Radial oxygen gradients over rat cortex arterioles.

PURPOSE: We present the results of the visualisation of radial oxygen gradients in rats' cortices and their potential use in neurocritical management. METHODS: PO2 maps of the cortex of ten sedated, intubated and controlled ventilated Wistar rats were obtained with a camera (SensiMOD, PCO, Kelheim, Germany). Those pictures were analysed and edited by a custom-made software. A virtual matrix, designed to evaluate the cortical O2 partial pressure, was placed vertically to the artery under investigation, and afterwards multiple regions of interest were measured (width 10 pixels, length 15-50 pixels). The results showed a map of the cerebral oxygenation, which allowed us to calculate radial oxygen gradients over arterioles. Three groups were defined according to the level of the arterial pO2: PaO2 < 80, PaO2 80-120 and PaO2 > 120. Gradients were analysed from the middle of the vessel to its border (1), from the border into the parenchyma next to the vessel (2) and a combination of both (3). RESULTS: Gradient 1 showed significantly different cortical pO2 values between the three different groups. The mean pO2 values were 2.62, 5.29 and 5.82 mmHg/mm. Gradient 2 measured 0.56, 0.90 and 1.02 mmHg/mm respectively. Gradient 3 showed significant results between the groups with values of 3.18, 6.19 and 6.84 mmHg/mm. CONCLUSION: Using these gradients, it is possible to describe and compare the distribution of oxygen to the brain parenchyma. With the presented technique, it is possible to detect pO2 changes in the oxygen supply of the brain cortex.

Non-invasive measurement of the superficial cortical oxygen partial pressure.

We present a non invasive fluorescein based method to measure and visualise the partial oxygen pressure of the rat cortex in a 2D picture. We studied 10 Wistar rats. A trepanation was done over the hemisphere and the dura was opened. A PMMA cylinder with a calibrated optical membrane was fixed over the surface of the brain. The CCD camera with the light source is placed over the cylinder. This allows the generation of two-dimensional maps of the pO2 pressure. Using the white light picture we defined regions of interest (ROI) in an artery, vein, parenchyma and an overall ROI. For every ROI a mean emission value was calculated. We increased, stepwise, the FiO2 from 30% up to 100%. Thereafter we established ventilation with an FiO2 of 30% and induced a stepwise hypo- and hyperventilation. The ROI's showed significantly different pO2 values. The apO2 showed a good correlation to the pO2 in the ROIs. This new set up seems to give reliable absolute pO2 values of the brain surface. This method seems to be able for the first time to give a non invasive pO2 map of the brain surface reflecting oxygenation and ventilation effects.

Effects of temporary clipping during aneurysm surgery.

OBJECTIVE: Intraoperative aneurysm rupture is associated with a high morbidity and mortality. Temporary vessel occlusion is an integral part of aneurysm clipping to avoid intraoperative hemorrhage. The information concerning the role of temporary occlusion regarding the development of cerebral vasospasm is sparse. The aim of this study was to provide more information in this field. METHODS: We operated on 292 patients suffering from cerebral aneurysms. The data were reviewed from a prospectively collected databank, which includes information about the severity of subarachnoid hemorrhage, as well as transcranial Doppler data and surgical data such as temporary occlusion. RESULTS: In 50% of our patients, temporary occlusion was performed during surgery. Twenty-nine percent showed an ischemic lesion in the CCT post-operatively, and in 58% of these patients, temporary occlusion was performed (versus 47% without temporary occlusion, p = 0.09). The mean occlusion time was longer in patients with radiologic signs of infarction. Furthermore, patients having unfavorable outcome showed a longer temporary occlusion time. Thirty-four percent of patients who underwent temporary vessel occlusion developed vasospasm postoperatively (versus 20% without temporary occlusion, p < 0.006). Temporary occlusion time correlated to the development of vasospasm as defined by transcranial Doppler flow velocity. Forty-eight percent of the patients treated using temporary occlusion suffered from middle cerebral artery aneurysm (versus 22% without temporary occlusion, p < 0.0001). An increased blood flow velocity was mostly seen in this region (p < 0.003). CONCLUSION: According to our results, it seems to be the possible that temporary vessel occlusion is an additional factor in aggravating vasospasm after aneurysmatic subarachnoid hemorrhage.

