Cerebral hemodynamic changes in severe head injury patients undergoing decompressive craniectomy

Prolonged course of brain edema and neurological recovery in a translational model of decompressive craniectomy after closed head injury in mice

Background

The use of decompressive craniectomy in traumatic brain injury (TBI) remains a matter of debate. According to the DECRA trial, craniectomy may have a negative impact on functional outcome, while the RescueICP trial revealed a positive effect of surgical decompression, which is evolving over time. This ambivalence of craniectomy has not been studied extensively in controlled laboratory experiments.

Objective

The goal of the current study was to investigate the prolonged effects of decompressive craniectomy (both positive and negative) in an animal model.

Methods

Male mice were assigned to the following groups: sham, decompressive craniectomy, TBI and TBI followed by craniectomy. The analysis of functional outcome was performed at time points 3d, 7d, 14d and 28d post trauma according to the Neurological Severity Score and Beam Balance Score. At the same time points, magnetic resonance imaging was performed, and brain edema was analyzed.

Results

Animals subjected to both trauma and craniectomy presented the exacerbation of the neurological impairment that was apparent mostly in the early course (up to 7d) after injury. Decompressive craniectomy also caused a significant increase in brain edema volume (initially cytotoxic with a secondary shift to vasogenic edema and gliosis). Notably, delayed edema plus gliosis appeared also after decompression even without preceding trauma.

Conclusion

In prolonged outcomes, craniectomy applied after closed head injury in mice aggravates posttraumatic brain edema, leading to additional functional impairment. This effect is, however, transient. Treatment options that reduce brain swelling after decompression may accelerate neurological recovery and should be explored in future experiments.

Assessment of cerebral blood flow velocities, brain midline shift and optic nerve sheath diameter by ultrasound in patients undergoing elective craniotomy: A prospective observational feasibility study

BACKGROUND

Brain ultrasound allows measuring the cerebral flow velocity, brain midline shift and optic nerve sheath diameter. Literature is scarce in determining the feasibility to perioperatively perform these measurements altogether and the cerebrovascular behavior in patients scheduled for elective craniotomy.

METHODS

We assessed bilateral cerebral flow velocities, composite index, brain midline shift and optic nerve sheath diameter by cerebral ultrasound in patients scheduled for elective craniotomy before anesthetic induction, at extubation, and at 6 and 24 h after. The aim was to assess the feasibility of brain ultrasound in patients for elective craniotomy and to describe the changes in cerebral flow velocities, brain midline shift and optic nerve sheath diameter from baseline values at different times in the postoperative period.

RESULTS

Sixteen patients were included, of these two were excluded from analysis due to an inadequate sonographic window. There were no changes throughout the study regarding cerebral flow velocity, brain midline shift nor optic nerve sheath diameter assessments. All parameters were maintained in the physiological range without significant variations during the procedure. No perioperative complications were detected.

CONCLUSIONS

The results of our study show the feasibility to perform a perioperative assessment of cerebral flow velocity, brain midline shift or optic nerve sheath diameter jointly and successfully to obtain additional information of baseline cerebral hemodynamics in patients scheduled for elective craniotomy and their postoperative changes during the first 24 h. Future studies with lager samples are needed to address the efficacy of cerebral ultrasound as a monitoring tool.

Comparative Study of Cerebral Perfusion in Different Types of Decompressive Surgery for Traumatic Brain Injury

Introduction Computed tomography perfusion (CTP) brain usefulness in the treatment of traumatic brain injury (TBI) is still being investigated. Comparative research of CTP in the various forms of decompressive surgery has not yet been reported to our knowledge. Patients with TBI who underwent decompressive surgery were studied using pre- and postoperative CTP. CTP findings were compared with patient's outcome.

Materials and Methods This was a single-center, prospective cohort study. A prospective analysis of patients who were investigated with CTP from admission between 2019 and 2021 was undertaken. The patients in whom decompressive surgery was required for TBI, were included in our study after applying inclusion and exclusion criteria. CTP imaging was performed preoperatively and 5 days after decompressive surgery to measure cerebral perfusion. Numbers of cases included in the study were 75. Statistical analysis was done.

Results In our study, cerebral perfusion were improved postoperatively in the all types of decompressive surgery (p-value < 0.05). But association between type of surgery with improvement in cerebral perfusion, Glasgow Coma Scale at discharge, and Glasgow Outcome Scale-extended at 3 months were found to be statistically insignificant (p-value > 0.05).

Conclusion CTP brain may play a role as a prognostic tool in TBI patients undergoing decompressive surgery.

Massive Brain Swelling Following Reduction Cranioplasty for Secondary Turricephaly

ABSTRACT

Cranioplasty is commonly performed to treat craniosynostosis. A rare postsurgical complication is massive brain swelling with elevated intracranial pressure. This commonly presents with mydriasis, coma, and seizures; radiologic findings include cerebral edema, parenchymal hemorrhages, and ischemic changes.The authors describe a 9-year-old boy who developed massive brain swelling following reduction cranioplasty for secondary turricephaly. His history included surgical repair of metopic-craniosynostosis at age 5.5 months, by means of an anterior cranial-vault reconstruction with fronto-orbital advancement. After presenting to our clinic with a significant turricephalic skull deformity, he underwent cranial reduction cranioplasty. On postoperative day 1, mild neurological signs associated to increased intracranial pressure were noticed. As they worsened and massive brain swelling was identified, he was treated pharmacologically. On postoperative day 13, the patient was operated for decompression.A literature review yielded 4 articles related to massive brain swelling for post-traumatic craniectomies. None described elevated intracranial pressure or massive brain swelling following cranial reduction for secondary craniosynostosis. The main dilemma regarding our patient was the necessity and timing of a second operation.The literature did not reveal relevant recommendations regarding treatment timing nor preventative measures.The authors recommend presurgical neuro-ophthalmological and imaging evaluation, for comparisons and management during the immediate and short-term follow-ups. The authors suggest that for a patient presenting with signs and symptoms of cerebral edema or high intracranial pressure following reduction-cranioplasty, pharmacological treatment should be initiated promptly, and careful drainage and eventual surgical-treatment should be considered if no improvement is shown in the subsequent days.

