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.

The prognostic value of NSE and S100B from serum and cerebrospinal fluid in patients with spontaneous subarachnoid hemorrhage.

Neuron-specific enolase (NSE) and S100B protein have been shown to be increased in cerebrospinal fluid (CSF) and serum of patients suffering from subarachnoid hemorrhage. This study was designed to evaluate the accuracy of NSE and S100B from CSF and serum for the prognosis of outcome and the detection of cerebral infarction, vasospasm and intracranial hypertension. In 55 patients with spontaneous subarachnoid hemorrhage and requiring external ventricular drainage the concentrations of NSE and S100B were determined daily from the serum and the CSF from admission until day 8. At ICU discharge patients' outcome was assessed by the Glasgow outcome scale and occurrence of cerebral infarction, vasospasm and intracranial hypertension were registered. Mean and peak values of each parameter for each patient were calculated. For accuracy assessment receiver operating characteristics were used. Bad outcome (Glasgow outcome scale 1 to 3) was found in 33 patients. Cerebral infarction, vasospasm, and intracranial hypertension were found in 31 (56%), 34 (62%), and 36 (65%) patients. Mean and peak values of NSE CSF (P<0.001), S100B CSF (P<0.001), and S100B serum (P<0.001) but not of NSE serum provided the ability to distinguish between patients with good and bad outcome. The accuracy of NSE CSF and S100B CSF did not differ significantly from that of S100B serum. NSE CSF (P<0.001), S100B CSF (P<0.001), and S100B serum (P<0.001) allowed the detection of cerebral infarction and intracranial hypertension. Cerebral vasospasm was detected by none of the parameters. In conclusion, NSE CSF, S100B CSF, and S100B serum provide similar prognostic values for outcome, intracranial hypertension and cerebral infarction. Significantly lower accuracy was found for NSE serum.

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.

Simultaneous imaging of cortical partial oxygen pressure and anatomic structures using a transparent optical sensor foil.

BACKGROUND/PURPOSE: Reliable information of cerebral oxygenation is-besides the monitoring of the intracranial pressure-of eminent interest when treating patients with brain injuries. In this study, we introduce a new, fast, and sensitive method capable of determining the cortical partial oxygen pressure on the surface of the cortex using a special sensor foil. METHODS: The introduced method exploits the O2-dependent phosphorescence of a thin sensor foil, which is excited by a short light-emitting diode flash. The optical signal is registered by a charge-coupled device camera and analyzed with PC-based software. The adequacy of this method was tested in 10 animals. The sensor device was placed directly over the cortex after craniotomy and removal of the dura. Arterial oxygen pressure was systematically varied by modifying the ventilation gas mixture. A total of 225 measurements were performed within 4 regions of interest. RESULTS: Obtained results were sufficient in each case. The pO2 over the cortex correlated well with arterial pO2. Measurements over arteries showed a correlation coefficient of 0.72 (P<0.001), over veins 0.58 (P<0.001), over cortical parenchyma 0.46 (P<0.001), and in a larger region of interest containing vessels and cortical tissue 0.59 (P<0.001). The frequency of the measurements was 7 Hz with a single measurement covering an area of 30 x 30 microm. CONCLUSIONS: For the first time, nearly online pO2 maps of a brain cortex can be generated, allowing simultaneously also separate measurements over distinct anatomic structures yielding a good spatial resolution.

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.

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.

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.

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.

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.

ICAM-1 and VCAM-1 expression following aneurysmal subarachnoid hemorrhage and their possible role in the pathophysiology of subsequent ischemic deficits.

BACKGROUND: The pathophysiology of ischemic cerebral lesions following aneurysmal subarachnoid hemorrhage (SAH) is poorly understood. There is growing evidence that inflammatory reactions could be involved in the pathogenesis of such delayed occurring ischemic lesions. The aim of this study was to evaluate adhesion molecules with regard to these lesions following SAH. METHODS: Serum and cerebrospinal fluid (CSF) samples were taken daily from 15 patients up to day 9 after SAH and evaluated for intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1). RESULTS: CSF and serum samples correlated well during nearly the whole time course (p < 0.0001). A secondary increase in ICAM-1 and VCAM-1 in the serum and CSF correlated with an increase in flow velocity in the transcranial Doppler (p > 0.0001 and p < 0.007) but not to a delayed lesion in the CT scan. CONCLUSION: We believe that inflammatory processes are involved in the pathogenesis of cerebral vasospasm but they might only be a part of a multifactorial pathogenesis.

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.

High re-bleeding rate in young adults after subarachnoid haemorrhage from giant aneurysms.

Low re-bleeding rates within the first 14 days of aneurysmal subarachnoid haemorrhage are reported in young patients. Furthermore, re-bleeding rate for giant aneurysms does not exceed 20% according to the literature. Our own clinical impression is that the re-bleeding rate seems to be much higher in giant aneurysms than reported, particularly in young patients. The aim of this study was to evaluate re-bleeding rate after subarachnoid haemorrhage following rupture of giant aneurysms in a younger population. We reviewed records of 23 patients who were treated in our institution for subarachnoid haemorrhage from giant aneurysms between 1994 and 2003. By definition, the aneurysms were larger than 25 mm in diameter. Five patients were younger than 40 years of age at the time of the aneurysmal subarachnoid haemorrhage. All younger patients (<40 years of age) showed re-bleeding after the first subarachnoid haemorrhage within the first 14 days of the initial event. In four patients (20%) older than 40 years at the time of the haemorrhage re-bleeding could be observed within the first 14 days of subarachnoid haemorrhage. We can confirm the re-bleeding rate of approximately 20% in patients suffering from subarachnoid haemorrhage (SAH) in the group of patients older than 40 years of age. However, younger patients seem to be at much higher risk of re-bleeding from giant aneurysms.

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.

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.

Pumpless extracorporeal lung assist (pECLA) in patients with acute respiratory distress syndrome and severe brain injury.

BACKGROUND: A retrospective analysis was performed to estimate the practicability of a pumpless extracorporeal lung assist system (pECLA) in trauma patients suffering from severe brain injury and the acute respiratory distress syndrome (ARDS). METHODS: Five patients with acute severe brain injury and ARDS, ventilated in a lung protective mode, were connected to pECLA to avoid the detrimental effects of hypercapnia on intracranial pressure (ICP) and cerebral outcome. With pECLA hypercapnia was eliminated in all patients while the minute volume of artificial ventilation could be reduced. Subsequently, ICP was reduced, systemic hemodynamics and cerebral perfusion pressure remained stable. One patient died due to multi-organ failure as a consequence of multi-trauma. The remaining patients survived showing a good neurologic function. CONCLUSIONS: pECLA is a promising alternative compared with conventional pump-driven systems for patients with ARDS and brain injury, since the pECLA system has minor restrictions, limitations and side effects.

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.