Cerebral vasospasm after aneurysmal subarachnoid hemorrhage and traumatic brain injury

Vasospasm in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young individuals. Management of TBI is complex and aims to prevent secondary injury and optimise conditions for neurological recovery. Vasospasm is a possible complication of TBI, and its significance is unknown. Its incidence is underestimated and there are currently no preventive or therapeutic approaches with proven efficacy. The occurrence of vasospasm contributes to secondary brain injury and worsens prognosis. The diagnosis of vasospasm in TBI is challenging due to the difficulty in perceiving neurological deterioration in these patients. We present a case of a young patient admitted to the neurocritical care unit following TBI. He presented a partial neurological recovery, followed by clinical deterioration and persistent coma. The diagnosis of extensive ischaemic lesions due to severe vasospasm was established. Suspicion of vasospasm and timely screening, particularly in high-risk patients, may improve survival and outcomes in TBI.

Predicting Vasospasm and Early Mortality in Severe Traumatic Brain Injury: A Model Using Serum Cytokines, Neuronal Proteins, and Clinical Data

BACKGROUND AND OBJECTIVES

Prediction of patient outcomes after severe traumatic brain injury (sTBI) is limited with current clinical tools. This study aimed to improve such prognostication by combining clinical data and serum inflammatory and neuronal proteins in patients with sTBI to develop predictive models for post-traumatic vasospasm (PTV) and mortality.

METHODS

Fifty-three adult civilian patients were prospectively enrolled in the sTBI arm of the Surgical Critical Care Initiative (SC2i). Clinical, serum inflammatory, and neuronal protein data were combined using the parsimonious machine learning methods of least absolute shrinkage and selection operator (LASSO) and classification and regression trees (CART) to construct parsimonious models for predicting development of PTV and mortality.

RESULTS

Thirty-six (67.9%) patients developed vasospasm and 10 (18.9%) died. The mean age was 39.2 years; 22.6% were women. CART identified lower IL9, lower presentation pulse rate, and higher eotaxin as predictors of vasospasm development (full data area under curve (AUC) = 0.89, mean cross-validated AUC = 0.47). LASSO identified higher Rotterdam computed tomography score and lower age as risk factors for vasospasm development (full data AUC 0.94, sensitivity 0.86, and specificity 0.94; cross-validation AUC 0.87, sensitivity 0.79, and specificity 0.93). CART identified high levels of eotaxin as most predictive of mortality (AUC 0.74, cross-validation AUC 0.57). LASSO identified higher serum IL6, lower IL12, and higher glucose as predictive of mortality (full data AUC 0.9, sensitivity 1.0, and specificity 0.72; cross-validation AUC 0.8, sensitivity 0.85, and specificity 0.79).

CONCLUSION

Inflammatory cytokine levels after sTBI may have predictive value that exceeds conventional clinical variables for certain outcomes. IL-9, pulse rate, and eotaxin as well as Rotterdam score and age predict development of PTV. Eotaxin, IL-6, IL-12, and glucose were predictive of mortality. These results warrant validation in a prospective cohort.

Cerebral Infarction Due to Post-traumatic Cerebral Vasospasm in a 12-Year-Old Female

Cerebral infarction due to post-traumatic cerebral vasospasm is rare. Although some modalities are recommended to detect post-traumatic cerebral vasospasm, its diagnosis remains controversial and challenging. Therefore, in this report, we will use a case report to highlight challenges and to delineate the characteristics of post-traumatic cerebral vasospasm in pediatric patients, including the diagnostic and treatment options. A 12-year-old female was admitted to our hospital following a motor vehicle collision. Her consciousness was severely impaired. Initial computed tomography (CT) revealed an acute subdural hematoma along the tentorium, and a focal subarachnoid hemorrhage was observed in the Sylvian fissure. The patient underwent the insertion of an intracranial pressure sensor and received therapy for increased intracranial pressure (ICP) control under sedation. On the second day, CT angiography (CTA) revealed no signs of arterial abnormality. A patient who is comatose or under sedation has masked neurological symptoms. Thus, new neurological events could only be detected via an intracranial pressure sensor. Her ICP increased on the seventh day, and a CT scan showed a new cerebral infarction in the right middle cerebral artery (MCA) region. We performed decompressive craniectomy to reduce ICP. Postoperative CTA confirmed severe vasospasm in the right MCA. The severe cerebral vasospasm induced the cerebral infarction. Our review suggests that physicians in trauma departments should frequently perform vascular evaluations by CTA, magnetic resonance angiography (MRA), transcranial Doppler ultrasound, or digital subtraction angiography (DSA), especially within two weeks from onset, to detect post-traumatic cerebral vasospasm.

