Abstract TMP13: Individual Patient Data Meta-analysis of Hypothermia for Acute Ischaemic Stroke

Background: It remains unclear whether inducing hypothermia is safe and effective for improving outcome after hyperacute ischaemic stroke. An individual patient data meta-analysis of completed trials was performed.

Methods: Following electronic searches for trials comparing hypothermia to control, Chief Investigators were approached to share individual patient data (IPD). Odds ratios (OR, 95% confidence intervals, 95% CI) were analysed with ordinal logistic regression and binary logistic regression with adjustment for trial, cooling method (endovascular, surface or unknown) and age.

Results: Data were obtained for 10 trials (320 participants): COAST-I, COAST-II, COOL AID pilot, COOL AID, COOLIST, HAIS-SE, ICTuS-L, ICTuS-2, MASCOT and MHAIS; IPD were not available for two studies. Trial designs varied and most had a small sample size, mean (SD) age 66 (11.5) years, female 42%, NIHSS 13.4 (5.3), time to treatment 4.5 (1.2) hours, thrombolysis 53%. In patients whose temperature was recorded (n=74), the lowest achieved temperature was in the hypothermia arm: 34.3 o C vs. 36.6 o C (p<0.001). Functional outcome (modified Rankin Scale) at day 90 did not differ between cooling vs. no cooling: n=297 OR 0.93 (95% CI 0.63-1.39, p=0.74). Serious adverse events (n=287) were increased in the cooling arm: 81.5% vs. 65.5% (p<0.001); pneumonia: 30.2% vs. 10.9% (p<0.001) and aspiration: 13.3% vs. 3.5% (p=0.004). There was no difference in death: 17.2% vs. 13.6% (p=0.21).

Conclusion: Hypothermia lowered temperature by 2.3 C, did not alter functional outcome or mortality, but was associated with more SAEs. Larger trials are needed to assess hypothermia in hyperacute stroke.

Seizure-associated central apnea in a rat model: Evidence for resetting the respiratory rhythm and activation of the diving reflex

Respiratory derangements, including irregular, tachypnic breathing and central or obstructive apnea can be consequences of seizure activity in epilepsy patients and animal models. Periods of seizure-associated central apnea, defined as periods >1s with rapid onset and offset of no airflow during plethysmography, suggest that seizures spread to brainstem respiratory regions to disrupt breathing. We sought to characterize seizure-associated central apneic episodes as an indicator of seizure impact on the respiratory rhythm in rats anesthetized with urethane and given parenteral kainic acid to induce recurring seizures. We measured central apneic period onsets and offsets to determine if onset-offset relations were a consequence of 1) a reset of the respiratory rhythm, 2) a transient pausing of the respiratory rhythm, resuming from the pause point at the end of the apneic period, 3) a transient suppression of respiratory behavior with apnea offset predicted by a continuation of the breathing pattern preceding apnea, or 4) a random re-entry into the respiratory cycle. Animals were monitored with continuous ECG, EEG, and plethysmography. One hundred ninety central apnea episodes (1.04 to 36.18s, mean: 3.2±3.7s) were recorded during seizure activity from 7 rats with multiple apneic episodes. The majority of apneic period onsets occurred during expiration (125/161 apneic episodes, 78%). In either expiration or inspiration, apneic onsets tended to occur late in the cycle, i.e. between the time of the peak and end of expiration (82/125, 66%) or inspiration (34/36, 94%). Apneic period offsets were more uniformly distributed between early and late expiration (27%, 34%) and inspiration (16%, 23%). Differences between the respiratory phase at the onset of apnea and the corresponding offset phase varied widely, even within individual animals. Each central apneic episode was associated with a high frequency event in EEG or ECG records at onset. High frequency events that were not associated with flatline plethysmographs revealed a constant plethysmograph pattern within each animal, suggesting a clear reset of the respiratory rhythm. The respiratory rhythm became highly variable after about 1s, however, accounting for the unpredictability of the offset phase. The dissociation of respiratory rhythm reset from the cessation of airflow also suggested that central apneic periods involved activation of brainstem regions serving the diving reflex to eliminate the expression of respiratory movements. This conclusion was supported by the decreased heart rate as a function of apnea duration. We conclude that seizure-associated central apnea episodes are associated with 1) a reset of the respiratory rhythm, and 2) activation of brainstem regions serving the diving reflex to suppress respiratory behavior. The significance of these conclusions is that these details of seizure impact on brainstem circuitry represent metrics for assessing seizure spread and potentially subclassifying seizure patterns.