The accuracy of jugular bulb venous monitoring in detecting cerebral ischemia in awake patients undergoing carotid endarterectomy.

To investigate the accuracy of jugular bulb venous monitoring in detecting cerebral ischemia, we performed ipsilateral jugular bulb venous monitoring in 48 patients undergoing carotid surgery under regional anesthesia. Cerebral ischemia was assumed when neurologic deterioration occurred. During carotid clamping, the maximal arterial-jugular venous oxygen content difference [AJDO2 (max)], the minimal jugular venous oxygen saturation [SjO2 (min)], the maximal arterial-jugular venous lactate content difference [AJDL (max)], the maximal lactate oxygen index [LOI (max)], and the maximal modified LOI [mLOI (max)] were determined. To quantify the selectivity of each parameter, we performed receiver operating characteristic analysis and determined the area under the curve. The cutoff points providing the highest accuracy and the corresponding sensitivity (Se) and specificity (Spec) were determined. Neurologic deterioration occurred in 12 patients. All parameters, except AJDO2 (max), showed significant ability to distinguish between ischemic and nonischemic patients. The area under the curve for AJDL (max) was 0.840, for SjO2 (min) 0.766, for LOI 0.745, for mLOI 0.748, and for AJDO2 (max) 0.672. We found cutoff points of > or =0.16 mmol/L for AJDL (max) (Se=67%; Spec=86%) and < or =55% for SjO2 (Se=75%; Spec=83%). In conclusion, the present investigation shows that AJDL, SjO2, LOI, and mLOI provide the ability to detect cerebral hypoperfusion. The highest accuracy was found for AJDL. Neither the calculation of LOI nor of mLOI showed improved results.

A new semi-invasive method for two dimensional pO2 measurements of cortical structures.

BACKGROUND: Measuring brain oxygenation in patients with TBI or SAH is of major interest. We present a new semi-invasive method for two dimensional measurements of cortical pO2. METHODS: For this feasibility study, a porphyrin containing sensor foil was placed directly on the cortex of intubated and variably ventilated Wistar rats. The sensor was excited with a light pulse and pictures of the foil's pO2 dependant emissions were captured with a CCD camera. After online data processing, two-dimensional maps of cortex oxygenation were displayed and analyzed using ROIs (here: arteriole, vein, parenchyma) with a display rate of 7 Hz. The size of one single measurement pixel was 0.03 x 0.03 mm2. FINDINGS: The mean pO2 over cortex arterioles was 20.3 +/- 0.69, over veins 17.1 +/- 0.5 and over parenchyma 9.1 +/- 0.6 (mmHg +/- SD). The arterial pO2 showed a good correlation to the pO2 in the ROIs (r = 0.46-0.72, p < 0.0001, n = 198). Comparing groups with different paO2 and paCO2 we found significantly different pO2 values in the ROIs of the cortex. CONCLUSIONS: This prototype is capable of obtaining cortical pO2 maps with excellent temporal and spatial resolution and provides simultaneous imaging of the cortex structures.

Doppler ultrasound measurement of blood flow volume in the extracranial internal carotid artery for evaluation of brain perfusion after aneurysmal subarachnoid hemorrhage.

Monitoring of cerebral blood flow (CBF) is an essential part in the early diagnosis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH). Several methods have been established to monitor cerebral perfusion in these patients. During last few years, a new sonographic approach has been introduced, the so called 'angle independent ultrasound system' for monitoring volume flow in the internal carotid artery (ICA). The angle independent Doppler ultrasound system Quantix ND (Cardiosonix Ltd, Israel) determines the diameter of the ICA as well as the velocity of blood flow in the extracranial part of this vessel. Thus, a determination of the global CBF in the anterior circulation can be achieved. Aim of our study was to compare the Quantix ND system and the commonly used transcranial Doppler sonography (TCD) in patients suffering from aneurysmal SAH. We included 11 patients (eight female and three male; Hunt and Hess I-V) and performed post-operatively/post-interventionally daily measurement of blood flow volume in the ICA, and determined the blood flow velocity in middle and anterior cerebral artery (MCA and ACA) with TCD. Six patients post-operatively/post-interventionally developed cerebral vasospasm, resulting in ischemia and territorial infarction. Three patients were chosen as case studies. In contrast to the TCD, we found a strong significant correlation of blood flow volume with Quantix ND in the ICA and the occurrence of cerebral infarction (p<0.001). These preliminary data justify further investigation of this angle independent Doppler ultrasound device. We postulate that this new tool might be effective for monitoring the CBF in the critical post-operative/post-interventional interval following aneurysmal SAH.

