Acute Decompressive Hemicraniectomy to Control High Intracranial Pressure in Patients with Malignant MCA Ischemic Strokes

Characterization of tissue and functional deficits in a clinically translational pig model of acute ischemic stroke

The acute stroke phase is a critical time frame used to evaluate stroke severity, therapeutic options, and prognosis while also serving as a major tool for the development of diagnostics. To further understand stroke pathophysiology and to enhance the development of treatments, our group developed a translational pig ischemic stroke model. In this study, the evolution of acute ischemic tissue damage, immune responses, and functional deficits were further characterized. Stroke was induced by middle cerebral artery occlusion in Landrace pigs. At 24 h post-stroke, magnetic resonance imaging revealed a decrease in ipsilateral diffusivity, an increase in hemispheric swelling resulting in notable midline shift, and intracerebral hemorrhage. Stroke negatively impacted white matter integrity with decreased fractional anisotropy values in the internal capsule. Like patients, pigs showed a reduction in circulating lymphocytes and a surge in neutrophils and band cells. Functional responses corresponded with structural changes through reductions in open field exploration and impairments in spatiotemporal gait parameters. Characterization of acute ischemic stroke in pigs provided important insights into tissue and functional-level assessments that could be used to identify potential biomarkers and improve preclinical testing of novel therapeutics.

Large animal ischemic stroke models: replicating human stroke pathophysiology

The high morbidity and mortality rate of ischemic stroke in humans has led to the development of numerous animal models that replicate human stroke to further understand the underlying pathophysiology and to explore potential therapeutic interventions. Although promising therapeutics have been identified using these animal models, with most undergoing significant testing in rodent models, the vast majority of these interventions have failed in human clinical trials. This failure of preclinical translation highlights the critical need for better therapeutic assessment in more clinically relevant ischemic stroke animal models. Large animal models such as non-human primates, sheep, pigs, and dogs are likely more predictive of human responses and outcomes due to brain anatomy and physiology that are more similar to humans-potentially making large animal testing a key step in the stroke therapy translational pipeline. The objective of this review is to highlight key characteristics that potentially make these gyrencephalic, large animal ischemic stroke models more predictive by comparing pathophysiological responses, tissue-level changes, and model limitations.

Cerebral edema detection in vivo after middle cerebral artery occlusion using swept-source optical coherence tomography

Cerebral edema is a severe complication of ischemic cerebrovascular disease, which can lead to microcirculation compression resulting in additional ischemic damage. Real-time and continuous in vivo imaging techniques for edema detection are of great significance to basic research on cerebral edema. We attempted to monitor the cerebral edema status in rats with middle cerebral artery occlusion (MCAO) over time, using a wide field-of-view swept-source optical coherence tomography (SS-OCT) system. Optical attenuation coefficients (OACs) were calculated by an optimized depth-resolved estimation method, and en face OAC maps covering the whole cortex were obtained. Then, the tissue affected by edema was segmented from the OAC maps, and the cortical area affected by edema was estimated. Both magnetic resonance image (MRI) and brain water content measurements were used to verify the presence of cerebral edema. The results showed that the average OAC of the ischemic area gradually decreased as cerebral edema progressed, and the edema area detected by SS-OCT had high similarity in position and shape to that obtained by MRI. This work extends the application of OCT and provides an option for detecting cerebral edema in vivo after ischemic stroke.

Decompressive hemicraniectomy for malignant middle cerebral artery infarction. Experience from the Western Province of Saudi Arabia

Objective:

To describe our experience implementing decompressive hemicraniectomy (DH) for eligible patients with malignant middle cerebral artery (MCA) infarcts.

Methods:

We retrospectively collected data of malignant MCA infarction patients requiring DH at King Abdulaziz University Hospital & King Faisal Specialist Hospital & Research Center, Jeddah, Kingdom of Saudi Arabia between October 2010 and July 2015. Clinical outcome was assessed immediately postoperatively using Glasgow Coma Score (GCS), and at 12 months using the modified Rankin scale (mRS) and Barthel index. Survival was evaluated at thirty-days and one year after surgery.

Results:

Six out of 10 patients diagnosed with malignant MCA infarction underwent DH. Among the surgically treated patients (n=6), 4 were males (66%), and the median age was 22.5 years. The median time from admission to surgery was 35.5 hours. The median post-operative GCS was 6.5. Three patients (50%) died within 30 days of DH. In those who survived, the median mRS was 4.5 and BI was 7.5.

