Intra-individual, randomised comparison of the MRI contrast agents gadobutrol versus gadoteridol in patients with primary and secondary brain tumours, evaluated in a blinded read.

OBJECTIVE: To prove that 1.0 M gadobutrol provides superior contrast enhancement and MRI image characteristics of primary and secondary brain tumours compared with 0.5 M gadoteridol, thereby providing superior diagnostic information. METHODS: Brain MRI was performed in two separate examinations in patients scheduled for neurosurgery. Independent injections of 1.0 M gadobutrol and 0.5 M gadoteridol at doses of 0.1 mmol Gd/kg body weight were administered per patient in randomised order. Evaluation was performed in an off-site blinded read. RESULTS: Fifty-one patients in the full analysis set (FAS) were eligible for efficacy analysis and 44 for the per-protocol analysis. For the primary efficacy variable "preference in contrast enhancement for one contrast agent or the other", the rate of "gadobutrol preferred" was estimated at 0.73 (95 % confidence interval 0.61; 0.83), showing significant superiority of gadobutrol over gadoteridol. Calculated lesion-to-brain contrast and the results of all qualitative secondary efficacy variables were also in favour of gadobutrol. Keeping a sufficient time delay after contrast application proved to be essential to get optimal image quality. CONCLUSION: Compared with 0.5 M gadoteridol, 1.0 M gadobutrol was proven to have significantly superior contrast enhancement characteristics in a routine MRI protocol of primary and secondary brain tumours.

Perimesencephalic hemorrhage and vessel variants.

BACKGROUND: In 95% of patients with an apparently normal distribution of blood using unenhanced computed tomography (CT), no ruptured aneurysm for a perimesencephalic subarachnoid hemorrhage (PMSAH) will be detected. In general, the clinical course of these patients is more favorable than that of patients with a detected ruptured aneurysm. We wanted to assess whether vessel variants of the vertebro-basilar circulation are more common in patients with PMSAH than in patients with SAH caused by intracranial aneurysms. Furthermore, we wanted to investigate whether CT angiography (CTA) as a sole diagnostic modality in PMSAH is sufficient. MATERIAL AND METHODS: In patients diagnosed with PMSAH (study group), a CTA was performed routinely as the first-line diagnostic modality. If no aneurysm was found, digital subtraction angiography (DSA) was done. CTA and DSA data sets were analyzed for the presence of an intracranial aneurysm. Furthermore, the diameter of the arteries in the posterior circulation was measured. Special attention was paid to vascular variations. Moreover, CTA and DSA findings were compared with data sets from patients with SAH and an intracranial aneurysm of the posterior circulation (control group). RESULTS: Between January 2002 and June 2007, 28 patients with PMSAH were enrolled in our study. All patients received both CTA and DSA. Furthermore, 28 control data sets were analyzed. Image analysis showed hypoplasia of one or more arterial vessels in 92.9% of PMSAH patients vs. 60.7% of the patients in the control group (p=0.010). Moreover, aplasia of one vessel occurred significantly more often in the study group (53.6%) than in the control group (21.4%; p=0.026). 8 patients in the control group vs. no patients in the study group showed no vessel variants (p=0.004). DSA did not show additional vessel variants, nor did it provide additional information regarding the vessel diameter. CONCLUSION: Interestingly, an increased number of arterial vessel hypoplasia was detected in PMSAH patients. Furthermore, CTA as a sole diagnostic modality in patients with typical PMSAH is sufficient.

Microsurgically induced pure arterial aneurysm model in rats.

INTRODUCTION: The aim of the study was to develop a reliable and reproducible arterial aneurysm model for microsurgical training and further research with dimensions comparable to those encountered in aneurysms in humans. METHODS: The arterial aneurysm models were created microsurgically at the bifurcation of the abdominal aorta using a graft of the carotid artery in 20 Wistar rats. RESULTS: The aneurysms were created successfully and no complications occurred. The average volume of this arterial aneurysm model was 35.19±5.64 mm (3). The time required to create this kind of aneurysm was 192±14.4 min. The central zone of blood inflow into the aneurysm was not affected by any thrombus formation. CONCLUSION: The presented model at the aortic bifurcation in the rat is reliable and immediately available for microsurgical and technical training as well as for scientific studies on aneurysms. Since this kind of model also reproduces arterial aneurysms, basic techniques such as suturing and microtechniques needed for the dissection and repair of vessels can be taught during its creation.

Anterior cervical discectomy and titanium cage fusion - 7-year follow-up.

