoptosis as demonstrated by flow cytometry and decreased cleaved caspase-3 protein expression. L-arginine induced autophagy, which was demonstrated by decreased expression of p62 and p-mTOR/mTOR, and increased expression of LC3B. The protein expression levels of TJ proteins also enhanced by L-arginine in IEC-6 cells. Taken together, these results suggest that L-arginine can alleviate intestinal damage and protect the intestinal integrity by suppressing local inflammation response, promoting the production of TJs and facilitating autophagy under HS conditions.

Obesity Paradox in Ischemic Stroke: Clinical and Molecular Insights

It has recently emerged the concept of "obesity paradox," a term used to describe the unexpected improved prognosis and lower mortality rates found in several diseases in patients with higher body weight. Concerning stroke, few clinical studies have assessed this obesity paradox showing contradictory results. Therefore, our aim was to compare clinical evolution and inflammatory balance of obese and non-obese patients after ischemic stroke. We designed a prospective case-control study in patients with acute ischemic stroke categorized into obese (body mass index, BMI ≥ 30 kg/m²) and non-obese (BMI < 30 kg/m²). We compared clinical, anthropometric, radiological, and laboratory variables. The main outcome variable was the functional outcome at 3 months. We included 98 patients (48 non-obese and 50 obese). No differences in functional outcome at 3 months were found (p = 0.882) although a tendency of a greater recovery on neurological impairments was seen in obese subjects. Importantly, obese patients (p = 0.007) and patients who experienced poor outcome (p = 0.006) exhibited a higher reduction in body weight at 3 months after stroke. Moreover, pro-inflammatory IL-6 levels (p = 0.002) were higher in the obese group. However, IL-6 levels decreased over the first week in obese while increased in non-obese. On the contrary, levels of the anti-inflammatory IL-10 rose over the first week in obese patients, whereas remained stable in non-obese. In summary, despite exhibiting several factors associated with poor outcome, obese patients do not evolve worse than non-obese after ischemic stroke. Obesity may counterbalance the inflammatory reaction through an anti-inflammatory stream enhanced in the first moments of stroke.

The impact of hyperthermia after acute carbon monoxide poisoning on neurological sequelae

This study investigated whether hyperthermia within the first 24 h after presentation was associated with long-term neurological outcomes after acute carbon monoxide (CO) poisoning. This retrospective study included 200 patients with acute severe CO poisoning. Hyperthermia (≥ 37.5°C) developed during the first 24 h after presentation in 55 (27.5%) patients, and poor long-term neurological sequelae assessed at 23 months after acute CO poisoning developed in 19.5% of the patients. The incidence of poor long-term neurological outcomes was significantly higher in the hyperthermia group than in the normothermia group. Patients with poor long-term neurological outcomes had higher maximum temperatures than patients with good outcomes. No significant difference was found in the time of hyperthermia onset within the first day according to the neurological outcomes. Hyperthermia (adjusted odds ratio (aOR) 5.009 (95% confidence interval (CI) 1.556-16.126)) and maximum temperature (aOR 2.581 (95% CI 1.098-6.063)) within the first 24 h after presentation to the emergency department were independently associated with poor long-term neurological outcomes. Body temperature measurements, which are easily and noninvasively recorded at the bedside in any facility, help to predict the risk for poor long-term neurological outcomes. This study carefully emphasizes fastidious control of pyrexia, particularly during the early period after acute CO poisoning.

Association of survival and hyperthermia after rt-PA for ischemic stroke

BACKGROUND

Hyperthermia in patients with acute ischemic stroke is associated with poor outcome. Although previous studies have shown a negative effect on functional outcome, even in patients treated with intravenous recombinant tissue plasminogen activator (rt-PA), the effect on survival remains unclear.

AIMS OF THE STUDY

The aim of this study was to evaluate the association between the functional and survival prognosis and hyperthermia in patients with acute ischemic stroke treated with rt-PA.

METHODS

We studied 120 patients treated with rt-PA from 2306 consecutive Japanese patients with acute cerebral infarction at Aomori Prefectural Central Hospital between December 2009 and March 2017. We defined hyperthermia as ≥38°C within 72 hours after rt-PA administration. Propensity score matching was used to compare 34 non-hyperthermia and hyperthermia patient pairs.

RESULTS

Final modified Rankin Scale scores were higher in the hyperthermia group than in the non-hyperthermia group. In addition, the Kaplan-Meier model showed that the non-hyperthermia group had significantly better survival rates than the hyperthermia group (hazard ratio, 5.3; 95% confidence intervals, 1.2-24.8).