Direct Consequences of Cranioplasty to the Brain: Intracranial Pressure Study

ABSTRACT

Intracranial pressure (ICP) is a crucial factor that we need to take into account in all major pathophysiological changes of the brain after decompressive craniectomy (DC) and cranioplasty (CP). The purpose of our study was to check ICP values before and after cranioplasty and its relation to various parameters (imaging, demographics, time of cranioplasty, and type of graft) as well as its possible relation to postsurgical complications. The authors performed a prospective study in which they selected as participants adults who had undergone unilateral frontotemporoparietal DC and were planned to have cranioplasty. Intracranial pressure was measured with optical fiber sensor in the epidural space and did not affect cranioplasty in any way.Twenty-five patients met the criteria. The mean vcICP (value change of ICP) was 1.2 mm Hg, the mean ΔICP (absolute value change of the ICP) was 2.24 mm Hg and in the majority of cases there was an increase in ICP. The authors found 3 statistically significant correlations: between gender and ΔICP, Δtime (time between DC and CP) and vcICP, and pre-ICP and ±ICP (quantitative change of the ICP).Μale patients tend to develop larger changes of ICP values during CP. As the time between the 2 procedures (DC and CP) gets longer, the vcICP is decreased. However, after certain time it shows a tendency to remain around zero. Lower pre-ICP values (close to or below zero) are more possible to increase after bone flap placement. It seems that the brain tends to restore its pre-DC conditions after CP by taking near-to-normal ICP values.

Asymmetric TCD Findings in Malignant MCA Infarction, Resolution after Decompressive Hemicraniectomy: A Case Report

Transcranial Doppler (TCD) is a non-invasive method for assessing cerebral hemodynamics in the acute phase of stroke. We report a case of a 33-year-old man who presented with a massive left hemispheric infarct developing into “malignant” MCA infarction. TCD was utilized to monitor intracranial hemodynamics while the clinical and neuroimaging findings were used to help us in the decision to proceed with decompressive craniectomy (DC). Pre-operatively, there was reduced mean flow velocities (MFV) of the middle cerebral artery (MCA) with increasing pulsatility index (PI) ipsilateral to the infarct. The subsequent but smaller rise in the PI in the contralateral MCA was suggestive of very high intracranial pressure (ICP) from massive brain swelling. Serial TCD examinations post-operatively showed normalization of the PI, and subsequent rise in the left MCA MFV. Clinical improvement was also noted as the TCD findings improved. The asymmetry in TCD findings can be attributed to occlusion of the MCA with subsequent spontaneous recanalisation, occlusion of the MCA with subsequent recanalisation due to the DC, or initial occlusion and subsequent pressure effects on the arterioles of the MCA due to the “malignant” edema of that hemisphere that was relieved by DC. This case illustrates the value of TCD as a useful modality in monitoring intracranial hemodynamics in acute stroke.

Decompressive Craniectomy in Traumatic Brain Injury: An Institutional Experience of 131 Cases in Two Years

Decompressive craniectomy (DC) effectively reduces intracranial pressure (ICP), but is not considered to be a first-line procedure. We retrospectively analyzed sociodemographic, clinical, and surgical characteristics associated with the prognosis of patients who underwent DC to treat traumatic intracranial hypertension (ICH) at the Restauração Hospital (HR) in Recife, Brazil between 2015 and 2016, and compared the clinical features with surgical timing and functional outcome at discharge. The data were collected from 131 medical records in the hospital database. A significant majority of the patients were young adults (age 18-39 years old; 75/131; 57.3%) and male (118/131; 90.1%). Road traffic accidents, particularly those involving motorcycles (57/131; 44.5%), were the main cause of the traumatic event. At initial evaluation, 63 patients (48.8%) were classified with severe traumatic brain injury (TBI). Pupil examination showed no abnormalities for 91 patients (71.1%), and acute subdural hematoma was the most frequently observed lesion (83/212; 40%). Glasgow Outcome Scale (GOS) score was used to categorize surgical results and 51 patients (38.9%) had an unfavorable outcome. Only the Glasgow Coma Scale (GCS) score on admission (score of 3-8) was more likely to be associated with unfavorable outcome (p-value = 0.009), indicating that this variable may be a determinant of mortality and prognostic of poor outcome. Patients who underwent an operation sooner after injury, despite having a worse condition on admission, presented with clinical results that were similar to those of patients who underwent surgery 12 h after hospital admission. These results emphasize the importance of early DC for management of severe TBI. This study shows that DC is a common procedure used to manage TBI patients at HR.

Use of a Doppler-Based Pulsatility Index to Evaluate Cerebral Hemodynamics in Neurocritical Patients After Hemicraniectomy

OBJECTIVES

As a noninvasive method for evaluation of cerebral hemodynamics, the correct interpretation of transcranial Doppler or transcranial imaging (TCI) data remains a major challenge. We explored how to interpret the pulsatility index (PI) derived via TCI during evaluations of cerebral hemodynamics in posthemicraniectomy patients.

METHODS

We included patients who underwent invasive arterial pressure and intracranial pressure (ICP) monitoring and simultaneous TCI examinations after hemicraniectomy. We classified the PI of the middle cerebral artery (MCA) into ipsilateral (craniectomy side) and contralateral (opposite side) and analyzed both data sets. The statistical analysis was performed by the Bland-Altman approach, by calculating intraclass correlation coefficients and Spearman correlations, and by drawing receiver operating characteristic curves. Pulsatility index probability charts were created for ICPs exceeding 20, 25, and 30 mm Hg and cerebral perfusion pressures (CPPs) lower than 70, 60, and 50 mm Hg; we thus explored defined ICP and CPP values.