The Nociceptin/Orphanin FQ peptide receptor antagonist, SB-612111, improves cerebral blood flow in a rat model of traumatic brain injury

Traumatic brain injury (TBI) affects more than 2.5 million people in the U.S. each year and is the leading cause of death and disability in children and adults ages 1 to 44. Approximately 90% of TBI cases are classified as mild but may still lead to acute detrimental effects such as impaired cerebral blood flow (CBF) that result in prolonged impacts on brain function and quality of life in up to 15% of patients. We previously reported that nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor antagonism reversed mild blast TBI-induced vestibulomotor deficits and prevented hypoxia. To explore mechanisms by which the NOP receptor-N/OFQ pathway modulates hypoxia and other TBI sequelae, the ability of the NOP antagonist, SB-612111 (SB), to reverse TBI-induced CBF and associated injury marker changes were tested in this study. Male Wistar rats randomly received sham craniotomy or craniotomy + TBI via controlled cortical impact. Injury severity was assessed after 1 h (modified neurological severity score (mNSS). Changes in CBF were assessed 2 h post-injury above the exposed cortex using laser speckle contrast imaging in response to the direct application of increasing concentrations of vehicle or SB (1, 10, and 100 µM) to the brain surface. TBI increased mNSS scores compared to baseline and confirmed mild TBI (mTBI) severity. CBF was significantly impaired on the ipsilateral side of the brain following mTBI, compared to contralateral side and to sham rats. SB dose-dependently improved CBF on the ipsilateral side after mTBI compared to SB effects on the respective ipsilateral side of sham rats but had no effect on contralateral CBF or in uninjured rats. N/OFQ levels increased in the cerebral spinal fluid (CSF) following mTBI, which correlated with the percent decrease in ipsilateral CBF. TBI also activated ERK and cofilin within 3 h post-TBI; ERK activation correlated with increased CSF N/OFQ. In conclusion, this study reveals a significant contribution of the N/OFQ-NOP receptor system to TBI-induced dysregulation of cerebral vasculature and suggests that the NOP receptor should be considered as a potential therapeutic target for TBI.

Cellular and molecular mechanisms in vascular repair after traumatic brain injury: a narrative review

Traumatic brain injury (TBI) disrupts normal brain function and is associated with high morbidity and fatality rates. TBI is characterized as mild, moderate or severe depending on its severity. The damage may be transient and limited to the dura matter, with only subtle changes in cerebral parenchyma, or life-threatening with obvious focal contusions, hematomas and edema. Blood vessels are often injured in TBI. Even in mild TBI, dysfunctional cerebral vascular repair may result in prolonged symptoms and poor outcomes. Various distinct types of cells participate in vascular repair after TBI. A better understanding of the cellular response and function in vascular repair can facilitate the development of new therapeutic strategies. In this review, we analyzed the mechanism of cerebrovascular impairment and the repercussions following various forms of TBI. We then discussed the role of distinct cell types in the repair of meningeal and parenchyma vasculature following TBI, including endothelial cells, endothelial progenitor cells, pericytes, glial cells (astrocytes and microglia), neurons, myeloid cells (macrophages and monocytes) and meningeal lymphatic endothelial cells. Finally, possible treatment techniques targeting these unique cell types for vascular repair after TBI are discussed.

Treatment during cerebral vasospasm phase-complication association and outcome in aneurysmal subarachnoid haemorrhage

Background

Aneurysm treatment during cerebral vasospasm (CVS) phase is frequently considered as particularly dangerous, mainly because of the risk of cerebral infarct.

Objective

We aimed to evaluate the risk of aneurysmal subarachnoid haemorrhage (aSAH)-specific complications and functional outcome in patients treated during CVS phase.

Methods

We retrospectively analysed a large, retro- and prospectively collected database of aSAH patients admitted to our department between March 2006 and March 2020. We conducted a uni- and multivariable logistic regression analysis to evaluate influencing factors on rebleeding, cerebral infarct, Glasgow Outcome Score (GOS) at discharge and mortality and assessed the rate of angiographic vasospasm on admission.