CONCLUSIONS

Hyperthermia within 3 days after rt-PA is associated with poor functional prognosis and survival outcome in patients with acute cerebral infarction.

Inflammation, edema and poor outcome are associated with hyperthermia in hypertensive intracerebral hemorrhages

Background and purpose

The deleterious effect of hyperthermia on intracerebral hemorrhage (ICH) has been studied. However, the results are not conclusive and new studies are needed to elucidate clinical factors that influence the poor outcome. The aim of this study was to identify the clinical factors (including ICH etiology) that influence the poor outcome associated with hyperthermia and ICH. We also tried to identify potential mechanisms involved in hyperthermia during ICH.

Methods

We conducted a retrospective study enrolling patients with non‐traumatic ICH from a prospective registry. We used logistic regression models to analyze the influence of hyperthermia in relation to different inflammatory and endothelial dysfunction markers, hematoma growth and edema volume in hypertensive and non‐hypertensive patients with ICH.

Results

We included 887 patients with ICH (433 hypertensive, 50 amyloid, 117 by anticoagulants and 287 with other causes). Patients with hypertensive ICH showed the highest body temperature (37.5 ± 0.8°C) as well as the maximum increase in temperature (0.9 ± 0.1°C) within the first 24 h. Patients with ICH of hypertensive etiologic origin, who presented hyperthermia, showed a 5.3‐fold higher risk of a poor outcome at 3 months. We found a positive relationship (r = 0.717, P < 0.0001) between edema volume and hyperthermia during the first 24 h but only in patients with ICH of hypertensive etiologic origin. This relationship seems to be mediated by inflammatory markers.

Conclusion

Our data suggest that hyperthermia, together with inflammation and edema, is associated with poor outcome only in ICH of hypertensive etiology.

Fever worsens outcomes in animal models of ischaemic stroke: A systematic review and meta-analysis

Background

Subfebrile temperatures and fever in the first days after stroke are associated with a greater risk of a poor outcome. If this relation is causal, prevention of hyperthermia may improve outcome. Causality can be tested in animal models. We therefore assessed the effects of hyperthermia on outcomes in animal models of ischaemic stroke and explored under which conditions prevention of hyperthermia could be most effective.

Methods

We performed a systematic review and meta-analysis of data from animal experiments testing the effect of spontaneous or induced hyperthermia on outcome after focal cerebral ischaemia. Our primary outcome measure was infarct size. Normalised mean differences were combined using the random effects model and stratified meta-analysis was used to explore the impact of study characteristics.

Results

We included 19 publications, reporting on 49 comparisons involving 603 animals. Overall, hyperthermia increased infarct size by 43.4% (95% confidence interval, 29.8-56.9%) and worsened neurobehavioral outcomes by 48.5% (17.2-79.8%). The increase in infarct size was larger with higher temperatures. Hyperthermia was most harmful if present for more than 2 h and when started at the time of artery occlusion rather than later.

Conclusion

Hyperthermia substantially increased infarct size in animal models of ischaemic stroke, suggesting that the relation between fever and poor outcome observed in patients is at least in part causal. These data provide support to trials testing the effect of the prevention of fever with antipyretic drugs in patients with acute stroke.

Procalcitonin as a Biomarker for Malignant Cerebral Edema in Massive Cerebral Infarction

The objective of this study is to explore whether procalcitonin (PCT) can serve as an early biomarker of malignant cerebral edema in patients with massive cerebral infarction (MCI). Ninety-three patients with acute MCI were divided into death or survival groups based on whether they died or survived within 1 week of cerebral herniation. Differences in laboratory parameters between these two groups were analyzed by univariate analysis, followed by multivariate logistic regression analyses if the influencing factors were significantly different. Compared with the survival group, the patients in the death group had a larger cerebral infarct area, higher body temperature, neutrophil counts, PCT level, and neuron-specific enolase (NSE) level within 48 h of onset. Multivariate logistic regression analyses revealed an odds ratio (OR) of 1.830 or 1.235 for PCT and neutrophil counts respectively, suggesting that PCT and neutrophil counts are two independent risk factors for death in MCI. The area under receiver operating characteristic (ROC) curve was 0.754 for PCT, larger than that for neutrophil counts. Thus, both serum PCT levels and neutrophil counts can be used as biomarkers to predict malignant cerebral edema at the early stages after MCI, but PCT levels are superior predictors of malignant cerebral edema.

Is temperature an important variable in recovery after mild traumatic brain injury?

