Factors affecting resolution of oculomotor nerve palsy following endovascular embolization of posterior communicating artery aneurysms.

PURPOSE: To investigate the effect of endovascular embolization of posterior communicating artery (Pcom) aneurysms on concomitant oculomotor nerve palsy (OMNP) and factors affecting the effect of treatment. MATERIALS AND METHODS: Patients with the Pcom aneurysms concomitant with OMNP were retrospectively enrolled for endovascular treatment of the aneurysms. All patients had the endovascular management. The clinical effect, degree of OMNP, size of the aneurysm, type of treatment, subarachnoid hemorrhage (SAH), and time from onset to treatment were analyzed on the resolution of OMNP. RESULTS: Ninety-six patients with 99 Pcom aneurysms were enrolled and treated endovascularly, with the success rate of 100%. Immediately after endovascular treatment, 75 aneurysms (75.75%) got complete occlusion, and 24 (24.24%) nearly complete occlusion. Followed up for 3-18 (mean 8.52±0.56) months, complete resolution of the OMNP was achieved in 63 patients (65.63%), partial resolution in 21 (21.88%), and non-recovery in the other 12 (12.50%). The degree of OMNP at onset, SAH, and time from onset to treatment were significantly (P<0.05) correlated with the resolution of OMNP. Univariate analysis revealed that younger age of the patient, degree of OMNP at onset, presence of subarachnoid hemorrhage, and time from disease onset to treatment were significantly (P<0.05) associated with the recovery of OMNP. Multivariate analysis revealed that the younger age, degree of OMNP at onset, and time from disease onset to treatment were significantly (P<0.05) associated with the recovery of OMNP. CONCLUSION: Endovascular embolization of Pcom aneurysms concomitant with OMNP can effectively improve the OMNP symptoms, especially for patients with moderate and a shorter history of OMNP. Younger age, degree of oculomotor nerve palsy at onset, and time from onset to treatment may significantly affect recovery of oculomotor nerve palsy.

Dual-Energy Computed Tomography in the Evaluation and Management of Subarachnoid Hemorrhage, Intracranial Hemorrhage, and Acute Ischemic Stroke.

Dual-energy computed tomography (DECT) has emerged as a valuable imaging modality in the diagnosis and management of various cerebrovascular pathologies, including subarachnoid hemorrhage, intracranial hemorrhage, and acute ischemic stroke. This article reviews the principles of DECT and its applications in the evaluation and management of these conditions. The authors discuss the advantages of DECT over conventional computed tomography, as well as its limitations, and provide an overview of current research and future directions in the field.

Chemical angioplasty vs. balloon plus chemical angioplasty for delayed cerebral ischemia: a pilot study of PbtO2 outcomes.

BACKGROUND: Delayed cerebral ischaemia (DCI) is a major cause of morbidity and mortality after aneurysmal subarachnoid haemorrhage (aSAH). Chemical angioplasty (CA) and transluminal balloon angioplasty (TBA) are used to treat patients with refractory vasospasm causing DCI. Multi-modal monitoring including brain tissue oxygenation (PbtO2) is routinely used at this centre for early detection and management of DCI following aSAH. In this single-centre pilot study, we are comparing these two treatment modalities and their effects on PbtO2. METHODS: Retrospective case series of patients with DCI who had PbtO2 monitoring as part of their multimodality monitoring and underwent either CA or TBA combined with CA. PbtO2 values were recorded from intra-parenchymal Raumedic NEUROVENT-PTO® probes. Data were continuously collected and downloaded as second-by-second data. Comparisons were made between pre-angioplasty PbtO2 and post-angioplasty PbtO2 median values (4 h before angioplasty, 4 h after and 12 h after). RESULTS: There were immediate significant improvements in PbtO2 at the start of intervention in both groups. PbtO2 then increased by 13 mmHg in the CA group and 15 mmHg in the TBA plus CA group in the first 4 h post-intervention. This improvement in PbtO2 was sustained for the TBA plus CA group but not the CA group. CONCLUSION: Combined balloon plus chemical angioplasty results in more sustained improvement in brain tissue oxygenation compared with chemical angioplasty alone. Our findings suggest that PbtO2 is a useful tool for monitoring the response to angioplasty in vasospasm.

[Management of SAH]. / Prise en charge de la HSA.