BACKGROUND AND STUDY AIMS: The purpose of this study was to prospectively evaluate long-term results after anterior cervical discectomy and titanium cage fusion (ACDF) and titanium cage fusion. Special focus was on the adjacent levels. METHODS: 54 patients (age: 48+/-10 years; one level operation in 44 patients and two level operation in 10 patients) entered the study. Re-evaluation consisted of a clinical out patient investigation and was possible in 33 patients. VAS, PROLO and Oswestry scores were used. Lateral radiographs were taken and changes in the operated and adjacent segments were measured and compared to radiographs directly after surgery. Clinical patient data was compared with the data prior to surgery. RESULTS: The mean follow-up time of the 33 patients was 7.26 +/- 0.22 years. One patient needed re-surgery of the cervical spine above the fused segment. PROLO results showed a significant improvement (PROLO F 1.52+/-0.67 to 3.79+/-1.17 p<0.01; PROLO E 1.52+/-0.5 to 3.55+/-1.42 p<0.01). Mean VAS at the time of investigation was 3.2+/-2.5. Oswestry score was 16.4+/-9.5. The alignment of the whole cervical spine was stable lordotic (Katsuura 10.9+/-9.0 degrees to 11.5+/-7.8 degrees ; p=0.76). Total segmental height had reduced from 36.6+/-4.6 mm to 34.6+/-3.9 mm (p=0.04). No significant reduction of disc space height of adjacent levels was detectable (superior: 5.8+/-1.6 mm to 5.2+/-1.6 mm; inferior: 6.0+/-1.7 mm to 5.3+/-1.9 mm). One adjacent superior level showed spontaneous fusion. Ventral and dorsal osteophytes in the superior and inferior adjacent levels increased in number and increased significantly in degree. Patients with bi-segmental fusion (n=7) showed similar results. CONCLUSION: ACDF with titanium cages has good clinical long-term results. A significant progression of degenerative changes can be observed on radiographs without clinical consequences for the patients. A comparison with patients without surgery and conservative therapy is needed to allow a better interpretation of the radiological results.

Computed tomographic angiography: diagnostic procedure of choice in the management of subarachnoid hemorrhage in the elderly patient?

BACKGROUND: The objective of this study was to establish whether 3D computed tomographic angiography (CTA) can be used to determine further management in patients older than 70 years admitted with acute subarachnoid hemorrhage (SAH). PATIENTS AND METHODS: CTA evaluation included analysis of the source images, image-slice-based multiplanar reconstruction, multi-intensity projection (MIP) and finally 3-dimensional rendering. The location and size of the aneurysm, its precise anatomical morphology and the configuration of the circle of Willis were evaluated. Based on these findings, surgery, endovascular coiling or conservative management was selected. RESULTS: Between October 2001 and June 2005, 44 patients over 70 years of age (38 females, 6 males) were admitted to our neurosurgical department with acute SAH. All patients underwent CTA, and additional 2D digital subtraction angiography (2D-DSA) was performed in 14 patients. Forty-five aneurysms (38 ruptured and 7 unruptured) were diagnosed. Six patients were found to have SAH of unknown origin (no aneurysm on CTA nor 2D-DSA). In 20 patients surgery was performed, in 10 patients endovascular coiling of the aneurysm was carried out, and 12 patients were treated conservatively. The findings on CTA and 2D-DSA could be compared for 26 patients (59%). Correlation between CTA and 2D-DSA was good in 25 of these cases (96%). Glasgow Outcome Scale scores of 4 or 5 were calculated for 37% of the operated patients, 27% of those treated with coils, and 36% of the patients treated conservatively. CONCLUSION: In older patients with degenerative vascular diseases, CTA can replace 2D-DSA in most cases if the image quality is excellent and analysis is performed carefully.

Perioperative complication rate of lumbar disc microsurgery depending on the surgeon's level of training.

