The Role of Radiotherapy for Meningeal Melanocytomas - A 20 Year Update

BACKGROUND/AIM

Meningeal melanocytomas are rare tumors of the central nervous system and optimal treatment needs further clarification. This study compared subtotal resection (STR), STR plus radiation therapy (RT), gross total resection (GTR), and GTR+RT to better define the role of postoperative RT.

PATIENTS AND METHODS

All cases reported in the literature were reviewed. Patients (n=184) with complete data were analyzed for local control (LC) and overall survival (OS).

RESULTS

On univariate analysis, GTR (vs. STR) was associated with improved LC (p=0.016). When comparing the treatment regimens, best and worst results were found after GTR+RT and STR alone, respectively (p<0.001). On univariate analysis, GTR resulted in better OS than STR (p=0.041). Moreover, the treatment regimen had a significant impact on OS (p=0.049). On multivariate analyses of LC and OS, extent of resection and treatment regimen were found to be significant factors. After STR, RT significantly improved LC but not OS. After GTR, RT did not significantly improve LC or OS.

CONCLUSION

GTR was significantly superior to STR regarding LC and OS. STR+RT resulted in significantly better LC when compared to STR alone.

Whole-brain Radiotherapy With or Without a Simultaneous Integrated Boost for Treatment of Brain Metastases

BACKGROUND/AIM

Many patients with brain metastases receive whole-brain radiotherapy (WBRT), despite the increasing use of stereotactic radiotherapy alone. A more recent approach includes WBRT combined with simultaneous integrated boost (WBRT+SIB). This study compared WBRT alone and WBRT+SIB for unresected brain metastases.

PATIENTS AND METHODS

One-hundred-and-three patients receiving WBRT+SIB were compared to 275 patients receiving WBRT alone for intracerebral control (IC) and overall survival (OS).

RESULTS

Both treatment groups (WBRT alone and WBRT+SIB) were balanced with respect to patient characteristics. On multivariate analyses, WBRT+SIB (p=0.041), Karnofsky performance score (KPS) >70 (p<0.001), and 1-3 brain metastases (p=0.016) were significantly associated with IC. KPS >70 (p<0.001), favorable tumor type (p=0.011), 1-3 brain metastases (p=0.011), and absence of extracranial metastases (p<0.001) were significantly associated with OS.

CONCLUSION

WBRT+SIB is associated with improved IC but similar OS when directly compared to WBRT for brain metastases. Selected patients with a high risk of intracerebral recurrence may benefit from SIB.

Stereotactic Radiotherapy or Whole-Brain Irradiation Plus Simultaneous Integrated Boost After Resection of Brain Metastases

BACKGROUND/AIM

Most patients with resected brain metastases receive post-operative radiotherapy. This study investigated outcomes of fractionated stereotactic radiotherapy (FSRT) alone or whole-brain irradiation plus simultaneous integrated boost (WBI+SIB) in the post-operative setting.

PATIENTS AND METHODS

Forty-four patients receiving FSRT alone (n=32) or WBI+SIB (n=12) after resection of 1-3 brain metastases from 2014-2022 were analyzed. Twelve factors were evaluated for local control (LC), distant brain control (DBC), and overall survival (OS).

RESULTS

On univariate and multivariate analyses, single brain metastasis was associated with improved LC and DBC. Longer interval between tumor diagnosis and radiotherapy, single brain metastasis, and Karnofsky performance score >80 were associated with improved OS. WBI+SIB showed a trend towards better DBC.

CONCLUSION

Several independent predictors of outcomes after FSRT or WBI+SIB following resection of brain metastases were identified. Given similar survival in the post-operative setting between FSRT and WBI+SIB, potential toxicity remains a significant factor in treatment recommendations.

Cerebral effects of resuscitation with either epinephrine or vasopressin in an animal model of hemorrhagic shock

PURPOSE

The use of epinephrine (EN) or vasopressin (VP) in hemorrhagic shock is well established. Due to its specific neurovascular effects, VP might be superior in concern to brain tissue integrity. The aim of this study was to evaluate cerebral effects of either EN or VP resuscitation after hemorrhagic shock.

METHODS

After shock induction fourteen pigs were randomly assigned to two treatment groups. After 60 min of shock, resuscitation with either EN or VP was performed. Hemodynamics, arterial blood gases as well as cerebral perfusion pressure (CPP) and brain tissue oxygenation (PtiO2) were recorded. Interstitial lactate, pyruvate, glycerol and glutamate were assessed by cerebral and subcutaneous microdialysis. Treatment-related effects were compared using one-way ANOVA with post hoc Bonferroni adjustment (p < 0.05) for repeated measures.

RESULTS

Induction of hemorrhagic shock led to a significant (p < 0.05) decrease of mean arterial pressure (MAP), cardiac output (CO) and CPP. Administration of both VP and EN sufficiently restored MAP and CPP and maintained physiological PtiO2 levels. Brain tissue metabolism was not altered significantly during shock and subsequent treatment with VP or EN. Concerning the excess of glycerol and glutamate, we found a significant EN-related release in the subcutaneous tissue, while brain tissue values remained stable during EN treatment. VP treatment resulted in a non-significant increase of cerebral glycerol and glutamate.

CONCLUSIONS

Both vasopressors were effective in restoring hemodynamics and CPP and in maintaining brain oxygenation. With regards to the cerebral metabolism, we cannot support beneficial effects of VP in this model of hemorrhagic shock.

Cerebral Vasospasm After Spontaneous Subarachnoid Hemorrhage: Angiographic Pattern and Its Impact on the Clinical Course

OBJECTIVE

To analyze angiographic characteristics of cerebral vasospasm (CVS) after spontaneous subarachnoid hemorrhage (sSAH) and their potential impact on secondary infarction and functional outcome.

METHODS

Demographic, clinical, and imaging data of sSAH patients with angiographic CVS admitted over a 6-year period were retrospectively analyzed.

RESULTS

A total of 85 patients were included in the final analysis. A total of 311 arterial territories in 85 angiographies demonstrated angiographic CVS. The anterior cerebral artery (ACA) was the most common site of angiographic CVS (42.1%), followed by the middle cerebral artery (MCA) (26.7%). In 29 angiographies (34%) CVS was found in more than 3 vessels and a bilateral pattern was identified in 53 cases (62%). Older age (OR 3.24 [95% CI 1.30-8.07], P = 0.012) was identified as the only significant risk factor for CVS-related infarction (OR 22.67, P = 0.015). Unfavorable outcome was associated with older age (OR 3.24, P = 0.023) and poor World Federation of Neurosurgical Societies grade (OR 3.64, P = 0.015). Analyses of angiographic characteristics did not reveal any risk factors for unfavorable outcome. We identified distal CVS as a significant risk factor for CVS-related infarction (OR 2.89, P = 0.026).

