A Systematic Review and Meta-Analysis of Animal Studies Testing Intra-Arterial Chilled Infusates After Ischemic Stroke

A Systematic Review and Meta-Analysis of Therapeutic Hypothermia and Pharmacological Cotherapies in Animal Models of Ischemic Stroke

Therapeutic hypothermia (TH) lessens ischemic brain injury. Cytoprotective agents can augment protection, although it is unclear which combinations are most effective. The objective of this study is to identify which cytoprotective drug works best with delayed TH. Following PRISMA guidelines, a systematic review (PubMed, Web of Science, MEDLINE, Scopus) identified controlled experiments that used an in vivo focal ischemic stroke model and evaluated the efficacy of TH (delay of ≥1 hour) coupled with cytoprotective agents. This combination was our main intervention compared with single treatments with TH, drug, or no treatment. Endpoints were brain injury and neurological impairment. The CAMARADES checklist for study quality and the SYRCLE's risk of bias tool gauged study quality. Twenty-five studies were included. Most used young, healthy male rats, with only one using spontaneously hypertensive rats. Two studies used mice models, and six used adult animals. Study quality was moderate (median score = 6), and risk of bias was high. Pharmacological agents provided an additive effect on TH for all outcomes measured. Magnesium coupled with TH had the greatest impact compared with other agent-TH combinations on all outcomes. Longer TH durations improved both behavioral and histological outcomes and had greater cytoprotective efficacy than shorter durations. Anti-inflammatories were the most effective in reducing infarction (standardized mean difference [SMD]: -1.64, confidence interval [CI]: [-2.13, -1.15]), sulfonylureas reduced edema the most (SMD: -2.32, CI: [-3.09, -1.54]), and antiapoptotic agents improved behavioral outcomes the most (normalized mean difference: 52.38, CI: [45.29, 59.46]). Statistically significant heterogeneity was observed (I2 = 82 - 98%, all p < 0.001), indicating that studies wildly differ in their effect size estimates. Our results support the superiority of adding cytoprotective therapies with TH (vs. individual or no therapy). Additional exploratory and confirmatory studies are required to identify and thoroughly assess combination therapies owing to limited work and inconsistent translational quality.

A Pilot Systematic Review and Meta-analysis of Neuroprotective Studies in Female Rodent Models of Ischemic Stroke

Most ischemic stroke (IS) patients go untreated due to limited treatment windows, restrictive eligibility criteria, and poor availability of current clinical therapies. Neuroprotective treatments targeting protracted neurodegeneration are needed yet keep failing in clinical trials. Over half of IS patients are female, and the scarcity of neuroprotective studies using female animals hinders translational success. This pilot review and meta-analysis assessed the relationship between the risk of bias and efficacy of studies testing post-ischemic neuroprotective therapies using female rodent models of IS. We carried out a systematic search of the PubMed database for studies published between 1999 and May 2022, used the CAMARADES checklist to evaluate study quality, and extracted data pertaining to lesion volume and behavioral assessment. We found that 34 studies met our inclusion criteria, with pooled effect sizes depicting a significant treatment effect. However, researchers used mostly healthy young females, administered therapies within short time windows, ignored hormonal influences, and did not assess long-term outcomes. Interestingly, studies failing to report factors impacting internal validity, such as blinding and random allocation, had inflated effect sizes or did not reach statistical significance. There was also a relationship between low study quality and larger effect sizes for functional outcome, stressing the need to follow the existing translational design, reporting, and data analysis guidelines. In this review, we cover previous recommendations and offer our own in hopes that rigorous and meticulous research using female animal models of IS will increase our chances of successful bench-to-bedside translation.

The Effect of Upper Cervical Mobilization/Manipulation on Temporomandibular Joint Pain, Maximal Mouth Opening, and Pressure Pain Thresholds: A Systematic Review and Meta-Analysis

Objective

To evaluate the efficacy of upper cervical joint mobilization and/or manipulation on reducing pain and improving maximal mouth opening (MMO) and pressure pain thresholds (PPTs) in adults with temporomandibular joint (TMJ) dysfunction compared with sham or other intervention.

Data Sources

MEDLINE, CINAHL, EMBASE, and Cochrane Library from inception to June 3, 2022, were searched.