Every year, the neurosurgical intensive care unit at Grenoble's university hospital (CHU) receives a large number of cerebrovascular patients. Data collected in the department during 2023 show that subarachnoid hemorrhage (SAH) is one of the most frequent causes of the pathologies treated. In this article, we focus on the appropriate course of action.

Trends in incidence and treatments of spontaneous subarachnoid hemorrhage- a 10 year hospital based study.

BACKGROUND: Improved endovascular methods make it possible to treat complex ruptured aneurysms, but surgery is still needed in certain cases. We evaluated the effects on the clinical results of the changes in aneurysm treatment. METHODS: The study cohort was 837 patients with spontaneous subarachnoid hemorrhage (SAH) and one or multiple aneurysms, admitted to Dept of Neurosurgery, Uppsala University Hospital from 2012 to 2021. Demography, location and treatment of aneurysms, neurologic condition at admission and discharge, mortality and last tier treatment of high intracranial pressure (ICP) was evaluated. Functional outcome was measured using the Extended Glasgow Outcome Scale (GOSE) Data concerning national incidences of stroke diseases was collected from open Swedish databases. RESULTS: Endovascular methods were used in 666 cases (79.6%). In 111 (13.3%) with stents. Surgery was performed in 115 cases (13.7%) and 56 patients (6.7%) had no aneurysm treatment. The indications for surgery were a hematoma (51 cases, 44.3%), endovascular treatment not considered safe (47 cases, 40.9%), or had been attempted without success (13 cases, 11.3%). Treatment with stent devices increased, and with surgery decreased over time. There was a trend in decrease in hemicraniectomias over time. Both the patient group admitted awake (n = 681) and unconscious (n = 156) improved significantly in consciousness between admission and discharge. Favorable outcome (GOSE 5-8) was seen in 69% for patients admitted in Hunt & Hess I-II and 25% for Hunt & Hess III-V. Mortality at one year was 10.9% and 42.7% for those admitted awake and unconscious, respectively.The number of cases decreased during the study period, which was in line with Swedish national data. CONCLUSIONS: The incidence of patients with SAH gradually decreased in our material, in line with national data. The treatment policy in our unit has been shifting to more use of endovascular methods. During the study period the use of hemicraniectomies decreased.

Explainable machine learning in outcome prediction of high-grade aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Accurate prognostic prediction in patients with high-grade aneruysmal subarachnoid hemorrhage (aSAH) is essential for personalized treatment. In this study, we developed an interpretable prognostic machine learning model for high-grade aSAH patients using SHapley Additive exPlanations (SHAP). METHODS: A prospective registry cohort of high-grade aSAH patients was collected in one single-center hospital. The endpoint in our study is a 12-month follow-up outcome. The dataset was divided into training and validation sets in a 7:3 ratio. Machine learning algorithms, including Logistic regression model (LR), support vector machine (SVM), random forest (RF), and extreme gradient boosting (XGBoost), were employed to develop a prognostic prediction model for high-grade aSAH. The optimal model was selected for SHAP analysis. RESULTS: Among the 421 patients, 204 (48.5%) exhibited poor prognosis. The RF model demonstrated superior performance compared to LR (AUC = 0.850, 95% CI: 0.783-0.918), SVM (AUC = 0.862, 95% CI: 0.799-0.926), and XGBoost (AUC = 0.850, 95% CI: 0.783-0.917) with an AUC of 0.867 (95% CI: 0.806-0 .929). Primary prognostic features identified through SHAP analysis included higher World Federation of Neurosurgical Societies (WFNS) grade, higher modified Fisher score (mFS) and advanced age, were found to be associated with 12-month unfavorable outcome, while the treatment of coiling embolization for aSAH drove the prediction towards favorable prognosis. Additionally, the SHAP force plot visualized individual prognosis predictions. CONCLUSIONS: This study demonstrated the potential of machine learning techniques in prognostic prediction for high-grade aSAH patients. The features identified through SHAP analysis enhance model interpretability and provide guidance for clinical decision-making.

Brain metabolism response to intrahospital transfers in neurocritical ill patients and the impact of microdialysis probe location.