RESULTS

The ipsilateral and contralateral MCA PI data differed. Only the ipsilateral MCA PI showed a weak correlation with ICP (r = 0.378; P < .001). The receiver operating characteristic curve analysis revealed limited diagnostic utility of bilateral MCA PIs for ICP and CPP assessments. An extremely elevated MCA PI indicated that patients were at high risk of a dangerous ICP elevation or CPP reduction. However, MCA PI values within the normal range did not effectively rule out an ICP of 20 mm Hg or higher but effectively eliminated a CPP lower than 50 mm Hg.

CONCLUSIONS

In posthemicraniectomy patients, the Doppler-based MCA PI value was ineffectively for quantitative ICP and CPP evaluations but a useful index for assessment of cerebral hemodynamics in terms of the probability of an ICP elevation or a CPP reduction.

When the air hits your brain: decreased arterial pulsatility after craniectomy leading to impaired glymphatic flow

OBJECTIVE

Cranial neurosurgical procedures can cause changes in brain function. There are many potential explanations, but the effect of simply opening the skull has not been addressed, except for research into syndrome of the trephined. The glymphatic circulation, by which CSF and interstitial fluid circulate through periarterial spaces, brain parenchyma, and perivenous spaces, depends on arterial pulsations to provide the driving force for bulk flow; opening the cranial cavity could dampen this force. The authors hypothesized that a craniectomy, without any other pathological insult, is sufficient to alter brain function due to reduced arterial pulsatility and decreased glymphatic flow. Furthermore, they postulated that glymphatic impairment would produce activation of astrocytes and microglia; with the reestablishment of a closed cranial compartment, the glymphatic impairment, astrocytic/microglial activation, and neurobehavioral decline caused by opening the cranial compartment might be reversed.

METHODS

Using two-photon in vivo microscopy, the pulsatility index of cortical vessels was quantified through a thinned murine skull and then again after craniectomy. Glymphatic influx was determined with ex vivo fluorescence microscopy of mice 0, 14, 28, and 56 days following craniectomy or cranioplasty; brain sections were immunohistochemically labeled for GFAP and CD68. Motor and cognitive performance was quantified with rotarod and novel object recognition tests at baseline and 14, 21, and 28 days following craniectomy or cranioplasty.

RESULTS

Penetrating arterial pulsatility decreased significantly and bilaterally following unilateral craniectomy, producing immediate and chronic impairment of glymphatic CSF influx in the ipsilateral and contralateral brain parenchyma. Craniectomy-related glymphatic dysfunction was associated with an astrocytic and microglial inflammatory response, as well as with the development of motor and cognitive deficits. Recovery of glymphatic flow preceded reduced gliosis and return of normal neurological function, and cranioplasty accelerated this recovery.

CONCLUSIONS

Craniectomy causes glymphatic dysfunction, gliosis, and changes in neurological function in this murine model of syndrome of the trephined.

Ultrasound Imaging for Traumatic Brain Injury

Traumatic brain injury (TBI) is challenging to assess even with recent advancements in computed tomography and magnetic resonance imaging. Ultrasound (US) imaging has previously been less utilized in TBI compared to conventional imaging because of limited resolution in the intracranial space. However, there have been substantial improvements in contrast-enhanced US and development of novel techniques such as intravascular US. Also, continued research provides further insight into cerebrovascular parameters from transcranial Doppler imaging. These advancements in US imaging provides the community of TBI imaging researchers and clinicians new opportunities in clinically monitoring and understanding the pathologic mechanisms of TBI.

Impact of positive end expiratory pressure on cerebral hemodynamic in paediatric patients with post-traumatic brain swelling treated by surgical decompression

Introduction

The objective of our present study is to evaluate the impact of different PEEP levels on cerebral hemodynamic, gas exchanges and respiratory system mechanics in paediatric patients with post-traumatic brain swelling treated with decompressive craniectomy (DC).

Materials and methods

A prospective physiologic study was carried out on 14 paediatric patients presenting with severe traumatic brain swelling treated with DC. Transcranial Doppler ultrasonography was performed on the middle cerebral artery bilaterally after DC. After assessment at ZEEP, intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP), central venous pressure (CVP) and gas exchanges were recorded at PEEP 4 and PEEP 8.

Results

From ZEEP to PEEP 8, the compliance of respiratory system indexed to the weight of the patient significantly increased (P = 0.02) without ICP modifications. No significant variation of the MAP, CPP, Vmed, the total resistance of respiratory system and ohmic resistance of the respiratory system indexed to the weight of the patients was observed. CVP significantly increased between ZEEP and PEEP 8 (P = 0.005), and between PEEP 4 and PEEP 8 (P = 0.05).

Conclusions

PEEP values up to 8 cmH20 seem to be safe in paediatric patients with a severe post-traumatic brain swelling treated with DC.

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

OBJECTIVE

In severe traumatic brain injury (TBI), the effects of decompressive craniectomy (DC) on brain tissue oxygen pressure (PbtO2) and outcome are unclear. The authors aimed to investigate whether changes in PbtO2 after DC could be used as an independent prognostic factor.

METHODS

The authors conducted a retrospective, observational study at 2 university hospital ICUs. The study included 42 patients who were admitted with isolated moderate or severe TBI and underwent intracranial pressure (ICP) and PbtO2 monitoring before and after DC. The indication for DC was an ICP higher than 25 mm Hg refractory to first-tier medical treatment. Patients who underwent primary DC for mass lesion evacuation were excluded. However, patients were included who had undergone previous surgery as long as it was not a craniectomy. ICP/PbtO2 monitoring probes were located in an apparently normal area of the most damaged hemisphere based on cranial CT scanning findings. PbtO2 values were routinely recorded hourly before and after DC, but for comparisons the authors used the first PbtO2 value on ICU admission and the number of hours with PbtO2 < 15 mm Hg before DC, as well as the mean PbtO2 every 6 hours during 24 hours pre- and post-DC. The end point of the study was the 6-month Glasgow Outcome Scale; a score of 4 or 5 was considered a favorable outcome, whereas a score of 1–3 was considered an unfavorable outcome.

