Prognostic value of changes in brain tissue oxygen pressure before and after decompressive craniectomy following severe traumatic brain injury

Decompressive craniectomy in subarachnoid hemorrhage compared to other etiologies: An institutional experience of 11 years

Introduction

Decompressive craniectomy (DC) is a last-tier procedure to lower intracranial pressure in otherwise fatal brain injuries. DC significantly reduces mortality following traumatic brain injury (TBI) and ischemic stroke, but benefits in subarachnoid hemorrhage (SAH) are less clear.

Research question

We compared the mortality and functional outcomes in patients who underwent DC after SAH with those who underwent DC following TBI or ischemic stroke.

Materials and methods

All DC procedures performed in the Oulu University Hospital between January 2009 and December 2019 were retrospectively identified. Mortality and functional outcomes were assessed during a median follow-up of 20.7 months. Extended Glasgow Outcome Scale scores ≥5 were considered favorable.

Results

One hundred twenty-four DCs were conducted to patients aged a median of 40 years (SD 16), of whom 88 (71%) were male. Fifty-eight (47%) DCs were due to TBI and 66 (53%) due to stroke. Of the strokes, 41 (62%) were ischemic and 21 (32%) SAH.In multivariate models, the rates of unfavorable outcome were 48% in TBI, 78% in ischemic stroke (OR 2.73, 95% CI 0.70-10.64) and 86% in SAH (OR 3.15, 95%CI 0.67-14.77). Mortality rates were 22% in TBI, 17% in ischemic stroke (OR 0.50, 95%CI 0.11-2.31) and 33% in SAH (OR 0.97, 95%CI 0.24-3.99).

Discussion and conclusion

Favorable outcomes were more common in TBI compared to stroke in univariate but not in multivariate analysis. There was no statistically significant difference in the rates of favorable outcomes between SAH and ischemic stroke.

Cerebral multimodality monitoring in adult neurocritical care patients with acute brain injury: A narrative review

Cerebral multimodality monitoring (MMM) is, even with a general lack of Class I evidence, increasingly recognized as a tool to support clinical decision-making in the neuroscience intensive care unit (NICU). However, literature and guidelines have focused on unimodal signals in a specific form of acute brain injury. Integrating unimodal signals in multiple signal monitoring is the next step for clinical studies and patient care. As such, we aimed to investigate the recent application of MMM in studies of adult patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), acute ischemic stroke (AIS), and hypoxic ischemic brain injury following cardiac arrest (HIBI). We identified continuous or daily updated monitoring modalities and summarized the monitoring setting, study setting, and clinical characteristics. In addition, we discussed clinical outcome in intervention studies. We identified 112 MMM studies, including 11 modalities, over the last 7 years (2015-2022). Fifty-eight studies (52%) applied only two modalities. Most frequently combined were ICP monitoring (92 studies (82%)) together with PbtO₂ (63 studies (56%). Most studies included patients with TBI (59 studies) or SAH (53 studies). The enrollment period of 34 studies (30%) took more than 5 years, whereas the median sample size was only 36 patients (q1- q3, 20-74). We classified studies as either observational (68 studies) or interventional (44 studies). The interventions were subclassified as systemic (24 studies), cerebral (10 studies), and interventions guided by MMM (11 studies). We identified 20 different systemic or cerebral interventions. Nine (9/11, 82%) of the MMM-guided studies included clinical outcome as an endpoint. In 78% (7/9) of these MMM-guided intervention studies, a significant improvement in outcome was demonstrated in favor of interventions guided by MMM. Clinical outcome may be improved with interventions guided by MMM. This strengthens the belief in this application, but further interdisciplinary collaborations are needed to overcome the heterogeneity, as illustrated in the present review. Future research should focus on increasing sample sizes, improved data collection, refining definitions of secondary injuries, and standardized interventions. Only then can we proceed with complex outcome studies with MMM-guided treatment.