Conclusion:

Decompressive hemicraniectomy saves life and has the potential of improving survival functional outcome when done fast and in carefully selected patients. We call for national awareness of the management of such cases and early intervention.

Decompressive craniectomy in acute brain injury

Decompressive surgery to reduce pressure under the skull varies from a burrhole, bone flap to removal of a large skull segment. Decompressive craniectomy is the removal of a large enough segment of skull to reduce refractory intracranial pressure and to maintain cerebral compliance for the purpose of preventing neurologic deterioration. Decompressive hemicraniectomy and bifrontal craniectomy are the most commonly performed procedures. Bifrontal craniectomy is most often utilized with generalized cerebral edema in the absence of a focal mass lesion and when there are bilateral frontal contusions. Decompressive hemicraniectomy is most commonly considered for malignant middle cerebral artery infarcts. The ethical predicament of deciding to go ahead with a major neurosurgical procedure with the purpose of avoiding brain death from displacement, but resulting in prolonged severe disability in many, are addressed. This chapter describes indications, surgical techniques, and complications. It reviews results of recent clinical trials and provides a reasonable assessment for practice.

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).

Elevated Intracranial Pressure and Cerebral Edema following Permanent MCA Occlusion in an Ovine Model

INTRODUCTION

Malignant middle cerebral artery (MCA) stroke has a disproportionately high mortality due to the rapid development of refractory space-occupying cerebral edema. Animal models are essential in developing successful anti-edema therapies; however to date poor clinical translation has been associated with the predominately used rodent models. As such, large animal gyrencephalic models of stroke are urgently needed. The aim of the study was to characterize the intracranial pressure (ICP) response to MCA occlusion in our recently developed ovine stroke model.

MATERIALS AND METHODS

30 adult female Merino sheep (n = 8-12/gp) were randomized to sham surgery, temporary or permanent proximal MCA occlusion. ICP and brain tissue oxygen were monitored for 24 hours under general anesthesia. MRI, infarct volume with triphenyltetrazolium chloride (TTC) staining and histology were performed.

RESULTS

No increase in ICP, radiological evidence of ischemia within the MCA territory but without space-occupying edema, and TTC infarct volumes of 7.9+/-5.1% were seen with temporary MCAO. Permanent MCAO resulted in significantly elevated ICP, accompanied by 30% mortality, radiological evidence of space-occupying cerebral edema and TTC infarct volumes of 27.4+/-6.4%.

CONCLUSIONS

Permanent proximal MCAO in the sheep results in space-occupying cerebral edema, raised ICP and mortality similar to human malignant MCA stroke. This animal model may prove useful for pre-clinical testing of anti-edema therapies that have shown promise in rodent studies.

Nationwide survey of decompressive hemicraniectomy for malignant middle cerebral artery infarction in Japan

OBJECTIVE

Decompressive hemicraniectomy (DHC) for malignant middle cerebral artery (MCA) infarction has been shown to reduce mortality and improve functional outcomes in young adults; however, there is currently debate regarding how routinely such surgery should be performed in the clinical setting, considering the very high rate of disability and functional dependence among survivors. We herein report the current status of the frequency of and indications for DHC for malignant MCA infarction in Japan.

METHODS

We retrospectively studied of cohort cases of DHC for malignant MCA infarction treated at pivotal teaching neurosurgical departments in Japan between January 2011 and December 2011. Information was obtained regarding patient characteristics, radiologic features, and outcomes during follow-up. The end points included 30-day mortality rate and functional outcomes, as measured according to the modified Rankin scale (mRS) score at 3 months.