CONCLUSIONS

Angiographic CVS after sSAH shows a specific distribution pattern in favor of ACA and MCA and in most cases 2-3 affected vessels are affected, often bilaterally. Patients exhibiting distal CVS have a higher risk for CVS-related infarction and should be observed closely. Nonetheless, the majority of angiographic characteristics did not allow conclusions about functional outcome nor the occurrence of CVS-related infarction in sSAH patients.

The Impact of Intrahospital Transports on Brain Tissue Metabolism in Patients with Acute Brain Injury

BACKGROUND

Patients with severe acute brain injury (ABI) often require intrahospital transports (IHTs) for repeated computed tomography (CT) scans. IHTs are associated with serious adverse events (AE) that might pose a risk for secondary brain injury. The goal of this study was to assess IHT-related alterations of cerebral metabolism in ABI patients.

METHODS

We included mechanically ventilated patients with ABI who had continuous multimodality neuromonitoring during an 8-h period before and after routine IHT. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygenation (PtiO₂) as well as cerebral and subcutaneous microdialysis parameters (lactate, pyruvate, glycerol, and glutamate) were recorded. Values were compared between an 8-h period before (pre-IHT) and after (post-IHT) the IHT.

RESULTS

A total of 23 IHT for head CT scans in 18 patients were analyzed. Traumatic brain injury (n = 7) was the leading cause of ABI, followed by subarachnoid hemorrhage (n = 6) and intracerebral hemorrhage (n = 5). The analyzed microdialysis parameters in the brain tissue as in the subcutaneous tissue did not show significant changes between the pre-IHT and post-IHT period. In addition, we observed no significant increase in ICP or decrease in CPP and PtiO₂ in the 8-h period after IHT.

CONCLUSIONS

While the occurrence of AE during IHT is a known risk factor for ABI patients, our results demonstrate that IHTs do not alter the brain tissue chemistry in a significant manner. This fact may help assess the risk for routine IHT more accurately.

The Impact of Extubation Failure in Patients with Good-Grade Subarachnoid Hemorrhage

OBJECTIVE

To analyze the clinical impact of extubation failure (EF) in patients with good-grade subarachnoid hemorrhage (SAH), in whom a good clinical course usually is expected.

PATIENTS AND METHODS

We reviewed the clinical data from 141 patients with SAH and 1) initial Hunt & Hess grade 1-3; 2) induction of general anesthesia for intervention; and 3) the presence of data about the functional outcome. Patients were divided into 3 groups: 1) primary tracheotomized patients (PT); 2) patients with successful extubation (ES); and 3) patients with EF (reintubation within 48 hours).

RESULTS

EF occurred with a rate of 0.12. The leading cause of EF was respiratory insufficiency (n = 7), followed by impaired consciousness (n = 5). Multivariate logistic regression did not show any neurologic predictor of EF. Patients with ES showed an excellent outcome after 6 months (favorable outcome: 95.7%), whereas the outcome of patients with EF and PT was significantly (P < 0.05) poorer. The case fatality rate was nonsignificantly greater in the EF group (0.15 vs. 0.03). Hospitalization was significantly reduced for patients with ES, whereas the occurrence of symptomatic cerebral vasospasms and vasospastic cerebral infarction was similar between patients with EF, ES, or PT.

CONCLUSIONS

We showed that EF is a frequent condition in good grade-SAH but is not predictable using common neurologic parameters. Regarding the functional outcome, we were able to show that the result of an extubation trial clearly delineates the patients in 2 distinct groups, in which ES predicts an excellent outcome.

Safety of Percutaneous Dilatational Tracheostomy in Patients with Acute Brain Injury and Reduced PaO2/FiO2 Ratio-Retrospective Analysis of 54 Patients

OBJECTIVE

Percutaneous dilatational tracheostomy (PDT) is a commonly performed method in neurocritical care, and its safety has been proven in numerous studies. Nevertheless, data regarding the application in patients with acute brain injury and poor respiratory function are poor. The purpose of this study was to evaluate the incidence of hypoxemia and hypercapnia during PDT in those patients.

METHODS

In a retrospective analysis, we acquired data from 54 patients with an acute brain injury (ABI) and a reduced PaO₂/FiO₂ ratio (PaO₂/FiO₂ < 300 mm Hg). In all cases, blood gas analyses before, during, and approximately 12 hours after PDT were available. We reviewed the patients' ventilator settings, results of gas exchange, and radiographic signs of acute respiratory distress syndrome (ARDS). Patients with ARDS were defined using the Berlin criteria.

RESULTS

We observed 2 cases (3.6%) of intraoperative hypoxemia (PaO₂ < 60 mm Hg) and 4 cases (7.4%) of intraoperative hypercapnia (PaCO₂ > 55 mm Hg). Twenty patients fulfilled the Berlin criteria for ARDS. While mean PaO₂ did not differ significantly between ARDS and non-ARDS patients, intraoperative hypoxemia only occurred in the ARDS group (2/20). Mean PaCO₂ was similar in the ARDS and non-ARDS groups, and cases of hypercapnia were apparent in both groups. The mean PaO₂/FiO₂ ratio of all patients improved from 229.1 mm Hg before PDT to 255.3 mm Hg.

CONCLUSIONS

Regarding the intraoperative gas exchange, indication of PDT in patients with ABI and ARDS should be considered carefully. However, PDT in ABI patients with reduced PaO₂/FiO₂ ratio alone appears to be a safe procedure.

Analysis of extracellular brain chemistry during percutaneous dilational tracheostomy: A retrospective study of 19 patients

OBJECTIVE

The purpose of this study was to analyze changes in brain tissue chemistry around percutaneous dilational tracheostomy (PDT) in patients with acute brain injury (ABI) in a retrospective single-center analysis.

PATIENTS AND METHODS

We included 19 patients who had continuous monitoring of brain tissue chemistry and intracranial pressure (ICP) during a 20h period before and after PDT. Different microdialysis parameters (lactate, pyruvate, lactate pyruvate ratio (LPR), glycerol and glutamate) and values of ICP, cerebral perfusion pressure (CPP) and brain tissue oxygenation (PBrO₂) were recorded per hour. Mean values were compared between a 10h period before PDT (prePDT) and after PDT (postPDT).