Intrahospital transfer (IHT), a routine in the management of neurocritical patients requiring imaging or interventions, might affect brain metabolism. Studies about IHT effects using microdialysis (MD) have produced conflicting results. In these studies, only the most damaged hemisphere was monitored, and those may not reflect the impact of IHT on overall brain metabolism, nor do they address differences between the hemispheres. Herein we aimed to quantify the effect of IHT on brain metabolism by monitoring both hemispheres with bilateral MD. In this study, 27 patients with severe brain injury (10 traumatic brain injury and 17 subarachnoid hemorrhage patients) were included, with a total of 67 IHT. Glucose, glycerol, pyruvate and lactate were measured by MD in both hemispheres for 10 h pre- and post-IHT. Alterations in metabolite levels after IHT were observed on both hemispheres; although these changes were more marked in hemisphere A (most damaged) than B (less damaged). Our results suggest that brain metabolism is altered after an IHT of neurocritical ill patients particularly but not limited to the damaged hemisphere. Bilateral monitorization may be more sensitive than unilateral monitorization for detecting metabolic disturbances not directly related to the course of the disease.

An assistive listening device improves hearing following aneurysmal subarachnoid haemorrhage.

BACKGROUND AND PURPOSE: Hearing impairment is common following aneurysmal subarachnoid haemorrhage (aSAH). Previous studies have demonstrated that auditory processing disorder (APD) is the primary underlying pathology. Assistive listening devices (ALDs) can be used to manage APD but have not been explored in aSAH. The aim of this study was to assess the benefit of an ALD for patients reporting hearing difficulty after aSAH. METHODS: This was a prospective pilot single-arm intervention study of an ALD for APD following aSAH. Patients who reported subjective hearing difficulty following aSAH were identified from the Wessex Neurological Centre aSAH database. Speech-in-noise was evaluated using the Bamford-Kowal-Bench (BKB) test under 60 and 65 dB noise conditions. BKB performance was compared with and without an ALD. Cognition was assessed using the Addenbrooke's Cognitive Examination-III. RESULTS: Fourteen aSAH patients with self-reported hearing loss were included in the analysis. Under both noise conditions the ALD significantly improved BKB performance (60 dB, Z = -3.30, p < 0.001; 65 dB, Z = -3.33, p < 0.001). There was no relationship between cognition and response to the ALD. CONCLUSIONS: This study demonstrates the marked benefit of ALDs to manage APD following aSAH, regardless of cognitive status. This finding has implications for the management of this common yet disabling deficit which impacts quality of life and employment. A further trial of ALDs in this patient group is needed to test whether these large, short-term benefits can be practically translated to the community for long-term benefit when used at home.

Secondary Ischemia Assessment in Murine and Rat Preclinical Subarachnoid Hemorrhage Models: A Systematic Review.

BACKGROUND: Delayed cerebral ischemia represents a significant contributor to death and disability following aneurysmal subarachnoid hemorrhage. Although preclinical models have shown promising results, clinical trials have consistently failed to replicate the success of therapeutic strategies. The lack of standardized experimental setups and outcome assessments, particularly regarding secondary vasospastic/ischemic events, may be partly responsible for the translational failure. The study aims to delineate the procedural characteristics and assessment modalities of secondary vasospastic and ischemic events, serving as surrogates for clinically relevant delayed cerebral ischemia, in recent rat and murine subarachnoid hemorrhage models. METHODS AND RESULTS: We conducted a systematic review of rat and murine in vivo subarachnoid hemorrhage studies (published: 2016-2020) using delayed cerebral ischemia/vasospasm as outcome parameters. Our analysis included 102 eligible studies. In murine studies (n=30), the endovascular perforation model was predominantly used, while rat studies primarily employed intracisternal blood injection to mimic subarachnoid hemorrhage. Particularly, the injection models exhibited considerable variation in injection volume, rate, and cerebrospinal fluid withdrawal. Peri-interventional monitoring was generally inadequately reported across all models, with body temperature and blood pressure being the most frequently documented parameters (62% and 34%, respectively). Vasospastic events were mainly assessed through microscopy of large cerebral arteries. In 90% of the rat and 86% of the murine studies, only male animals were used. CONCLUSIONS: Our study underscores the substantial heterogeneity in procedural characteristics and outcome assessments of experimental subarachnoid hemorrhage research. To address these challenges, drafting guidelines for standardization and ensuring rigorous control of methodological and experimental quality by funders and journals are essential. REGISTRATION: URL: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42022337279.

