High Rate of Pulmonary Cement Embolism after Cement-Augmented Pedicle Screw Fixation: A 12-Year Single-Center Study

BACKGROUND

 The global trend toward increased life expectancy because of remarkable improvements in health care quality has drawn increased attention to osteoporotic fractures and degenerative spine diseases. Cement-augmented pedicle screw fixation has been established as the mainstay treatment for patients with poor bone quality. This study aimed to determine the number of patients with cement leakage and pulmonary cement embolism (PCE) as detected on thoracic computed tomography (CT), and to assess the potential risk factors for PCE.

METHODS

 Patients undergoing cement-augmented pedicle screw placement in our institution between May 2008 and December 2020 were included. Data regarding baseline characteristics, complications, and cement leakage rates were collected. Indications for the performance of a postoperative thoracic CT due to the suspicion of PCE were intra- or postoperative complications, or postoperative oxygen supplementation. Moreover, PCE was accidently diagnosed because the thoracic CT was performed for medical reasons other than the suspicion of PCE (tumor staging, severe pneumonia, or exacerbated chronic pulmonary obstructive disease).

RESULTS

 A total of 104 patients with a mean age of 72.8 years (standard deviation of 6.7) were included. Of 802 screws, 573 were cement augmented. Of the 104 patients, 44 (42.3%) underwent thoracic CT scans to diagnose PCE; additionally, 67 (64.4%) demonstrated cement leakage, of whom 27 developed PCE and 4 were symptomatic. Cement-augmented thoracic screws were a risk factor for PCE (odds ratio: 1.5; 95% confidence interval: 1.2-2.1; p = 0.004).

CONCLUSIONS

 This study showed a high prevalence of cement leakage after cement-augmented pedicle screw insertion, with a relatively frequent incidence of PCE, as tracked by thoracic CT scans. Cement-augmented thoracic screw placement was a unique risk factor for PCE.

Anterior Access to the Cervicothoracic Junction via Partial Sternotomy: A Clinical Series Reporting on Technical Feasibility, Postoperative Morbidity, and Early Surgical Outcome

Surgical access to the cervicothoracic junction (CTJ) is challenging. The aim of this study was to assess technical feasibility, early morbidity, and outcome in patients undergoing anterior access to the CTJ via partial sternotomy. Consecutive cases with CTJ pathology treated via anterior access and partial sternotomy at a single academic center from 2017 to 2022 were retrospectively reviewed. Clinical data, perioperative imaging, and outcome were assessed with regards to the aims of the study. A total of eight cases were analyzed: four (50%) bone metastases, one (12.5%) traumatic instable fracture (B3-AO-Fracture), one (12.5%) thoracic disc herniation with spinal cord compression, and two (25%) infectious pathologic fractures from tuberculosis and spondylodiscitis. The median age was 49.9 years (range: 22-74 y), with a 75% male preponderance. The median Spinal Instability Neoplastic Score (SINS) was 14.5 (IQR: 5; range: 9-16), indicating a high degree of instability in treated cases. Four cases (50%) underwent additional posterior instrumentation. All surgical procedures were performed uneventfully, with no intraoperative complications. The median length of hospital stay was 11.5 days (IQR: 9; range: 6-20), including a median of 1 day in an intensive care unit (ICU). Two cases developed postoperative dysphagia related to stretching and temporary dysfunction of the recurrent laryngeal nerve. Both cases completely recovered at 3 months follow-up. No in-hospital mortality was observed. The radiological outcome was unremarkable in all cases, with no case of implant failure. One case died due to the underlying disease during follow-up. The median follow-up was 2.6 months (IQR: 23.8; range: 1-45.7 months). Our series indicates that the anterior approach to the cervicothoracic junction and upper thoracic spine via partial sternotomy can be considered an effective option for treatment of anterior spinal pathologies, exhibiting a reasonable safety profile. Careful case selection is essential to adequately balance clinical benefits and surgical invasiveness for these procedures.

Morbidity and Mortality in Patients over 90 Years of Age Following Posterior Stabilization for Acute Traumatic Odontoid Type II Fractures: A Retrospective Study with a Mean Follow-Up of Three Years

Odontoid type II fractures represent the most common cervical spine injuries in the elderly. The decision for surgical treatment in very elderly patients is still controversial. The aim of this study was to assess morbidity and mortality in patients over 90 years of age undergoing CT-guided posterior stabilization for unstable odontoid type II fractures. A total of 15 patients with an acute traumatic odontoid type II fracture who received surgical treatment for unstable odontoid type II fractures were retrospectively analyzed. Complications, morbidity, and mortality as well as length of ICU and hospital stay were determined. Clinical follow-up evaluation was based on outpatient presentation and information from family members and general practitioners. Finally, we conducted a comparison of complications rates between patients over 90 years of age and patients between 65 and 89 years old with a type II odontoid fracture after CT-guided posterior stabilization in our institution. The mean age was 91.4 years. Patients were predominately female (87%). In-hospital deaths did not occur. The average length of the hospital stay was 13.4 days and 1.9 days for the ICU. Blood transfusion was necessary in two patients (13%). Two patients (13%) developed urinary tract infection, one patient (7%) a delirium, and another epistaxis (7%). One patient (7%) developed pneumonic sepsis and fully recovered within several weeks. The mean follow-up was 36 months (range 9–72 months). Implant-related complications developed in one patient (7%). Five patients died during the follow-up period, with an average time to death of 26.6 months. Postoperative bracing was not needed in any of the patients. Posterior stabilization of unstable odontoid fractures type II using CT-guided navigation in patients over 90 years of age is a safe and effective procedure with low complications and mortality rates.

A multicenter, open-label, controlled trial on acceptance, convenience, and complications of rechargeable internal pulse generators for deep brain stimulation: the Multi Recharge Trial

OBJECTIVE

Rechargeable neurostimulators for deep brain stimulation have been available since 2008, promising longer battery life and fewer replacement surgeries compared to non-rechargeable systems. Long-term data on how recharging affects movement disorder patients are sparse. This is the first multicenter, patient-focused, industry-independent study on rechargeable neurostimulators.

METHODS

Four neurosurgical centers sent a questionnaire to all adult movement disorder patients with a rechargeable neurostimulator implanted at the time of the trial. The primary endpoint was the convenience of the recharging process rated on an ordinal scale from "very hard" (1) to "very easy" (5). Secondary endpoints were charge burden (time spent per week on recharging), user confidence, and complication rates. Endpoints were compared for several subgroups.

RESULTS

Datasets of 195 movement disorder patients (66.1% of sent questionnaires) with Parkinson's disease (PD), tremor, or dystonia were returned and included in the analysis. Patients had a mean age of 61.3 years and the device was implanted for a mean of 40.3 months. The overall convenience of recharging was rated as "easy" (4). The mean charge burden was 122 min/wk and showed a positive correlation with duration of therapy; 93.8% of users felt confident recharging the device. The rate of surgical revisions was 4.1%, and the infection rate was 2.1%. Failed recharges occurred in 8.7% of patients, and 3.6% of patients experienced an interruption of therapy because of a failed recharge. Convenience ratings by PD patients were significantly worse than ratings by dystonia patients. Caregivers recharged the device for the patient in 12.3% of cases. Patients who switched from a non-rechargeable to a rechargeable neurostimulator found recharging to be significantly less convenient at a higher charge burden than did patients whose primary implant was rechargeable. Age did not have a significant impact on any endpoint.