[Critical illness polyneuropathy and myopathy as neurological complications of sepsis]

Intensive care unit acquired weakness (ICUAW) is a frequent and severe complication of intensive care management. Within ICUAW critical illness polyneuropathy (CIP) and myopathy (CIM) can be differentiated. The major symptom of ICUAW is progressive quadriparesis, which makes weaning from the respirator more difficult, can appear early after admission to an ICU and can often be detected several months after discharge from the ICU. The pathophysiology of ICUAW is multifactorial and complex. Potential therapeutic approaches are the early and sufficient therapy of mulitorgan dysfunction, optimal control of glucose levels as well as early and intensive physiotherapy. This review article discusses the data on incidence, pathophysiology, diagnostic approaches and prognosis of ICUAW.

Laryngospasm, central and obstructive apnea during seizures: Defining pathophysiology for sudden death in a rat model

Seizure spread into the autonomic nervous system can result in life-threatening cardiovascular and respiratory dysfunction. Here we report on a less-studied consequence of such autonomic derangements-the possibility of laryngospasm and upper-airway occlusion. We used parenteral kainic acid to induce recurring seizures in urethane-anesthetized Sprague Dawley rats. EEG recordings and combinations of cardiopulmonary monitoring, including video laryngoscopy, were performed during multi-unit recordings of recurrent laryngeal nerve (RLN) activity or head-out plethysmography with or without endotracheal intubation. Controlled occlusions of a tracheal tube were used to study the kinetics of cardiac and respiratory changes after sudden obstruction. Seizure activity caused significant firing increases in the RLN that were associated with abnormal, high-frequency movements of the vocal folds. Partial airway obstruction from laryngospasm was evident in plethysmograms and was prevented by intubation. Complete glottic closure (confirmed by laryngoscopy) occurred in a subset of non-intubated animals in association with the largest increases in RLN activity, and cessation of airflow was followed in all obstructed animals within tens of seconds by ST-segment elevation, bradycardia, and death. Periods of central apnea occurred in both intubated and non-intubated rats during seizures for periods up to 33s and were associated with modestly increased RLN activity, minimal cardiac derangements, and an open airway on laryngoscopy. In controlled complete airway occlusions, respiratory effort to inspire progressively increased, then ceased, usually in less than 1min. Respiratory arrest was associated with left ventricular dilatation and eventual asystole, an elevation of systemic blood pressure, and complete glottic closure. Severe laryngospasm contributed to the seizure- and hypoxemia-induced conditions that resulted in sudden death in our rat model, and we suggest that this mechanism could contribute to sudden death in epilepsy.

Estimating the Quantitative Demand of NOAC Antidote Doses on Stroke Units

BACKGROUND

The first specific antidote for non-vitamin K antagonist oral anticoagulants (NOAC) has recently been approved. NOAC antidotes will allow specific treatment for 2 hitherto problematic patient groups: patients with oral anticoagulant therapy (OAT)-associated intracerebral hemorrhage (ICH) and maybe also thrombolysis candidates presenting on oral anticoagulation (OAT). We aimed to estimate the frequency of these events and hence the quantitative demand of antidote doses on a stroke unit.

METHODS

We extracted data of patients with acute ischemic stroke and ICH (<24 h after symptom onset) in the years 2012-2015 from a state-wide prospective stroke inpatient registry. We selected 8 stroke units and determined the mode of OAT upon admission in 2012-2013. In 2015, the mode of OAT became a mandatory item of the inpatient registry. From the number of anticoagulated patients and the NOAC share, we estimated the current and future demand for NOAC antidote doses on stroke units.

RESULTS

Eighteen percent of ICH patients within 6 h of symptom onset or an unknown symptom onset were on OAT. Given a NOAC share at admission of 40%, about 7% of all ICH patients may qualify for NOAC reversal therapy. Thirteen percent of ischemic stroke patients admitted within 4 h presented on anticoagulation. Given the availability of an appropriate antidote, a NOAC share of 50% could lead to a 6.1% increase in thrombolysis rate.

