Management of large hemispheric strokes in the neurological intensive care unit

Veterinary medical care in rodent models of stroke: Pitfalls and refinements to balance quality of science and animal welfare

Rodent models of cerebral ischemia provide a valuable contribution to a better understanding of stroke pathophysiology, to validate diagnostic methods, and to enable testing of new treatments for ischemia-reperfusion damage and comorbidities. However, ethical concerns have led to increased attention to the welfare aspects of such models. Supportive therapies are an essential part of the overall animal care and use program and should be tailored to the experimental model being studied, the regulatory requirements, and research objectives to achieve high-quality preclinical studies and ethical research practices. On the other hand, the use of veterinary medical treatments in preclinical models of stroke must balance the needs of animal care and potential sources of bias in experimental results. This report provides a systematic review of the scientific literature covering the relevant period from years 1988 to September 2024, with the aim to investigating veterinary medical interventions useful to minimize suffering in rodent models of stroke without producing experimental bias. The research findings, consolidated from 181 selected studies, published from 1991 to 2023, indicate the feasibility of implementing personalized protocols of anesthesia, analgesics, antibiotics, and other supportive therapies in rodent models of stroke, while avoiding scientific interferences. These data fill a gap in current knowledge and could be of interest for an interdisciplinary audience working with rodent models of stroke, stimulating further refinements to safeguard both animal welfare and the validity of experimental findings, and may promote the culture of ethical conduct in various research fields and disciplines.

TRPV4 activation by core body temperature has multimodal functions in the central nervous system

Brain temperature is strictly regulated by various endogenous mechanisms and significantly contributes to brain function in homeothermic animals, making it an important factor for health. Thermosensitive transient receptor potential (TRP) channels convert temperature information into electrical signals through cation influx. In particular, TRPV4 is involved in the regulation of brain function. TRPV4, constitutively active in neurons through its activation by brain temperature, increases neuronal firing. TRPV4KO mice have electroencephalogram abnormalities, resulting in depression-like and social behavioral abnormalities. This basic function of TRPV4, as a translator of brain temperature information, has been implicated in several diseases, including epilepsy and stress-induced depression. In addition to its neuronal functions, TRPV4 has many key functions in glia and vasculature that depend on brain temperature and contribute to brain activity. In this review, I summarize the importance of TRPV4 activities in relation to brain temperature and focus on how hyperthermia-induced TRPV4 dysfunction exacerbates brain diseases.

Ischemic Brain Injury Leads to Brain Edema via Hyperthermia-Induced TRPV4 Activation

Brain edema is characterized by an increase in net brain water content, which results in an increase in brain volume. Although brain edema is associated with a high fatality rate, the cellular and molecular processes of edema remain largely unclear. Here, we developed an in vitro model of ischemic stroke-induced edema in which male mouse brain slices were treated with oxygen-glucose deprivation (OGD) to mimic ischemia. We continuously measured the cross-sectional area of the brain slice for 150 min under macroscopic microscopy, finding that OGD induces swelling of brain slices. OGD-induced swelling was prevented by pharmacologically blocking or genetically knocking out the transient receptor potential vanilloid 4 (TRPV4), a member of the thermosensitive TRP channel family. Because TRPV4 is activated at around body temperature and its activation is enhanced by heating, we next elevated the temperature of the perfusate in the recording chamber, finding that hyperthermia induces swelling via TRPV4 activation. Furthermore, using the temperature-dependent fluorescence lifetime of a fluorescent-thermosensitive probe, we confirmed that OGD treatment increases the temperature of brain slices through the activation of glutamate receptors. Finally, we found that brain edema following traumatic brain injury was suppressed in TRPV4-deficient male mice in vivo Thus, our study proposes a novel mechanism: hyperthermia activates TRPV4 and induces brain edema after ischemia.SIGNIFICANCE STATEMENT Brain edema is characterized by an increase in net brain water content, which results in an increase in brain volume. Although brain edema is associated with a high fatality rate, the cellular and molecular processes of edema remain unclear. Here, we developed an in vitro model of ischemic stroke-induced edema in which mouse brain slices were treated with oxygen-glucose deprivation. Using this system, we showed that the increase in brain temperature and the following activation of the thermosensitive cation channel TRPV4 (transient receptor potential vanilloid 4) are involved in the pathology of edema. Finally, we confirmed that TRPV4 is involved in brain edema in vivo using TRPV4-deficient mice, concluding that hyperthermia activates TRPV4 and induces brain edema after ischemia.