With nearly 42 million mild traumatic brain injuries (mTBIs) occurring worldwide every year, understanding the factors that may adversely influence recovery after mTBI is important for developing guidelines in mTBI management. Extensive clinical evidence exists documenting the detrimental effects of elevated temperature levels on recovery after moderate to severe TBI. However, whether elevated temperature alters recovery after mTBI or concussion is an active area of investigation. Individuals engaged in exercise and competitive sports regularly experience body and brain temperature increases to hyperthermic levels and these temperature increases are prolonged in hot and humid ambient environments. Thus, there is a strong potential for hyperthermia to alter recovery after mTBI in a subset of individuals at risk for mTBI. Preclinical mTBI studies have found that elevating brain temperature to 39°C before mTBI significantly increases neuronal death within the cortex and hippocampus and also worsens cognitive deficits. This review summarizes the pathology and behavioral problems of mTBI that are exacerbated by hyperthermia and discusses whether hyperthermia is a variable that should be considered after concussion and mTBI. Finally, underlying pathophysiological mechanisms responsible for hyperthermia-induced altered responses to mTBI and potential gender considerations are discussed.

Temporal profile of body temperature in acute ischemic stroke: relation to infarct size and outcome

Background

High body temperatures after ischemic stroke have been associated with larger infarct size, but the temporal profile of this relation is unknown. We assess the relation between temporal profile of body temperature and infarct size and functional outcome in patients with acute ischemic stroke.

Methods

In 419 patients with acute ischemic stroke we assessed the relation between body temperature on admission and during the first 3 days with both infarct size and functional outcome. Infarct size was measured in milliliters on CT or MRI after 3 days. Poor functional outcome was defined as a modified Rankin Scale score ≥3 at 3 months.

Results

Body temperature on admission was not associated with infarct size or poor outcome in adjusted analyses. By contrast, each additional 1.0 °C in body temperature on day 1 was associated with 0.31 ml larger infarct size (95% confidence interval (CI) 0.04–0.59), on day 2 with 1.13 ml larger infarct size(95% CI, 0.83–1.43), and on day 3 with 0.80 ml larger infarct size (95% CI, 0.48–1.12), in adjusted linear regression analyses. Higher peak body temperatures on days two and three were also associated with poor outcome (adjusted relative risks per additional 1.0 °C in body temperature, 1.52 (95% CI, 1.17–1.99) and 1.47 (95% CI, 1.22–1.77), respectively).

Conclusions

Higher peak body temperatures during the first days after ischemic stroke, rather than on admission, are associated with larger infarct size and poor functional outcome. This suggests that prevention of high temperatures may improve outcome if continued for at least 3 days.

Reduction of the systemic inflammatory induced by acute cerebral infarction through ultra-early thrombolytic therapy

Acute ischemic stroke induces systemic inflammation, exhibited as changes in body temperature, white blood cell counts and C-reactive protein (CRP) levels. The aim of the present study was to observe the effects of intravenous thrombolytic therapy on inflammatory indices in order to investigate the hypothesis that post-stroke systemic inflammatory response occurs in response to the necrosis of brain tissues. In this study, 62 patients with acute cerebral infarction and indications for intravenous thrombolysis were divided into three groups on the basis of their treatment and response: Successful thrombolysis (n=36), failed thrombolysis (n=12) and control (n=14) groups. The body temperature, white blood cell counts and high-sensitivity (hs)-CRP levels were recorded pre-treatment and on post-stroke days 1, 3, 5 and 7. Spearman's correlation analysis showed that the pre-treatment National Institutes of Health Stroke Scale (NIHSS) score positively correlated with body temperature, white blood cell count and hs-CRP levels. On day 3 of effective intravenous thrombolysis, the body temperature and white blood cell were decreased and on days 3 and 5, the serum levels of hs-CRP were reduced compared with those in the failed thrombolysis and control groups. The results indicate that the systemic inflammatory response following acute cerebral infarction was mainly caused by ischemic injury of local brain tissue; the more serious the stroke, the stronger the inflammatory response. Ultra-early thrombolytic therapy may inhibit the necrosis of brain tissue and thereby reduce the inflammatory response.