Twelve controversial questions in aneurysmal subarachnoid hemorrhage / Doce preguntas controvertidas en hemorragia subaracnoidea aneursmática

Critical care management of aneurysmal subarachnoid hemorrhage (aSAH) remains a major challenge. Despite the recent publication of guidelines from the American Heart Association/American Stroke Association and the Neurocritical Care Society, there are many controversial questions in the intensive care unit (ICU) management of this population. The authors provide an analysis of common issues in the ICU and provide guidance on the daily management of this specific population of neurocritical care patients. (AU)

El manejo en la unidad de cuidados intensivos (UCI) de los pacientes con hemorragia subaracnoidea aneurismática continua siendo un reto. A pesar de la publicación de las guías de la American Heart Association/American Stroke Association y la Neurocritical Care Society todavía existen muchos aspectos controvertidos en el manejo de esta población en la UCI. Los autores proporcionan un detenido análisis de los problemas habituales en la UCI y proporcionan recomendaciones en el manejo diario de esta población específica de pacientes neurocríticos. (AU)

Perioperative complications of arteriovenous tirofiban administration versus oral dual antiplatelet therapy for stent-assisted embolization treated aneurysmal subarachnoid hemorrhage: A retrospective, controlled cohort analysis.

BACKGROUND: Major perioperative complications of stent-assisted embolization treated for aneurysmal subarachnoid hemorrhage patients include the formation of thromboembolic events (TEs) and hemorrhagic events (HEs), for which antiplatelet protocols play a key role. METHODS: We conducted a single-center retrospective analysis to compare the differences between arteriovenous tirofiban administration with traditional oral dual antiplatelet therapy (DAPT). A total of 417 consecutive patients were enrolled. General clinical characteristics, as well as the perioperative ischemic and hemorrhagic events, were retracted in digital documents. Logistic regression was conducted to identify both risk and protective factors of perioperative TEs and HEs. RESULTS: Perioperative TEs occurred in 21 patients, with an overall perioperative TEs rate of approximately 5.04%; among these patients, the incidence of perioperative TEs in the tirofiban group was less than that in the DAPT group. Additionally, 66 patients developed perioperative HEs, with an incidence of approximately 15.83%; among these patients, the incidence of perioperative HEs was less than that in the DAPT group. No significant differences were seen between the two groups in terms of the mRS score at the time of discharge. CONCLUSION: This study indicated that an improved perioperative antiplatelet drug tirofiban was an independent protective factor for perioperative TEs in stent-assisted embolization of ruptured intracranial aneurysms, but it did not impart an elevated risk of perioperative HEs and had no significant effects on the near-term prognosis of the patients.

Diagnosis and management of subarachnoid haemorrhage.

Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. Advancements in computed tomography (CT), endovascular treatments, and neurocritical care have contributed to declining mortality rates. The critical care of aSAH prioritises cerebral perfusion, early aneurysm securement, and the prevention of secondary brain injury and systemic complications. Early interventions to mitigate cardiopulmonary complications, dyselectrolytemia and treatment of culprit aneurysm require a multidisciplinary approach. Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. Health care disparities, particularly in the resource allocation for SAH treatment, affect outcomes significantly, with telemedicine and novel technologies proposed to address this health inequalities. This article underscores the necessity for comprehensive multidisciplinary care and the urgent need for large-scale studies to validate standardised treatment protocols for improved SAH outcomes.

Subarachnoid Hemorrhage Trials: Cutting, Sliding, or Keeping mRS Scores and WFNS Grades.

Rigorous evidence generation with randomized controlled trials has lagged for aneurysmal subarachnoid hemorrhage (SAH) compared with other forms of acute stroke. Besides its lower incidence compared with other stroke subtypes, the presentation and outcome of patients with SAH also differ. This must be considered and adjusted for in designing pivotal randomized controlled trials of patients with SAH. Here, we show the effect of the unique expected distribution of the SAH severity at presentation (World Federation of Neurological Surgeons grade) on the outcome most used in pivotal stroke randomized controlled trials (modified Rankin Scale) and, consequently, on the sample size. Furthermore, we discuss the advantages and disadvantages of different options to analyze the outcome and control the expected distribution of the World Federation of Neurological Surgeons grades in addition to showing their effects on the sample size. Finally, we offer methods that investigators can adapt to more precisely understand the effect of common modified Rankin Scale analysis methods and trial eligibility pertaining to the World Federation of Neurological Surgeons grade in designing their large-scale SAH randomized controlled trials.