RESULTS

Mean values of cerebral lactate, pyruvate, LPR, glycerol and glutamate did not differ significantly between prePDT and postPDT. In addition, the rate of patients, which exceeded the known threshold was similar between prePDT and postPDT. Only one patient showed a strong increase of cerebral glycerol during the postPDT period, but analysis of subcutaneous glycerol could exclude an intracerebral event. ICP, CPP and PBrO₂ did not exhibit significant changes.

CONCLUSIONS

We could exclude the occurrence of cerebral metabolic crisis and the excess release of cerebral glutamate and glycerol in a series of 19 patients. Our results support the safety of PDT in patients with ABI.

Isoflurane-Associated Mydriasis Mimicking Blown Pupils in a Patient Treated in a Neurointensive Care Unit

We report a misinterpretation of bilateral mydriasis as blown pupils related to elevated intracranial pressure (ICP) under volatile sedation with isoflurane (Anesthetic Conserving Device [AnaConDa], Hudson RCI, Uppland Vasby, Sweden) in a 59-year-old patient with a severe traumatic brain injury with frontal contusion. The patient showed bilateral mydriasis and a missing light reflex 8 hours after changing sedation from intravenous treatment with midazolam and esketamine to volatile administration of isoflurane. Because cranial computed tomography ruled out signs of cerebral herniation, we assumed the bilateral mydriasis was caused by isoflurane and reduced the isoflurane supply. Upon this reduction the mydriasis regressed, suggesting the observed mydriasis was related to an overdose of isoflurane. Intensivists should be aware of the reported phenomenon to avoid unnecessary diagnostic investigations that might harm the patient. We recommend careful control of the isoflurane dose when fixed and dilated pupils appear in patients without other signs of elevated ICP.

ERG expression in multiple myeloma-A potential diagnostic pitfall

INTRODUCTION

ERG expression has been described as a frequent event in prostate cancer indicating poor prognosis and promoting oncogenesis. It has also been demonstrated in Ewing's sarcoma, acute myeloid leukemia and acute T-lymphoblastic leukemia but could not be found in other epithelial tumors, Hodgkin's or Non-Hodgkin's lymphoma. We aimed to analyze ERG expression in multiple myeloma, following an index case of a patient with metastases of unknown origin in the spine strongly expressing ERG, which were thought to be of prostatic origin but turned out to be plasmacytic lesions.

MATERIAL AND METHODS

We subsequently selected 12 formalin-fixed, paraffin-embedded tissue samples of multiple myeloma from our archives and performed immunohistochemical staining for ERG.

RESULTS

All 12 analyzed cases showed strong nuclear expression of ERG in >90% of tumor cells (myeloma cells).

CONCLUSIONS

This report highlights a potential and critical diagnostic pitfall in biopsy specimens where morphology is only of limited assistance in reaching the correct diagnosis. It urges pathologists to exercise caution in cases where strong ERG-positivity implicates the presence of a prostatic neoplasia and illustrates the need for further immunohistochemical examination.

A New Predictive Tool for Optimization of the Treatment of Brain Metastases from Colorectal Cancer After Stereotactic Radiosurgery

AIM

To develop a predictive tool for survival after stereotactic radiosurgery of brain metastases from colorectal cancer.

PATIENTS AND METHODS

Out of nine factors analyzed for survival, those showing significance (p<0.05) or a trend (p≤0.06) were included. For each factor, 0 (worse survival) or 1 (better survival) point was assigned. Total scores represented the sum of the factor scores.

RESULTS

Performance status (p=0.010) and interval from diagnosis of colorectal cancer until radiosurgery (p=0.026) achieved significance, extracranial metastases showed a trend (p=0.06). These factors were included in the tool. Total scores were 0-3 points. Six-month survival rates were 17% for patients with 0, 25% for those with 1, 67% for those with 2 and 100% for those with 3 points; 12-month rates were 0%, 0%, 33% and 67%, respectively. Two groups were created: 0-1 and 2-3 points. Six- and 12-month survival rates were 20% vs. 78% and 0% vs. 44% (p=0.002), respectively.

CONCLUSION

This tool helps optimize the treatment of patients after stereotactic radiosurgery for brain metastases from colorectal cancer.

Impact of percutaneous dilatational tracheostomy in brain injured patients

OBJECTIVE

Tracheostomy is an established method in the airway management of critically ill patients with traumatic and non-traumatic brain injuries. High priority in the treatment of those patients is to protect vulnerable brain tissue. While bedside percutaneously dilatative tracheostomy (PDT) technique is increasingly used, there is disagreement about the harms of this intervention for the damaged brain. Therefore, discussions about the safety of tracheostomy in those patients must consider direct and indirect cerebral parameters.

METHODS

We examined a series of 289 tracheostomies regarding vital signs, respiratory and intracranial parameters in a retrospective study. Complications were recorded and risk factors for a complicated scenario statistically determined.

RESULTS

Severe complications were rare (1/289). Arterial hypotension occurred in 3 of 289 cases with a systolic blood pressure below 90mmHg. We had two patients (0.5%) with transient hypoxia, but 43 cases (15%) of severe hypercapnia during PDT. Invasive measurement of brain tissue oxygen tension (PBrO2) ruled out any cerebral hypoxia during the procedure in 39 available cases. Intracranial pressure (ICP) rose temporarily in 24% of the cases. Cerebral perfusion pressure (CPP) however remained unaffected. Surgery time and hypercapnia are capable risk factors for intraoperative ICP elevation. There is no significant difference in intraoperative ICP rises between disease entities.

CONCLUSION

PDT is a safe procedure for the most common neurosurgical diseases, even for patients with respiratory insufficiency. Shortening surgical time seems to be the most important factor to avoid ICP increase.

Predicting overall survival in patients with brain metastases from esophageal cancer

AIM

To identify survival predictors and develop a survival score for patients with brain metastases from esophageal cancer.

PATIENTS AND METHODS

In 16 patients, seven factors were analyzed including age, gender, Karnofsky performance score (KPS), time from diagnosis of esophageal cancer to irradiation, number of brain metastases, histology, and presence of extracerebral metastases.

RESULTS

Improved survival was significantly associated with KPS≥80 (p<0.001), the presence of one brain metastasis (p=0.007), and no extra-cerebral metastases (p=0.002). These factors were included in the final score. Factor scores were calculated by dividing 6-month survival rates by 10. Total survival scores represented the sums of factor scores and were 2, 7, 10, 19 or 24 points. Six-month survival rates by score were 0%, 0%, 0%, 67% and 100%, respectively. Two groups were formed, those of patients with 2-10 points and those with 19-24 points; 6-month survival was 0% and 88%, respectively (p<0.001).