CONCLUSIONS

Stroke units serving populations with a comparable demographic structure should prepare to treat up to 1% of all acute ischemic stroke patients and 7% of all acute ICH patients with NOAC antidotes. These numbers may increase with the mounting prevalence of atrial fibrillation and an increasing use of NOAC.

Is Hypothermia Helpful in Severe Subarachnoid Hemorrhage? An Exploratory Study on Macro Vascular Spasm, Delayed Cerebral Infarction and Functional Outcome after Prolonged Hypothermia

Background: Therapeutic hypothermia (TH) is an established treatment after cardiac arrest and growing evidence supports its use as neuroprotective treatment in stroke. Only few and heterogeneous studies exist on the effect of hypothermia in subarachnoid hemorrhage (SAH). A novel approach of early and prolonged TH and its influence on key complications in poor-grade SAH, vasospasm and delayed cerebral ischemia (DCI) was evaluated. Methods: This observational matched controlled study included 36 poor-grade (Hunt and Hess Scale >3 and World Federation of Neurosurgical Societies Scale >3) SAH patients. Twelve patients received early TH (<48 h after ictus), mild (35°C), prolonged (7 ± 1 days) and were matched to 24 patients from the prospective SAH database. Vasospasm was diagnosed by angiography, macrovascular spasm serially evaluated by Doppler sonography and DCI was defined as new infarction on follow-up CT. Functional outcome was assessed at 6 months by modified Rankin Scale (mRS) and categorized as favorable (mRS score 0-2) versus unfavorable (mRS score 3-6) outcome. Results: Angiographic vasospasm was present in 71.0% of patients. TH neither influenced occurrence nor duration, but the degree of macrovascular spasm as well as peak spastic velocities were significantly reduced (p < 0.05). Frequency of DCI was 87.5% in non-TH vs. 50% in TH-treated patients, translating into a relative risk reduction of 43% and preventive risk ratio of 0.33 (95% CI 0.14-0.77, p = 0.036). Favorable functional outcome was twice as frequent in TH-treated patients 66.7 vs. 33.3% of non-TH (p = 0.06). Conclusion: Early and prolonged TH was associated with a reduced degree of macrovascular spasm and significantly decreased occurrence of DCI, possibly ameliorating functional outcome. TH may represent a promising neuroprotective therapy possibly targeting multiple pathways of DCI development, notably macrovascular spasm, which strongly warrants further evaluation of its clinical impact.

EuroHYP-1: European multicenter, randomized, phase III clinical trial of therapeutic hypothermia plus best medical treatment vs. best medical treatment alone for acute ischemic stroke

RATIONALE

Cooling reduced infarct size and improved neurological outcomes in animal studies modeling ischemic stroke, and also improved outcome in randomized clinical trials in patients with hypoxic-ischemic brain injury after cardiac arrest. Cooling awake patients with ischemic stroke has been shown feasible in phase II clinical trials.

PRIMARY AIM

To determine whether systemic cooling to a target body temperature between 34·0 and 35·0°C, started within six-hours of symptom onset and maintained for 24 h, improves functional outcome at three-months in patients with acute ischemic stroke.

DESIGN

International, multicenter, phase III, randomized, open-label clinical trial with blinded outcome assessment in 1500 patients aged 18 years or older with acute ischemic stroke and a National Institutes of Health Stroke Scale score of 6 up to and including 18. In patients randomized to hypothermia, cooling to a target body temperature of 34-35°C will be started within six-hours after symptom onset with rapid intravenous infusion of refrigerated normal saline or a surface cooling technique and maintained for 24 h with a surface or endovascular technique. Patients randomized to hypothermia will receive pethidine and buspirone to prevent shivering and discomfort.

PRIMARY OUTCOME

Score on the modified Rankin Scale at 91 days, as analyzed with ordinal logistic regression and expressed as a common odds ratio.

DISCUSSION

With 750 patients per intervention group, this trial has 90% power to detect 7% absolute improvement at the 5% significance level. The full trial protocol is available at http://www.eurohyp1.eu. ClinicalTrials.gov Identifier: NCT01833312.

Granulocyte colony-stimulating factor does not promote neurogenesis after experimental intracerebral haemorrhage

BACKGROUND

Hematopoietic growth factors have been suggested to induce neuroprotective and regenerative effects in various animal models of cerebral injury. However, the pathways involved remain widely unexplored.