CONCLUSIONS

Overall, patients with movement disorders rated recharging as easy, with low complication rates and acceptable charge burden.

Cellular, molecular, and clinical mechanisms of action of deep brain stimulation-a systematic review on established indications and outlook on future developments

Deep brain stimulation (DBS) has been successfully used to treat movement disorders, such as Parkinson's disease, for more than 25 years and heralded the advent of electrical neuromodulation to treat diseases with dysregulated neuronal circuits. DBS is now superseding ablative techniques, such as stereotactic radiofrequency lesions. While serendipity has played a role in developing DBS as a therapy, research during the past two decades has shown that electrical neuromodulation is far more than a functional lesion that can be switched on and off. This understanding broadens the field to enable new types of stimulation, clinical indications, and research. This review highlights the complex effects of DBS from the single cell to the neuronal network. Specifically, we examine the electrical, cellular, molecular, and neurochemical mechanisms of DBS as applied to Parkinson's disease and other emerging applications.

Preoperative assessment of haemostasis in patients undergoing stereotactic brain biopsy

Parenchymal hemorrhage is considered a major risk factor for perioperative morbidity in patients undergoing stereotactic brain biopsy. Studies on patients undergoing surgical procedures have suggested that evaluation of prothrombin time (PT) and activated partial thromboplastin time (aPTT) is of limited value with regard to prevention of haemorrhagic complications. However, this issue has not yet been addressed in patients undergoing stereotactic biopsy of intracranial lesions. We retrospectively analysed the medical records of 159 consecutive patients undergoing stereotactic biopsy of supratentorial intracranial lesions during a three-year period. Laboratory values (PT, aPTT, platelet count) were reviewed as well as clinical characteristics, modalities of surgical treatment, histopathological results and the postoperative course of patients. The overall diagnostic yield was 93.7%. Histopathological examination revealed glioma (WHO°I: 5, WHO°II: 25, WHO°III: 23, WHO°IV: 65), lymphoma (n = 14), inflammation (n = 8) and other entities (n = 6). Surgery-associated neurological deficits occurred in 7 patients (4.4%) and completely resolved in 6 of these patients. CT-confirmed intracranial hemorrhage occurred in 2 patients (1.3%) and in both cases, histopathological examination revealed glioblastoma. Results of hemostatic parameters (PT: 99 ± 13%, aPTT: 24 ± 3s, platelet count: 274 ± 87 10³/μL) were within normal range values in all patients and did not correlate with postsurgical morbidity. Standard assessment of haemostasis seems to be of limited value in patients with intracranial lesions undergoing stereotactic biopsy. Further studies regarding the intratumoural vasculature's impact on the risk of biopsy-related bleeding are necessary.

Stereotactic biopsy and drainage of a brainstem abscess caused by Listeria monocytogenes

Listerial rhombencephalitis and brain abscesses are rare, but potentially life-threatening conditions. Early initiation of antibiotic therapy is crucial, but establishing the diagnosis of listerial brainstem abscess can be difficult. Stereotactic biopsy and drainage of space-occupying abscesses of the brainstem should be considered especially in cases of rapid clinical deterioration. We successfully performed stereotactic biopsy and drainage of a listerial brainstem abscess in a 42-year-old male patient who deteriorated despite antibiotic treatment, demonstrating that this approach is suitable in such patients.

Deep brain stimulation of the lateral habenular complex in treatment-resistant depression: traps and pitfalls of trajectory choice

BACKGROUND

Deep brain stimulation (DBS) has recently been discussed as a promising treatment option for severe cases of major depression. Experimental data have suggested that the lateral habenular complex (LHb-c) is a central region of depression-related neuronal circuits. Because of its location close to the midline, stereotactic targeting of the LHb-c presents surgeons with distinct challenges.

OBJECTIVE

To define the obstacles of DBS surgery for stimulation of the LHb-c and thus to establish safe trajectories.

METHODS

Stereotactic magnetic resonance imaging data sets of 54 hemispheres originating from 27 DBS patients were taken for analysis on a stereotactic planning workstation. After alignment of images according to the anterior commissure--posterior commissure definition, analyses focused on vessels and enlarged ventricles interfering with trajectories.

RESULTS

As major trajectory obstacles, enlarged ventricles and an interfering superior thalamic vein were found. A standard frontal trajectory (angle > 40° relative to the anterior commissure--posterior commissure in sagittal images) for bilateral stimulation was safely applicable in 48% of patients, whereas a steeper frontal trajectory (angle <40 relative to the anterior commissure--posterior commissure in sagittal images) for bilateral stimulation was possible in 96%. Taken together, safe bilateral targeting of the LHb-c was possible in 98% of all patients.

CONCLUSION

Targeting LHb-c is a feasible and safe technique in the majority of patients undergoing surgery for DBS. However, meticulous individual planning to avoid interference with ventricles and thalamus-related veins is mandatory because an alternative steep frontal entry point has to be considered in about half of the patients.

One ring to rule them all?--Temporospatial specificity of deep brain stimulation for treatment-resistant depression

Deep brain stimulation (DBS) for intractable cases of depression has emerged as a valuable therapeutic option during the last decade. While several locations have been intensely investigated in recent years, the literature is lacking an all-encompassing perspective thereupon asking if and how these stimulation sites relate to each other and what this may imply for the underlying mechanisms of action of this treatment modality. We aim at proposing a model of DBS mechanism of action with particular focus on several puzzling aspects regarding an apparent temporo-spatial specificity of antidepressant action, i.e. the discrepancy between protracted response after initiation of stimulation and rapid relapse upon discontinuation, as well as differential effects on psychopathology. We suggest that the pre-treatment depressive state is determined by the interaction of individual traits with dysfunctional adaptive processes as responses to stress, resulting in a disease-associated, overtly dysfunctional, equilibrium. The antidepressant action of DBS is thought to modify and re-set this equilibrium in a temporospatially distinct manner by influencing the activity states of two different brain circuitries. The idea of sequential and temporospatially distinct mechanisms of action bears implications for the assessment of psychopathology and behavior in clinical and preclinical studies as well as investigations into brain circuit activity states.

Brain tissue oxygen monitoring and hyperoxic treatment in patients with traumatic brain injury

Cerebral ischemia is a well-recognized contributor to high morbidity and mortality after traumatic brain injury (TBI). Standard of care treatment aims to maintain a sufficient oxygen supply to the brain by avoiding increased intracranial pressure (ICP) and ensuring a sufficient cerebral perfusion pressure (CPP). Devices allowing direct assessment of brain tissue oxygenation have showed promising results in clinical studies, and their use was implemented in the Brain Trauma Foundation Guidelines for the treatment of TBI patients in 2007. Results of several studies suggest that a brain tissue oxygen-directed therapy guided by these monitors may contribute to reduced mortality and improved outcome of TBI patients. Whether increasing the oxygen supply to supraphysiological levels has beneficial or detrimental effects on TBI patients has been a matter of debate for decades. The results of trials of hyperbaric oxygenation (HBO) have failed to show a benefit, but renewed interest in normobaric hyperoxia (NBO) in the treatment of TBI patients has emerged in recent years. With the increased availability of advanced neuromonitoring devices such as brain tissue oxygen monitors, it was shown that some patients might benefit from this therapeutic approach. In this article, we review the pathophysiological rationale and technical modalities of brain tissue oxygen monitors, as well as its use in studies of brain tissue oxygen-directed therapy. Furthermore, we analyze hyperoxia as a treatment option in TBI patients, summarize the results of clinical trials, and give insights into the recent findings of hyperoxic effects on cerebral metabolism after TBI.