Precision Stroke Animal Models: the Permanent MCAO Model Should Be the Primary Model, Not Transient MCAO

An argument for preclinical stroke research to make more use of the permanent middle cerebral artery occlusion (MCAO) model, rather than transient MCAO, is presented. Despite STAIR recommending permanent MCAO as the primary model, preclinical stroke research has not been listened. In 2012, Hossmann reported that 64% of the treatment studies for MCAO used prompt transient MCAO models and only 36% of the studies used permanent MCAO or gradual transient MCAO (i.e., embolic stroke model). Then, in 2014 and 2015, 88% of published basic science studies on large vessel occlusion used the transient MCAO model. However, this model only represents 2.5-11.3% of large vessel stroke patients. Therefore, the transient MCAO model, which mimics stroke with reperfusion, does not accurately reflect the majority of clinical stroke cases. Thus, once again, the argument for studying permanent MCAO as a primary model is made and supported.

Hemicraniectomy versus medical treatment with large MCA infarct: a review and meta-analysis

OBJECTIVE

Large middle cerebral artery stroke (space-occupying middle-cerebral-artery (MCA) infarction (SO-MCAi)) results in a very high incidence of death and severe disability. Decompressive hemicraniectomy (DHC) for SO-MCAi results in large reductions in mortality; the level of function in the survivors, and implications, remain controversial. To address the controversy, we pooled available randomised controlled trials (RCTs) that examined the impact of DHC on survival and functional ability in patients with large SO-MCAi and cerebral oedema.

METHODS

We searched MEDLINE, EMBASE and Cochrane library databases for randomised controlled trials (RCTs) enrolling patients suffering SO-MCAi comparing conservative management to DHC administered within 96 hours after stroke symptom onset. Outcomes were death and disability measured by the modified Rankin Scale (mRS). We used a random effects meta-analytical approach with subgroup analyses (time to treatment and age). We applied GRADE methods to rate quality/confidence/certainty of evidence.

RESULTS

7 RCTs were eligible (n=338 patients). We found DHC reduced death (69-30% in medical vs surgical groups, 39% fewer), and increased the number of patients with mRS of 2-3 (slight to moderate disability: 14-27%, increase of 13%), those with mRS 4 (severe disability: 10-32%, increase of 22%) and those with mRS 5 (very severe disability 7-11%: increase of 4%) (all differences p<0.0001). We judged quality/confidence/certainty of evidence high for death, low for functional outcome mRS 0-3, and moderate for mRS 0-4 (wide CIs and problems in concealment, blinding of outcome assessors and stopping early).

CONCLUSIONS

DHC in SO-MCAi results in large reductions in mortality. Most of those who would otherwise have died are left with severe or very severe disability: for example, inability to walk and a requirement for help with bodily needs, though uncertainty about the proportion with very severe, severe and moderate disability remains (low to moderate quality/confidence/certainty evidence).

Neuroprotective effects of penehyclidine hydrochloride against cerebral ischemia/reperfusion injury in mice

Various reports have suggested that penehyclidine hydrochloride (PHC), a new cholinergic antagonist, exhibits a variety of biological actions such as anti-tumor and cardioprotective effects. This study aimed to investigate the effects of PHC on cerebral ischemia/reperfusion (I/R) injury and evaluate whether the c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (p38MAPK) pathway is involved in the protective effects of PHC. Male C57BL/6 mice were randomly assigned to Sham group, ischemia/reperfusion (I/R) group, I/R+PHC (0.1mg/kg) group, and I/R+PHC (1mg/kg) group. Mice were subjected to 2h of transient middle cerebral artery occlusion, followed by 24h of reperfusion except the mice in the sham group. Neurological deficits, infarct volume, brain water content, blood-brain barrier (BBB) integrity, and neuronal apoptosis were evaluated. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), superoxide production, malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were measured. The expressions of the key proteins in the JNK/p38MAPK pathway were detected using the Western blot. The results suggested that compared to the I/R group, the PHC-treated group showed improved neurological deficits and BBB integrity, and reduced infarction volume, brain water content, and apoptosis. In addition, PHC significantly suppressed the levels of TNF-α, IL-1β, superoxide production, and MDA, and increased the levels of SOD and GSH-Px. Finally, PHC significantly downregulated the phosphorylation of JNK, p38MAPK, and c-Jun, indicating PHC protects against cerebral I/R injury by downregulating the JNK/p38MAPK signaling pathway.