AIMS

This study aimed to investigate effects of local and systemic administration of granulocyte colony-stimulating factor on brain damage, functional recovery, and cerebral neurogenesis in an intracerebral haemorrhage whole blood injection model in rats.

METHODS

Eight-week-old male Wistar rats (n = 100) underwent induction of striatal intracerebral haemorrhage by autologous whole blood injection or sham procedure and were randomly assigned to either (a) systemic treatment with granulocyte colony-stimulating factor (60 μg/kg) for five-days; (b) single intracerebral injection of granulocyte colony-stimulating factor (60 μg/kg) into the cavity; or (c) application of vehicle for five-days. Bromodeoxyuridine-labelling and immunohistochemistry were used to analyze proliferation and survival of newly born cells in the sub-ventricular zone and the hippocampal dentate gyrus. Moreover, functional deficits and lesion volume were assessed until day 42 after intracerebral haemorrhage.

RESULTS

Differences in lesion size or hemispheric atrophy between granulocyte colony-stimulating factor-treated and control groups did not reach statistical significance. Neither systemic, nor local granulocyte colony-stimulating factor administration induced neurogenesis within the dentate gyrus or the sub-ventricular zone. The survival of newborn cells in these regions was prevented by intracerebral granulocyte colony-stimulating factor application. A subtle benefit in functional recovery at day 14 after intracerebral haemorrhage induction was observed after granulocyte colony-stimulating factor treatment.

CONCLUSION

There was a lack of neuroprotective or neuroregenerative effects of granulocyte colony-stimulating factor in the present rodent model of intracerebral haemorrhage. Conflicting results from functional outcome assessment require further research.

Different treatment settings of Granulocyte-Colony Stimulating Factor and their impact on T cell-specific immune response in experimental stroke

BACKGROUND

Cerebral ischemia is associated with infectious complications due to immunosuppression and decreased T lymphocyte activity. G-CSF, which has neuroprotective properties, is known to modulate inflammatory processes after induced stroke. The aim of our study was to investigate the impact of G-CSF in experimental stroke and to compare two different modes of treatment, focusing on circulating T lymphocytes.

METHODS

Cerebral ischemia was induced in Wistar rats by occlusion of the middle cerebral artery, followed by reperfusion after 1h. G-CSF was applied either as a single dose 30 min after occlusion, or daily for seven days. Silver staining was used to determine infarct size. T lymphocytes in the peripheral blood were measured before and 7 days after induced cerebral ischemia by flow cytometry. In addition, migration of CD3-expressing T lymphocytes into the brain was investigated by immunohistochemistry.

RESULTS

Both single dose and daily treatment with G-CSF significantly reduced infarct size. A significant improvement of neurological outcome was only observed after single application of G-CSF. While a decrease in peripheral T lymphocytes was detected seven days after induced stroke, no reduction was observed in the G-CSF-treated groups. Apart from that, G-CSF significantly reduced the number of brain migrated T lymphocytes in both treatment settings as compared to vehicle.

CONCLUSION

A single dose of G-CSF exerted neuroprotective effects in ischemic stroke, which were less pronounced after daily G-CSF application. Both treatment strategies inhibited stroke-induced reduction of T lymphocytes in peripheral blood, which may have contributed to the reduction of infarct size.

Mild prolonged hypothermia for large intracerebral hemorrhage

BACKGROUND

Perihemorrhagic edema (PHE) develops after intracerebral hemorrhage (ICH). It can worsen the clinical situation by its additional mass effect. Therapeutic hypothermia (TH) might be an effective method to control PHE, but has not been sufficiently studied in ICH patients.

METHODS

We report data on n = 25 consecutive patients with large supratentorial ICH (volume > 25 ml) who were treated by mild TH of 35 °C for 8-10 days. Body temperature was controlled by endovascular cooling catheters. We followed the clinical course during hospital stay and measured volumes of ICH and PHE in regularly performed serial cranial computed tomography. Outcome was assessed after 3 and 12 months. These data were compared to a historical group of n = 25 patients with large ICH.