Quality of Life following Surgery for Malignancies of the Anterior Skull Base.

Radical surgery combined with postoperative radiation is recommended to achieve the best outcomes in patients suffering from malignant anterior skull base tumors. However, information on the impact of such treatment on the quality of life of these patients is sparse. This retrospective study evaluated quality of life in patients with anterior skull base malignancies after transdural resection and radiotherapy. At follow-up, 36% of the patients were alive (mean survival time, 39 months). Only 45% of the patients were able to work in their previous occupation a mean of 15 months after surgery. At follow-up, 58% of the patients had a recurrent tumor. The mean quality of life index was 42 points (range, 0 to 100). The lowest values were on the job item, and the highest mean value was on the family item. All patients, dependents, or both would agree to surgery in the future. Based on these findings, quality of life after transdural surgery for the treatment of anterior skull base malignancies seems to be low.

Possible role of the C-reactive protein and white blood cell count in the pathogenesis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

The delayed ischemic neurologic deficit (DIND) is a common and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Recent evidence suggests that various constituents of the inflammatory response may be critical in the pathogenesis of this ischemic complication. The aim of this study was to evaluate the possible relationship between the C-reactive protein (CRP)/white blood cell (WBC) count and DIND. A total of 88 patients with acute SAH were included. CRP and WBC count were estimated on a daily basis. Outcome was evaluated 1 year after the initial ictus according to the Glasgow Outcome Scale. CRP levels on days 5, 6, 7, and 8 were statistically significantly higher in the group of patients developing a DIND (P < 0.025, P < 0.016, P < 0.011, P < 0.0002). WBC counts were higher in this patient group on days 1, 4, 5, 6, and 7 (P < 0.0253, P < 0.0087, P < 0.00167, P < 0.0026, P < 0.0045). Overall CRP values were higher with increasing severity of the initial ictus according to the Hunt and Hess Scale and to the outcome according to the Glasgow Outcome Scale from day 3 on. A statistically significant relationship between WBCs and outcome could not be observed. The presented data do not prove that WBCs and CRP values have a direct contribution to the pathogenesis of ischemic complications following SAH, but it supports the assertion that inflammation may present a common pathogenic pathway in the development of such complications.

Long-term outcome after hemicraniectomy for space occupying right hemispheric MCA infarction.

OBJECTIVE: To examine the long-term prognosis in patients with 'malignant' supratentorial ischemia of the right hemisphere treated with hemicraniectomy, especially in respect to depression, with a focus on age as a possible predictor of outcome. METHODS: We performed a prospective, long-term, follow-up examination in 23 survivors of 32 patients (mortality 28.1%) treated with hemicraniectomy for malignant middle cerebral artery (MCA) infarction of the right hemisphere, who were identified in our data bank since 1993. Long-term was defined as at least 20 months after craniectomy. Outcome data consisted of the items functionality, depression and quality of life. Tests applied included the Barthel Index (BI), the modified Rankin Scale (mRS), Beck Depression Inventory (BDI) and stroke-specific quality of life (QoL) scale. RESULTS: Of the 23 patients 15 (65.2%) had a BI>or=60, 11 (47.8%) a mRS<4 and 9 (39.1%) a SS-QOL>or=60%, each representing a favourable outcome. In retrospect, 14 (60.9%) patients approved the surgery. Depression, i.e. a BDI>9, was diagnosed in 13 (56.5%) patients and 5 (38.5%) of them were treated with antidepressants. In a multiple linear regression analysis age at craniectomy was a predictor of a low BI (beta=-0.863; p=0.031), but not of the other outcome parameters. CONCLUSIONS: Depression is a common and rarely treated long-term complication after 'malignant' right hemispheric ischemia. While high age is a strong predictor of poor functional outcome, it has no impact on depression and retrospective approval of craniectomy.