Systemic inflammation as a therapeutic target in acute ischemic stroke

Acute systemic inflammatory reaction superimposed on chronic low-grade inflammation accompanies acute ischemic stroke. Elevated blood levels of systemic inflammatory markers such as IL-6 or C-reactive protein are associated with an unfavorable functional outcome and increased mortality after stroke. Animal studies have demonstrated a causal relationship between systemic inflammation and ischemic brain damage. The mechanisms linking systemic inflammation with poor outcome include increased neutrophil infiltration of cerebral cortex, disruption of the blood-brain barrier, impaired tissue reperfusion, increased platelet activation and microvascular coagulation and complement-dependent brain injury. Non-selective (e.g., by statins) or selective (e.g., by inhibition of IL-6) attenuation of systemic inflammation, enhancement of systemic anti-inflammatory response (e.g., by infusion of IL-1 receptor antagonist), prevention of infections that exacerbate systemic inflammation or inhibition of neuronal pathways triggering inflammatory reaction are potential therapeutic targets in stroke patients. This review discusses the relationship between systemic inflammation, cerebral ischemia and prognosis in the context of therapeutic strategies.

Hyperthermia in human ischemic and hemorrhagic stroke: similar outcome, different mechanisms

Hyperthermia is a predictor of poor outcome in ischemic (IS) and intracerebral hemorrhagic (ICH) stroke. Our aim was to study the plausible mechanisms involved in the poor outcome associated to hyperthermia in stroke. We conducted a case-control study including patients with IS (n = 100) and ICH (n = 100) within the first 12 hours from symptom onset. Specifically, IS and ICH patients were consecutively included into 2 subgroups, according to the highest body temperature within the first 24 hours: Tmax <37.5°C and Tmax ≥37.5°C, up to reach 50 patients per subgroup of temperature for both IS and ICH patients. Body temperature was determined at admission and every 4 hours during the first 48 hours. Main outcome variable was poor functional outcome (modified Rankin scale score >2) at 3 months. Serum levels of glutamate and active MMP-9 were measured at admission. Our results showed that Tmax ≥37.5°C within the first 24 hours was independently associated with poor outcome in both IS (OR, 12.43; 95% CI, 3.73-41.48; p<0.0001) and ICH (OR, 4.29; 95% CI, 1.32-13.91; p = 0.015) after adjusting for variables with a proven biological relevance for outcome. However, when molecular markers levels were included in the logistic regression model, we observed that glutamate (OR, 1.01; 95% CI, 1.00-1.02; p = 0.001) and infarct volume (OR, 1.06; 95% CI, 1.01-1.10; p = 0.015) were the only variables independently associated to poor outcome in IS, and active MMP-9 (OR, 1.04; 95% CI, 1.00-1.08; p = 0.002) and National Institute of Health Stroke Scale (NIHSS) at admission (OR, 1.29; 95% CI, 1.13-1.49; p<0.0001) in ICH. In conclusion, these results suggest that although the outcome associated to hyperthermia is similar in human IS and ICH, the underlying mechanisms may be different.

Effectively managing intractable central hyperthermia in a stroke patient by bromocriptine: a case report

Central hyperthermia is characterized by a rapid onset, high temperature, marked temperature fluctuation, and poor response to antipyretics and antibiotics. Although poststroke central hyperthermia is common, prolonged instances are rare. We report a case of prolonged central fever after an intracranial hemorrhage. Before the accurate diagnosis and management of central fever, the patient underwent long-term antibiotic use that led to pseudomembranous colitis. Bromocriptine was used to treat the prolonged central hyperthermia, after which the fever did not exceed 39°C. A week later, the body temperature baseline was reduced to 37°C and a low-grade fever with minor temperature fluctuation occurred only a few times. No fever occurred in the month following the treatment. After the fever subsided, the patient could undergo an aggressive rehabilitation program.

Temporal profile of body temperature in acute ischemic stroke: relation to stroke severity and outcome

Background

Pyrexia after stroke (temperature ≥37.5°C) is associated with poor prognosis, but information on timing of body temperature changes and relationship to stroke severity and subtypes varies.

Methods

We recruited patients with acute ischemic stroke, measured stroke severity, stroke subtype and recorded four-hourly tympanic (body) temperature readings from admission to 120 hours after stroke. We sought causes of pyrexia and measured functional outcome at 90 days. We systematically summarised all relevant previous studies.