RESULTS

While PHE continuously increased in the historical control group up to day 10, PHE volumes in the hypothermia group remained stable. There was a significant difference from day 3 after symptom onset. Shivering (36 %) and pneumonia (96 %) were the most frequent complications during TH. Mortality rate was 8.3 % in TH versus 16.7 % in the control group after 3 months and 28 versus 44 % after 1 year.

CONCLUSIONS

These data support the promising results of our first case series on TH in large ICH. TH prevents the development of PHE and its complications. Side effects of TH appeared often, but could be treated sufficiently. Therefore, TH might represent a new therapy for PHE after large ICH, but has to be further tested in randomized trials.

Granulocyte colony-stimulating factor in patients with acute ischemic stroke: results of the AX200 for Ischemic Stroke trial

BACKGROUND AND PURPOSE

Granulocyte colony-stimulating factor (G-CSF; AX200; Filgrastim) is a stroke drug candidate with excellent preclinical evidence for efficacy. A previous phase IIa dose-escalation study suggested potential efficacy in humans. The present large phase IIb trial was powered to detect clinical efficacy in acute ischemic stroke patients.

METHODS

G-CSF (135 µg/kg body weight intravenous over 72 hours) was tested against placebo in 328 patients in a multinational, multicenter, randomized, and placebo-controlled trial (NCT00927836; www.clinicaltrial.gov). Main inclusion criteria were ≤9-hour time window after stroke onset, infarct localization in the middle cerebral artery territory, baseline National Institutes of Health Stroke Scale score range of 6 to 22, and baseline diffusion-weighted imaging lesion size ≥15 mL. Primary and secondary end points were the modified Rankin scale score and the National Institutes of Health Stroke Scale score at day 90, respectively. Data were analyzed using a prespecified model that adjusted for age, National Institutes of Health Stroke Scale score at baseline, and initial infarct volume (diffusion-weighted imaging).

RESULTS

G-CSF treatment failed to meet the primary and secondary end points of the trial. For additional end points such as mortality, Barthel index, or infarct size at day 30, G-CSF did not show efficacy either. There was, however, a trend for reduced infarct growth in the G-CSF group. G-CSF showed the expected peripheral pharmacokinetic and pharmacodynamic profiles, with a strong increase in leukocytes and monocytes. In parallel, the cytokine profile showed a significant decrease of interleukin-1.

CONCLUSIONS

G-CSF, a novel and promising drug candidate with a comprehensive preclinical and clinical package, did not provide any significant benefit with respect to either clinical outcome or imaging biomarkers.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00927836.

Lithium alters the morphology of neurites regenerating from cultured adult spiral ganglion neurons

The small-molecule drug lithium (as a monovalent ion) promotes neurite regeneration and functional recovery, is easy to administer, and is approved for human use to treat bipolar disorder. Lithium exerts its neuritogenic effect mainly by inhibiting glycogen synthase kinase 3, a constitutively-active serine/threonine kinase that is regulated by neurotrophin and "wingless-related MMTV integration site" (Wnt) signaling. In spiral ganglion neurons of the cochlea, the effects of lithium and the function of glycogen synthase kinase 3 have not been investigated. We, therefore, set out to test whether lithium modulates neuritogenesis from adult spiral ganglion neurons. Primary cultures of dissociated spiral ganglion neurons from adult mice were exposed to lithium at concentrations between 0 and 12.5 mM. The resulting neurite morphology and growth-cone appearance were measured in detail by using immunofluorescence microscopy and image analysis. We found that lithium altered the morphology of regenerating neurites and their growth cones in a differential, concentration-dependent fashion. Low concentrations of 0.5-2.5 mM (around the half-maximal inhibitory concentration for glycogen synthase kinase 3 and the recommended therapeutic serum concentration for bipolar disorder) enhanced neurite sprouting and branching. A high concentration of 12.5 mM, in contrast, slowed elongation. As the lithium concentration rose from low to high, the microtubules became increasingly disarranged and the growth cones more arborized. Our results demonstrate that lithium selectively stimulates phases of neuritogenesis that are driven by microtubule reorganization. In contrast, most other drugs that have previously been tested on spiral ganglion neurons are reported to inhibit neurite outgrowth or affect only elongation. Lithium sensitivity is a necessary, but not sufficient condition for the involvement of glycogen synthase kinase 3. Our results are, therefore, consistent with, but do not prove lithium inhibiting glycogen synthase kinase 3 activity in spiral ganglion neurons. Experiments with additional drugs and molecular-genetic tools will be necessary to test whether glycogen synthase kinase 3 regulates neurite regeneration from spiral ganglion neurons, possibly by integrating neurotrophin and Wnt signals at the growth cone.