Initial neurocritical care of severe traumatic brain injury: New paradigms and old challenges

Background:

Early neurocritical care aims to ameliorate secondary traumatic brain injury (TBI) and improve neural salvage. Increased engagement of neurosurgeons in neurocritical care is warranted as daily briefings between the intensivist and the neurosurgeon are considered a quality indicator for TBI care. Hence, neurosurgeons should be aware of the latest evidence in the neurocritical care of severe TBI (sTBI).

Methods:

We conducted a narrative literature review of bibliographic databases (PubMed and Scopus) to examine recent research of sTBI.

Results:

This review has several take-away messages. The concept of critical neuroworsening and its possible causes is discussed. Static thresholds of intracranial pressure (ICP) and cerebral perfusion pressure may not be optimal for all patients. The use of dynamic cerebrovascular reactivity indices such as the pressure reactivity index can facilitate individualized treatment decisions. The use of ICP monitoring to tailor treatment of intracranial hypertension (IHT) is not routinely feasible. Different guidelines have been formulated for different scenarios. Accordingly, we propose an integrated algorithm for ICP management in sTBI patients in different resource settings. Although hyperosmolar therapy and decompressive craniectomy are standard treatments for IHT, there is a lack high-quality evidence on how to use them. A discussion of the advantages and disadvantages of invasive ICP monitoring is included in the study. Addition of beta-blocker, anti-seizure, and anticoagulant medications to standardized management protocols (SMPs) should be considered with careful patient selection.

Conclusion:

Despite consolidated research efforts in the refinement of SMPs, there are still many unanswered questions and novel research opportunities for sTBI care.

Brain-Lung Crosstalk: Management of Concomitant Severe Acute Brain Injury and Acute Respiratory Distress Syndrome

Purpose of Review

To summarize pathophysiology, key conflicts, and therapeutic approaches in managing concomitant severe acute brain injury (SABI) and acute respiratory distress syndrome (ARDS).

Recent Findings

ARDS is common in SABI and independently associated with worse outcomes in all SABI subtypes. Most landmark ARDS trials excluded patients with SABI, and evidence to guide decisions is limited in this population. Potential areas of conflict in the management of patients with both SABI and ARDS are (1) risk of intracranial pressure (ICP) elevation with high levels of positive end-expiratory pressure (PEEP), permissive hypercapnia due to lung protective ventilation (LPV), or prone ventilation; (2) balancing a conservative fluid management strategy with ensuring adequate cerebral perfusion, particularly in patients with symptomatic vasospasm or impaired cerebrovascular blood flow; and (3) uncertainty about the benefit and harm of corticosteroids in this population, with a mortality benefit in ARDS, increased mortality shown in TBI, and conflicting data in other SABI subtypes. Also, the widely adapted partial pressure of oxygen (PaO2) target of > 55 mmHg for ARDS may exacerbate secondary brain injury, and recent guidelines recommend higher goals of 80-120 mmHg in SABI. Distinct pathophysiology and trajectories among different SABI subtypes need to be considered.

Summary

The management of SABI with ARDS is highly complex, and conventional ARDS management strategies may result in increased ICP and decreased cerebral perfusion. A crucial aspect of concurrent management is to recognize the risk of secondary brain injury in the individual patient, monitor with vigilance, and adjust management during critical time windows. The care of these patients requires meticulous attention to oxygenation and ventilation, hemodynamics, temperature management, and the neurological exam. LPV and prone ventilation should be utilized, and supplemented with invasive ICP monitoring if there is concern for cerebral edema and increased ICP. PEEP titration should be deliberate, involving measures of hemodynamic, pulmonary, and brain physiology. Serial volume status assessments should be performed in SABI and ARDS, and fluid management should be individualized based on measures of brain perfusion, the neurological exam, and cardiopulmonary status. More research is needed to define risks and benefits in corticosteroids in this population.

Incidence and characteristics of cerebral hypoxia after craniectomy in brain-injured patients: a cohort study

OBJECTIVE

After craniectomy, although intracranial pressure (ICP) is controlled, episodes of brain hypoxia might still occur. Cerebral hypoxia is an indicator of poor outcome independently of ICP and cerebral perfusion pressure. No study has systematically evaluated the incidence and characteristics of brain hypoxia after craniectomy. The authors' objective was to describe the incidence and characteristics of brain hypoxia after craniectomy.