Effects of lisuride hydrogen maleate on pericontusional tissue metabolism, brain edema formation, and contusion volume development after experimental traumatic brain injury in rats

After traumatic brain injury (TBI), the primary insult is followed by a cascade of secondary events which lead to enlargement of the primary lesion and are potentially amenable to therapeutic intervention. Lisuride is a dopaminergic agonist with additional serotoninergic, adrenergic, and glutamate antagonistic properties. In lack of previous data on lisuride in TBI, and based on well documented changes of dopamine metabolism after TBI, we speculated that lisuride could provide neuroprotection in the acute and post-acute stage of controlled cortical impact (CCI) injury in rats. The effect of varying dosages of lisuride on physiological parameter was investigated. Cerebral microdialysis (CMD) was employed to provide a temporal profile of lactate, pyruvate, glucose and glutamate in the pericontusional brain tissue. Additionally, brain edema formation and the development of contusion volume were assessed. In this study, no effect of treatment was seen on physiological parameters or microdialysis profiling of tissue metabolites. Whereas posttraumatic increase in brain water content and an increase in contusion volume could be observed, there was no significant effect of treatment. Taken together, our results suggest that lisuride does not provide neuroprotection in the CCI model at the acute and subacute stages. Based on the available literature, however, it might be possible that dopamine agonists such as lisuride, respectively, improve outcome in terms of cognitive function in a chronic setting.

Cerebral microdialysis in acutely brain-injured patients with spreading depolarizations

Multimodal cerebral monitoring was utilized to examine the relationship between pathological changes in microdialysis parameters and the occurrence of spreading depolarizations (SD) in brain-injured patients. SD are a relatively newly discovered phenomenon in man found to be linked to secondary insults and infarct growth and they can be detected via electrocorticography (ECoG). A total of 24 brain-injured patients (mean age: 52±11 years) requiring craniotomy took part in this prospective observational study. Each patient was monitored with a linear strip electrode for ECoG data and a cerebral microdialysis probe. SD were detected in 13 of the 24 patients. Pathological concentrations of glucose and lactate in brain parenchyma were significantly correlated with various time points prior to and/or immediately following the SD. Severe systemic hyperglycemia and systemic hypoglycemia were also found to be correlated with the occurrence of SD. The present study shows a clear relationship between SD and pathological changes in cerebral metabolism; further studies are needed to elucidate these complex interactions with the ultimate goal of developing therapeutic strategies for improving outcome in brain-injured patients.

Anticonvulsive effects of the dopamine agonist lisuride maleate after experimental traumatic brain injury

Traumatic brain injury is a heterogeneous disease, encompassing a wide range of pathologies. The dopamine agonist lisuride is well established in the therapy of Parkinson's disease. Additionally to its dopaminergic effects it decreases prolactine release, reducing the amount of inflammatory mediators such as TNF-alpha or Il-6. Lisuride has strong binding affinity to serotonergic and histaminergic receptors on neuronal and glial cells leading to scavenging of highly reactive free radicals. Due to its interaction with dopaminergic D2 and D4 receptors as well as 5-HT-1A receptors, NMDA-receptor signaling and glutamate-mediated excitotoxicity can be modulated beneficially. Despite of these promising neuroprotective effects, experimental data scrutinizing the effects of lisuride after acute brain injury are sparse. We therefore investigated the effect of lisuride after controlled cortical impact injury (CCII) in rats. 70 male Sprague-Dawley rats were randomized to lisuride or to placebo treatment by an initial s.c. loading dose (0.3mg/kg BW) and following continuous application (0.5mg/kg/d) by s.c. implanted osmotic pumps. In three experimental groups we determined (sub)acute neuro-physiological changes after trauma. Mean arterial blood pressure, intracranial pressure, and electrical brain activity were monitored acutely for up to 3h after trauma. Brain edema formation was assessed 24h after CCII. Furthermore, contusion volumes were quantified by magnetic resonance tomography and neurological testing was performed for up to 7 days after injury. Associated with the administration of lisuride there was a significant reduction in duration and number of post-traumatic seizures. Despite of a sustained arterial hypotension following the initial bolus administration in the treatment group, contusion volumes and neurological function tests did not differ significantly in comparison to the control group. Overall, lisuride seems to have significant anticonvulsive effects but seems not to influence secondary brain damage in this experimental model.

[Intracranial pressure-volume relationship. Physiology and pathophysiology]

Posttraumatic increase of intracranial pressure (ICP) is a strong prognostic factor for the outcome of patients after traumatic brain injury. After exhausting all compensatory mechanisms ICP increases exponentially, where ICP(norm)=(CSF production*CSF flow resistance)+venous pressure((sinus sagittalis))=10-15 mmHg. The ICP curve is influenced by the compliance (DeltaV/DeltaP) and elasticity (DeltaP/DeltaV) of the brain. Marmarou could demonstrate that the non-linear cranio-spinal pressure-volume relationship describes a logarithmic, mono-exponential, strongly linear relationship between pressure and volume and named this the pressure volume index (PVI=log ICP/DeltaV). The pressure volume index describes the volume necessary to increase ICP by a factor of 10. Additionally to PVI the measurement of volume-pressure response (VPR) was introduced. The continuous intracranial compliance could be determined on the principle of pulsatile volume increases as an equivalent of very small intra-cranial volume increases. However, to ascertain functional status of the injured brain a combination of measurements of different parameters, such as tissue oxygen partial pressure (p(ti)O2), cerebral blood flow (CBF), microdialysis and electrocorticography (ECoG) is recommended.

Preliminary evidence that ketamine inhibits spreading depolarizations in acute human brain injury

BACKGROUND AND PURPOSE

Spreading depolarizations, characterized by large propagating, slow potential changes, have been demonstrated with electrocorticography in patients with cerebral hemorrhage and ischemic stroke. Whereas spreading depolarizations are harmless under normal conditions in animals, they cause or augment damage in the ischemic brain. A fraction of spreading depolarizations is abolished by N-methyl-d-aspartate receptor antagonists. Summary of Case- In 2 patients with severe acute brain injury (traumatic and spontaneous intracranial hemorrhage), spreading depolarizations were inhibited by the noncompetitive N-methyl-d-aspartate receptor antagonist ketamine. This restored electrocorticographic activity.

CONCLUSIONS

These anecdotal electrocorticographic findings suggest that ketamine has an inhibitory effect on spreading depolarizations in humans. This is of potential interest for future neuroprotective trials.

Transorbital penetrating head injury by a toilet brush handle

BACKGROUND

Transorbital penetrating brain injuries are rare lesions without defined therapy standards.

CLINICAL PRESENTATION AND INTERVENTION

A male patient presented at our institution with a toilet brush handle in the right cerebral hemisphere. CT imaging identified the object entering the right orbit and having crossed the right hemisphere in the ventricular plane. After performing a medium-sized craniotomy, the object was removed step-by-step under monitoring with an intraoperative CT scan to ensure no involving major hemorrhage.

CONCLUSION

Transorbital penetrating brain injuries are treated best by utilizing all up-to-date technical developments such as intraoperative CT-scanning to increase the safety in the management of such exceptional lesions with increased risk of immediate life-threatening intracranial bleeding.