Diagnosis of spontaneous cervical artery dissection may be associated with increased prevalence of posttraumatic stress disorder

BACKGROUND

Receiving information that one has a dissected cervical artery, which can cause a stroke at any time, is obviously traumatic, but details about the psychiatric and psychosocial sequelae are not known. We investigated the prevalence of and risk factors for posttraumatic stress disorder (PTSD) in patients with spontaneous cervical artery dissection (CD) and the impact of PTSD on their psychosocial functioning.

METHODS

Patients admitted because of CD between 2006 and 2010 were retrospectively examined using a diagnostic PTSD measure (Posttraumatic Diagnostic Scale). Patients between 2011 and 2012 were examined prospectively. To identify potential predictors for PTSD, we examined all patients' stress coping strategies (brief COPE inventory), anxiety and depression (Hospital Anxiety and Depression Scale), impairment by preventive medication, time since diagnosis and their neurologic (modified Rankin Scale) and cognitive status. To identify the psychosocial impact of PTSD, we examined quality of life (Short-Form 36).

RESULTS

Data of 47 retrospectively contacted patients and 15 prospectively examined patients were included. Twenty-eight patients (45.2%) met the diagnostic criteria for PTSD. A significantly reduced health-related quality of life (HRQoL) was found in 27 patients (43.5%) for mental health and in 8 patients (12.9%) for physical health. Results of logistic regression analysis revealed that the use of maladaptive coping strategies was predictive of the disorder (P < .0001). Age, sex, mRS score, impairment caused by medication, and time since diagnosis were not predictive for PTSD. The presence of PTSD itself was the only significant predictor for reduced mental HRQol (P = .0004). Age, sex, mRS score, impairment caused by medication, and total Hospital Anxiety and Depression Scale score were not predictive for reduced mental HRQoL.

CONCLUSIONS

PTSD seems to occur frequently in patients with CD and is associated with reduced mental HRQoL. Because the presence of a maladaptive coping style is correlated with PTSD, teaching patients better coping skills might be helpful.

DEcompressive Surgery plus hypoTHermia for Space-Occupying Stroke (DEPTH-SOS): A Protocol of a Multicenter Randomized Controlled Clinical Trial and a Literature Review

Rationale

Although decompressive hemicraniectomy clearly reduces mortality in severe space-occupying middle cerebral artery infarction (so-called malignant middle cerebral artery infarction), every fifth patient still dies in the acute phase and every third patient is left with moderate to severe disability. Therapeutic hypothermia is a neuroprotective and antiedematous treatment option that has shown promising effects in severe stroke. A combination of both treatment strategies may have the potential to further reduce mortality and morbidity in malignant middle cerebral artery infarction, but needs evaluation of its efficacy within the setting of a randomized clinical trial.

Aims

The DEcompressive surgery Plus hypoTHermia for Space-Occupying Stroke (DEPTH-SOS) trial aims to investigate safety and feasibility of moderate therapeutic hypothermia (33°C ± 1) over at least 72 h in addition to early decompressive hemicraniectomy (≤48 hours after symptom onset) in patients with malignant middle cerebral artery infarction.

Design

The DEcompressive surgery Plus hypoTHermia for Space-Occupying Stroke is a prospective, multicenter, open, two-arm (1:1) comparative, randomized, controlled trial.

Study outcomes

The primary end-point is mortality at day 14. The secondary end-points include functional outcome at day 14 and at 12 months follow-up, and complications related to hypothermia.

Discussion

The results of this trial will provide data on safety and feasibility of moderate hypothermia in addition to decompressive hemicraniectomy in malignant middle cerebral artery infarction. Furthermore, efficacy data on early mortality and long-term functional outcome will be obtained, forming the basis of subsequent trials.