Results

Amongst 44 patients (21 males, mean age 72 years SD 11) with median National Institute of Health Stroke Score (NIHSS) 7 (range 0–28), 14 had total anterior circulation strokes (TACS). On admission all patients, both TACS and non-TACS, were normothermic (median 36.3°C vs 36.5°C, p=0.382 respectively) at median 4 hours (interquartile range, IQR, 2–8) after stroke; admission temperature and NIHSS were not associated (r²=0.0, p=0.353). Peak temperature, occurring at 35.5 (IQR 19.0 to 53.8) hours after stroke, was higher in TACS (37.7°C) than non-TACS (37.1°C, p<0.001) and was associated with admission NIHSS (r²=0.20, p=0.002). Poor outcome (modified Rankin Scale ≥3) at 90 days was associated with higher admission (36.6°C vs. 36.2°C p=0.031) and peak (37.4°C vs. 37.0°C, p=0.016) temperatures. Sixteen (36%) patients became pyrexial, in seven (44%) of whom we found no cause other than the stroke.

Conclusions

Normothermia is usual within the first 4 hours of stroke. Peak temperature occurs at 1.5 to 2 days after stroke, and is related to stroke severity/subtype and more closely associated with poor outcome than admission temperature. Temperature-outcome associations after stroke are complex, but normothermia on admission should not preclude randomisation of patients into trials of therapeutic hypothermia.

A higher body temperature is associated with haemorrhagic transformation in patients with acute stroke untreated with recombinant tissue-type plasminogen activator (rtPA)

Higher body temperature is a prognostic factor of poor outcome in acute stroke. Our aim was to study the relationship between body temperature, HT (haemorrhagic transformation) and biomarkers of BBB (blood-brain barrier) damage in patients with acute ischaemic stroke untreated with rtPA (recombinant tissue-type plasminogen activator). We studied 229 patients with ischaemic stroke <12 h from symptom onset. Body temperature was determined at admission and every 6 h during the first 3 days. HT was evaluated according to ECASS II (second European Co-operative Acute Stroke Study) criteria in a multimodal MRI (magnetic resonance imaging) at 72 h. We found that 55 patients (34.1%) showed HT. HT was associated with cardioembolic stroke (64.2% against 23.0%; P<0.0001), higher body temperature during the first 24 h (36.9°C compared with 36.5°C; P<0.0001), more severe stroke [NIHSS (National Institutes of Health Stroke Scale) score, 14 (9-20) against 10 (7-15); P=0.002], and greater DWI (diffusion-weighted imaging) lesion volume at admission (23.2 cc compared with 13.2 cc; P<0.0001). Plasma MMP-9 (matrix metalloproteinase 9) (187.3 ng/ml compared with 44.2 ng/ml; P<0.0001) and cFn (cellular fibronectin) levels (16.3 μg/ml compared with 7.1 μg/ml; P=0.001) were higher in patients with HT. Body temperature within the first 24 h was independently associated with HT {OR (odds ratio), 7.3 [95% CI (confidence interval), 2.4-22.6]; P<0.0001} after adjustment for cardioembolic stroke subtype, baseline NIHSS score and DWI lesion volume. This effect remained unchanged after controlling for MMP-9 and cFn. In conclusion, high body temperature within the first 24 h after ischaemic stroke is a risk factor for HT in patients untreated with rtPA. This effect is independent of some biological signatures of BBB damage.

Neuroinflammation and cerebrovascular disease in old age: a translational medicine perspective

The incidence of cerebrovascular disease is highest in the elderly population. However, the pathophysiological mechanisms of brain response to cerebral ischemia in old age are currently poorly understood. Ischemic changes in the commonly used young animal stroke models do not reflect the molecular changes associated with the aged brain. Neuroinflammation and oxidative stress are important pathogenic processes occurring during the acute phase of cerebral ischemia. Free radical generation is also implicated in the aging process, and the combination of these effects in elderly stroke patients could explain the higher risk of morbidity and mortality. A better understanding of stroke pathophysiology in the elderly patient would assist in the development of new therapeutic strategies for this vulnerable age group. With the increasing use of reperfusion therapies, inflammatory pathways and oxidative stress remain attractive therapeutic targets for the development of adjuvant neuroprotective agents. This paper will discuss these molecular aspects of acute stroke and senescence from a bench-to-bedside research perspective.

Mild-to-moderate neurogenic pyrexia in acute cerebral infarction

BACKGROUND

Pyrexia is often associated with unfavorable stroke outcomes. However, limited information is available on the relationship between the causes of poststroke hyperthermia and stroke prognosis, especially for mild-to-moderate neurogenic pyrexia in acute cerebral infarction.

AIMS

To compare the differences in the clinical features and characteristics of pyrexia as well as its prognosis among acute cerebral infarction patients with mild-to-moderate neurogenic pyrexia, with infectious pyrexia, and without pyrexia. The focus was on mild-to-moderate neurogenic pyrexia.