METHODS

The authors included 25 consecutive patients who underwent a craniectomy after traumatic brain injury or intracerebral hemorrhage and who were monitored afterward with a brain tissue oxygen pressure monitor.

RESULTS

The frequency of hypoxic values after surgery was 14.6% despite ICP being controlled. Patients had a mean of 18 ± 23 hypoxic episodes. Endotracheal (ET) secretions (17.4%), low cerebral perfusion pressure (10.3%), and mobilizing the patient (8.6%) were the most common causes identified. Elevated ICP was rarely identified as the cause of hypoxia (4%). No cause of cerebral hypoxia could be determined 31.2% of the time. Effective treatments that were mainly used included sedation/analgesia (20.8%), ET secretion suctioning (15.4%), and increase in fraction of inspired oxygen or positive end-expiratory pressure (14.1%).

CONCLUSIONS

Cerebral hypoxia is common after craniectomy, despite ICP being controlled. ET secretion and patient mobilization are common causes that are easily treatable and often not identified by standard monitoring. These results suggest that monitoring should be pursued even if ICP is controlled. The authors' findings might provide a hypothesis to explain the poor functional outcome in the recent randomized controlled trials on craniectomy after traumatic brain injury where in which brain tissue oxygen pressure was not measured.

Intracranial Compliance Assessed by Intracranial Pressure Pulse Waveform

BACKGROUND

Morphological alterations in intracranial pressure (ICP) pulse waveform (ICPW) secondary to intracranial hypertension (ICP >20 mmHg) and a reduction in intracranial compliance (ICC) are well known indicators of neurological severity. The exclusive exploration of modifications in ICPW after either the loss of skull integrity or surgical procedures for intracranial hypertension resolution is not a common approach studied. The present study aimed to assess the morphological alterations in ICPW among neurocritical care patients with skull defects and decompressive craniectomy (DC) by comparing the variations in ICPW features according to elevations in mean ICP values.

METHODS

Patients requiring ICP monitoring because of acute brain injury were included. A continuous record of 10 min-length for the beat-by-beat analysis of ICPW was performed, with ICP elevation produced by means of ultrasound-guided manual internal jugular vein compression at the end of the record. ICPW features (peak amplitude ratio (P2/P1), time interval to pulse peak (TTP) and pulse amplitude) were counterweighed between baseline and compression periods. Results were distributed for three groups: intact skull (exclusive burr hole for ICP monitoring), craniotomy/large fractures (group 2) or DC (group 3).

RESULTS

57 patients were analyzed. A total of 21 (36%) presented no skull defects, 21 (36%) belonged to group 2, whereas 15 (26%) had DC. ICP was not significantly different between groups: ±15.11 for intact, 15.33 for group 2 and ±20.81 mmHg for group 3, with ICP-induced elevation also similar between groups (p = 0.56). Significant elevation was observed for the P2/P1 ratio for groups 1 and 2, whereas a reduction was observed in group 3 (elevation of ±0.09 for groups 1 and 2, but a reduction of 0.03 for group 3, p = 0.01), and no significant results were obtained for TTP and pulse amplitudes.

CONCLUSION

In the present study, intracranial pressure pulse waveform analysis indicated that intracranial compliance was significantly more impaired among decompressive craniectomy patients, although ICPW indicated DC to be protective for further influences of ICP elevations over the brain. The analysis of ICPW seems to be an alternative to real-time ICC assessment.

Endoscopic Surgery Without Decompressive Craniectomy in Large Putaminal Intracerebral Hemorrhage: Assessment of Efficacy and Safety

Background

Decompressive craniectomy (DC) is performed conventionally for large putaminal intracerebral hemorrhage (ICH). However, DC causes local skull defect and leads to post-surgical cranioplasty. The aim of this study is to investigate the effectiveness and safety of an endoscopic procedure to treat large putaminal ICH without DC.