[Therapeutic hypothermia in acute brain injury]

Induced therapeutic hypothermia (TH) is defined as a controlled reduction of the core body temperature below the physiological range. While TH is neuroprotective in many different models of brain injury, it is only recommended for patients after cardiopulmonary resuscitation and newborns suffering from perinatal hypoxic-ischemic encephalopathy (HIE). Although a strong association exists between elevated body core temperature (fever) and worsening of outcome, TH has so far not been proven to influence outcome after ischemic stroke, intracerebral hemorrhage or subarachnoidal hemorrhage because of insufficient clinical data. This review summarizes the data on TH for different clinical indications and discusses relevant aspects of its use in neurological intensive care units.

Suppression of dendritic cell functions contributes to the anti-inflammatory action of granulocyte-colony stimulating factor in experimental stroke

Cerebral ischemia provokes an inflammatory cascade, which is assumed to secondarily worsen ischemic tissue damage. Linking adaptive and innate immunity dendritic cells (DCs) are key regulators of the immune system. The hematopoietic factor G-CSF is able to modulate DC-mediated immune processes. Although G-CSF is under investigation for the treatment of stroke, only limited information exists about its effects on stroke-induced inflammation. Therefore, we investigated the impact of G-CSF on cerebral DC migration and maturation as well as on the mediated immune response in an experimental stroke model in rats by means of transient middle cerebral artery occlusion (tMCAO). Immunohistochemistry and quantitative PCR were performed of the ischemic brain and flow cytometrical analysis of peripheral blood. G-CSF led to a reduction of the infarct size and an improved neurological outcome. Immunohistochemistry confirmed a reduced migration of DCs and mature antigen-presenting cells after G-CSF treatment. Compared to the untreated tMCAO group, G-CSF led to an inhibited DC activation and maturation. This was shown by a significantly decreased cerebral transcription of TLR2 and the DC maturation markers, CD83 and CD86, as well as by an inhibition of stroke-induced increase in immunocompetent DCs (OX62⁺OX6⁺) in peripheral blood. Cerebral expression of the proinflammatory cytokine TNF-α was reduced, indicating an attenuation of cerebral inflammation. Our data suggest an induction of DC migration and maturation under ischemic conditions and identify DCs as a potential target to modulate postischemic cerebral inflammation. Suppression of both enhanced DC migration and maturation might contribute to the neuroprotective action of G-CSF in experimental stroke.

Head and neck cooling decreases tympanic and skin temperature, but significantly increases blood pressure

BACKGROUND AND PURPOSE

Localized head and neck cooling might be suited to induce therapeutic hypothermia in acute brain injury such as stroke. Safety issues of head and neck cooling are undetermined and may include cardiovascular autonomic side effects that were identified in this study.

METHODS

Ten healthy men (age 35±13 years) underwent 120 minutes of combined head and neck cooling (Sovika, HVM Medical). Before and after onset of cooling, after 60 and 120 minutes, we determined rectal, tympanic, and forehead skin temperatures, RR intervals, systolic and diastolic blood pressures (BP), laser-Doppler skin blood flow at the index finger and cheek, and spectral powers of mainly sympathetic low-frequency (0.04-0.15 Hz) and parasympathetic high-frequency (0.15-0.5 Hz) RR interval oscillations and sympathetic low-frequency oscillations of BP. We compared values before and during cooling using analysis of variance with post hoc analysis; (significance, P<0.05).

RESULTS

Forehead skin temperature dropped by 5.5±2.2°C with cooling onset and by 12.4±3.2°C after 20 minutes. Tympanic temperature decreased by 4.7±0.7°C within 40 minutes, and rectal temperature by only 0.3±0.3°C after 120 minutes. Systolic and diastolic BP increased immediately on cooling onset and rose by 15.3±20.8 mm Hg and 16.5±13.4 mm Hg (P=0.004) after 120 minutes, whereas skin blood flow fell significantly during cooling. RR intervals and parasympathetic RR interval high-frequency powers increased with cooling onset and were significantly higher after 60 and 120 minutes than they were before cooling.

CONCLUSIONS

Head and neck cooling prominently reduced tympanic temperature and thus might also induce intracerebral hypothermia; however, it did not significantly lower body core temperature. Profound skin temperature decrease induced sympathetically mediated peripheral vasoconstriction and prominent BP increases that are not offset by simultaneous parasympathetic heart rate slowing. Prominent peripheral vasoconstriction and BP increase must be considered as possibly harmful during head and neck cooling.