Results

We included 853 patients. The majority of patients were female (66.6%), mean age was 57.3 years. Out of 853 included patients, 92 (10.8%) were treated during CVS phase, 312 (36.6%) underwent clipping and 541 (63.4%) endovascular treatment. Treatment during CVS phase was significantly associated with cerebral infarct in the multivariable logistic regression analysis, unrelated to the nature of intervention (OR 2.42, 1.29–4.54 95% CI p-value = 0.006). However, patients treated during CVS phase did not have increased risk of unfavourable outcome by GOS on discharge. In addition, they did not have a higher rate of rebleeding or mortality.

Conclusions

Treatment during CVS phase was significantly associated with a higher rate of cerebral infarct as confirmed by imaging. This did not reflect on GOS on discharge, rebleeding, or mortality. Aneurysm treatment during CVS phase is relatively safe and should not be postponed due to the risk of rebleeding and subsequent devastating deterioration.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11212-w.

Case report: Delayed posttraumatic cortical laminar necrosis secondary to spreading depolarization induced spreading ischemia from old subarachnoid hemorrhage

Cortical laminar necrosis usually occurs secondary to infarcts or hypoxia, however other causes, including hypoglycemia, status epilepticus and immunosuppressive therapy have been reported. To our knowledge, CLN is not a phenomenon expected in the case of trauma. We report a unique case of delayed post-traumatic CLN which occurred 30 days after the initial trauma, without any proven cause apart from possible spreading depolarization induced spreading ischemia from adjacent subarachnoid hemorrhage with distinct radiologic features.

Admission rate-pressure product as an early predictor for in-hospital mortality after aneurysmal subarachnoid hemorrhage

Early prediction of in-hospital mortality in aneurysmal subarachnoid hemorrhage (aSAH) is essential for the optimal management of these patients. Recently, a retrospective cohort observation has reported that the rate-pressure product (RPP, the product of systolic blood pressure and heart rate), an objective and easily calculated bedside index of cardiac hemodynamics, was predictively associated with in-hospital mortality following traumatic brain injury. We thus wondered whether this finding could also be generalized to aSAH patients. The current study aimed to examine the association of RPP at the time of emergency room (ER) admission with in-hospital mortality and its predictive performance among aSAH patients. We retrospectively included 515 aSAH patients who had been admitted to our ER between 2016 and 2020. Their baseline heart rate and systolic blood pressure at ER presentation were extracted for the calculation of the admission RPP. Meanwhile, we collected relevant clinical, laboratory, and neuroimaging data. Then, these data including the admission RPP were examined by univariate and multivariate analyses to identify independent predictors of hospital mortality. Eventually, continuous and ordinal variables were selected from those independent predictors, and the performance of these selected predictors was further evaluated and compared based on receiver operating characteristic (ROC) curve analyzes. We identified both low (< 10,000; adjusted odds ratio (OR) 3.49, 95% CI 1.93-6.29, p < 0.001) and high (> 15,000; adjusted OR 8.42, 95% CI 4.16-17.06, p < 0.001) RPP on ER admission to be independently associated with in-hospital mortality after aSAH. Furthermore, after centering the admission RPP by its median, the area under its ROC curve (0.761, 95% CI 0.722-0.798, p < 0.001) was found to be statistically superior to any of the other independent predictors included in the ROC analyzes (all p < 0.01). In light of the predictive superiority of the admission RPP, as well as its objectivity and easy accessibility, it is indeed a potentially more applicable predictor for in-hospital death in aSAH patients.

Vitamin D as a modifiable risk factor, predictor, and theoretical therapeutic agent for vasospasm in spontaneous subarachnoid hemorrhage