RESULTS

Three hundred fifty-five patients underwent DHC at 259 neurosurgical departments who replied to the survey, corresponding to a rate of 8.7% of the 4092 candidates with malignant MCA infarction, the latter being equivalent to 8.5% of patients with acute ischemic stroke identified during the same period. Among the patients undergoing DHC, the mean age was 67.0 years, and those ≥60 years of age comprised 80.2% of all DHC patients. The most frequently used modality for vascular imaging was magnetic resonance angiography (77.2%). DHC generally was performed between 24 and 48 hours after onset (38.9%), with 36.9% of patients undergoing surgery at ≥48 hours. At the time of surgery, 26.1% of the patients had a Glasgow Coma Scale score of ≤6. Presurgical midbrain compression was noted in 52.1% of the patients. The 30-day mortality after DHC was 18.6%, and factors affecting death were a Glasgow Coma Scale score of ≤6 (odds ratio [OR] 1.88, 95% confidence interval [95% CI] 1.05-3.32, P = 0.03) and midbrain compression (OR 2.28, 95% CI 1.31-4.09, P = 0.005). According to the multivariate analysis, only midbrain compression was an independent risk factor (OR 2.12, 95% CI 1.16-3.95, P = 0.01) for 30-day mortality. Modified Rankin scale scores at 3 months were available in 175 patients (49.3%), only 5.2% of whom exhibited a favorable functional outcome (mRS score ≤3). Meanwhile, 22.9% of the patients had an mRS score of 4, 26.9% had an mRS score of 5, and 45.1% were found to have died.

CONCLUSIONS

In the present study, less than one-tenth of candidates with malignant MCA infarction in Japan underwent decompressive surgery, and the vast majority of patients were elderly. Age was not found to be an independent factor for immediate mortality in this study, and performing surgery in the elderly may be justified based on additional evidence of functional improvements.

Malignant hemispheric infarction of the middle cerebral artery. Diagnostic considerations and treatment options

INTRODUCTION

Malignant hemispheric infarction (MHI) is a specific and devastating type of ischemic stroke. It usually affects all or part of the territory of the middle cerebral artery although its effects may extend to other territories as well. Its clinical outcome is frequently catastrophic when only conventional medical treatment is applied.

OBJECTIVE

The purpose of this review is to analyse the available scientific evidence on the treatment of this entity.

DEVELOPMENT

MHI is associated with high morbidity and mortality. Its clinical characteristics are early neurological deterioration and severe hemispheric syndrome. Its hallmark is the development of space-occupying cerebral oedema between day 1 and day 3 after symptom onset. The mass effect causes displacement, distortion, and herniation of brain structures even when intracranial hypertension is initially absent. Until recently, MHI was thought to be fatal and untreatable because mortality rates with conventional medical treatment could exceed 80%. In this unfavourable context, decompressive hemicraniectomy has re-emerged as a therapeutic alternative for selected cases, with reported decreases in mortality ranging between 15% and 40%.

CONCLUSIONS

In recent years, several randomised clinical trials have demonstrated the benefit of decompressive hemicraniectomy in patients with MHI. This treatment reduces mortality in addition to improving functional outcomes.

A surgical model of permanent and transient middle cerebral artery stroke in the sheep

Background

Animal models are essential to study the pathophysiological changes associated with focal occlusive stroke and to investigate novel therapies. Currently used rodent models have yielded little clinical success, however large animal models may provide a more suitable alternative to improve clinical translation. We sought to develop a model of acute proximal middle cerebral artery (MCA) ischemic stroke in sheep, including both permanent occlusion and transient occlusion with reperfusion.

Materials and Methods

18 adult male and female Merino sheep were randomly allocated to one of three groups (n = 6/gp): 1) sham surgery; 2) permanent proximal MCA occlusion (MCAO); or 3) temporary MCAO with aneurysm clip. All animals had invasive arterial blood pressure, intracranial pressure and brain tissue oxygen monitoring. At 4 h following vessel occlusion or sham surgery animals were killed by perfusion fixation. Brains were processed for histopathological examination and infarct area determination. 6 further animals were randomized to either permanent (n = 3) or temporary MCAO (n = 3) and then had magnetic resonance imaging (MRI) at 4 h after MCAO.

Results

Evidence of ischemic injury in an MCA distribution was seen in all stroke animals. The ischemic lesion area was significantly larger after permanent (28.8%) compared with temporary MCAO (14.6%). Sham animals demonstrated no evidence of ischemic injury. There was a significant reduction in brain tissue oxygen partial pressure after permanent vessel occlusion between 30 and 210 mins after MCAO. MRI at 4 h demonstrated complete proximal MCA occlusion in the permanent MCAO animals with a diffusion deficit involving the whole right MCA territory, whereas temporary MCAO animals demonstrated MRA evidence of flow within the right MCA and smaller predominantly cortical diffusion deficits.

Conclusions

Proximal MCAO can be achieved in an ovine model of stroke via a surgical approach. Permanent occlusion creates larger infarct volumes, however aneurysm clip application allows for reperfusion.