RESULTS

Of the 42 patients included, 26 underwent unilateral DC and 16 bilateral DC. The median Glasgow Coma Scale score at the scene of the accident or at the initial hospital before the patient was transferred to one of the 2 ICUs was 7 (interquartile range [IQR] 4–14). The median time from admission to DC was 49 hours (IQR 7–301 hours). Before DC, the median ICP and PbtO2 at 6 hours were 35 mm Hg (IQR 28–51 mm Hg) and 11.4 mm Hg (IQR 3–26 mm Hg), respectively. In patients with favorable outcome, PbtO2 at ICU admission was higher and the percentage of time that pre-DC PbtO2 was < 15 mm Hg was lower (19 ± 4.5 mm Hg and 18.25% ± 21.9%, respectively; n = 28) than in those with unfavorable outcome (12.8 ± 5.2 mm Hg [p < 0.001] and 59.58% ± 38.8% [p < 0.001], respectively; n = 14). There were no significant differences in outcomes according to the mean PbtO2 values only during the last 12 hours before DC, the hours of refractory intracranial hypertension, the timing of DC from admission, or the presence/absence of previous surgery. In contrast, there were significant differences in PbtO2 values during the 12- to 24-hour period before DC. In most patients, PbtO2 increased during the 24 hours after DC but these changes were more pronounced in patients with favorable outcome than in those with unfavorable outcome (28.6 ± 8.5 mm Hg vs 17.2 ± 5.9 mm Hg, p < 0.0001; respectively). The areas under the curve for the mean PbtO2 values at 12 and 24 hours after DC were 0.878 (95% CI 0.75–1, p < 0.0001) and 0.865 (95% CI 0.73–1, p < 0.0001), respectively.

CONCLUSIONS

The authors’ findings suggest that changes in PbtO2 before and after DC, measured with probes in healthy-appearing areas of the most damaged hemisphere, have independent prognostic value for the 6-month outcome in TBI patients.

Multimodal monitoring combined with hypothermia for the management of severe traumatic brain injury: A case report

Traumatic brain injury (TBI) is a prominent public health issue that has a significant negative impact on patients and their family members. It is the leading cause of mortality and disability among young (below 50 years old) individuals. Intracranial hypertension (ICH) remains the single most difficult therapeutic challenge for the management of severe TBI. Therapeutic hypothermia may reduce intracranial hypertension and improve patient outcomes; however, the use of hypothermia is controversial. It has been reported that therapeutic hypothermia elicits no therapeutic benefit for patients with TBI. The present study presents two patients with severe(s) TBI who were admitted to 101st Hospital of the People's Liberation Army Between June 2017 to October 2017. Multimodal brain monitoring measurements of intracranial pressure, cerebral perfusion pressure (CPP) and bispectral index (BIS) were used during assisted hypothermia for management of patients with sTBI. The duration, degree of hypothermia treatment and speed of re-warming were assessed.

Novel Approaches to the Diagnosis of Chronic Disorders of Consciousness: Detecting Peripersonal Space by Using Ultrasonics

The assessment of behavioral responsiveness in patients suffering from chronic disorders of consciousness (DoC), including Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS), is challenging. Even if a patient is unresponsive, he/she may be covertly aware in reason of a cognitive-motor dissociation, i.e., a preservation of cognitive functions despite a solely reflexive behavioral responsiveness. The approach of an external stimulus to the peripersonal space (PPS) modifies some biological measures (e.g., hand-blink reflex amplitude) to the purpose of defensive responses from threats. Such modulation depends on a top-down control of subcortical neural circuits, which can be explored through changes in cerebral blood flow velocity (CBFV), using functional transcranial Doppler (fTCD) and, thus, gaining useful, indirect information on brain connectivity. These data may be used for the DoC differential diagnosis. We evaluated the changes in CBFV by measuring the pulsatility index (PI) in 21 patients with DoC (10 patients with MCS and 11 with UWS) and 25 healthy controls (HC) during a passive movement and motor imagery (MI) task in which the hand of the subject approached and, then, moved away from the subject’s face. In the passive movement task, the PI increased progressively in the HCs when the hand was moved toward the face and, then, it decreased when the hand was removed from the face. The PI increased when the hand was moved toward the face in patients with DoC, but then, it remained high when the hand was removed from the face and up to 30 s after the end of the movement in the patients with MCS (both MCS+ and MCS−) and 1 min in those with UWS, thus differentiating between patients with MCS and UWS. In the MI task, all the HCs, three out of four patients with MCS+, and one out of six patients with MCS− showed an increase–decrease PI change, whereas the remaining patients with MCS and all the patients with UWS showed no PI changes. Even though there is the possibility that our findings will not be replicated in all patients with DoC, we propose fTCD as a rapid and very easy tool to differentiate between patients with MCS and UWS, by identifying residual top-down modulation processes from higher-order cortical areas to sensory-motor integration networks related to the PPS, when using passive movement tasks.

Massive Brain Swelling and Death After Cranioplasty: A Systematic Review

BACKGROUND

Although cranioplasty is a common procedure, it may cause a variety of complications. Massive brain swelling after cranioplasty (MBSC) is an unusual complication that has been reported more frequently in recent years. Most of the existing information about this condition is speculative and the cause remains unclear.

METHODS

A PubMed and Scopus search adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was performed to include studies reporting patients with MBSC. Different information was analyzed in these cases to describe the characteristics and identify risk factors for MBSC.

RESULTS

The search yielded 19 articles with a total of 26 patients. All studies were case reports and small case series. In most patients, preoperative intracranial hypotension and a considerable degree of sinking of skin flap were identified; this was the only constant finding observed in these cases. In addition, we propose a grading system to estimate the degree of preoperative sinking of skin flap and an algorithm with recommendations to decrease the incidence of MBSC.