CONCLUSION

This new score facilitates the selection of individual therapies for patients with brain metastases from esophageal cancer.

Radiosurgery alone for 1-3 newly-diagnosed brain metastases from melanoma: impact of dose on treatment outcomes

BACKGROUND/AIM

To compare different doses of stereotactic radiosurgery (SRS) for 1-3 newly-diagnosed cerebral metastases from melanoma.

PATIENTS AND METHODS

Fifty-four patients were assigned to dose groups of 20 Gy (N=36) and 21-22.5 Gy (N=18). Variables additionally analyzed were age, gender, Karnofsky Performance Score (KPS), lactate dehydrogenase (LDH) before SRS, number of cerebral lesions, extracranial lesions, time from melanoma diagnosis to SRS.

RESULTS

The 12-month local control was 72% after 20 Gy and 100% after 21-22.5 Gy (p=0.020). Freedom from new cerebral metastases (p=0.13) and survival (p=0.13) showed no association with SRS dose. On multivariate analyses, improved local control showed significant associations with SRS doses of 21-22.5 Gy (p=0.007) and normal lactate dehydrogenase levels (p=0.018). Improved survival was associated with normal LDH levels (p=0.006) and KPS 90-100 (p=0.046).

CONCLUSION

SRS doses of 21-22.5 Gy resulted in better local control than 20 Gy. Freedom from new brain metastases and survival were not significantly different.

Ventriculocisternostomy versus ventriculoperitoneal shunt in the treatment of hydrocephalus: a retrospective, long-term observational study

OBJECTIVE

The goal of this study was the retrospective analysis of long-term data on endoscopic ventriculocisternostomy versus ventriculoperitoneal shunt placement in the treatment of hydrocephalus.

METHODS

A total of 159 patients were included in the study. One hundred and twenty-three patients received a ventriculoperitoneal shunt, whereas 36 patients were treated with an endoscopic procedure. Only patients with a postoperative observation period of at least 3 years were included in the analyses of the long-term data. In addition to general patient and operation data, the number and frequency of perioperative complications (infections, dysfunctions) and the frequency and type of necessary revision operations were collected.

RESULTS

The average observation period was 69 months for both groups. The risk of operative revision was significantly elevated in the shunt group despite a comparable observation period. Whereas 86.11% of the endoscopy group did not require an operative revision, that only applied to 68.85% of the shunt group. The complication rate was 42.7% in the shunt group per procedure, which was clearly higher than in the endoscopy group at only 9.4%.

CONCLUSION

The risk of operative revision and/or complications is significantly lower in the endoscopic ventriculocisternostomy group compared to the ventriculoperitoneal shunt group. Given the appropriate indication, endoscopic ventriculocisternostomy is thus the treatment of choice.

Progression of chronic subdural haematomas in an infant boy after abusive head trauma

Abusive head trauma is a serious form of child abuse that can lead to severe neuropsychological sequelae or death in infants. In questionable cases, without a confession from the caregivers and ambiguous clinical information, evidence for the diagnosis of abusive head trauma is often based on typical patterns that have been observed in neuro-imaging. This study shows the progressive evolution of multifocal chronic subdural haematomas, including re-bleedings, in a case of abusive head trauma in an infant boy who was documented with repeated magnetic resonance imaging. The chronic subdural haematomas occurred during closely monitored in-patient rehabilitative care, and repeated maltreatment did not appear to be likely. Due to excessive growth, neurosurgical intervention with endoscopic craniotomy, evacuation of the subdural haematomas and temporal external cerebrospinal fluid drainage was performed with a favourable recovery. This study discusses the current pathophysiological knowledge concerning the development and clinical course of chronic subdural haematomas and draws relevant conclusions for the clinical practice and psychosocial management of caring for victims of abusive head trauma.

Resection plus whole-brain irradiation versus resection plus whole-brain irradiation plus boost for the treatment of single brain metastasis

BACKGROUND

The optimal treatment for patients with a single brain metastasis is controversial. This study investigated the value of a radiation boost given in addition to neurosurgerical resection and whole-brain irradiation (WBI).

PATIENTS AND METHODS

In this retrospective study, outcome data of 105 patients with a single brain metastasis receiving metastatic surgery plus WBI (S + WBI) were compared to 90 patients receiving the same treatment plus a boost to the metastatic site (S + WBI + B). The outcomes that were compared included local control of the resected metastasis (LC) and overall survival (OS). In addition to the treatment regimen, eight potential prognostic factors were evaluated including age, gender, performance status, extent of metastatic resection, primary tumor type, extracerebral metastases, recursive partitioning analysis (RPA) class, and interval from first diagnosis of cancer to metastatic surgery.

RESULTS

The LC rates at 1 year, 2 years, and 3 years were 38%, 20%, and 9%, respectively, after S + WBI, and 67%, 51%, and 33%, respectively, after S + WBI + B (p = 0.002). The OS rates at 1 year, 2 years, and 3 years were 52%, 25%, and 19%, respectively, after S + WBI, and 60%, 40%, and 26%, respectively, after S + WBI + B (p = 0.11). On multivariate analyses, improved LC was significantly associated with OP + WBI + B (p = 0.006) and total resection of the metastasis (p = 0.014). Improved OS was significantly associated with age ≤ 60 years (p = 0.028), Karnofsky Performance Score > 70 (p = 0.015), breast cancer (p = 0.041), RPA class 1 (p = 0.012), and almost with the absence of extracerebral metastases (p = 0.05).

CONCLUSION

A boost in addition to WBI significantly improved LC but not OS following resection of a single brain metastasis.

Structural brain changes following peripheral vestibulo-cochlear lesion may indicate multisensory compensation

BACKGROUND

Do central mechanisms account for the variability of clinical recovery following peripheral vestibulo-cochlear lesions?

OBJECTIVE

To investigate structural (morphological) plasticity in the human brain following unilateral vestibulo-cochlear lesions which might contribute to central vestibular compensation.

METHODS

The authors compared regional grey matter volume (GMV) changes in patients after surgical removal of unilateral acoustic neuroma with age-matched control subjects, and hypothesised morphometric changes in the vestibular and auditory cortices which may be related to functional disability scores. Patients were examined with a battery of neuro-otological tests and clinical scores to assess vestibular and auditory disability.