[Classification and therapy of craniocerebral injury (CCI)]

In spite of great success in research severe traumatic brain injury (TBI) remains the most frequent cause for morbidity and mortality in the age < 45 years. The primary lesion emerges at the moment of trauma. Due to several pathophysiological mechanisms secondary lesions occur that enlarge size of contusions significantly. As a consequence of intracranial bleedings and brain edema intracranial pressure (ICP) increases and threaten the patient. Extent of severity (declared in Glasgow Coma Scale Score [GCS]), expansion and type of bleedings (acute and chronic subdural hemorrhage, epidural bleeding, contusion bleedings and intracerebral hemorrhage) determinate operative and conservative therapy as well as intensive care medicine. A specific feature represents frontobasal lesions that, apart of penetrating injuries, are treated interdisciplinary not before ICP is stable, brain edema declining and coagulation sufficient several days after trauma. A persisting rhinoliquorrhoe cause meningitis up to 85 % within 10 years. Patient with GCS < 8 have to be intubated and controlled ventilated. Basic monitoring does not differ from those of other patients treated at the intensive care ward (sufficient breathing [pO (2), pCO (2)], arterial blood pressure, CBC and coagulation parameters, fluid monitoring and nutrition). Additionally, ICP have to be measured and be treated corresponding to the algorithm of ICP treatment. Complementary, oxygen saturation of brain tissue (ptiO (2)), local cerebral blood flow (r-CBF) and cerebral metabolism (micro dialysis) can be measured. Just the combination of the single monitoring parameters gives evidence of the functional condition of the injured brain and relieved planning and performing of the appropriate therapy.

Thirty days complication rate following surgery performed for deep‐brain‐stimulation

Serious adverse events (SAEs) during the first 30 postoperative days after stereotactic surgery for Deep-Brain-Stimulation performed in 1,183 patients were retrospectively collected from five German stereotactic centers. The mortality rate was 0.4% and causes for death were pneumonia, pulmonary embolism, hepatopathy, and a case of complicated multiple sclerosis. The permanent surgical morbidity rate was 1%. The most frequently observed SAEs were intracranial hemorrhage (2.2%) and pneumonia (0.6%). Skin infection occurred in 5 of 1,183 patients (0.4%). Surgical complications caused secondary AEs (e.g. pneumonia) preferentially in older patients and in patients treated for Parkinson's disease (PD). Complication rates did not differ among the five centers.

Effects of Mannitol Bolus Administration on Intracranial Pressure, Cerebral Extracellular Metabolites, and Tissue Oxygenation in Severely Head-Injured Patients

BACKGROUND

Osmotic agents are widely used to lower elevated intracranial pressure (ICP). However, little data are available regarding cerebral oxygenation and metabolism in the traumatized brains studied under clinical conditions. The present prospective, open-labeled clinical study was designed to investigate whether administration of mannitol, with the aim of reducing moderate intracranial hypertension, improves cerebral metabolism and oxygenation in patients after severe traumatic brain injury (TBI).

METHODS

Multimodal cerebral monitoring (MCM), consisting of intraparenchymal ICP, tissue oxygenation (ptiO2), and micro dialysis measurements was initiated in six male TBI patients (mean age 45 years; Glasgow Coma Scale score <9). A total of 14 mannitol boli (20%, 0.5g/kg, 20 minutes infusion time) were administered to treat ICP exceeding 20 mm Hg (2.7 kPa). Temporal alterations determined by MCM after mannitol infusions were recorded for 120 minutes. Microdialysates were assayed immediately for extracellular glucose, lactate, pyruvate, and glutamate concentrations.

RESULTS

Elevated ICP was successfully treated in all cases. This effect was maximal 40 minutes after start of infusion (25 +/- 6 mm Hg [3.3 +/- 0.8 kPa] to 17 +/- 3 mm Hg [2.3 +/- 0.4 kPa], p < 0.05) and lasted up to 100 minutes. Cerebral ptiO2 remained unaffected (21 +/- 5 mm Hg [2.8 +/- 0.7 kPa] to 23 +/- 6 mm Hg [3.1 +/- 0.8 kPa], n.s.). Microdialysate concentrations of all analytes rose unspecifically by 10% to 40% from baseline, reaching maximum concentrations 40 to 60 minutes after start of the infusion.

CONCLUSIONS

Mannitol efficiently reduces increased ICP. At an ICP of up to 30 mm Hg [4 kPa] it does not affect cerebral oxygenation. Unspecific increases of extracellular fluid metabolites can be explained by transient osmotic dehydration. Additional mechanisms, such as increased cerebral perfusion and blood volume, might explain an accelerated return to baseline.

Granulocyte colony-stimulating factor does not affect contusion size, brain edema or cerebrospinal fluid glutamate concentrations in rats following controlled cortical impact

INTRODUCTION

Granulocyte colony-stimulating factor (G-CSF) is an established treatment in the neutropenic host. Usage in head-injured patients at risk for infection may aggravate brain damage. In contrast, evidence of G-CSF neuroprotective effects has been reported in rodent models of focal cerebral ischemia. We investigated effects of G-CSF in acute focal traumatic brain injury (TBI) in rats.

METHODS

Thirty-six male Sprague-Dawley rats were anesthetized with 1.2%) to 2.0% isoflurane and subjected to controlled cortical impact injury (CCII). Thirty minutes following CCII, either vehicle or G-CSF was administered intravenously. Animals were sacrificed 24 hours following CCII. Glutamate concentrations were determined in cisternal cerebrospinal fluid (CSF). Brain edema was assessed gravimetrically. Contusion size was estimated by 2,3,5-triphenyltetrazolium chloride staining and volumetric analysis.

RESULTS

Dose-dependent leukocytosis was induced by infusion of G-CSF. Physiological variables were unaffected. Water content of the traumatized hemisphere and CSF glutamate concentrations were unchanged by treatment. Contusion volume was similar in all groups.

CONCLUSIONS

A single injection of G-CSF did not influence cortical contusion volume, brain edema, or glutamate concentrations in CSF determined 24 hours following CCII in rats. G-CSF, administered 30 minutes following experimental TBI, failed to exert neuroprotective effects.

Contemporary Management of Aneurysmal Subarachnoid Hemorrhage in Germany: Results of a Survey among 100 Neurosurgical Departments

OBJECTIVE

To assess the status quo of clinical management in patients with ruptured intracranial aneurysms in Germany. In addition to preferences in vascular treatment (i.e., surgical versus endovascular), the choice of diagnostics and treatment options in the pre- and postprocedural phase is emphasized.

METHODS

A standardized questionnaire was used in a postal survey. Participants were representatives of neurosurgical departments in Germany (n = 130, total number of departments). Comparisons between groups of respondents were tested using chi statistics (Fisher's exact test, two-sided).

RESULTS

The overall response rate was 77% (n = 100). Preoperative assessment is standard by computed tomography and conventional angiography. Currently, endovascular treatment options are available in 71% of all responding centers. On the basis of self estimates it is projected that 63% of all ruptured aneurysms are treated surgically, whereas 37% are treated endovascularly. For anterior circulation aneurysms, a significantly higher number of respondents commit to routine or frequent use of surgical techniques compared with endovascular treatment options (93 versus 52%, P < or = 0.05). In contrast, for posterior circulation aneurysms, endovascular treatment is preferred (24 versus 94%, P < or = 0.05). Acute posthemorrhagic hydrocephalus is treated by external ventricular drainage routinely (97%). Doppler sonography, monitoring of cerebral perfusion pressure, and electrophysiology are used by a significant number of respondents. Specific treatment of subarachnoid hemorrhage (SAH) patients includes calcium antagonists (70%), glucocorticosteroids (35%), and hemorheologic agents (30%).