Pyogenic spinal infections and outcome according to the 36-item short form health survey.

OBJECT: Pyogenic vertebral infections are rare. In most papers investigators have focused on risk factors, clinical characteristics, and diagnostic findings, and discussed different management strategies. The optimal strategy for dealing with spinal infections, however, remains controversial. Additionally, outcome data regarding quality of life (QOL) after pyogenic spinal infections are sparse. The aim of this study was to provide further data in this field. METHODS: The authors retrospectively investigated 62 patients suffering from pyogenic spinal infections. In 37 patients (59%), lumbar lesions were observed; thoracic and thoracolumbar infections were documented in 19 (31%) and a cervical infection was demonstrated in six patients (10%). Overall 28 patients (45%) underwent conservative treatment, and 34 (55%) underwent surgery with or without the placement of instrumentation. At follow-up examination the authors recorded each patient's satisfaction as well as QOL according to the 36-Item Short Form Health Survey. Quality of life after treatment of pyogenic spine infections did not reach the level of the normative sample. Most patients continued to suffer some sort of pain. Despite different indications, the surgically treated patients experienced a slightly better QOL and self-reported satisfaction levels, as well as a statistically significant better outcome, than patients treated conservatively. CONCLUSIONS: The results obtained in the present study suggest that surgery, especially in conjunction with the placement of instrumentation, may be more beneficial than conservative treatment in patients with a spinal infection.

Comparison of craniotomy and craniectomy in patients with acute subdural haematoma.

Despite the increasing acceptance of craniectomy in patients with traumatic brain injury, the value of early decompressive craniectomy in patients with acute subdural haematoma is still under debate. In this retrospective study, we reviewed 180 patients with traumatic acute subdural haematoma, 111 of whom were treated with haematoma evacuation via craniotomy and 69 of whom were treated with early decompressive craniectomy. Due to the higher incidence of signs of herniation for patients in the craniectomy group, the mortality rate in this group was higher than that in the craniotomy group (53% vs. 32.3%). However, overall there was no significant difference in outcome between the two groups. Age and clinical signs of herniation were significantly associated with an unfavourable outcome, regardless of the type of surgery. Decompressive craniectomy did not seem to have a therapeutic advantage over craniotomy in traumatic acute subdural haematoma.

Diagnostic and therapeutic value due to suspected diagnosis, long-term complications, and indication for sural nerve biopsy.

In order to elicit the usefulness of sural nerve biopsy we retrospectively evaluated the courses of disease of every patient, who underwent this procedure in our department between January 1995 and March 2000. Sixty seven patients with the suspected diagnosis of peripheral neuropathy could be included. From these chart reviews and patient questionings were done. Inflammatory-demyelinating neuropathies were suspected in 14 patients (20.9%), specific histological findings confirmed diagnosis in 50% of these patients and resulted in therapy. In cases of polyneuropathy of unknown etiology (46 patients, 68.6%) diagnosis was made in 11 patients (23.9%), and lead to therapy in 9 patients (19.6%), merely. In all, diagnostic consequences arouse in 32.8%, therapeutic consequences in 26.9%. The follow-up of 47 patients (mean 24.4 months) found chronic pain in the distribution of the sural nerve in 14 patients (29.8%), dysesthesia in 22 patients (46.8%), and persistent sensory loss in 34 patients (72.3%). Only 24 patients (51.1%) would submit to biopsy again. Because of high complication rates and poor results we conclude that sural nerve biopsy should be done only in carefully selected cases after thorough clinical work-up, and should be limited to cases of suspected inflammatory neuropathies, collagenoses and immunologic neuropathies, and hereditary neuropathies.

Level of evidence in the literature concerning brain tumor resection.