RESULTS

Voxel-based morphometry was used for categorical comparison between patients and age- and gender-matched controls. GMV increase was found bilaterally in primary somatosensory cortices and motion-sensitive areas in the medial temporal gyrus (MT). Simple regression analysis revealed a GMV increase (1) in the contralesional superior temporal gyrus/posterior insula to be correlated with decreasing clinically assessed vestibular deficits; (2) in the contralesional inferior parietal lobe with decreasing functional impairment of daily living activities; and (3) in the contralesional auditory cortex (Heschl gyrus) with decreasing hearing impairment.

CONCLUSIONS

These data may suggest structural cortical plasticity in multisensory vestibular cortex areas of patients with unilateral peripheral vestibulo-cochlear lesion after surgical removal of acoustic neuroma. As changes of GMV were related to vestibular function, structural brain changes may reflect central mechanisms of vestibular compensation.

Pulmonary hypertension after ventriculoatrial shunt implantation

Object

Ventriculoatrial (VA) shunts inserted for the treatment of hydrocephalus are known to be a risk factor for pulmonary hypertension. The aim of this study was to evaluate the incidence of pulmonary hypertension among adult patients with VA shunts.

Methods

All patients who had received a VA shunt at one of two institutions between 1985 and 2000 were invited for a cardiopulmonary evaluation. The investigation included a thorough history taking, clinical examination, echocardiography, and pulmonary function testing including diffusing capacity of the lung for carbon monoxide (DLCO). Pulmonary hypertension was defined as systolic pulmonary artery pressure > 35 mm Hg at rest.

Results

The study group consisted of 86 patients, of whom 38 (44%) could be examined. The patients' mean age was 47.1 ± 18.4 years; the median interval between shunt insertion and cardiopulmonary evaluation was 15 years (range 5–20 years). Of the 38 patients, 20 (53%) had Doppler velocity profiles of tricuspid regurgitation that were adequate for the estimation of pulmonary artery systolic pressure. Doppler-defined pulmonary hypertension was observed in 3 patients (8%), 2 of whom underwent right heart catheterization. Chronic thromboembolic pulmonary hypertension was confirmed in both patients, and medical therapy, including anticoagulation, was started. The VA shunt was removed in both cases and replaced with a different type of device. Pulmonary function tests revealed a restrictive pattern in 15% and typical obstructive findings in 9% of patients. In 30% of patients the DLCO was less than 80% of predicted, and blood gas analysis showed hypoxemia in 6% of patients. No significant differences in pulmonary function tests were noted between the patients with and without echocardiographic evidence of pulmonary hypertension. However, patients with pulmonary hypertension had significantly lower DLCO values.

Conclusions

The authors detected pulmonary hypertension by using Doppler echocardiography in a significant proportion of patients with VA shunts. It is therefore recommended that practitioners perform regular echocardiography and pulmonary function tests, including single-breath DLCO in these patients to screen for pulmonary hypertension to prevent hazardous late cardiopulmonary complications.

[Deep brain stimulation in the posterior hypothalamus for chronic cluster headache. Case report and review of the literature]

Primary chronic cluster headache (CCH) is a rare but severe pain syndrome and pathophysiological explanations are still missing. PET studies revealed activation in the hypothalamus and therefore it became a target for therapeutic deep brain stimulation (DBS). A case of a 39-year-old woman and a literature review are presented. The patient suffered from left-sided primary CCH for 14 months. The headache was resistant to any pharmacological therapy or treatment was limited by major drug side effects. Using a stereotactic approach a quadripolar lead was inserted in the left posterior hypothalamus. A test trial was performed and attack frequency, intensity, and adverse events were noted. Intraoperative test stimulation evoked typical side effects like tachycardia, diplopia and panic attacks. During the trial test a marked reduction in frequency and intensity of CCH was recorded. After 7 days the stimulation device was implanted subcutaneously. DBS with implantation of a lead in the ipsilateral inferior posterior hypothalamus is an experimental treatment option and should be offered to selected patients in a prospective controlled clinical trial. Data concerning the long-term follow-up need to be collected.

[Brachytherapy in combination with function-preserving surgery. An interdisciplinary challenge]

A multimodal, interdisciplinary approach known as intensity-modified brachytherapy is a promising alternative for patients with advanced head and neck cancer infiltrating the orbita and skull base. An 87-year-old man presented with a recurrence of squamous cell carcinoma of the medial corner of the left eye that had been locally resected and irradiated by external beam radiotherapy multiple times. The cancer was resected with preservation of the eye with close margins, implantation of afterloading catheters, and reconstruction of the defect with a median forehead flap. The patient was irradiated with a total radiation dose of 30 Gy IMBT. After 1 year, there was no evidence of locoregional recurrence. The background of this therapeutic process and analysis of the current literature regarding this interdisciplinary treatment of head and neck cancer infiltrating the orbita and skull base are discussed based on this case report.

Interstitial glycerol increase in microdialysis after glycerol enema

Microdialysis allows the measurement of extracellular concentrations of various endogenous substances, such as excitotoxic amino acids or metabolic end products. Recent advances in microdialysis techniques have led to widespread use in patients with brain disorders. Microdialysis has proved to be a useful tool for monitoring cerebral biochemical metabolism and secondary brain damage in severe head injury, subarachnoid haemorrhage, stroke, and epilepsy. In our neurosurgical intensive care unit, microdialysis was performed on 42 patients. Four patients received a glycerol enema for therapy of a paralytic ileus. A glycerol peak was observed in both intracerebral and subcutaneous microdialysis occurring three to four hours after the glycerol enema in all four patients. The highest glycerol value was 1187micromol/l cerebral and 2997micromol/l in the subcutaneous tissue. Our study indicates that besides the measurement of serum osmolality and serum glycerol level, microdialysis may be an additional valuable tool to control glycerol therapy in patients with cerebral oedema and elevated intracranial pressure.

Outcome Prediction of Third Ventriculostomy: A Proposed Hydrocephalus Grading System

An important factor in making a recommendation for different treatment modalities in hydrocephalus patients (VP shunt versus endoscopic third ventriculostomy) is the definition of the underlying pathology which determines the prognosis/outcome of the surgical procedure. Third ventriculostomies (3rd VS) are successful mainly in obstructive hydrocephalus but also in some subtypes of communicating hydrocephalus. A simple, easily applicable grading system that is designed to predict the outcome of 3rd VS is proposed. The hydrocephalus is graded on the basis of the extent of downward bulging of the floor of the third ventricle, which reflects the pressure gradient between the 3rd ventricle and the basal cisterns, presence of directly visualised CSF pathway obstruction in MRI, and the progression of the clinical symptoms resulting in five different grades. In this proposed grading system, grade 1 hydrocephalus subtype shows no downward bulged floor of the 3rd ventricle, no obstruction of the CSF pathway, and no progressive symptoms of hydrocephalus. There is no indication for 3rd VS. Grades 2 to 4 show different combinations of the described parameters. Grade 5 subtype shows a markedly downward bulged floor of the 3rd ventricle and direct detection of the CSF pathway obstruction (i.e., aqueductal stenosis) with progressive clinical deterioration. Retrospective application of this grading scheme to a series of 72 3rd VS has demonstrated a high correlation with the outcome: The success rate in grade 3 reached 40%, in grade 4: 58%, and in grade 5: 95%. This standardised grading system predicts the outcome of 3rd VS and helps in decision making for 3rd VS versus VP shunting.