Antiedema therapy in ischemic stroke

Life-threatening, space-occupying brain edema occurs in up to 10% of patients with supratentorial infarcts and is traditionally associated with a high mortality rate of up to 80%. Management of these patients is currently being changed to an earlier and more aggressive treatment regimen. Early surgical decompression has recently been proven effective to reduce mortality and increase the number of patients with a favorable outcome in randomized controlled trials and is now the "antiedema" therapy of first choice for patients with large middle cerebral artery infarction aged 60 years or younger. Several medical treatment strategies have been proposed to control brain edema and reduce intracranial pressure, including different osmotherapeutics, hyperventilation, tromethamine, hypothermia, and barbiturate coma. None of these treatments is supported by level 1 evidence of efficacy in clinical trials, and some of them may even be detrimental. Preliminary results on hypothermia for space-occupying hemispheric infarction are encouraging, but far from definitive.

Treatment of massive cerebral infarction

Stroke is the third leading cause of death in the United States, with a person dying every 3 minutes of a stroke. Massive ischemic stroke accounts for 10% to 20% of ischemic strokes, has traditionally been associated with a high mortality and morbidity, and requires a unique management strategy. Recent advances in management, fueled by an increased understanding of the pathophysiology, may help decrease mortality and improve outcomes. Rapid access to reperfusion therapies remains the most critical element of stroke care and the cornerstone of therapy. This article focuses on newer therapies, including osmotic therapy, hypothermia, maintained normothermia, strict glycemic control, induced hypertension, and hemicraniectomy, all of which show promise for reducing mortality and improving functional outcome. These interventions have become integrated into neurologic intensive care units around the world. They are complicated, require a high level of expertise, and carry a significant learning curve. In order for these new management techniques to be effective, an expedited, aggressive, meticulous, and potentially prolonged medical management approach is needed. To accomplish this there is a growing need for focused specialists in the areas of neurointensive care and stroke.

Management of massive cerebral infarct

Patients with large hemispheric strokes frequently develop neurologic deterioration secondary to cerebral edema. Regardless of the medical and surgical management of cerebral edema, there is high morbidity and mortality. This article reviews the clinical and radiographic features of large hemispheric strokes and examines the various therapeutic options for management of cerebral edema.

Functional impairment, disability, and quality of life outcome after decompressive hemicraniectomy in malignant middle cerebral artery infarction

Object. Whether decompressive hemicraniectomy is an appropriate treatment for space-occupying middle cerebral artery (MCA) infarction is still a controversial issue. Previous studies are in agreement on a reduction of the mortality rate, but the reported functional outcome was highly variable. The authors sought to determine functional impairment, disability, and health-related quality of life (QOL) outcome in long-term survivors who had undergone this procedure, and tried to identify factors related to functional outcome.

Methods. The study included 36 consecutive patients (mean age 58.8 ± 12.7 years, 20 men and 16 women) who underwent decompressive hemicraniectomy for treatment of malignant MCA infarction (29 on the right and seven on the left side; mean time to surgery 37.8 ± 20 hours). The survival rate was determined at 6 months: 13.7 ± 6.7 months after the stroke, a cross-sectional personal investigation of survivors was performed to assess functional impairment, disability, and health-related QOL.

Survival rates were 78% at 6 months and 64% at the time of the follow-up investigation; one patient was lost to follow up. Sixteen of 22 long-term survivors lived at home. The median Barthel Index (BI) was 45 (25th and 75th percentile 19 and 71) and the BI correlated negatively with patient age (r = −0.58, p = 0.005). Three patients reached a BI of at least 90. Older age, more severe neurological deficit on admission, and longer duration of intensive care treatment and mechanical ventilation were significantly associated with worse disability (BI < 50). The health-related QOL was considerably impaired in the subscales of mobility, household management, and body care.

Conclusions. Decompressive hemicraniectomy improves survival in patients with malignant MCA infarction when compared with earlier reports of conservative treatment alone. Functional outcome and QOL remain markedly impaired, especially among elderly patients and in those with a severe neurological deficit at admission.