Delayed deterioration associated with cerebral vasospasm (CVS) is a feared complication after spontaneous subarachnoid hemorrhage (SAH) and is one of the leading causes of death in patients with intracranial hemorrhage. The pathophysiology of vasospasm is complex and not fully understood, involving multiple inflammatory pathways in addition to vasoconstriction induced ischemia. Current treatment with anti-inflammatory or vasodilatory medications has been met with limited success and has not led to a decrease in vasospastic associated mortality prompting continued investigation of potential treatment options. The active form of vitamin D, 1,25-dihydroxyvitamin D₃ (1,25-VitD3), is a hormone with downstream effects that induce anti-inflammatory pathways, promote nitric oxide (NO) induced vasodilation, and lead to neuroprotective-gene expression, which may be useful in mitigating the vascular pathogenesis associated with CVS. A high prevalence of vitamin D deficiency has been identified in patients admitted with SAH. Low vitamin D levels in patients, as determined by time of year, has also been correlated to an increased incidence and severity of CVS. Further, the therapeutic usefulness of 1,25-VitD3 has been demonstrated in animal models leading to a decreased incidence of CVS but has yet to be thoroughly investigated in human studies. In this review, we will discuss the findings that suggest the potential of utilizing vitamin D as a predictive indicator, method of prevention, and or treatment option for CVS in patients following spontaneous SAH.

Decreased Superoxide Dismutase Concentrations (SOD) in Plasma and CSF and Increased Circulating Total Antioxidant Capacity (TAC) Are Associated with Unfavorable Neurological Outcome after Aneurysmal Subarachnoid Hemorrhage

Background: Subarachnoid hemorrhage (SAH) is a devastating disease with high morbidity and mortality. Hypoxia-induced changes and hemoglobin accumulation within the subarachnoid space are thought to lead to oxidative stress, early brain injury, and delayed vasospasm. This study aimed to evaluate the antioxidant status and its impact on neurological outcome in patients with aneurysmal SAH. Methods: In this prospective observational study, 29 patients with aneurysmal SAH were included (mean age 54.7 ± 12.4). Blood and cerebrospinal fluid (CSF) samples were collected on days (d) 1, 3, and 7. In addition, 29 patients without intracranial hemorrhage served as controls. The antioxidant system was analyzed by glutathione peroxidase (GSH-Px; U/L) and total and free glutathione-sulfhydryl (GSH; mg/L) in the plasma. Superoxide dismutase (SOD, U/mL) and total antioxidant capacity (TAC, µmol/L) were measured in the serum and CSF. Clinical data were compiled on admission (Hunt and Hess grade, Fisher grade, and GCS). Neurological and cognitive outcome (modified Rankin scale (mRS), Glasgow Outcome Scale Extended (GOSE) and Montreal Cognitive Assessment (MoCA)) was assessed after 6 weeks (6 w) and 6 months (6 m). Results: Plasma levels of SOD increased from day 1 to 7 after SAH (d1: 1.22 ± 0.36 U/L; d3: 1.25 ± 0.33 U/L, p = 0.99; d7: 1.52 ± 0.4 U/L, p = 0.019) and were significantly higher compared to controls (1.11 ± 0.27 U/L) at day 7 (p < 0.001). Concordantly, CSF levels of SOD increased from day 1 to 7 after SAH (d1: 1.22 ± 0.41 U/L; d3: 1.77 ± 0.73 U/L, p = 0.10; d7: 2.37 ± 1.29 U/L, p < 0.0001) without becoming significantly different compared to controls (1.74 ± 0.8 U/L, p = 0.09). Mean plasma TAC at day 1 (d1: 77.87 ± 49.72 µmol/L) was not statistically different compared to controls (46.74 ± 32.42 µmol/L, p = 0.25). TAC remained unchanged from day 1 to 7 (d3: 92.64 ± 68.58 µmol/L, p = 0.86; d7: 74.07 ± 54.95 µmol/L, p = 0.8) in plasma. TAC in CSF steeply declined from day 1 to 7 in patients with SAH becoming significantly different from controls at days 3 and 7 (d3: 177.3 ± 108.7 µmol/L, p = 0.0046; d7: 85.35 ± 103.9 µmol/L, p < 0.0001). Decreased SOD levels in plasma and CSF are associated with a worse neurological outcome 6 weeks (mRS: CSF p = 0.0001; plasma p = 0.027/GOSE: CSF p = 0.001; plasma p = 0.001) and 6 months (mRS: CSF p = 0.001; plasma p = 0.09/GOSE: CSF p = 0.001; plasma p = 0.001) after SAH. Increased plasma TAC correlated with a worse neurological outcome 6 weeks (mRS: p = 0.001/GOSE p = 0.001) and 6 months (mRS p = 0.001/GOSE p = 0.001) after SAH. Conclusion: In our study, a reduction in the antioxidative enzyme SOD and elevated TAC were associated with a poorer neurological outcome reflected by mRS and GOSE at 6 weeks and 6 months after SAH. A lower initial SOD CSF concentration was associated with the late deterioration of cognitive ability. These findings support the mounting evidence of the role of oxidative stress in early brain injury formation and unfavorable outcome after SAH.