Frontoethmoidal encephalocele with ocular leakage of cerebrospinal fluid. Case report

The authors present the case of a 2-year-old boy who was born with a small bulging mass in the middle frontonasal area and hypertelorism. In the neonatal period he suffered from a continuous lacrimal secretion mistaken for recurrent conjunctivitis. Cranial computerized tomography scanning and magnetic resonance imaging revealed a frontoethmoidal encephalocele associated with an ocular leakage of cerebrospinal fluid. One-stage repair of the encephalocele, along with correction of hypertelorism and bone grafting of the forehead, was performed with good result. During a 2-year follow-up period no neurological deficits appeared.

Hydrocephalus therapy: reduction of shunt occlusions using a peel-away sheath

In order to avoid shunt occlusions through particles of brain parenchyma a new procedure was used. Conventionally during ventricle puncture brain tissue may intrude into perforating holes of the ventricular catheter and subsequently shunt dysfunction may occur. By using a peel-away sheath the ventricular catheter can be protected during puncture. The conventional technique (n=90) was compared with the peel-away sheath technique (n=20) in a retrospective analyses in regard to shunt revisions during a 1-year period. Shunt revision was done in 18% (16/90) within 1 year using the conventional technique, respectively, 5% (1/20) using the peel-away sheath technique. Although criteria for statistical significance were not reached these data are worth to be mentioned. A randomised prospective study is initiated and the key features are presented.

Cerebral haemodynamic pathologies in HELLP syndrome

The syndrome of haemolysis, elevated liver enzymes and low platelets (HELLP syndrome) is understood as a unique variant of severe preeclampsia. This disorder complicates between 2 and 7% of gestations and is associated with a high perinatal morbidity and a maternal morbidity ranging between 1 and 4%. Intracerebral complications only rarely occur, especially intracerebral haemorrhage was described only in single cases, often correlated with fatal maternal outcome. The analysis of patients with HELLP syndrome treated at our hospital revealed three cases with severe neurological deterioration. Possible pathogenetic factors are discussed.

The Mechanism of Fornix Lesions in 3rdVentriculostomy

Fornix lesions as a complication of 3rd ventriculostomy are rare and almost not reported. However, in our series of 94 procedures we observed 5 fornix lesions. Although we did not find any clinical deterioration, we were alarmed by these unexpected incidences and analysed the mechanism. All fornix lesions occurred using an endoscope sheath with separated channels for the endoscope itself, the instruments and for rinsing and suction. The limited field of view suggests the surgeon to be already inside the 3rd ventricle while the tip of the scope is still in the lateral ventricle just before the foramen of Monro. The instrument enters the optic field--depending on the used optic--as lately as 2 to 3 mm. The analysis showed that the lesions happened when the instruments were in the blind angle of the endoscope's optic which itself was outside of the foramen of Monro. Being aware of this mechanism with its potential risks it did not occurred again.

Pro and Cons of Different Designs of Rigid Endoscopes

Experience with more than 200 neuroendoscopic procedures taught us the advantages and disadvantages of the different endoscope designs. Using an endoscope with a sheath with separate channels for the endoscope, the instruments as well as for rinsing and suction we found advantages in rinsing properties, handling, and preciseness of instrument steering. On the other hand an endoscope with a sheath with a singular channel for the endoscope itself, the instruments, rinsing, and suction the advantages were better in visualization of the instruments, more available instruments, and easier extraction of larger specimen. The knowledge of these advantages makes it possible to select the adequate endoscope regarding its design, especially in more complicated cases.

Proliferation, migration, and invasion of human glioma cells exposed to fractionated radiotherapy in vitro

Radiotherapy is a well established treatment for malignant gliomas. This study describes the migration, proliferation, and invasion behaviour of two human glioma cell lines (GaMg and U-87 Mg) grown as multicellular tumour spheroids after radiotherapy. Migration and proliferation studies were performed using conventional and accelerated fractionation up to 60 Gy and 59.4 Gy, respectively. A dose-dependent growth and migratory response to irradiation independent of the type of fractionation was observed. A coculture system in which tumour spheroids were confronted with foetal rat brain aggregates was used for invasion studies. Marked invasion of the glioma spheroids into the brain aggregates occurred with or without radiotherapy. For the GaMg cells, flow cytometric DNA histograms after treatment with 10 Gy and 40 Gy showed an accumulation of cells in the G2/M phase of the cell cycle. Radiotherapy inhibits tumour cell growth and migration, but the invasiveness of the remaining tumour cells seems to be unaffected.

Tissue metabolism during endotoxin shock after pretreatment with monophosphoryl lipid A

OBJECTIVE

Preconditioning pigs with low doses of monophosphoryl lipid A (MPL), a non toxic derivate of lipid A, has been shown to induce endotoxin hyporesponsiveness and to reduce the metabolic and hemodynamic consequences of endotoxin shock. However, the mechanism is presently unclear. This study was designed to elucidate the effects of pretreatment with MPL on tissue metabolism in different organs by in vivo microdialysis of interstitial fluid.

METHODS

In a controlled animal study at the university research laboratory, seven female mixed-breed pigs were exposed to an endotoxin infusion (1 microg/kg b.w. per h) after pretreatment with MPL in incremental doses of endotoxin during days 5-2 before the experiments. Seven animals receiving a saline pretreatment served as a control group. Hemodynamic variables and blood gas analyses including blood lactate were determined every 30 min until the animals died. Interstitial lactate and glycerol levels were measured in muscle, subcutaneous tissue and liver using in vivo microdialysis.

RESULTS

Survival time was significantly prolonged after MPL preconditioning (8.95 (7.5-9.1) h vs. 5.35 (5.0-5.6) h, P<0.05). Hemodynamic parameters were not significantly different between the treatment and control groups, while mixed venous saturation (81% (70-93%) vs. 30% (22-48%)) and arterial blood pH (7.39 (7.33-7.44) vs. 7.21 (7.1-7.25)) and pO(2) were significantly higher in the preconditioned group (P<0.05). The interstitial concentrations of lactate and glycerol in all investigated tissues were significantly higher in control animals than the those who had been pretreated with MPL (P<0.05).