METHODS

A total of 709 patients with acute cerebral infarction were prospectively recruited and their clinical data were analyzed.

RESULTS

No significant difference was detected in age, gender, history of smoking, hypertension, or diabetes among the 3 groups (p > 0.05). Patients with mild-to-moderate neurogenic pyrexia and those with infectious pyrexia had higher baseline National Institutes of Health Stroke Scale (NIHSS) scores (15.1 ± 6.7, p = 0.003; 14.3 ± 8.1, p = 0.002, respectively), lower 3-month Barthel index (BI) values (64.2 ± 40.7, p < 0.001; 61.9 ± 49.3, p < 0.001, respectively) and higher 3-month mortality rates (13%, p = 0.026; 16%, p < 0.001, respectively) than patients without pyrexia (NIHSS score 11.4 ± 7.9; BI 82.6 ± 39.8, and mortality rate 6%, respectively). No difference existed in these parameters between the 2 pyrexia groups (p > 0.05), but mild-to-moderate neurogenic pyrexia had an earlier onset and a shorter duration than infectious pyrexia (p < 0.001).

CONCLUSIONS

Acute cerebral infarction patients with mild-to-moderate neurogenic pyrexia had a similar prognosis compared to those with infectious pyrexia. Mild-to-moderate neurogenic pyrexia is possibly associated with stroke severity.

Temperature patterns in the early postresuscitation period after pediatric inhospital cardiac arrest

OBJECTIVE

To describe the prevalence of postarrest hyperthermia among children during the first 24 hrs after inhospital cardiac arrest and to determine the association of persistent postarrest hyperthermia with neurologic outcome and death before hospital discharge.

DESIGN

Multicenter, national registry of inhospital cardiopulmonary resuscitation.

SETTING

A total of 196 hospitals reporting to the American Heart Association's National Registry of Cardiopulmonary Resuscitation from January 1, 2005 to December 31, 2007.

PATIENTS

A total of 547 pediatric patients who suffered inhospital pulseless cardiac arrests reported to the National Registry of Cardiopulmonary Resuscitation, who survived resuscitative efforts and who had the maximum and the minimum temperature in the first 24 hrs postresuscitation reported to the National Registry of Cardiopulmonary Resuscitation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among 547 children with pulseless cardiac arrests, 238 (43.5%) had at least one temperature of ≥38°C, and 30 (5.5%) had "persistent hyperthermia" (i.e., both the minimum and the maximum temperature of ≥38°C) during the first 24 hrs postarrest. After adjusting for potential confounders by multivariate logistic regression, persistent hyperthermia in the first 24 hrs postarrest was associated with unfavorable neurologic outcome (adjusted odds ratio, 2.7; 95% confidence interval, 1.1-6.7), but not with death before hospital discharge (adjusted odds ratio, 1.2; 95% confidence interval, 0.4-3.4).

CONCLUSIONS

Despite current guidelines to avoid postarrest hyperthermia, a temperature of ≥38°C occurred commonly among children in the first 24 hrs postarrest. Persistent postarrest hyperthermia was associated with unfavorable neurologic outcomes, even after controlling for potential confounding factors.

Neuroprotective properties of prostaglandin I2 IP receptor in focal cerebral ischemia

We and others have identified that inhibition of cyclooxygenase might not be the optimal approach to limiting brain damage after stroke. Now we are investigating the unique properties of the various prostaglandin receptors to determine whether blocking those that mediate toxicity or stimulating those that reduce toxicity will improve neurological outcomes. Here, we determined the respective contribution of the prostaglandin I(2) (PGI(2)) receptor in transient middle cerebral artery (MCA) occlusion (tMCAO) and permanent MCAO (pMCAO) preclinical stroke models by using male wildtype (WT) and IP receptor knockout (IP(-/-)) C57Bl/6 mice. In addition, we investigated the putative preventive and therapeutic effects of the IP receptor agonist beraprost. The infarct volumes and neurological deficit scores (NDS) were significantly greater in IP(-/-) than in WT mice after both tMCAO and pMCAO. Interestingly, beraprost pretreatment (50 or 100 microg/kg p.o.) 30 min before tMCAO and post-treatment (100 microg/kg p.o.) at 2 or 4.5 h of reperfusion significantly reduced the neurological deficit score and infarct volume in WT mice. Post-treatment with beraprost (100 microg/kg p.o.) 4.5 h after pMCAO also significantly decreased neurological deficits and infarct volume in WT mice. Together, these novel findings suggest for the first time that PGI(2) IP receptor activation can attenuate anatomical and functional damage following ischemic stroke.