Translational Genomics in Neurocritical Care: a Review

Translational genomics represents a broad field of study that combines genome and transcriptome-wide studies in humans and model systems to refine our understanding of human biology and ultimately identify new ways to treat and prevent disease. The approaches to translational genomics can be broadly grouped into two methodologies, forward and reverse genomic translation. Traditional (forward) genomic translation begins with model systems and aims at using unbiased genetic associations in these models to derive insight into biological mechanisms that may also be relevant in human disease. Reverse genomic translation begins with observations made through human genomic studies and refines these observations through follow-up studies using model systems. The ultimate goal of these approaches is to clarify intervenable processes as targets for therapeutic development. In this review, we describe some of the approaches being taken to apply translational genomics to the study of diseases commonly encountered in the neurocritical care setting, including hemorrhagic and ischemic stroke, traumatic brain injury, subarachnoid hemorrhage, and status epilepticus, utilizing both forward and reverse genomic translational techniques. Further, we highlight approaches in the field that could be applied in neurocritical care to improve our ability to identify new treatment modalities as well as to provide important information to patients about risk and prognosis.

A Comparison of Pathophysiology in Humans and Rodent Models of Subarachnoid Hemorrhage

Non-traumatic subarachnoid hemorrhage (SAH) affects an estimated 30,000 people each year in the United States, with an overall mortality of ~30%. Most cases of SAH result from a ruptured intracranial aneurysm, require long hospital stays, and result in significant disability and high fatality. Early brain injury (EBI) and delayed cerebral vasospasm (CV) have been implicated as leading causes of morbidity and mortality in these patients, necessitating intense focus on developing preclinical animal models that replicate clinical SAH complete with delayed CV. Despite the variety of animal models currently available, translation of findings from rodent models to clinical trials has proven especially difficult. While the explanation for this lack of translation is unclear, possibilities include the lack of standardized practices and poor replication of human pathophysiology, such as delayed cerebral vasospasm and ischemia, in rodent models of SAH. In this review, we summarize the different approaches to simulating SAH in rodents, in particular elucidating the key pathophysiology of the various methods and models. Ultimately, we suggest the development of standardized model of rodent SAH that better replicates human pathophysiology for moving forward with translational research.

Pathophysiological and behavioral deficits in developing mice following rotational acceleration-deceleration traumatic brain injury

Abusive head trauma (AHT) is the leading cause of death from trauma in infants and young children. An AHT animal model was developed on 12-day-old mice subjected to 90° head extension-flexion sagittal shaking repeated 30, 60, 80 and 100 times. The mortality and time until return of consciousness were dependent on the number of repeats and severity of the injury. Following 60 episodes of repeated head shakings, the pups demonstrated apnea and/or bradycardia immediately after injury. Acute oxygen desaturation was observed by pulse oximetry during respiratory and cardiac suppression. The cerebral blood perfusion was assessed by laser speckle contrast analysis (LASCA) using a PeriCam PSI system. There was a severe reduction in cerebral blood perfusion immediately after the trauma that did not significantly improve within 24 h. The injured mice began to experience reversible sensorimotor function at 9 days postinjury (dpi), which had completely recovered at 28 dpi. However, cognitive deficits and anxiety-like behavior remained. Subdural/subarachnoid hemorrhage, damage to the brain-blood barrier and parenchymal edema were found in all pups subjected to 60 insults. Proinflammatory response and reactive gliosis were upregulated at 3 dpi. Degenerated neurons were found in the cerebral cortex and olfactory tubercles at 30 dpi. This mouse model of repetitive brain injury by rotational head acceleration-deceleration partially mimics the major pathophysiological and behavioral events that occur in children with AHT. The resultant hypoxia/ischemia suggests a potential mechanism underlying the secondary rotational acceleration-deceleration-induced brain injury in developing mice.

Traumatic brain injury and intracranial hemorrhage–induced cerebral vasospasm: a systematic review

OBJECTIVE

Little is known regarding the natural history of posttraumatic vasospasm. The authors review the pathophysiology of posttraumatic vasospasm (PTV), its associated risk factors, the efficacy of the technologies used to detect PTV, and the management/treatment options available today.