CONCLUSIONS

Preconditioning with low doses of monosphosphoryl lipid A attenuates the negative effects of endotoxemia on tissue metabolism, probably by reducing O(2)-consumption. These changes may be subtle and, hence, only fully detectable by monitoring tissue metabolism.

Atypical delayed intracranial haematoma following stereotactic biopsy of a right parietal anaplastic oligodendroglioma

The history of a 73-year-old woman with an anaplastic oligodendroglioma is presented, in whom cerebral magnetic resonance imaging (MRI) and brain single-photon emission tomography (SPECT) revealed an intracerebral lesion 17 months before, which was misinterpreted as cerebral infarction. Stereotactic biopsy confirmed the diagnosis, but 4 days after biopsy an unexpected fatal subdural and intraparenchymal bleeding occurred on the biopsy site. Neuroradiological aspects in the differential diagnosis of cerebral lesions as well as the role of small silent postbiopsy haematoma concerning further clinical deterioration are discussed.

Clinical biochemical tissue monitoring during ischaemia and reperfusion in major vascular surgery

BACKGROUND

Major vascular surgery with aortic cross-clamping is associated with temporary ischaemia of the lower limb due to lack of tissue blood flow. The present study was designed to determine if the short-term changes in cellular metabolism occurring during this situation can be detected by subcutaneous microdialysis. It was also hoped to ascertain if this new technique is useful in the continuous bedside monitoring of metabolism during aortic surgery.

METHODS

In a controlled clinical study 20 patients undergoing elective aortic surgery were monitored using microdialysis probes that were inserted in the subcutaneous tissue of the left lower limb and a non-ischaemic region (shoulder). Interstitial fluid was obtained and the concentrations of glucose and lactate during lower limb ischaemia and during reperfusion were measured and compared with concentrations observed in fluid obtained from the non-ischaemic control tissue.

RESULTS

Circulatory occlusion caused an immediate and significant decrease in the glucose/lactate ratio from 3.1+/-1.3 to 0.48+/-0.5 (P<0.05) that returned to preocclusion values within 2 h of commencing reperfusion.

CONCLUSION

We suggest that microdialysis may be used both to assess acute changes in tissue metabolism during ischaemic periods and also to act as an additional tool for the detection of peri-operative acute variations in limb blood flow.

Migration, proliferation, and invasion of human glioma cells following treatment with simvastatin

This study describes the migration, proliferation, and invasion behaviour of two human glioma cell lines, GaMg and U-87 Mg, grown as multicellular tumour spheroids after 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitor (simvastatin) therapy. Migration and proliferation studies were performed using simvastatin in concentrations of 0.2-30 microg/ml(-1). A coculture system in which tumour spheroids were confronted with foetal rat brain aggregates was used for invasion studies. A dose-dependent growth and migratory inhibitory response to simvastatin treatment was observed. Marked invasion of the glioma spheroids into the brain aggregates could be seen in both treated and nontreated groups. Simvastatin therapy inhibits tumour cell growth and migration, but the invasiveness of the remaining tumour cells seems to be unaffected.

Neuroradiological findings in primary cerebral lymphomas of non-AIDS patients

Primary central nervous system lymphomas (PCNSL's) are rare tumours which generally accounted for 1.0-1.5% of all intracranial neoplasms. However, within the last decade the frequency of cerebral lymphomas has dramatically increased. We retrospectively analysed the neuroradiological findings (computed tomography (CT), MRI, angiography) in 37 patients with PCNSL. Thirty patients with the clinically and neuroradiologically suspected diagnosis of cerebral lymphoma underwent CT- or MRI-guided stereotactic biopsy. In seven cases an open surgical intervention was performed. Preoperatively, CT with and without contrast medium was performed in all but two cases. Twenty-eight patients received MRI (axial SE T2 weighted, triplanar SE T1 weighted, triplanar SE T1+Gadolinium). Additionally, in 9 patients cerebral angiography was performed. Typical neuroradiological patterns are: (1) iso- or hyper-density (85.5%) on unenhanced CT scan with marked contrast enhancement (87.7%); (2) infiltration/contact of leptomeningeal and/or ependymal spaces (97.3%); (3) hyperintensity on T2 with moderate oedema (80.3%). Histopathological work-up included conventional and immunohistochemical stains performed on formalin fixed and paraffin embedded bioptical specimen. Despite widely used preoperative dexamethasone treatment, an accurate histopathological diagnosis of PCNSL of B cell type was established in all cases except one. The high percentage of accurate histopathological diagnosis was based on: (1) great mean sample volume per biopsy site; (2) great number of biopsies in patients suspected to have cerebral lymphomas; and (3) MR-guided stereotactic procedures if the lesion was not clearly identifiable on CT scan.

Biochemical tissue monitoring during hypoxia and reoxygenation

Oxygen deficiency during critical illness may cause profound changes in cellular metabolism and subsequent tissue and organ dysfunction. Clinical treatment in these cases targets rapid reoxygenation to avoid a prolonged impaired synthesis of cellular high-energy phosphates (ATP). However, the effect of this therapeutic intervention on tissue metabolism has not been determined yet. Thus the present study was designed to determine the effects of hypoxia and reoxygenation with either room air or 100% oxygen on variables of interstitial metabolism in different tissues using in vivo microdialysis. Twenty-seven adult, male CD-rats (407-487 g; Ivanovas, Kisslegg, Germany) were studied during general anesthesia. Following preparation and randomization, rats were normoventilated for 45 min (FiO(2) 0.21), followed by induction of hypoxia (FiO(2) 0.1, 40 min) and reoxygenated for 50 min either with FiO(2) 1.0 (group 1, n=10) or FiO(2) 0.21 (group 2, n=10). Control animals (n=7) were ventilated with 21% oxygen during the observation period. Additional to invasive haemodynamic parameters, biochemical tissue monitoring was performed using CMA 20 microdialysis probes, inserted into muscle, subcutaneous space, liver, and the peritoneal cavity allowing analyses of lactate and pyruvate at short intervals. Hypoxia induced a significant reduction in mean arterial pressure (MAP) in group 1 and 2 compared with the control group (P<0.05) without any significant differences between both treatment groups. This was accompanied by a significant increase in blood lactate (10.5+/-3.1 mM (group 1) and 12.3+/-4.1 mM (group 2) vs. 1.5+/-0.3 mM (control); P<0.05) and severe metabolic acidosis (base excess (BE): -18.3+/-5 mM (1) and -17.3+/-7 mM (2) vs. -2.6+/-1.8 mM (control), P<0.05). During hypoxia, the interstitial lacate/pyruvate ratio in groups 1 and 2 increased to 455+/-199% (muscle), 468+/-148% (intraperitoneal), 770+/-218% (hepatic) and 855+/-432% (subcutaneous) (P<0.05 vs. control, respectively). No significant inter-organ or inter-group differences in interstitial dialysates were observed in the treatment groups, neither during hypoxia nor during reoxygenation. Our data suggest, that hypoxia induces comparable metabolic alterations in various tissues and that reoxygenation with 100% oxygen is not superior to 21% oxygen in restoring tissue metabolism after critical hypoxia.