The diagnostic role of procalcitonin and other biomarkers in discriminating infectious from non-infectious fever

Fever is not only observed in the course of a bacterial or viral infection, but can be a symptom of, for instance, auto-immune, malignant or thromboembolic disease. Determining the etiology of fever in a fast and reliable way is of pivotal importance, as different causes of fever may ask for different therapies. Neither clinical signs and symptoms, nor traditional biomarkers, such as CRP, leukocytes and ESR have sufficient sensitivity and specificity to guide treatment decisions. In this review we focus on the value of traditional and newer biomarkers in non-infectious febrile diseases. Procalcitonin (PCT) seems to be the most helpful laboratory marker for the differentiation of causes of fever, particularly in autoimmune, autoinflammatory and malignant diseases.

Hyperthermia Exacerbates Ischaemic Brain Injury

Hyperthermia frequently occurs in stroke patients. Hyperthermia negatively correlates with clinical outcome and adversely effects treatment regiments otherwise successful under normothermic conditions. Preclinical studies also demonstrate that hyperthermia converts salvageable penumbra to ischaemic infarct. The present article reviews the knowledge accumulated from both clinical and preclinical studies about hyperthermia and ischaemic brain injury, examines current treatment strategies and discusses future research directions.

Body temperature and response to thrombolytic therapy in acute ischaemic stroke

OBJECTIVE

To determine the relationship between body temperature (BT), arterial recanalization, functional outcome, and hemorrhagic transformation (HT) of cerebral infarction in patients treated with i.v. tissue plasminogen activator (tPA).

METHODS

We studied 254 patients treated with tPA within 3 h from stroke onset. National Institute of Health Stroke Scale score, BT, and transcranial Doppler ultrasound (n = 99) on admission and at 24 h were recorded. Hypodensity volume and HT were evaluated on CT at 24-36 h. Poor outcome (Rankin Scale > 2) was evaluated at 3 months.

RESULTS

Arterial recanalization at 24 h was found in 70.7% of patients, HT in 24.8% (symptomatic in 4.7%) and poor outcome in 44.1%. Baseline BT was not associated with greater stroke severity at admission or at 24 h, HT or poor outcome. However, BT at 24 h correlated to stroke severity (P < 0.001) and hypodensity volume (P < 0.001) at 24 h, and was higher in patients who did not recanalize (P = 0.001), had symptomatic HT (P = 0.063) and poor outcome (P < 0.001). The adjusted odds ratio of poor outcome for patients with BT at 24 h > or = 37 degrees C was 2.56 (1.19-5.50, P = 0.016).

CONCLUSION

Body temperature > or =37 degrees C at 24 h, but not at baseline, is associated with a lack of recanalization, greater hypodensity volume and worse outcome in stroke patients treated with tPA.

Immune and inflammatory responses to stroke: good or bad?

Inflammatory and immune responses play important roles following ischaemic stroke. Inflammatory responses contribute to damage and also contribute to repair. Injury to tissue triggers an immune response. This is initiated through activation of the innate immune system. In stroke there is microglial activation. This is followed by an influx of lymphocytes and macrophages into the brain, triggered by production of pro-inflammatory cytokines. This inflammatory response contributes to further tissue injury. There is also a systemic immune response to stroke, and there is a degree of immunosuppression that may contribute to the stroke patient's risk of infection. This immunosuppressive response may also be protective, with regulatory lymphocytes producing cytokines and growth factors that are neuroprotective. The specific targets of the immune response after stroke are not known, and the details of the immune and inflammatory responses are only partly understood. The role of inflammation and immune responses after stroke is twofold. The immune system may contribute to damage after stroke, but may also contribute to repair processes. The possibility that some of the immune response after stroke may be neuroprotective is exciting and suggests that deliberate enhancement of these responses may be a therapeutic option.