CONCLUSIONS

MBSC is an unusual, highly lethal, and probably underreported condition. The information gathered in this review indicates that MBSC occurs secondary to a cascade of pathologic events triggered by the bone flap implantation. This evidence suggests that the primary pathologic change is a sudden increase in the intracranial pressure acting on a brain chronically exposed to intracranial hypotension.

Quantitative cerebral blood flow using xenon-enhanced CT after decompressive craniectomy in traumatic brain injury

OBJECTIVE Few studies have reported on changes in quantitative cerebral blood flow (CBF) after decompressive craniectomy and the impact of these measures on clinical outcome. The aim of the present study was to evaluate global and regional CBF patterns in relation to cerebral hemodynamic parameters in patients after decompressive craniectomy for traumatic brain injury (TBI). METHODS The authors studied clinical and imaging data of patients who underwent xenon-enhanced CT (XeCT) CBF studies after decompressive craniectomy for evacuation of a mass lesion and/or to relieve intractable intracranial hypertension. Cerebral hemodynamic parameters prior to decompressive craniectomy and at the time of the XeCT CBF study were recorded. Global and regional CBF after decompressive craniectomy was measured using XeCT. Regional cortical CBF was measured under the craniectomy defect as well as for each cerebral hemisphere. Associations between CBF, cerebral hemodynamics, and early clinical outcome were assessed. RESULTS Twenty-seven patients were included in this study. The majority of patients (88.9%) had an initial Glasgow Coma Scale score ≤ 8. The median time between injury and decompressive surgery was 9 hours. Primary decompressive surgery (within 24 hours) was performed in the majority of patients (n = 18, 66.7%). Six patients had died by the time of discharge. XeCT CBF studies were performed a median of 51 hours after decompressive surgery. The mean global CBF after decompressive craniectomy was 49.9 ± 21.3 ml/100 g/min. The mean cortical CBF under the craniectomy defect was 46.0 ± 21.7 ml/100 g/min. Patients who were dead at discharge had significantly lower postcraniectomy CBF under the craniectomy defect (30.1 ± 22.9 vs 50.6 ± 19.6 ml/100 g/min; p = 0.039). These patients also had lower global CBF (36.7 ± 23.4 vs 53.7 ± 19.7 ml/100 g/min; p = 0.09), as well as lower CBF for the ipsilateral (33.3 ± 27.2 vs 51.8 ± 19.7 ml/100 g/min; p = 0.07) and contralateral (36.7 ± 19.2 vs 55.2 ± 21.9 ml/100 g/min; p = 0.08) hemispheres, but these differences were not statistically significant. The patients who died also had significantly lower cerebral perfusion pressure (52 ± 17.4 vs 75.3 ± 10.9 mm Hg; p = 0.001). CONCLUSIONS In the presence of global hypoperfusion, regional cerebral hypoperfusion under the craniectomy defect is associated with early mortality in patients with TBI. Further study is needed to determine the value of incorporating CBF studies into clinical decision making for severe traumatic brain injury.

Transcranial parenchymal sonography in patients with Chronic Disorders of Consciousness: Association with neuroimaging data, and beyond

Differential diagnosis of patients with Chronic Disorders of Consciousness (DoC) is rather challenging, owing to the lack of objective approaches highlighting residual awareness. Sophisticated functional neuroimaging have provided high diagnostic value, but their application in the clinical setting is limited due to their relative complexity, cost, availability and poor collaboration of persons with DoC. By using a specific ultrasound-based methodology, namely Transcranial B-mode Parenchymal Sonography (TCS), it is possible to obtain images of the main parenchymal brain structures. We assessed the TCS abnormalities in three patients with DoC, demonstrating widespread alterations of brain parenchyma morphology that matched to MRI findings and were associated with the degree of consciousness disorders. Thus, TCS might represent a valuable tool for routine assessment and follow-up of brain structures functioning of patients with DoC, potentially helping in differential diagnosis and prognosis.

APOE ε4 positive patients suffering severe traumatic head injury are more prone to undergo decompressive hemicraniectomy

OBJECT

In this paper we tested the hypothesis if patients with severe traumatic brain injury and presence of the apolipoprotein E (APOE) ε4 allele are more prone to undergo the surgical procedure decompressive hemicraniectomy (DC) in order to bring the intracranial pressure (ICP) under control.

METHODS

In this prospective consecutive study patients with sTBI were enrolled (n=48). Inclusion criteria were arrival to our level one trauma university hospital within 24h after trauma, patient age between 15 and 70years, Glasgow Coma Scale (GCS) score ≤8 at the time of intubation and sedation, an initial cerebral perfusion pressure >10mmHg. Venous blood was sampled for APOE genotype determination. Clinical outcome at 6months after injury was assessed with the Extended Glasgow Outcome Scale (GOSE). All surgical procedures needed for each patient were registered.

RESULTS

Patients with the APOE ε4 allele were significantly overrepresented in the DC group. In the APOE ε4+DC group, ICP_max and ICP_mean during the first 36h were significantly higher and GOSE was significantly worse at 6months.

CONCLUSION

Our data suggest that patients with the APOE ε4 allele are predisposed for the need of DC more often than patients without the APOE ε4 allele. Thus, it seems to be of importance to consider the APOE genotype in patients suffering severe traumatic brain injury in order to forecast the need for a more exquisite intensive care.

Contrast-Enhanced Ultrasound Imaging in Detection of Changes in Cerebral Perfusion

Contrast-enhanced ultrasonography (CEU) is a non-invasive imaging technique that provides real-time, bedside information on changes in global and segmental organ perfusion. Currently, there is a lack of data concerning changes in the distribution of segmental brain perfusion in acute ischemic stroke treated by decompressive craniectomy. The aim of our case series was to assess the role of CEU after decompressive craniectomy in patients with acute ischemic stroke. CEU was performed in 12 patients at baseline and after any one of the following interventions was performed as dictated by the patient's clinical condition: vasoactive drug administration (in order to achieve cerebral perfusion pressure ≥70 mm Hg and mean arterial pressure <100 mm Hg for management of arterial blood pressure) and mild hyperventilation (carbon dioxide arterial pressure = 30-35 mm Hg). CEU was able to detect a significant variation in cerebral contrast distribution in both normal and pathologic hemispheres after induced hyperventilation (difference in time to peak [dTTP] = -38.4%), vasodilation (dTTP = -6.6%) and vasoconstriction (dTTP = +31.2%) (p < 0.05). CEU can be useful in assessing real-time cerebral perfusion changes in neurocritical care patients.