Neurological intervention transition model for dynamic prediction of good outcome in spontaneous subarachnoid haemorrhage.

Deterioration of neurovascular conditions can be rapid in patients with spontaneous subarachnoid haemorrhage (SAH) and often lead to poor clinical outcomes. Therefore, it is crucial to promptly assess and continually track the progression of the disease. This study incorporated baseline clinical conditions, repeatedly measured neurological grades and haematological biomarkers for dynamic outcome prediction in patients with spontaneous SAH. Neurological intervention, mainly aneurysm clipping and endovascular embolisation, was also incorporated as an intermediate event in developing a neurological intervention transition (NIT) joint model. A retrospective cohort study was performed on 701 patients in spontaneous SAH with a study period of 14 days from the MIMIC-IV dataset. A dynamic prognostic model predicting outcome of patients was developed based on combination of Cox model and piecewise linear mixed-effect models to incorporate different types of prognostic information. Clinical baseline covariates, including cerebral oedema, cerebral infarction, respiratory failure, hydrocephalus and vasospasm, as well as repeated measured Glasgow Coma Scale (GCS), glucose and white blood cell (WBC) levels were covariates contributing to the optimal model. Incorporation of neurological intervention as an intermediate event increases the prediction performance compared with baseline joint modelling approach. The average AUC of the optimal model proposed in this study is 0.7783 across different starting points of prediction and prediction intervals. The model proposed in this study can provide dynamic prognosis for spontaneous SAH patients and significant potential benefits in critical care management.

Non-aneurysmal subarachnoid hemorrhage in aplastic or twig-like middle cerebral artery: A case report and literature review.

BACKGROUND: Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare vascular anomaly that can cause hemorrhagic and ischemic stroke. Ap/T-MCA can induce aneurysms due to the fragility of the vessel wall, consequently leading to subarachnoid hemorrhage. Herein, we report a case of Ap/T-MCA with subarachnoid hemorrhage without an aneurysm. CASE PRESENTATION: A 67-year-old man presented to our hospital with a sudden onset of headache. Computed tomography of the head revealed subarachnoid hemorrhage (SAH) in the left Sylvian fissure; however, no aneurysm was observed on digital subtraction angiography. Following conservative treatment, follow-up imaging showed no aneurysm or no recurrent stroke. CONCLUSION: Non-aneurysmal SAH is a possible indication of vessel wall fragility in Ap/T-MCA; however, a standardized treatment strategy for this condition remains to be established.

Early mobilization of patients with subarachnoid haemorrhage: a national survey of french intensive care units.

OBJECTIVE: To describe French intensive care unit practices regarding the mobilization of patients with subarachnoid haemorrhage. DESIGN: A cross-sectional nationwide survey study. SUBJECTS: Intensivists and physiotherapists or nurses from French intensive care units managing patients with subarachnoid haemorrhage. METHODS: An online questionnaire survey was distributed through the Neurocritical Care and Neuro Anesthesiology French Speaking Society. RESULTS: The response rate was 89%. Of these, 90% did not have a mobilization protocol for patients with subarachnoid haemorrhage. Sixteen percent of departments prohibited all forms of motor physiotherapy for a predefined period. Nineteen percent systematically prohibited out-of-bed mobilization, regardless of the severity of subarachnoid haemorrhage and in the absence of any complication, for a predefined period. The main factors that would delay or interrupt physiotherapy prescription were intracranial hypertension (79%), currently treated vasospasm (59%), and suspicion of vasospasm (44%). Ninety-one percent of the centres identified at least one complication that could be associated with standing upright. These mainly included decreased cerebral perfusion (71%), dislodged external ventricular or lumbar derivations (68%), and haemodynamic instability (65%). CONCLUSION: Mobilization of patients with subarachnoid haemorrhage is heterogeneous among French neuro-intensive care units and several barriers preclude improvement of mobilization practices. Interventional studies assessing mobilization practices, as well as education and training of staff, are crucial to ensure the proper management of patients with subarachnoid haemorrhage and to improve outcomes.