Early changes in physiological variables after stroke

Several aspects of physiology, notably blood pressure, body temperature, blood glucose, and blood oxygen saturation, may be altered after an ischemic stroke and intracerebral hemorrhage. Generally, blood pressure and temperature rise acutely after a stroke, before returning to normal. Blood glucose and oxygen levels may be abnormal in individuals, but they do not follow a set pattern. Several aspects of these physiological alterations remain unclear, including their principal determinants - whether they genuinely affect prognosis (as opposed to merely representing underlying processes such as inflammation or a stress response), whether these effects are adaptive or maladaptive, whether the effects are specific to certain subgroups (e.g. lacunar stroke) and whether modifying physiology also modifies its prognostic effect. Hypertension and hyperglycemia may be helpful or harmful, depending on the perfusion status after an ischemic stroke; the therapeutic response to their lowering may be correspondingly variable. Hypothermia may provide benefits, in addition to preventing harm through protection from hyperthermia. Hypoxia is harmful, but normobaric hyperoxia is unhelpful or even harmful in normoxic patients. Hyperbaric hyperoxia, however, may be beneficial, though this remains unproven. The above-mentioned uncertainties necessitate generally conservative measures for physiology management, although there are notably specific recommendations for thrombolysis-eligible patients. Stroke unit care is associated with better outcome, possibly through better management of poststroke physiology. Stroke units can also facilitate research to clarify the relationship between physiology and prognosis, and to subsequently clarify management guidelines.

The effect of physiologic derangement in patients with stroke treated with thrombolysis

BACKGROUND

Body temperature, blood glucose, and blood pressure (BP) may interfere with outcome in patients with acute ischemic stroke treated with thrombolysis.

METHODS

We prospectively studied 127 patients who received thrombolysis with tissue plasminogen activator for acute stroke in Bergen, Norway. Body temperature, blood glucose, and BP were measured before thrombolysis. Maximum body temperature and maximum blood glucose within the first 5 days after thrombolysis and maximum BP within the first 24 hours after thrombolysis were measured. The outcome was measured with modified Rankin scale score obtained at 3 months after stroke onset. Variables were tested using multiple logistic regression analysis after adjusting for National Institute of Health Stroke Scale score before thrombolysis and potential confounders.

RESULTS

The average age of the patients was 63 years and the median National Institute of Health Stroke Scale score was 13. On admission, diabetes mellitus was present in 6% of patients and hypertension in 51% of patients. High body temperature and high blood glucose after thrombolysis were associated with poor prognosis (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.29-6.25, P = .01; OR 1.33, 95% CI 1.02-1.74, P = .03). High body temperature and high blood glucose before thrombolysis were not associated with outcome (OR 0.79, 95% CI 0.39-1.58, P = .5; OR 1.04, 95% CI 0.75-1.20, P = .08). High systolic BP both before and after thrombolysis was associated with poor outcome (OR 1.27, 95% CI 1.03-1.52, P = .025; OR 1.22, 95% CI 1.00-1.44, P = .045). High diastolic BP both before and after thrombolysis was not associated with outcome (OR 1.03, 95% CI 0.97-1.36, P =.85; OR 1.16, 95% CI 0.99-1.46, P = .29).

CONCLUSIONS

The current study indicates that in patients with ischemic stroke, high body temperature and high blood glucose after thrombolysis are associated with poor prognosis. Frequent monitoring of these parameters and the appropriate treatment of it, if elevated, are important during the first few days after thrombolysis. High systolic BP both before and after thrombolysis was associated with poor outcome. This finding may support the practice of reducing systolic BP below 185 mm Hg both before and after thrombolysis.

Altered kynurenine metabolism correlates with infarct volume in stroke

Inflammation and oxidative stress are involved in brain damage following stroke, and tryptophan oxidation along the kynurenine pathway contributes to the modulation of oxidative stress partly via the glutamate receptor agonist quinolinic acid and antagonist kynurenic acid, and via redox-active compounds such as 3-hydroxyanthranilic acid. We have confirmed that following a stroke, patients show early elevations of plasma neopterin, S100B and peroxidation markers, the latter two correlating with infarct volume assessed from computed tomography (CT) scans, and being consistent with a rapid inflammatory response. We now report that the kynurenine pathway of tryptophan metabolism was also activated, with an increased kynurenine : tryptophan ratio, but with a highly significant decrease in the ratio of 3-hydroxyanthranilic acid : anthranilic acid, which was strongly correlated with infarct volume. Levels of kynurenic acid were significantly raised in patients who died within 21 days compared with those who survived. The results suggest that increased tryptophan catabolism is initiated before or immediately after a stroke, and is related to the inflammatory response and oxidative stress, with a major change in 3-hydroxyanthranilic acid levels. Together with previous evidence that inhibiting the kynurenine pathway reduces brain damage in animal models of stroke and cerebral inflammation, and that increased kynurenine metabolism directly promotes oxidative stress, it is proposed that oxidative tryptophan metabolism may contribute to the oxidative stress and brain damage following stroke. Some form of anti-inflammatory intervention between the rise of S100B and the activation of microglia, including inhibition of the kynurenine pathway, may be valuable in modifying patient morbidity and mortality.