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

The incidence of traumatic brain injury (TBI) in the United States was 3.5 million cases in 2009, according to the Centers for Disease Control and Prevention. It is a contributing factor in 30.5% of injury-related deaths among civilians. Additionally, since 2000, more than 260,000 service members were diagnosed with TBI, with the vast majority classified as mild or concussive (76%). The objective assessment of TBI via imaging is a critical research gap, both in the military and civilian communities. In 2011, the Department of Defense (DoD) prepared a congressional report summarizing the effectiveness of seven neuroimaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], transcranial Doppler [TCD], positron emission tomography, single photon emission computed tomography, electrophysiologic techniques [magnetoencephalography and electroencephalography], and functional near-infrared spectroscopy) to assess the spectrum of TBI from concussion to coma. For this report, neuroimaging experts identified the most relevant peer-reviewed publications and assessed the quality of the literature for each of these imaging technique in the clinical and research settings. Although CT, MRI, and TCD were determined to be the most useful modalities in the clinical setting, no single imaging modality proved sufficient for all patients due to the heterogeneity of TBI. All imaging modalities reviewed demonstrated the potential to emerge as part of future clinical care. This paper describes and updates the results of the DoD report and also expands on the use of angiography in patients with TBI.

Primary or Secondary Decompressive Craniectomy: Different Indication and Outcome

Background:

Intracranial hypertension can cause secondary damage after a traumatic brain injury. Aggressive medical management might not be sufficient to alleviate the increasing intracranial pressure (ICP), and decompressive craniectomy (DC) can be considered. Decompressive craniectomy can be divided into categories, according to the timing and rationale for performing the procedure: primary (done at the time of mass lesion evacuation) and secondary craniectomy (done to treat refractory ICP). Most studies analyze primary and secondary DC together. Our hypothesis is that these two groups are distinct and the aim of this retrospective study is to evaluate the differences in order to better predict outcome after DC.

Methods:

Seventy patients had DC over a period of four years at our center. They were divided into two groups based on the timing of the DC. Primary DC (44 patients) was done within 24 hours of the injury for mass lesion evacuation. Secondary DC (26 patients) was done after 24 hours and purely for the treatment of refractory ICP. Pre-op characteristics and post-op outcomes were compared between the two groups.

Results:

There was a significant difference in the mechanism of injury, the pupil abnormalities and Marshall grade between primary and secondary DC. There was also a significant difference in outcome with primary DC showing 45.5% good outcome and 40.9% mortality and secondary DC showing 73.1% good outcome and 15.4% mortality.

Conclusions:

Primary and secondary DC have different indications and patients characteristics. Outcome prediction following DC should be adjusted according to the surgical indication.

Temporal changes in CT perfusion values before and after cranioplasty in patients without symptoms related to external decompression: a pilot study

INTRODUCTION

Little is known about hemodynamic disturbances affecting cerebral hemispheres in traumatic brain injury (TBI) after cranioplasty.

METHODS

We prospectively investigated six stable TBI patients who underwent cranioplasty more than 90 days after effective decompressive craniectomy. Computerized tomography perfusion (CTP) studies and evaluation of clinical outcome were performed for each patient before cranioplasty and at 7 days and 3 months after surgery. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were measured in multiple cortical circular regions positioned in cranioplasty-treated and contralateral hemispheres.

RESULTS

Neither complications associated with cranioplasty nor changes in outcome were observed. On the treated side, CBF and CBV values were higher before and 7 days after cranioplasty than at 3 months after surgery, whereas MTT values were lower at 7 days than at 3 months after surgical treatment.

CONCLUSIONS

Our results indicate that cortical perfusion progressively declines in the cranioplasty treated hemisphere but remains stable in the contralateral hemisphere after surgery and suggest that CTP can represent a promising tool for a longitudinal analysis of hemodynamic abnormalities occurring in TBI patients after cranioplasty. In addition, these data imply a possible role of cranioplasty in restoring flow to meet the prevailing metabolic demand.

Ultrasound-based imaging in neurocritical care patients: a review of clinical applications

OBJECTIVE

To analyze the diagnostic, monitoring, and procedural applications of ultrasound (US) imaging in neurocritical care (NCC) patients.

METHOD

US imaging has been extensively validated in various subset of critically ill patients, but not specifically in the NCC population. We reviewed the clinical applications of US imaging for heart, vascular, brain, and lung evaluation and for possible procedural uses in NCC patients. Major neurosurgical books, journals, testimonials, authors' personal experience, and scientific databases were analyzed.

RESULTS

Cardiac US imaging provides accurate information at NCC arrival to stratify risk factors, including presence of atrial septal defect/patent formen ovale, abnormal ventricular function, or pericardial effusion, and to monitor cardiac anatomy and function during the NCC stay for guiding goal-directed therapy. Vascular US in NCC patients has three especially relevant indications: to screen anatomy and flow in extracranial supra-aortic arteries, to diagnose deep vein thrombosis, and to optimize the safety of central venous catheterization. Brain US has important clinical applications in the NCC, including transcranial Doppler and emerging techniques for cerebral blood flow evaluation with contrast-enhanced US imaging. Lung US, as demonstrated in other intensive care unit patients, provides accurate diagnosis of anatomical and functional abnormalities and enables diagnosis of pleural effusion, pneumothorax, lung consolidation, pulmonary abscess and interstitial-alveolar syndrome, and lung recruitment/derecruitment. US imaging can effectively guide percutaneous tracheostomy.