Study Selection

Eight randomized controlled trials with 437 participants evaluating manual therapy (MT) vs sham and MT vs other intervention were included. Two reviewers independently extracted data and assessed risk of bias.

Data Extraction

Two independent reviewers extracted information about origin, number of study participants, eligibility criteria, type of intervention, and outcome measures.

Data Synthesis

Manual therapy was statistically significant in reducing pain compared with sham (mean difference [MD]: -1.93 points, 95% confidence interval [CI]: -3.61 to -0.24, P=.03), and other intervention (MD: -1.03 points, 95% CI: -1.73 to -0.33, P=.004), improved MMO compared with sham (MD: 2.11 mm, 95% CI: 0.26 to 3.96, P=.03), and other intervention (MD: 2.25 mm, 95% CI: 1.01 to 3.48, P<.001), but not statistically significant in improving PPT of masseter compared with sham (MD: 0.45 kg/cm2, 95% CI: -0.21 to 1.11, P=.18), and other intervention (MD: 0.42 kg/cm2, 95% CI: -0.19 to 1.03, P=.18), or the PPT of temporalis compared with sham (MD: 0.37 kg/cm2, 95% CI: -0.03 to 0.77, P=.07), and other intervention (MD: 0.43 kg/cm2, 95% CI: -0.60 to 1.45, P=.42).

Conclusion

There appears to be limited benefit of upper cervical spine MT on TMJ dysfunction, but definitive conclusions cannot be made because of heterogeneity and imprecision of treatment effects.

Selective Brain Cooling: A New Horizon of Neuroprotection

Therapeutic hypothermia (TH), which prevents irreversible neuronal necrosis and ischemic brain damage, has been proven effective for preventing ischemia-reperfusion injury in post-cardiac arrest syndrome and neonatal encephalopathy in both animal studies and clinical trials. However, lowering the whole-body temperature below 34°C can lead to severe systemic complications such as cardiac, hematologic, immunologic, and metabolic side effects. Although the brain accounts for only 2% of the total body weight, it consumes 20% of the body's total energy at rest and requires a continuous supply of glucose and oxygen to maintain function and structural integrity. As such, theoretically, temperature-controlled selective brain cooling (SBC) may be more beneficial for brain ischemia than systemic pan-ischemia. Various SBC methods have been introduced to selectively cool the brain while minimizing systemic TH-related complications. However, technical setbacks of conventional SBCs, such as insufficient cooling power and relatively expensive coolant and/or irritating effects on skin or mucosal interfaces, limit its application to various clinical settings. This review aimed to integrate current literature on SBC modalities with promising therapeutic potential. Further, future directions were discussed by exploring studies on interesting coping skills in response to environmental or stress-induced hyperthermia among wild animals, including mammals and birds.

Targeting focal ischemic and hemorrhagic stroke neuroprotection: Current prospects for local hypothermia

Therapeutic hypothermia (TH) has applications dating back millennia. In modern history, however, TH saw its importation into medical practice where investigations have demonstrated that TH is efficacious in ischemic insults, notably cardiac arrest and hypoxic-ischemic encephalopathy. As well, studies have been undertaken to investigate whether TH can provide benefit in focal stroke (i.e., focal ischemia and intracerebral hemorrhage). However, clinical studies have encountered various challenges with induction and maintenance of post-stroke TH. Most clinical studies have attempted to use body-wide cooling protocols, commonly hindered by side effects that can worsen post-stroke outcomes. Some of the complications and difficulties with systemic TH can be circumvented by using local hypothermia (LH) methods. Additional advantages include the potential for lower target temperatures to be achieved and faster TH induction rates with LH. This systematic review summarizes the body of clinical and preclinical LH focal stroke studies and raises key points to consider for future LH research. We conclude with an overview of LH neuroprotective mechanisms and a comparison of LH mechanisms with those observed with systemic TH. Overall, whereas many LH studies have been conducted preclinically in the context of focal ischemia, insufficient work has been done in intracerebral hemorrhage. Furthermore, key translational studies have yet to be done in either stroke subtype (e.g., varied models and time-to-treat, studies considering aged animals or animals with co-morbidities). Few clinical LH investigations have been performed and the optimal LH parameters to achieve neuroprotection are unknown.