METHODS

The authors performed a systematic review in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the following databases: PubMed, Google Scholar, and CENTRAL (the Cochrane Central Register of Controlled Trials). Outcome variables extracted from each study included epidemiology, pathophysiology, time course, predictors of PTV and delayed cerebral ischemia (DCI), optimal means of surveillance and evaluation of PTV, application of multimodality monitoring, modern management and treatment options, and patient outcomes after PTV. Study types were limited to retrospective chart reviews, database reviews, and prospective studies.

RESULTS

A total of 40 articles were included in the systematic review. In many cases of mild or moderate traumatic brain injury (TBI), imaging or ultrasonographic studies are not performed. The lack of widespread assessment makes finding the true overall incidence of PTV a difficult endeavor. The clinical consequences of PTV are important, given the morbidity that can result from it. DCI manifests as new-onset neurological deterioration that occurs beyond the timeframe of initial brain injury. While there are many techniques that attempt to diagnose cerebral vasospasm, digital subtraction angiography is the gold standard. Some predictors of PTV include SAH, intraventricular hemorrhage, low admission Glasgow Coma Scale (GCS) score (< 9), and young age (< 30 years).

CONCLUSIONS

Given these results, clinicians should suspect PTV in young patients presenting with intracranial hemorrhage (ICH), especially SAH and/or intraventricular hemorrhage, who present with a GCS score less than 9. Monitoring and regulation of CNS metabolism following TBI/ICH-induced vasospasm may play an important adjunct role to the primary prevention of vasospasm.

Response of the cerebral vasculature following traumatic brain injury

The critical role of the vasculature and its repair in neurological disease states is beginning to emerge particularly for stroke, dementia, epilepsy, Parkinson's disease, tumors and others. However, little attention has been focused on how the cerebral vasculature responds following traumatic brain injury (TBI). TBI often results in significant injury to the vasculature in the brain with subsequent cerebral hypoperfusion, ischemia, hypoxia, hemorrhage, blood-brain barrier disruption and edema. The sequalae that follow TBI result in neurological dysfunction across a host of physiological and psychological domains. Given the importance of restoring vascular function after injury, emerging research has focused on understanding the vascular response after TBI and the key cellular and molecular components of vascular repair. A more complete understanding of vascular repair mechanisms are needed and could lead to development of new vasculogenic therapies, not only for TBI but potentially vascular-related brain injuries. In this review, we delineate the vascular effects of TBI, its temporal response to injury and putative biomarkers for arterial and venous repair in TBI. We highlight several molecular pathways that may play a significant role in vascular repair after brain injury.

The cerebral basal arterial network: morphometry of inflow and outflow components

The aim of this project was to study how the morphology of the incoming and outgoing arterial components of the cerebral basal arterial network influence the blood flow to the brain. The cerebral basal arterial network consists of the circulus arteriosus cerebri anteriorly and the basilar artery posteriorly. Diameters of inflow vessels (bilateral vertebral and internal carotid arteries), connecting vessels (anterior communicating, basilar and bilateral posterior communicating arteries) and outflow vessels (anterior, middle and posterior cerebral arteries) were measured and cross-sectional areas calculated in 51 cadaveric brain specimens. The individual and the average cross-sectional areas of inflow arteries (51.43 mm² ) were significantly bigger than the major outflow arteries (37.76 mm² ) but smaller than the combined cross-sectional areas of outflow (37.76 mm² ) and connecting (25.33 mm² ) arteries. The difference in the size of arterial cross-sectional area and the presence of the connecting arteries in the cerebral basal arterial network provides a mechanism for lowering peaks in pressure, and demonstrates a function of the cerebral basal arterial network.

Management of aneurysmal subarachnoid hemorrhage: State of the art and future perspectives

Background:

Aneurysmal subarachnoid hemorrhage (SAH) accounts for 5% of strokes and carries a poor prognosis. It affects around 6 cases per 100,000 patient years occurring at a relatively young age.

Methods:

Common risk factors are the same as for stroke, and only in a minority of the cases, genetic factors can be found. The overall mortality ranges from 32% to 67%, with 10–20% of patients with long-term dependence due to brain damage. An explosive headache is the most common reported symptom, although a wide spectrum of clinical disturbances can be the presenting symptoms. Brain computed tomography (CT) allow the diagnosis of SAH. The subsequent CT angiography (CTA) or digital subtraction angiography (DSA) can detect vascular malformations such as aneurysms. Non-aneurysmal SAH is observed in 10% of the cases. In patients surviving the initial aneurysmal bleeding, re-hemorrhage and acute hydrocephalus can affect the prognosis.