CONCLUSION

In Germany, aneurysmal subarachnoid hemorrhage remains a disease in which standardization of clinical management is highest in preoperative diagnostics, intensive care unit monitoring, and postoperative treatment. With respect to currently published guidelines for subarachnoid hemorrhage treatment, compliance is moderate. Preferred treatment for anterior circulation aneurysms is predominantly surgical, whereas endovascular treatment options are preferentially used in aneurysms of the posterior circulation. This survey serves as a basis to analyze future developments in the management of subarachnoid hemorrhage more effectively and as an aid in finding a consensus in treatment both nationally and internationally.

Neurochemical monitoring of glycerol therapy in patients with ischemic brain edema

BACKGROUND AND PURPOSE

Osmotic agents such as glycerol are used to treat brain edema in stroke patients. We investigated the pharmacokinetics of glycerol in brain tissue by cerebral microdialysis.

METHODS

Patients experiencing large middle cerebral artery infarction were included in this prospective study. The following variables were assessed before and every 10 minutes until 80 minutes after intravenous administration of 25 g of glycerol: intracranial pressure (ICP), serum osmolarity, and cerebral microdialysate concentrations of glycerol, glutamate, pyruvate, and lactate.

RESULTS

During 16 ICP crises in 7 patients, cerebral glycerol concentrations (baseline 73.9+/-17.0 micromol/L) increased immediately after glycerol administration by up to 350%. Conversely, ICP (baseline 25+/-2.4 mm Hg) rapidly decreased by almost 50%. Both effects lasted for 70 minutes. Serum osmolarity (baseline 305+/-5.6 mOsm/L) was only briefly raised, whereas glutamate, lactate, and pyruvate remained unaffected.

CONCLUSIONS

Treatment of stroke patients with intravenous glycerol has only a brief effect on plasma osmolarity, but a more sustained effect on ICP, which is, however, accompanied by a rapid glycerol accumulation in brain tissue.

Current Concepts in Diagnosis and Treatment of Traumatic Brain Injury: Implications for Healthcare in Nepal

Taumatic brain injury (TBI) is a leading cause of disability and death in the industrialized and in the developing world. With an incidence of 200-400 cases per 100.000, head injuries are a major contributor to socio-economic costs. The 20% suffering from severe head injury (SHI) requiring prolonged intensive care and/or neurosurgical intervention are of particular interest to specialist practitioners from multiple disciplines.This review covers the current concepts of diagnosis and treatment in these patients in the Western world, i.e. mainly the US and Western Europe. Special emphasis is laid upon evidence-based guidelines established during the last decade. Comparison is drawn to the current status of trauma care in Nepal.Management strategies for TBI can not be applied to Nepalese healthcare entirely. Effective management of head injured persons in Nepal is affected by its difficult geographical location, unavailability of trained personnel in the field, and difficulty in transporting the patients due to the lack of motorable roads. While some of the equipment for the treatment of TBI victims is readily available (e.g. ventricular drainage), others are scarce (e.g. operating room capacity, intensive care facilities) or completely unavailable (e.g. emergency medical service providers, specialized monitoring equipment). Realistic proposals for improvement of the current situation are made. Nepal Journal of Neuroscience, Volume 2, Number 1, 2005, page: 29-51

Assessment of the relationship between age and continuous intracranial compliance

The aim of this open, descriptive and prospective study was to determine if the new monitoring parameter "continuous intracranial compliance (cICC)" decreases with age in patients with traumatic brain injury (TBI). 30 patients with severe and moderate TBI (Glasgow Coma Scale score < or = 10) contributing to a European multicenter study, organized by the Brain-IT group, underwent computerized monitoring of blood pressure, intracranial pressure (ICP), cerebral perfusion pressure and cICC. Regression analyses of individual median ICP and median cICC versus patients' age revealed no significant dependency. Median cICC declined significantly with increasing ICP (when median ICP = 10, 20 and 30 mmHg, cICC = 0.64, 0.56 and 0.42 ml/mmHg respectively, p < 0.05). These three ICP groups were then subdivided according to age (0-20, 21-40, 41-60 and 61-80 years). Median cICC declined with age in both high ICP groups (median ICP = 20,30 mmHg). Percentage cICC values below a set pathological threshold of lower than 0.05 ml/mmHg across the four age groups were 28% (0-20 yrs), 59% (21-40 yrs), 60% (41-60 yrs) and 70% (61-80 yrs) respectively. The observed phenomenon of decreased intracranial volume challenge compensation with advancing age may contribute to the well-known fact of a worse outcome in elderly patients after TBI.

Neuromonitoring: brain oxygenation and microdialysis

Patients with cerebral lesions run a high risk of developing cerebral hypoxic and ischemic damage due to secondary insults. To minimize the risk of secondary cerebral hypoxia and ischemia, new monitoring techniques of cerebral oxygenation and metabolism have been developed and may help to understand the pathophysiology of secondary brain damage for a better treatment and outcome in critical patients. Cerebral microdialysis is a relatively new technique for measuring brain molecules of the extracellular space. The technical aspects, the interpretation of the commonly measured parameters, the use of the two commonly used oxygenation parameters (jugular venous oxygen saturation and monitoring of brain tissue PO(2) and the microdialysis technique to monitor cerebral metabolism in patients with head injury), subarachnoid hemorrhage, and ischemic stroke are considered. Pitfalls of the techniques and their future potential are discussed.

Edema and brain trauma

Brain edema leading to an expansion of brain volume has a crucial impact on morbidity and mortality following traumatic brain injury (TBI) as it increases intracranial pressure, impairs cerebral perfusion and oxygenation, and contributes to additional ischemic injuries. Classically, two major types of traumatic brain edema exist: "vasogenic" due to blood-brain barrier (BBB) disruption resulting in extracellular water accumulation and "cytotoxic/cellular" due to sustained intracellular water collection. A third type, "osmotic" brain edema is caused by osmotic imbalances between blood and tissue. Rarely after TBI do we encounter a "hydrocephalic edema/interstitial" brain edema related to an obstruction of cerebrospinal fluid outflow. Following TBI, various mediators are released which enhance vasogenic and/or cytotoxic brain edema. These include glutamate, lactate, H(+), K(+), Ca(2+), nitric oxide, arachidonic acid and its metabolites, free oxygen radicals, histamine, and kinins. Thus, avoiding cerebral anaerobic metabolism and acidosis is beneficial to control lactate and H(+), but no compound inhibiting mediators/mediator channels showed beneficial results in conducted clinical trials, despite successful experimental studies. Hence, anti-edematous therapy in TBI patients is still symptomatic and rather non-specific (e.g. mannitol infusion, controlled hyperventilation). For many years, vasogenic brain edema was accepted as the prevalent edema type following TBI. The development of mechanical TBI models ("weight drop," "fluid percussion injury," and "controlled cortical impact injury") and the use of magnetic resonance imaging, however, revealed that "cytotoxic" edema is of decisive pathophysiological importance following TBI as it develops early and persists while BBB integrity is gradually restored. These findings suggest that cytotoxic and vasogenic brain edema are two entities which can be targeted simultaneously or according to their temporal prevalence.