Microsurgical resection is a cornerstone in the treatment of brain tumors. However, the benefit of radical resection still remains controversial. We attempted to analyze the level of scientific evidence (LOE) and methodological aspects of studies concerning the impact of the extent of resection (EOR) on outcome. The LOE classification was Ia: 0%, Ib: 0%, IIa: 0.8%, IIb: 5.8%, IIc: 0%, IIIa: 13.3%, IIIb: 52.5%, IV: 10.8%, V:16.8%. 72.5% observed a positive effect of total tumor removal. 84.2% did not report the criteria for treatment assignment, 62.5% did not define the terms gross total; radical; partial; or subtotal resection. The average age of the treatment groups was reported in 29.2%, the Karnofsky index in 75.8%. Tumor size was reported in 32.5%, location in 51.7%. Assessment of EOR was based on the surgeon's impression in 75.0%, determined by postoperative CT/MRI scans in 20.8%, quantified by CT/MRI-based volumetry in 3.4%, and assessed by histological analysis in 0.8%. To date, no studies with high LOE are available addressing the benefit of gross total brain tumor removal. Although the majority of the reports found a positive effect of radical resection, the reviewed articles contain methodological limitations which may significantly influence the results.

A large, erosive intraspinal and paravertebral gout tophus. Case report.

Symptomatic gout tophi of the spine are a rare but well-characterized complication of tophaceous gout. The authors report the case of a 29-year-old previously healthy man who presented with L-5 radiculopathy. Lumbar magnetic resonance (MR) imaging revealed a 4.5 x 4.5 x 2.8-cm large gout tophus mimicking a malignant spinal tumor or abscess. The tophus completely destroyed both L-4 and L-5 facet joints and the left L-4 lamina and spread epidurally from L-3 to L-5, compressing the left L-5 nerve root. There has been no similar case reported so far with respect to the extent of bone destruction. The authors describe the case history and present intraoperative, MR imaging, and histological findings.

Comparison of near-infrared spectroscopy and tissue p(O2) time series in patients after severe head injury and aneurysmal subarachnoid hemorrhage.

Monitoring of local oxygen pressure in brain white matter (tip(O2)) and of local hemoglobin oxygen saturation (rS(O2)) with near-infrared spectroscopy (NIRS) are increasingly employed techniques in neurosurgical intensive care units. Using frequency-based mathematical methods, the authors sought to ascertain whether both techniques contained similar information. Twelve patients treated in the intensive care unit were included (subarachnoid hemorrhage, n = 3; traumatic brain injury, n = 9). A tip(O2) probe and an NIRS sensor were positioned over the frontal lobe with the most pathologic changes on initial computed tomography scan. The authors calculated coherence of tip(O2) and rS(O2) ts overall density distribution, its distribution per data set, and its time evolution. The authors identified a band of significantly correlated frequencies (from 0 to 1.3 x 10(3) Hz) in more than 90% of the data sets for coherence and overall density distribution. Time evolution showed slow but marked changes of significant coherence. By means of spectral analysis the authors show that tip(O2) and rS(O2)signals contain similar information, albeit using completely different registration methodologies.

Hyperemia following aneurysmal subarachnoid hemorrhage: incidence, diagnosis, clinical features, and outcome.

OBJECTIVE: Hyperemia is a known phenomenon after aneurysmal subarachnoid hemorrhage, but only a few reports describe and analyze hyperemia in these patients. This could be the result of diagnostic difficulties in order to identify elevated cerebral blood flow; thus, it seems that hyperemia could be an underdiagnosed clinical state. The aim of the study was to evaluate this phenomenon in comparison with clinical outcome and imaging data in order to describe the frequency of hyperemia after subarachnoid hemorrhage and maybe improve clinical diagnosis. DESIGN: Retrospective analysis of our cerebral blood flow and transcranial Doppler sonography data bank. SETTING: . Neurosurgical/Anesthesiological intensive care unit University of Regensburg, Regensburg, Germany. PATIENTS AND PARTICIPANTS: A total of 37 patients were included (24 women and 13 men). All patients suffered from aneurysmal subarachnoid hemorrhage. MEASUREMENTS AND RESULTS: Standard transcranial Doppler ultrasonography, as well as the Xenon(133) clearance technique for cerebral blood flow measurements, was employed. We observed 37 increases of flow velocities in 37 patients according to Doppler ultrasonography. In order to distinguish between ischemia and hyperemia a Xenon(133) regional cerebral blood flow examination was performed. Global hyperemia was detected in 5 patients (14%). Hyperemia correlated only to favorable outcome ( p=0.01) and fewer ischemic lesions in the computed tomography ( p<0.05). CONCLUSION: The results indicate that while global hyperemia is a frequent phenomenon that cannot be detected by standard Doppler ultrasonography or clinical examination, hyperemic cerebral blood flow values following aneurysmatic subarachnoid hemorrhage are correlated to favorable outcome.