Results:

Although occlusion of an aneurysm by surgical clipping or endovascular procedure effectively prevents rebleeding, cerebral vasospasm and the resulting cerebral ischemia occurring after SAH are still responsible for the considerable morbidity and mortality related to such a pathology. A significant amount of experimental and clinical research has been conducted to find ways in preventing these complications without sound results.

Conclusions:

Even though no single pharmacological agent or treatment protocol has been identified, the main therapeutic interventions remain ineffective and limited to the manipulation of systemic blood pressure, alteration of blood volume or viscosity, and control of arterial dioxide tension.

Cerebrovascular endothelial dysfunction induced by mercury exposure at low concentrations

Mercury (Hg) has many harmful vascular effects by increasing oxidative stress, inflammation and vascular/endothelial dysfunction, all of which may contribute to cerebrovascular diseases development. We aimed to explore the effects of chronic low-mercury concentration on vascular function in cerebral arteries and the mechanisms involved. Basilar arteries from control (vehicle-saline solution, im) and mercury chloride (HgCl2)-treated rats for 30 days (first dose 4.6μg/kg, subsequent dose 0.07μg/kg/day, im, to cover daily loss) were used. Vascular reactivity, protein expression, nitric oxide (NO) levels and superoxide anion (O2(-)) production were analyzed. HgCl2 exposure increased serotonin contraction and reduced the endothelium-dependent vasodilatation to bradykinin. After NO synthase inhibition, serotonin responses were enhanced more in control than in mercury-treated rats while bradykinin-induced relaxation was abolished. NO levels were greater in control than Hg-treated rats. Tiron and indomethacin reduced vasoconstriction and increased the bradykinin-induced relaxation only in HgCl2-treated rats. Vascular O2(-) production was greater in mercury-treated when compared to control rats. Protein expressions of endothelial NO synthase, copper/zinc (Cu/Zn), Manganese (Mn) and extracellular-superoxide dismutases were similar in cerebral arteries from both groups. Results suggest that Hg treatment increases cerebrovascular reactivity by reducing endothelial negative modulation and NO bioavailability; this effect seems to be dependent on increased reactive oxygen species and prostanoids generation. These findings show, for the first time, that brain vasculature are also affected by chronic mercury exposure and offer further evidence that even at small concentration, HgCl2 is hazardous and might be an environmental risk factor accounting for cerebral vasospasm development.

Ultrasound guided double injection of blood into cisterna magna: a rabbit model for treatment of cerebral vasospasm

Background

Double injection of blood into cisterna magna using a rabbit model results in cerebral vasospasm. An unacceptably high mortality rate tends to limit the application of model. Ultrasound guided puncture can provide real-time imaging guidance for operation. The aim of this paper is to establish a safe and effective rabbit model of cerebral vasospasm after subarachnoid hemorrhage with the assistance of ultrasound medical imaging.

Methods

A total of 160 New Zealand white rabbits were randomly divided into four groups of 40 each: (1) manual control group, (2) manual model group, (3) ultrasound guided control group, and (4) ultrasound guided model group. The subarachnoid hemorrhage was intentionally caused by double injection of blood into their cisterna magna. Then, basilar artery diameters were measured using magnetic resonance angiography before modeling and 5 days after modeling.

Results

The depth of needle entering into cisterna magna was determined during the process of ultrasound guided puncture. The mortality rates in manual control group and model group were 15 and 23 %, respectively. No rabbits were sacrificed in those two ultrasound guided groups. We found that the mortality rate in ultrasound guided groups decreased significantly compared to manual groups. Compared with diameters before modeling, the basilar artery diameters after modeling were significantly lower in manual and ultrasound guided model groups. The vasospasm aggravated and the proportion of severe vasospasms was greater in ultrasound guided model group than that of manual group. In manual model group, no vasospasm was found in 8 % of rabbits.

Conclusions

The ultrasound guided double injection of blood into cisterna magna is a safe and effective rabbit model for treatment of cerebral vasospasm.