CONCLUSION

In conclusion, US imaging is an important diagnostic tool that provides real-time information at the bedside to stratify risk, monitor for complications, and guide invasive procedures in NCC patients.

Posttraumatic refractory intracranial hypertension and brain herniation syndrome: cerebral hemodynamic assessment before decompressive craniectomy

Background. The pathophysiology of traumatic brain swelling remains little understood. An improved understanding of intracranial circulatory process related to brain herniation may have treatment implications. Objective. To investigate the cerebral hemodynamic changes associated with brain herniation syndrome due to traumatic brain swelling. Methods. Nineteen head-injured patients with evidence of refractory intracranial hypertension and transtentorial herniation were prospectively studied. Cerebral hemodynamic assessment by transcranial Doppler (TCD) ultrasonography was performed prior to decompressive craniectomy. Patients and their cerebral hemispheres were classified according to TCD-hemodynamic patterns, and the data correlated with neurological status, midline shift on CT scan, and Glasgow outcome scale scores at 6 months after injury. Results. A wide variety of cerebral hemodynamic findings were observed. Ten patients (52.7%) presented with cerebral oligoemia, 3 patients (15.8%) with cerebral hyperemia, and 6 patients with nonspecific circulatory pattern. Circulatory disturbances were more frequently found in the side of maximal cerebral swelling than in the opposite side. Pulsatility index (PI) values suggested that ICP varied from acceptable to considerably high; patients with increased PI, indicating higher microvascular resistance. No correlation was found between cerebral hemodynamic findings and outcome. Conclusions. There is a marked heterogeneity of cerebral hemodynamic disturbances among patients with brain herniation syndrome.

Decompressive craniectomy and head injury: brain morphometry, ICP, cerebral hemodynamics, cerebral microvascular reactivity, and neurochemistry

There has been renewed interest in decompressive craniectomy as a surgical treatment for elevated intracranial pressure (ICP), although evidence-based clinical data are still lacking and some experimental results are conflicting. Ongoing clinical trials on the use of this operation after traumatic brain injury (TBI) may clarify the clinical application of this technique, however, some pathophysiological issues, such as the timing of this operation, its effect on brain edema formation, and its role for secondary brain damage, are still controversial. This review addresses recent clinical data on the influence of decompressive craniectomy on the brain pathophysiology in TBI. Decompressive craniectomy with dural augmentation enlarges intracranial space so that the swollen cerebral hemisphere could expand out of normal cranial limits, avoiding progression of brain herniation. The gain in intracranial volume results in both the improvement of cerebral compliance and a decrease in ICP; the latter favors a rise in both cerebral blood flow and cerebral microvascular perfusion, which can be accompanied by elevation in brain tissue oxygen tension (PbtO2) as well as the return of abnormal metabolic parameters to normal values in cases of cerebral ischemia. Enhancement of edema formation, impairment of cerebrovascular pressure reactivity, and non-restoration of brain aerobic metabolism due to metabolic crisis may occur after craniectomy and require further investigations. This review suggests that decompressive craniectomy as the sole treatment is likely to be insufficient; efforts must be made to maintain adequate brain hemodynamics, preferably coupled with brain metabolism, in addition to treating brain metabolic abnormalities, during postoperative stages.

Cerebral blood flow, brain tissue oxygen, and metabolic effects of decompressive craniectomy

Decompressive craniectomy (DC) is used for patients with traumatic brain injury (TBI), malignant edema from middle cerebral artery infarction, aneurysmal subarachnoid hemorrhage, and non-traumatic intracerebral or cerebellar hemorrhage. The objective of the procedure is to relieve intractable intracranial hypertension and/or to prevent or reverse cerebral herniation. Decompressive craniectomy has been shown to decrease mortality in selected patients with large hemispheric infarction and to control intracranial pressure in addition to improving pressure-volume compensatory reserve after TBI. The clinical effectiveness of DC in patients with TBI is under evaluation in ongoing randomized clinical trials. There are several unresolved controversies regarding optimal candidate selection, timing, technique, and post-operative management and complications. The nature and temporal progression of alterations in cerebral blood flow, brain tissue oxygen, and microdialysis markers have only recently been researched. Elucidating the pathophysiology of pressure-flow and cerebral hemodynamic consequences of DC could assist in optimizing clinical decision making and further defining the role of decompressive craniectomy.

Controversies in the management of adults with severe traumatic brain injury

Despite progress in the management of adults with severe traumatic brain injury, several controversies persist. Among the unresolved issues of greatest concern to neurocritical care clinicians and scientists are the following: (1) the best use of technological advances and the data obtained from multimodality monitoring; (2) the use of mannitol and hypertonic saline in the management of increased intracranial pressure; (3) the use of decompressive craniectomy and barbiturate coma in refractory increased intracranial pressure; (4) therapeutic hypothermia as a neuroprotectant; (5) anemia and the role of blood transfusion; and (6) venous thromboembolism prophylaxis in severe traumatic brain injury. Each of these strategies for managing severe traumatic brain injury, including the postulated mechanism(s) of action and beneficial effects of each intervention, adverse effects, the state of the science, and critical care nursing implications, is discussed.

Decompressive craniectomy: a meta-analysis of influences on intracranial pressure and cerebral perfusion pressure in the treatment of traumatic brain injury

OBJECT

In recent years, the role of decompressive craniectomy for the treatment of traumatic brain injury (TBI) in patients with refractory intracranial hypertension has been the subject of several studies. The purpose of this review was to evaluate the contribution of decompressive craniectomy in reducing intracranial pressure (ICP) and increasing cerebral perfusion pressure (CPP) in these patients.

METHODS

Comprehensive literature searches were performed for articles related to the effects of decompressive craniectomy on ICP and CPP in patients with TBI. Inclusion criteria were as follows: 1) published manuscripts, 2) original articles of any study design except case reports, 3) patients with refractory elevated ICP due to traumatic brain swelling, 4) decompressive craniectomy as a type of intervention, and 5) availability of pre- and postoperative ICP and/or CPP data. Primary outcomes were ICP decrease and/or CPP increase for assessing the efficacy of decompressive craniectomy. The secondary outcome was the persistence of reduced ICP 24 and 48 hours after the operation.