Continuous monitoring of intracranial compliance after severe head injury: relation to data quality, intracranial pressure and brain tissue PO2

The objective of the present study was to test the new continuous intracranial compliance (cICC) device in terms of data quality, relationship to intracranial pressure (ICP) and brain tissue oxygenation (PtiO2). A total of 10 adult patients with severe traumatic brain injury underwent computerized monitoring of arterial blood pressure, ICP, cerebral perfusion pressure, end-tidal CO2, cICC and PtiO2 providing a total of 1726 h of data. (1) The data quality assessed by calculating the 'time of good data quality' (TGDQ, %), i.e. the median duration of artefact-free time as a percentage of total monitoring time reached 98 and 99% for ICP and PtiO2, while cICC measurements were free of artefacts in only 81%. (2) Individual regression analysis showed broad scattered correlation between cICC and ICP ranging from low (r = 0.05) to high (r = 0.52) correlation coefficients. (3) From 225 episodes of increased ICP (ICP > 20 mmHg > 10 min), only 37 were correctly predicted by a preceding decline in cICC to pathological values (< 0.5 ml/mmHg). (4) In all episodes of cerebral hypoxia (PtiO2 < 10 mmHg > 10 min), cICC was not pathologically altered. Based on the present results, we conclude that the current hardware and software version of the cICC monitoring system is unsatisfactory concerning data quality, prediction of increased ICP and revelance of cerebral hypoxic episodes.

Metabolic changes during impending and manifest cerebral hypoxia in traumatic brain injury

The objective was to measure metabolic changes monitored by bedside microdialysis during impending and manifest hypoxia in traumatic brain injury. In 41 patients, a PtiO2-catheter (Licox; 1/min) was placed into non-lesioned frontal white matter together with a microdialysis catheter (CMA, hourly). Data were analysed for identification of episodes of impending (PtiO2 < 10 - 15 mmHg > 5 min) and manifest cerebral hypoxia (PtiO2 < 10 mmHg, > 5 min). In 69% of patients hypoxic episodes occurred, most frequently associated with hyperventilation (p < 0.001). During impending hypoxia, glutamate was increased (p = 0.03), while the energy metabolites remained stable. Manifest hypoxia was reflected by significant increases of glutamate (p = 0.007) and lactate (p = 0.044), but normal lactate-pyruvate ratios. We conclude that hyperventilation had a potential adverse effect on cerebral metabolism and was most frequently associated with cerebral hypoxia. A PtiO2 < 10 mmHg can induce metabolic changes with increase of glutamate and lactate. The presence of anaerobic cerebral metabolism probably depends on duration and severity of the hypoxic episode.

Intracranial compliance as a bed-side monitoring technique in severely head-injured patients

A recently developed monitoring technology makes an on-line assessment of intracranial compliance (ICC) possible. Aims of our research: 1. Course and values of ICC (critical threshold: < 0.5 ml/mmHg) in episodes of pathological intracranial pressure (ICP) (> 20 mmHg) and reduced cerebral oxygenation (brain tissue PO2 (PtiO2) < 10 mmHg). 2. Mean ICC in different ages. 3. Relationship between ICC and outcome. 4. Evaluation of ICC as routine monitoring parameter by calculation of s.c. time-of-good-data-quality (TGDQ). Computer data assessment of 7 patients with severe closed head-injury was performed providing 830 hours of data. TGDQ resulted from the formula: TGDQ (%) = artifact free time (min) x 100 (%)/total monitoring time (min). Outcome was assessed 6 months posttrauma (Glasgow Outcome Score (GOS). 1. Analysis revealed 43 episodes of pathologically elevated ICP and 39 of critical ICC. In 17 cases overlapping periods were found. In 9 of these ICC preceded ICP. Reduced cerebral oxygenation was neither related with high ICP nor low ICC. 2. ICC was found to be age-related. At a cut-off-point of 20 mmHg in ICP, ICC in children (< or = 16 years) was 0.9, in adults (17-60 years) 0.7 and in elderly (> 60 years) 0.6 ml/mmHg. 3. Adverse outcome was indicated best by high ICP (up to 45% of monitoring time) followed by low ICC (up to 41% of monitoring time). 4. TGDQ in ICC was 72% compared to 95% in ICP and 98% in PtiO2. In predicting adverse outcome, ICP was equal to ICC. The different ICC in each age class points to the need of age-adjusted thresholds. Further refinements of ICC technology are needed to improve ICC data quality and therefore become a useful tool in neuromonitoring.

Decreased hemispheric Aquaporin-4 is linked to evolving brain edema following controlled cortical impact injury in rats

The cerebral Aquaporin-4 (AQP4) water channel is suggested to be involved in brain edema formation aggravated by reduced cerebral blood flow early after traumatic brain injury (TBI). Therefore, the temporal profile of brain edema formation, AQP4 expression, and cortical perfusion were investigated following focal TBI in rats. Brain edema was maximal by 24 h. Concurrently, AQP4 protein expression was decreased in both hemispheres, being more pronounced in the traumatized hemisphere (-50%) 48 h after trauma. Cortical perfusion was only decreased in the ipsilateral cortex (-40%) between 4 and 8 h after trauma, reaching baseline values at 24 h. Globally reduced AQP4 expression following induction of a focal contusion coincides with edema development and seems to be independent of changes in cortical perfusion.

Bedside microdialysis: a tool to monitor cerebral metabolism in subarachnoid hemorrhage patients?

OBJECTIVE

To analyze the time course and changes of cerebral microdialysis parameters after aneurysmal subarachnoid hemorrhage (SAH) in respect to the clinical course (asymptomatic, delayed, and acute ischemic neurologic deficits) to evaluate the method of bedside microdialysis in these patients.

DESIGN

Prospective, controlled study during a 3-yr period.

SETTING

Neurosurgical intensive care unit at a primary level university hospital, supervised and staffed by members of both the department of neurosurgery and the department of anesthesiology and intensive care medicine.

PATIENTS

Ninety-seven patients (51 females/21 males; 52 +/- 13 yrs; World Federation of Neurological Surgeons Scale grades 0-5) after aneurysmatic SAH.

MEASUREMENTS AND MAIN RESULTS

A microdialysis catheter (CMA 100) was inserted into the region most likely to be affected by vasospasm directly after aneurysm clipping, connected to a pump, and perfused with Ringer solution (0.3 microL/min). The dialysates were collected hourly and analyzed at the bedside for glucose, lactate, lactate-pyruvate ratio, glutamate, and glycerol (CMA 600). Patients were classified according to clinical presentation as being asymptomatic or having acute (AIND) or delayed (DIND) ischemic neurologic deficits. DIND patients (n = 18) had significantly higher lactate and glutamate concentrations on days 1-8 post-SAH and a higher lactate-pyruvate ratio on days 3-8 post-SAH compared with asymptomatic patients (n = 57; p <.025). Glucose and glycerol levels did not differ in asymptomatic and DIND patients. AIND patients (n = 22) had the worst metabolic pattern: the extracellular glucose concentration was low, whereas the lactate, lactate-pyruvate ratio, glutamate, and glycerol levels were significantly elevated compared with asymptomatic and DIND patients. In 83% of the DIND patients, the changes in metabolites indicative of cerebral ischemia preceded the onset of symptomatic vasospasm. All DIND patients clinically improved in their Glasgow Coma Scale scores with induced hypertension, intentional hypervolemia, and/or hemodilution therapy (p =.01).

CONCLUSION

Cerebral bedside microdialysis is a safe and promising technique for monitoring (impending) regional cerebral ischemia. The dialysate changes can indicate early the onset of delayed neurologic deterioration and are in good accordance with the clinical course of SAH patients. In the future, this technique may be used to monitor the efficacy of the intensive care therapy of these patients.