Twelve controversial questions in aneurysmal subarachnoid hemorrhage.

Critical care management of aneurysmal subarachnoid hemorrhage (aSAH) remains a major challenge. Despite the recent publication of guidelines from the American Heart Association/American Stroke Association and the Neurocritical Care Society, there are many controversial questions in the intensive care unit (ICU) management of this population. The authors provide an analysis of common issues in the ICU and provide guidance on the daily management of this specific population of neurocritical care patients.

Pre-treatment re-bleeding following aneurysmal subarachnoid hemorrhage: A systematic review of published prediction models with risk of bias and clinical applicability assessment.

BACKGROUND: Pre-treatment rebleeding following aneurysmal subarachnoid hemorrhage (aSAH) increases the risk of death and a poor neurological outcome. Current guidelines recommend aneurysm treatment "as early as feasible after presentation, preferably within 24 h of onset" to mitigate this risk, a practice termed ultra-early treatment. However, ongoing debate regarding whether ultra-early treatment is independently associated with reduced re-bleeding risk, together with the recognition that re-bleeding occurs even in centres practicing ultra-early treatment due to the presence of other risk-factors has resulted in a renewed need for patient-specific re-bleed risk prediction. Here, we systematically review models which seek to provide patient specific predictions of pre-treatment rebleeding risk. METHODS: Following registration on the International prospective register of systematic reviews (PROSPERO) CRD 42023421235; Ovid Medline (Pubmed), Embase and Googlescholar were searched for English language studies between 1st May 2002 and 1st June 2023 describing pre-treatment rebleed prediction models following aSAH in adults ≥18 years. Of 763 unique records, 17 full texts were scrutinised with 5 publications describing 4 models reviewed. We used the semi-automated template of Fernandez-Felix et al. incorporating the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS) checklist and the Prediction model Risk Of Bias ASsessment Tool (PROBAST) for data extraction, risk of bias and clinical applicability assessment. To further standardize risk of bias and clinical applicability assessment, we also used the published explanatory notes for the PROBAST tool and compared the aneurysm treatment practices each prediction model's formulation cohort experienced to a prespecified benchmark representative of contemporary aneurysm treatment practices as outlined in recent evidence-based guidelines and published practice pattern reports from four developed countries. RESULTS: Reported model discriminative performance varied between 0.77 and 0.939, however, no single model demonstrated a consistently low risk of bias and low concern for clinical applicability in all domains. Only the score of Darkwah Oppong et al. was formulated using a patient cohort in which the majority of patients were managed in accordance with contemporary, evidence-based aneurysm treatment practices defined by ultra-early and predominantly endovascular treatment. However, this model did not undergo calibration or clinical utility analysis and when applied to an external cohort, its discriminative performance was substantially lower that reported at formulation. CONCLUSIONS: No existing prediction model can be recommended for clinical use in centers practicing contemporary, evidence-based aneurysm treatment. There is a pressing need for improved prediction models to estimate and minimize pre-treatment re-bleeding risk.

Conditioning-based therapeutics for aneurysmal subarachnoid hemorrhage - A critical review.

Aneurysmal subarachnoid hemorrhage (SAH) carries significant mortality and morbidity, with nearly half of SAH survivors having major cognitive dysfunction that impairs their functional status, emotional health, and quality of life. Apart from the initial hemorrhage severity, secondary brain injury due to early brain injury and delayed cerebral ischemia plays a leading role in patient outcome after SAH. While many strategies to combat secondary brain injury have been developed in preclinical studies and tested in late phase clinical trials, only one (nimodipine) has proven efficacious for improving long-term functional outcome. The causes of these failures are likely multitude, but include use of therapies targeting only one element of what has proven to be multifactorial brain injury process. Conditioning is a therapeutic strategy that leverages endogenous protective mechanisms to exert powerful and remarkably pleiotropic protective effects against injury to all major cell types of the CNS. The aim of this article is to review the current body of evidence for the use of conditioning agents in SAH, summarize the underlying neuroprotective mechanisms, and identify gaps in the current literature to guide future investigation with the long-term goal of identifying a conditioning-based therapeutic that significantly improves functional and cognitive outcomes for SAH patients.