Methods

This retrospective study included 112 large putaminal ICH patients who underwent hematoma evacuations with either an endoscopic procedure (group A) or with DC (group B) between January 2009 and June 2017. The efficacy was evaluated by mean modified Rankin Scale (mRS) three months after surgery. Safety was evaluated by mortality rate and postoperative complications. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for clinical outcomes.

Results

The study included 49 patients in group A and 63 in group B. The mRS scores in both groups were similar after 3 months’ follow-up (p = 0.709). There was no difference in the mortality rate between the two groups (p = 0.538). The rate of complications was lower in group A than that in group B (p = 0.024). Smaller preoperative midline shift (p = 0.008) and absent intraventricular extension (p = 0.044) have contributed significantly to better outcomes.

Conclusion

Endoscopic hematoma evacuation without DC is safe and effective for patients with large putaminal ICH and deserves further investigation, preferably in a randomized controlled setting.

Rapid, label-free detection of cerebral ischemia in rats using hyperspectral imaging

BACKGROUND

Stroke is the third most common cause of disability and the second most common cause of death worldwide. Ischemia, one of the two broad categories of stroke, is characterized by a lack of sufficient amounts of blood in order to supply an adequate amount of oxygen and nutrients. It is important to assess the part of the brain that becomes ischemic and necrotic during neurosurgery or experiments in real time. However, there is currently no effective means to achieve this goal.

NEW METHOD

We proposed a method based on hyperspectral imaging (HSI) for the real-time detection of a varied range of ischemic brain tissues in vivo or ex vivo and assessed the practical utility of a model of ischemic stroke in rats.

RESULTS

The results showed that hyperspectral images processed with a ratio of spectral reflectance at 545 and 560 nm (R545/R560) could identify early brain ischemia and accurately show regions of ischemia.

COMPARISON WITH EXISTING METHODS

We verified the area imaged by HSI using hematoxylin and eosin (HE) and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining methods. This technique could precisely image the ischemic part of the brain in vivo and ex vivo.

CONCLUSIONS

These results demonstrate the practical utility of HSI for the real-time detection of cerebral ischemia in rats. By providing rapid assessment of brain tissue perfusion, HSI may help doctors recognize ischemic regions quickly and precisely during surgery as well as have great utility in the experimental process.

Decompressive Craniectomy for Traumatic Brain Injury: Postoperative TCD Cerebral Hemodynamic Evaluation

Background: There are no studies describing the cerebral hemodynamic patterns that can occur in traumatic brain injury (TBI) patients following decompressive craniectomy (DC). Such data have potentially clinical importance for guiding the treatment. The objective of this study was to investigate the postoperative cerebral hemodynamic patterns, using transcranial Doppler (TCD) ultrasonography, in patients who underwent DC. The relationship between the cerebral circulatory patterns and the patients' outcome was also analyzed. Methods: Nineteen TBI patients with uncontrolled brain swelling were prospectively studied. Cerebral blood circulation was evaluated by TCD ultrasonography. Patients and their cerebral hemispheres were categorized based on TCD-hemodynamic patterns. The data were correlated with neurological status, midline shift on CT scan, and Glasgow outcome scale scores at 6 months after injury. Results: Different cerebral hemodynamic patterns were observed. One patient (5.3%) presented with cerebral oligoemia, 4 patients (21%) with cerebral hyperemia, and 3 patients (15.8%) with cerebral vasospasm. One patient (5.3%) had hyperemia in one cerebral hemisphere and vasospasm in the other hemisphere. Ten patients (52.6%) had nonspecific circulatory pattern. Abnormal TCD-circulatory patterns were found in 9 patients (47.4%). There was no association between TCD-cerebral hemodynamic findings and outcome. Conclusion: There is a wide heterogeneity of postoperative cerebral hemodynamic findings among TBI patients who underwent DC, including hemodynamic heterogeneity between their cerebral hemispheres. DC was proved to be effective for the treatment of cerebral oligoemia. Our data support the concept of heterogeneous nature of the pathophysiology of the TBI and suggest that DC as the sole treatment modality is insufficient.