Lack of correlation between Xenon133 and near infrared spectroscopy/indocyanine green rCBF measurements.

In recent literature there are some reports describing cerebral blood flow measurements by a near infrared spectroscopy-based technique with indocyanine-green as an absorbant. To our knowledge there is no systematical study which evaluates this technique in comparison to absolute cerebral blood flow measurements. Ten patients suffering from head injury (n = 9) or subarachnoid hemorrhage (n = 1) were included. Twenty measurements of cerebral blood flow were performed, employing a Xenon133 clearance technique. Near-infrared spectroscopy measurements were performed with the Somanetics 4100 System. Indocyanine-green was given at a total dose of 0.2 mg kg-1 bodyweight intravenously. The indocyanine-green curve was compared to cerebral blood flow measurements according to rising time and area under the curve as suggested in the literature. No correlation between the indocyanine-green clearance curve and the Xenon133 cerebral blood flow measurements could be found. Neither the area under the curve (p = 0.93) nor the rising time (p = 0.75) showed a statistically significant correlation. The near-infrared spectroscopy based indocyanine-green clearance curve measurement method of cerebral blood flow seems not to give reliable results using simple mathematical models (area under the curve and rising time). In view of our findings, we have serious reservations in the potential of this technique.

Pain resolution after lumbar disc surgery is influenced by macrophage tissue infiltration. A prospective consecutive study on 177 patients.

The aim of this study was to assess the influence of inflammatory reactions in herniated lumbar disc specimens on pain resolution after lumbar disc surgery. Disc specimens of 200 patients who underwent surgery for lumbar disc herniation were studied immunohistologically. Preoperatively each patient received a verbal rating scale (VRS) for classification of the pain level and general clinical data were recorded prospectively. Varying amounts of macrophages could be demonstrated. Eighty-nine percent of patients could be followed up for a mean period of 7 months. A statistically significant correlation between the histologically observed macrophage infiltration and postoperative pain grading according to the VRS was found. Patients with evidence of inflammatory reactions rated their postoperative complaints lower than patients with no evidence of inflammatory reactions on the VRS (P = 0.04). In our study, a statistically significant correlation between inflammatory changes in the herniated lumbar disc specimen and outcome after lumbar disc surgery could be demonstrated.

Intracerebral haemorrhage: surgical therapy vs. patient-adapted treatment concept.

In spontaneous intracerebral haemorrhage (SICH), the indication for surgery is still controversial. Therefore we developed clinical guidelines for therapy and compared the outcome of these patients to an exclusively surgically treated group. We retrospectively evaluated outcome in 70 patients with SICH, who were treated only surgically and compared this group with 58 prospectively collected patients, who were treated surgically (n=13) or medically (n=45). Initial level of consciousness, haematoma volume, and ventricular extension of blood were inversely correlated with mortality (p<0.0001, respectively). Use of clinical guidelines reduced the number of operations without affecting the outcome. We can formulate the following guidelines according to our data: comatose patients with and without brain herniation signs should be treated conservatively. Patients with a haematoma volume between 25 and 85 ml and a clinical deterioration are candidates for surgical therapy.

Does bungee jumping release S-100B protein?

The S-100B protein is a recognised indicator of traumatic brain damage, but the impact threshold at which S-100B is released into serum still remains unknown. The aim of the study was to investigate whether moderate shear forces are able to release S-100B into serum in people who did a bungee jump. Eleven healthy probands jumped from a height of 50 microm and were exposed to an acceleration of about 2.8 g. Blood samples were drawn before the jump, immediately after and 71 min (mean) after the jump. The initial serum values of S-100B of all probands were normal (mean 0.22 microg/l). Also the serum values directly after and 71-min (mean) after the jump showed no increase of S-100B (0.22 microg/l and 0.23 microg/l, mean). This finding indicates that a moderate acceleration and deceleration force to the brain does not activate the release of the protein S-100B into the serum.