Extraventricular intracisternal obstructive hydrocephalus--a hypothesis to explain successful 3rd ventriculostomy in communicating hydrocephalus

The basis of successful 3rd ventriculostomy in cases of communicating hydrocephalus is not yet understood. We performed 3rd ventriculostomies in 5 patients with free cerebrospinal fluid (CSF) communication from the ventricles to the cisterna magna. Preoperative magnetic resonance images (MRIs) showed dilated ventricles, a downward bulging floor of the 3rd ventricle (interpreted as a sign of pressure gradient between the ventricles and basal cisterns) and a free communication to an enlarged cisterna magna. The other basal cisterns were of normal or smaller size. All patients recovered from their clinical symptoms and none of them needed a shunt. The hypothesis of an intracisternal CSF pathway obstruction (e.g. between the cisterna magna and the prepontine cistern) could explain the MRI findings, although such an obstruction cannot be directly visualized. It would also explain the successful 3rd ventriculostomies in these cases.

[Continuous biochemical tissue monitoring during acute hypoxia]

Oxygen deficiency during critical illness is known to cause profound changes in cellular metabolism with subsequent organ dysfunction. Clinical treatment in these patients is focussed on rapid reoxygenation to avoid a prolonged impaired synthesis of cellular high-energy phosphates (ATP). The effect of this therapeutical intervention on the level of the cell, however, has not yet been objectivized. The aim of the present experimental study was to biochemically monitor different tissues during hypoxia and reoxygenation using in vivo microdialysis. Eighteen adult male CD-rats (412-469 g; Ivanovas, Kisslegg, Germany) were normoventilated under general anaesthesia (FiO2 = 0.21). Ten were then subjected to a period of hypoxia (FiO2 = 0.1, 40 min) and reoxygenated with FiO2 = 0.21, while eight control animals were continuously ventilated with FiO2 = 0.21. In addition to invasive haemodynamic monitoring, biochemical tissue monitoring was performed using CMA 20 microdialysis probes, which were inserted into the muscle (m), subcutaneous space (s), liver (l) and peritoneal cave (p) with semicontinuous analyses of lactate and pyruvate at intervals of 15 minutes. Hypoxia induced a significant decrease in mean arterial pressure compared to the control group (p < 0.05). At the same time significant increases in blood lactate (12.3 + 4.1 mmol/l (hypoxia) vs. 1.5 +/- 0.3 mmol/l (control); p < 0.05) and in negative base excess (17.3 + 7 mmol/l (hypoxia) vs. 2.6 + 1.8 mmol/l (control), p < 0.05) occurred. Compared to unchanged levels in the control animals, the interstitital lacate/pyruvate ratio in the investigation group rose to significantly higher values (455 + 199% of baseline (m), 468 + 148% (p), 770 + 218% (l) and 855 + 432% (s) (p < 0.05). An immediate return to the baseline values after the start of reoxygenation was noted in the L/P ratio during the observation period. Using microdialysis, it was possible to objectify the effect of oxygen deficiency and restoration on tissue metabolism. Regarding clinical and preclinical practice, microdialysis monitoring should be performed to include biochemical cellular effects as an additional target for therapeutical interventions.

Long-time microdialysis in a patient with meningoencephalitis

As part of invasive neuromonitoring, long-time microdialysis was performed in a 32-year-old patient suffering from meningoencephalitis. Cerebral magnetic resonance imaging (MRI) revealed marked global brain oedema. An intracranial pressure (ICP) probe, brain tissue oxygen pressure measurement (pTiO(2)), and intraparenchymal microdialysis were used for intensive neuromonitoring. Despite high ICP, only intensive care therapy was applied for 16 days using deep propofol sedation, hyperventilation, and intermittent mannitol therapy. One year later, the condition of the patient was excellent. Intracerebral microdialysis with bedside measuring of lactate, pyruvate, glycerol, glucose, and glutamate is a useful additional tool for the monitoring of ICP management.

Intraperitoneal microdialysis for detection of splanchnic metabolic disorders

BACKGROUND AND AIMS

Due to its high oxygen demand the gastrointestinal tract is very susceptible to hypoxia or ischemia, which may result in local and systemic dysfunction. Early detection of any profound disorders (e.g., after abdominal surgery) remains an important target for the surgeon. This study investigates whether in vivo microdialysis monitoring of the intraperitoneal space adequately reflects hypoxic conditions.

METHODS

Hypoxic hypoxia by ventilation was induced in 14 rats under general anesthesia with FIO(2) of 0.1 (40 min) followed by reoxygenation with FIO(2) of 0.21. Hemodynamic and blood gas monitoring including blood lactate was performed. Microdialysis catheters were placed in the peritoneal cavity, and lactate, pyruvate, and glycerol were measured out of the ascites.

RESULTS

A significant decrease in mean arterial pressure and increase in blood lactate level during the hypoxic period was observed. Hypoxia induced an immediate and significant elevation in the intraperitoneal lactate/pyruvate ratio to 446+/-137% of the baseline values, and glycerol subsequently increased during reoxygenation to 389+/-109%. Values for the blood compartment showed less profound or no significant differences.

CONCLUSIONS

Biochemical monitoring of the intraperitoneal space by in vivo microdialysis, such as after laparatomy can measure metabolic changes in the gastrointestinal tract produced by hypoxia/ischemia. The surgeon may thus detect postoperative complications at an earlier stage than with routine monitoring devices.

A simple method of reapplying the Leksell stereotactic frame without any repetition of the CT scan

A simple method to reapply the Leksell stereotactic frame using marked carbon pins is described. This method allows the reapplication in a quick and safe manner without repetition of the CT scan. The reproducibility was very high.