RESULTS

Postoperative ICP values were significantly lower than preoperative values immediately after decompressive craniectomy (weighted mean difference [WMD] -17.59 mm Hg, 95% CI -23.45 to -11.73, p < 0.00001), 24 hours after (WMD -14.27 mm Hg, 95% CI -24.13 to -4.41, p < 0.00001), and 48 hours after (WMD -12.69 mm Hg, 95% CI -22.99 to -2.39, p < 0.0001). Postoperative CPP was significantly higher than preoperative values (WMD 7.37 mm Hg, 95% CI 2.32 to 12.42, p < 0.0001).

CONCLUSIONS

Decompressive craniectomy can effectively decrease ICP and increase CPP in patients with TBI and refractory elevated ICP. Further studies are necessary to define the group of patients that can benefit most from this procedure.

Brainstem hemorrhage following decompressive craniectomy

Decompressive craniectomy (DC) is used for the management of refractory raised intracranial pressure, but the impact of DC on surgical outcome is still controversial. We report a 21-year-old man admitted to our hospital after a road traffic accident. The brain CT scan revealed a left hemispheric acute subdural hematoma. After DC, he developed a brainstem hemorrhage. Recovery was, however, good.

Decompressive craniectomy and cerebral blood flow regulation in head injured patients: a case studied by perfusion CT

Previous studies have reported increased cerebral blood flow (CBF) velocity after decompressive craniectomy in traumatic brain injury (TBI) patients. A 27-year-old man presented with clinical and tomographic signs of cerebral herniation secondary to TBI. Prior to decompressive craniectomy, hemodynamic study by perfusion computed tomography (CT) indicated diffuse cerebral hyperperfusion. Following surgical decompression, the patient recovered neurologically and perfusion CT disclosed a decrease in the intensity of cerebral perfusion. The patient's blood pressure levels were similar at both pre- and postoperative perfusion CT examinations. This finding provides indirect evidence that decompressive craniectomy may improve mechanisms of CBF regulation in TBI, providing pathophysiological insights in the cerebral hemodynamics of TBI patients. This is the first report analyzing the hemodynamic changes through perfusion CT (PCT) in a patient with decompressive craniotomy due to TBI.

Cerebral blood flow velocity changes and the value of the pulsatility index post decompressive craniectomy

Decompressive craniectomy (DC) is used to relieve intractable intracranial hypertension and/or to prevent or reverse cerebral herniation. Significant controversy exists on selection of candidates, timing of the procedure and neurologic outcomes. Furthermore, the cerebral hemodynamic consequences post-DC have been researched only recently. We report on two consecutive patients who underwent DC in our institution and reviewed the literature on cerebral blood flow changes post-craniectomy. One patient had unilateral DC and the second had a suboccipital decompression (SOC). Cerebral blood flow velocities (FV) and pulsatility indices (PI) were recorded via transcranial Doppler (TCD). To our knowledge, this is the first report on FV/PI monitoring after SOC. TCD is a readily available, non-invasive test. The PI may provide useful information regarding timing and effectiveness of DC.

Cerebral blood flow and the injured brain: how should we monitor and manipulate it?

PURPOSE OF REVIEW

Cerebral ischemia plays a major role in the pathophysiology of the injured brain, including traumatic brain injury and subarachnoid hemorrhage, thus improvement in outcome may necessitate monitoring and optimization of cerebral blood flow (CBF). To interpret CBF results in a meaningful way, it may be necessary to quantify cerebral autoregulation as well as cerebral metabolism. This review addresses the recent evidence related to the changes in CBF and its monitoring/management in traumatic brain injury.

RECENT FINDINGS

Recent evidence on the management of patients with traumatic brain injury have focused on the importance of cerebral autoregulation in maintaining perfusion, which necessitates the measurement of CBF. However, adequate CBF measurements alone would not indicate the amount of oxygen delivered to neuronal tissues. Technologic advancements in measurement devices have enabled the assessment of the metabolic state of the cerebral tissue for the purpose of guiding therapy, progress as well as prognostification.

SUMMARY

Current neurocritical care management strategies are focused on the prevention and limitation of secondary brain injury where neuronal insult continues to evolve during the hours and days after the primary injury. Appropriately chosen multimodal monitoring including CBF and management measures can result in reduction in mortality and morbidity.

Selective 4 vessels angiography in brain death: a retrospective study

BACKGROUND

In Canada, ancillary tests, such as selective four vessels angiography (S4VA), are sometimes necessary for brain death (BD) diagnosis when the clinical exam cannot be completed or confounding factors are present. Recent Canadian guidelines assert that brain death is supported by the absence of arterial blood flow at the surface of the brain and that venous return should not be considered. However, neuropathologic and angiographic studies have suggested that arteries might still be patent in BD patients. Current clinical practices in BD diagnosis following S4VA need to be better understood.

METHODS

We conducted a retrospective study of all S4VA performed for the determination of BD in a level 1 NeuroTrauma centre from 2003 to 2007. The objective of the study was to describe the prevalence of intracranial arterial, capillary (parenchymogram) and venous opacification in our study population. All tests were reviewed independently by two neuroradiologists. Disagreements were resolved by consensus.

RESULTS

Thirty two patients were declared BD following S4VA during the study period. Nine of these patients (28%) presented some proximal opacification of intracranial arteries (95% CI 15-45%). As opposed, none had a cerebral capillary and deep venous drainage opacification (95% CI 0-10%).

CONCLUSION

The absence of cerebral deep venous drainage or parenchymogram might represent a better objective marker of cerebral circulatory arrest for brain death diagnosis when the use of S4VA is required. These findings open the path for further research in enhancing our interpretation of angiographic studies for brain death diagnosis.