Influence of hyperventilation on brain tissue-PO2, PCO2, and pH in patients with intracranial hypertension

A harmful effect of prolonged hyperventilation on outcome has been shown in comatose patients after severe head injury. The purpose of this study was to assess the acute effect of moderate hyperventilation for treatment of intracranial hypertension (ICP < 20 mmHg) on invasively measured brain tissue-PO2 (PtiO2), PCO2 (PtiCO2) and pH (tipH) in severely head injured patients. 15 severely head injured patients (GCS < or = 8) were prospectively studied. Intracranial pressure (ICP), mean arterial blood pressure (MABP), cerebral perfusion pressure (CPP), endtidal CO2 (ETCO2), PtiO2, PtiCO2 and tipH (Paratrend or Licox microsensors) were continuously recorded using multimodal monitoring. Following a baseline period of 15 minutes, patients were hyperventilated for 10 minutes. Arterial blood gas analysis was done before, during and after hyperventilation. At least three hyperventilation maneuvers were performed per patient. For statistical analysis the Friedman test was used. Hyperventilation (paCO2: 32.4 +/- 0.6 to 27.7 +/- 0.5 mmHg) significantly reduced ICP from 25.3 +/- 1.5 to 14.2 +/- 1.9 mmHg (p < 0.01). As a consequence, CPP increased by 9.6 +/- 3.4 mmHg to 76.8 +/- 3.2 mmHg. Brain tissue PCO2 decreased from 37.5 +/- 1.3 to 34.6 +/- 1.2 while tipH increased from 7.13 to 7.16. In all patients, hyperventilation led to a reduction of brain tissue PO2 (PtiO2/Licox: 24.6 +/- 1.4 to 21.9 +/- 1.7 mmHg, n.s.; PtiO2/Paratrend: 35.8 +/- 4.3 to 31.9 +/- 4.0 mmHg, n.s.). In one case hyperventilation even had to be stopped after 7 min because the drop in brain tissue PO2 below 10 mmHg signalized imminent hypoxia. As well known, hyperventilation improves CPP due to a reduction in ICP. However, this does not ameliorate cerebral oxygenation as demonstrated by the decrease in PtiO2. This underlines that hyperventilation should only be used with caution in the treatment of intracranial hypertension.

Bifrontal measurements of brain tissue-PO2 in comatose patients

The purpose of this study was to compare brain tissue-PO2 (PtiO2) in lesioned vs. non-lesioned brain tissue. PtiO2 was monitored bifrontally with a "Clark"-type microcatheter in patients following severe head injury (n = 6) and subarachnoid hemorrhage (SAH) (n = 1) from day 2 to day 12 posttrauma/post SAH. Mean arterial blood pressure, intracranial pressure (ICP), cerebral perfusion pressure and end-tidal CO2 were monitored. Data were stored and analyzed by a multimodal cerebral monitoring system. The CT of five patients was classified as "diffuse injury" and of one patients as "evacuated mass lesion". The patient with SAH (Hunt and Hess IV) had a concomitant intracerebral hematoma which was removed. In all cases, one catheter was placed close to the lesion, while the other was situated in an area with no visible pathology. For analysis, bifrontal PtiO2 data were taken from both on-line monitoring and O2 reactivity tests (FiO2 1.0 for 10 min). Two different patterns were identified: periods of concordance (22% of recordings) and periods in which PtiO2 was lower in lesioned cerebral white matter (78%) but always running parallel. In the latter case, O2-reactivity response was markedly reduced on the lesioned side. Our findings demonstrate a decreased PtiO2 and a reduced O2 reactivity in contused or infarcted brain tissue. Future studies have to clarify which PtiO2 is more important to be used as a guide for therapy.

Monitoring of brain tissue PO2 in traumatic brain injury: effect of cerebral hypoxia on outcome

This study investigates the effect of hypoxic brain tissue PO2 on outcome, and examines the incidence of possible causes for cerebral hypoxia. We studied 35 patients with severe head injury (GCS < or = 8). Age was 33.2 (+/- 11.3) years. Total time of monitoring of PtiO2, intracranial pressure (ICP), cerebral perfusion pressure (CPP), and endtidal PCO2 (ETCO2) was 119.3 (+/- 65.7) hours. Data were continuously recorded by a computer system. Outcome was assessed at discharge and after 6 months post injury. 56% of the patients with more than 300 minutes of PtiO2 < 10 mm Hg died, 22% had an unfavourable outcome, 22% had a favourable outcome. Cerebral hypoxia was associated with intracranial hypertension (ICP > 20 mm Hg) in 11.5 (+/- 15.1)%. CPP was compromised below 60 mm Hg in 16.8 (+/- 23.4)%. Hypocarbia (ETCO2 < 28 mm Hg) was present in 48.0% of the time of PtiO2 < 10 mm Hg. No obvious cause for cerebral hypoxia was found in 45% of the data. These result underscore the association of cerebral hypoxia with poor neurological outcome and stress the meaning of monitoring of PtiO2 as an independent parameter in patients following TBI.

Cerebral oxygenation in contusioned vs. nonlesioned brain tissue: monitoring of PtiO2 with Licox and Paratrend

Brain tissue PO2 in severely head injured patients was monitored in parallel with two different PO2-microsensors (Licox and Paratrend). Three different locations of sensor placement were chosen: (1) both catheters into non lesioned tissue (n = 3), (2) both catheters into contusioned tissue (n = 2), and (3) one catheter (Licox) into pericontusional versus one catheter (Paratrend) into non lesioned brain tissue (n = 2). Mean duration of PtiO2-monitoring with both microsensors in parallel was 68.1 hours. Brain tissue PO2 varied when measured in lesioned and nonlesioned tissue. In non lesioned tissue both catheters closely correlated (delta Licox/Paratrend: mean PtiO2 < 5 mm Hg) after 20 hours post insertion. In pericontusional tissue PtiO2 was reduced relative to non lesioned tissue (delta lesioned/non lesioned: mean PtiO2: 10.3 mm Hg). In contusioned brain tissue PtiO2 was always below the "hypoxic threshold" of 10 mm Hg, independent of the type of microsensor used. During a critical reduction in cerebral perfusion pressure (< 60 mm Hg), PtiO2 decreased measured with both microsensors. Elevation of inspired oxygen fraction, normally followed by a rapid increase in tissue PO2, only increased PtiO2 when measured in pericontusional and nonlesioned brain. To recognize critical episodes of hypoxia or ischemia, PtiO2-monitoring of cerebral oxygenation is recommended in nonlesioned brain tissue.

Decreased soluble adhesion molecule L-selectin plasma concentrations after major trauma

BACKGROUND

Binding of the leukocyte glycoprotein L-selectin to ligands expressed by activated endothelium directs leukocyte recruitment to areas of acute inflammation. Sequestration by activated microvascular endothelium has been proposed to explain the low plasma concentrations of soluble L-selectin (sCD62L) observed early in patients with acute respiratory distress syndrome. We hypothesized that inflammatory endothelial activation may occur in trauma patients, leading to decreased sCD62L plasma concentrations.

METHODS

This study was a prospective analysis of sCD62L plasma concentrations in patients with isolated head injuries and multiple trauma patients without head injuries admitted to two tertiary-level intensive care units. sCD62L plasma concentrations were determined in 18 consecutive adult patients with isolated moderate and severe head injuries and in 13 multiple trauma patients without head injuries immediately upon admission to the intensive care unit and then daily for up to 10 days after trauma.