The immune system in traumatic brain injury

Traumatic brain injury (TBI) is the major cause of death in children and young adults and one of the major reasons for long-term disability worldwide, however, no specific clinical treatment option could be established so far. This is surprising since it is well known that following the initial mechanical damage to the brain a plethora of delayed processes are activated which ultimately result in additional brain damage. Among these secondary mechanisms, acute and chronic activation of the innate and adaptive immune system is increasingly believed to play an important role for the pathogenesis of TBI. Understanding these processes may results in new, clinically applicable therapeutic options for TBI patients.

Posttraumatic cerebral infarction in severe traumatic brain injury: characteristics, risk factors and potential mechanisms

BACKGROUND

Posttraumatic cerebral infarction (PTCI) is a severe secondary insult of traumatic brain injury (TBI). This study aimed to evaluate the characteristics and risk factors of PTCI after severe TBI (sTBI) and explore possible mechanism.

METHODS

This retrospective study included a cohort of 339 patients with sTBI; they were divided into the PTCI and non-PTCI groups. Clinical data and follow-up charts were reviewed for comparison. The logistic regression model was used for multivariate analysis to detect the risk factors of PTCI. The Glasgow Outcome Scale (GOS) and Barthel index (BI) for activities of daily living (ADL) were applied to evaluate their outcome.

RESULTS

PTCI led to an increased mortality (43.5 % vs. 10.7 %, P < 0.001) and days of intensive care unit stay (14.3 days vs. 7.1 days, P < 0.001), decreased GOS (3.1 vs. 4.1, P < 0.001) and BI (25.0 vs. 77.9, P < 0.001). Increased infarction volume led to poor outcome assessed by GOS (r = -0.46, P < 0.0001) and BI for ADL (r = -0.36, P = 0.026) for surviving patients. Compared with non-PTCI patients, PTCI patients had a high incidence of midline shift (36.2 % vs. 20.7 %, P = 0.011) and posttraumatic vasospasm (PTV) (42.0 % vs. 27.4 %, P = 0.027). Daily prevalence of PTCI occurred in two peaks: one (73.9 %) was in the first 24 h after injury, while the other (18.8 %) was in the span of 43 to 60 h postinjury. In multivariate analysis, hyperthermia [adjusted odds ratio (OR), 3.11; P = 0.001] in the first 24 h, thrombocytopenia (OR, 27.08; P < 0.001), abnormal prothrombin time (OR, 7.66; P < 0.001) and traumatic subarachnoid hemorrhage (OR, 2.33; P = 0.022) were independent predictors for PTCI.

CONCLUSIONS

PTCI deteriorates the outcome of sTBI patients. Mechanical compression and hemocoagulative disturbance serve as potential mechanisms mediating this pathophysiological process. PTV may also contribute to PTCI, but its association with PTCI is weak and needs further exploration. Early recognition and intervention of these factors might be beneficial for preventing PTCI.

Role of Microvascular Disruption in Brain Damage from Traumatic Brain Injury

Traumatic brain injury (TBI) is acquired from an external force, which can inflict devastating effects to the brain vasculature and neighboring neuronal cells. Disruption of vasculature is a primary effect that can lead to a host of secondary injury cascades. The primary effects of TBI are rapidly occurring while secondary effects can be activated at later time points and may be more amenable to targeting. Primary effects of TBI include diffuse axonal shearing, changes in blood-brain barrier (BBB) permeability, and brain contusions. These mechanical events, especially changes to the BBB, can induce calcium perturbations within brain cells producing secondary effects, which include cellular stress, inflammation, and apoptosis. These secondary effects can be potentially targeted to preserve the tissue surviving the initial impact of TBI. In the past, TBI research had focused on neurons without any regard for glial cells and the cerebrovasculature. Now a greater emphasis is being placed on the vasculature and the neurovascular unit following TBI. A paradigm shift in the importance of the vascular response to injury has opened new avenues of drug-treatment strategies for TBI. However, a connection between the vascular response to TBI and the development of chronic disease has yet to be elucidated. Long-term cognitive deficits are common amongst those sustaining severe or multiple mild TBIs. Understanding the mechanisms of cellular responses following TBI is important to prevent the development of neuropsychiatric symptoms. With appropriate intervention following TBI, the vascular network can perhaps be maintained and the cellular repair process possibly improved to aid in the recovery of cellular homeostasis.