RESULTS

Compared with healthy adult controls (n=22), patient sCD62L plasma concentrations were significantly decreased upon admission (5.7+/-1.6 vs. 11.0+/-1.7 pmol/mL; p < 0.001). In all patients, sCD62L concentrations remained depressed throughout the study period. sCD62L concentrations did not differ significantly between patients with isolated head injuries and multiple trauma patients without head injuries, although repeated-measures analysis of variance showed significantly more depressed sCD62L concentrations associated with severe (n=14) compared with moderate head injuries (n=4) during the study period (p < 0.05).

CONCLUSION

Patients with major trauma present with a significant reduction of sCD62L plasma concentrations within the first 12 hours after trauma and during subsequent intensive care. This finding suggests widespread microvascular endothelial activation after trauma, which may be associated with increased neutrophil extravasation.

Multimodal cerebral monitoring in comatose head-injured patients

Monitoring of comatose patients in the neurosurgical intensive care unit (NICU) is constantly extended by the development of new methods for monitoring of cerebral function, metabolism and oxygenation. To simplify the interpretation of the rising number of parameters, and to avoid data overflow, a multimodal cerebral monitoring (MCM) system has been developed for the acquisition, display, on-line analysis and recording of physiological parameters from multiple bedside data sources. This article describes the technical details and the design of this computerized data acquisition system for variable applications in clinical patient monitoring and research. A Windows (Microsoft Corporation, Redmont, Washington) platform was equipped with an analog/digital converter board. Software for multimodal cerebral monitoring was developed using LabVIEW for Windows (National Instruments, Austin, Texas), a graphical programming system. Two software modules were created: One for the automatic acquisition of data, display of time dependent trend graphs, processing of on-line histograms, special functions for research, and storage of data in compatible format. The other module serves as an off-line monitor to display recorded data in various modalities. The MCM system has been used in 30 comatose patients with severe head injury. Mean time of MCM is 5.3 days (+/- 2.8 days), resulting in a total running time of the system of about 3800 hrs. Hardware and software proved to run stable and safe. The MCM system has become a valuable tool for monitoring of comatose patients. The simultaneous display of trend graphs of various monitoring parameters and the online processing of histograms improved the survey of the patient's condition in the ICU. Recorded data were analysed offline and contribute to a consecutively increasing data bank.

Characterisation of brain edema following "controlled cortical impact injury" in rats

Significance, origin and nature of posttraumatic brain edema are still being debated. Recently, a "controlled cortical impact injury" (CCII) was introduced to model traumatic brain injury. Purpose of this study was to investigate the development and nature of brain edema following CCII. Traumatic brain injury was applied to the intact dura of the left hemisphere in Sprague-Dawley rats (n = 52, 250-350 g b.w.). Ketamine/xylazine-anesthesia or inhalation-anesthesia were used. A pneumatic impactor with a diameter of 5 mm contused the temporo-parietal cortex with a velocity of 7 m/s and an impact depth of 2 mm. 24 hours post injury the brains were removed. Posttraumatic hemispheric swelling and water content were determined gravimetrically, Evans blue extravasation spectrophotometrically, area and volume of ischemia by staining with TTC. MRI studies were performed with T1-,T2- and diffusion-weighted sequences. Posttraumatic swelling following CCII was 14.3 +/- 3.1%. Brain water content increased to 82.5 +/- 0.5% in lesioned hemisphere compared to 79.9 +/- 0.2% in control hemisphere. Following TTC staining, the average ischemic tissue volume was 56.7 +/- 19.2 mm3. There was a moderate uptake of Evans blue into the lesioned hemisphere. MRI studies demonstrated edema in 35.4 +/- 9.5 mm3 of the lesioned hemisphere. Gd-DTPA was taken up early after trauma only. A significantly decreased ADC (apparent diffusion coefficient) indicates the cytotoxic (ischemic) component of edema in this model. In conclusion, CCII produces significant posttraumatic brain swelling and edema which is both, of vasogenic and cytotoxic nature. Thus, the CCII models the human cortical contusion more appropriately and opens new avenues for therapeutical studies focussing on cortical contusions.

Mannitol decreases ICP but does not improve brain-tissue pO2 in severely head-injured patients with intracranial hypertension

Little is known about the effect of post-traumatic mannitol infusion on cerebral metabolism and oxygenation. The purpose of this study was to investigate the effects of mannitol in comatose patients on PtiO2, PtiCO2 and brain tissue pH using Clark-type electrodes implanted into cerebral white matter. In the neurosurgical intensive care unit PtiO2, PtiCO2, brain tissue pH, arterial blood pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and jugular bulb oxygen saturation (SjvO2) were prospectively studied in eleven patients with severe traumatic brain injury (TBI) during a total of 30 mannitol administrations (125 ml of 20% Mannitol infused over 30 min through a central vein). When the initial ICP before mannitol infusion was below 20 mmHg neither ICP nor any of the other parameters changed significantly during or after mannitol infusion. With a pre-infusion ICP above 20 mmHg a significant effect was seen on ICP (decrease from 23 +/- 1 to 16 +/- 2 mmHg at 60 min) and CPP (increase from 68 +/- 2 to 80 +/- 3 mmHg at 120 min). These effects were not reflected in PtiO2 or SjvO2, which were 29 +/- 4 mmHg and 61 +/- 3%, respectively, at the beginning of mannitol injection and remained unchanged during the observation period. PtiCO2 and brain tissue pH were not affected by mannitol infusion. Future studies should focus on the identification of ICP or CPP thresholds where infusion of mannitol may actually improve O2-supply to the brain.

Effect of tromethamine (THAM) on infarct volume following permanent middle cerebral artery occlusion in rats

This study investigates the influence on tromethamine (THAM) on ischemic volume induced by permanent middle cerebral artery occlusion (MCAO) in rats. 14 male Sprague Dawley rats underwent left sided permanent MCAO by electro coagulation. Animals were treated either by 3-M THAM given intravenously in a single dosage of 0.6 mmol/kg body weight (THAM group: n = 7) 10 min following MCAO and again 1, 2, 3, 4 and 5 hours later or by NaCl 0.9% (placebo group: n = 7) in the same mode. Mean arterial blood pressure (MABP) was monitored for 30 min post MCAO and arterial blood gases were taken 10 min after the first injection. The extent of ischemia volume was assessed by planimetry of coronal sections stained with triphenyl-tetrazolium chloride (TTC) and with hematoxilin/eosin (HE). Tests for significance were accomplished by ANOVA on ranks. A difference of p < 0.05 was considered significant. The THAM group showed an insignificant decrease in MABP 1 min after injection (THAM: 75 +/- 11 mmHg, placebo: 86 +/- 10 mmHg). Arterial pH was significantly different (THAM: 7.46 +/- 0.04; placebo: 7.32 +/- 0.03). In TTC staining, the ischemia volume--given in absolute values and percentage of the total left volume--was significantly reduced in the THAM group (THAM: 43.9 +/- 8.3 mm3/7.0 +/- 1.3%; placebo: 95.2 +/- 13.8 mm3/14.2 +/- 2.0%). In HE staining, the reduction of ischemia, volume did not reach statistical significance (THAM: 49.1 +/- 9.9 mm3/9.6 +/- 1.8%; placebo: 66.3 +/- 14.5 mm3/13.1 +/- 2.8%). Based on these results, a moderate neuroprotective effect of THAM in experimental cerebral infarction could be demonstrated.