AIM: Lumbar disc surgery is one of the procedures performed early in neurosurgical training. Agreement exists concerning the use of microsurgical techniques. With increasing surgical experience the clinical outcome should improve, partly because of a reduction in the complication rate. The aim of this study was to evaluate the correlation between patients' immediate clinical outcome, the perioperative complication rate and the surgeons' level of experience. METHODS: Patients undergoing surgery for lumbar disc herniation between January 1998 and December 2000 were investigated. Exclusion criteria were recurrent disc herniations and spinal stenosis. The surgeons were divided into four groups depending on their neurosurgical experience (group A: < or =2 years, group B >2 to < or =6 years, group C: >6 to < or =10 years, group D: >10 years). Anthropometric data, duration of surgery, early and late surgery-related complications and outcome at discharge were analysed. RESULTS: A total of 1 205 patients (556 females, 649 males) were entered in the study. Six hundred and six of the 1 205 patients were treated by surgeons with < or =6 years of training. Seventy-five patients (6.2%) required re-operation. The re-operation rate was lowest (2.91%) in group A and higher (5.25-9.5%) in the other groups. The intraoperative complication rate was highest (4.75%) in group B and significantly lower (1.1-2.5%) in the other groups. On the other hand, fewer patients in group B had persistent postoperative radicular pain. CONCLUSIONS: The clinical outcome after surgery for lumbar disc herniation does not improve linearly with the surgeon's experience. The intraoperative complication rate is highest between the 3rd and the 6th year of training.

[Pigmented villonodular synovitis involving the thoracic spine: a case report]. / Pigmentierte villonoduläre Synovitis der thorakalen Wirbelsäule - operatives Langzeitergebnis: ein Fallbericht.

Spinal diffuse-type giant cell tumours (also known as pigmented villonodular synovitis [PVNS]) are benign. Their occurrence in the thoracic spine is a very rare entity, nevertheless it should be considered in the differential diagnosis. We report about the case of a 35-year-old male presenting with an osteolytic and expansive mass compressing the spinal cord from C7 to Th2. Surgical resection was performed. Histopathological diagnosis was PVNS. 2 years postoperatively the patient was without pain and fully reintegrated in his previous job as a physician.

[Asynchronous lumbar synovial cysts after surgical resection: a case report]. / Asynchrone Facettgelenks-Zyste nach Facettgelenks-Punktion: eine Falldemonstration.

Lumbar synovial cysts represent a rare condition, they are believed to arise from defects of the joint capsule due to degeneration, trauma, rheumatoid arthritis or spondylosis. The symptom spectrum ranges from neural claudication to neurological deficits. We report the case of a contralateral asynchronous facet joint cyst after surgical resection and review the literature.

Evaluation of clip artefacts in three-dimensional computed tomography.

OBJECTIVE: Recently, three-dimensional CT angiography (3D-CTA) has been used as a diagnostic method in postoperative evaluation after aneurysm clipping. A systematic analysis of possible predictors for good image quality needs to be conducted if 3D-CTA is to replace digital subtraction angiography in the postoperative setting. The aim of this study was to evaluate the influence of clip orientation on image quality and to assess titanium clip artefacts quantitatively on 3D-CTA. MATERIAL AND METHOD: Four different Yasargil titanium clips were placed on an acrylic glass tablet. Standardised 3D-CTA scanning was performed at clip-gantry angles of 0 degrees , 45 degrees and 90 degrees . Multiplanar reconstructions of the clips in frontal and lateral projections were performed. 3D-CTA image quality and the severity of titanium artefacts were judged by four observers. RESULTS: Twenty-four images were evaluated. Using frontal reconstructions, clip artefacts at a clip-gantry angle of 0 degrees were almost exclusively distributed along the long axis of the clip, with excellent evaluation quality at the lateral side of the clip branches. With decreasing clip-gantry angle (90 degrees and 45 degrees ) strong artefacts were localised laterally. On lateral reconstructions image quality was not significantly more restricted, regardless of the clip-gantry angles used. CONCLUSION: 3D-CTA image quality can be severely limited by clip artefacts. The expression and distribution of these artefacts depends on both the clip-gantry angle and the plane of image reconstruction. Overall, there is no correlation between clip-gantry angle and either the severity or the spatial distribution of clip artefacts leading to observable restrictions in the evaluation of surrounding structures.

[Occult sacral meningocele--a diagnostic challenge]. / Okkulte sakrale Meningozele--eine diagnostische Herausforderung.

Occult sacral meningoceles are a rare causative factor for neural claudication or radiculopathy. Facet joint cysts in the lumbar spine causing similar symptoms are much more frequent. We report the case of a patient with the radiological diagnosis of a facet joint cyst causing neural claudication. During surgery an occult sacral meningocele was diagnosed. In the literature there are only few cases reported. Hence, the findings and important differential diagnoses of cystic epidural lesions in the lumbar spine are discussed.

Treatment of degenerative cervical disc disease with uncoforaminotomy--intermediate clinical outcome.

BACKGROUND: Anterior cervical uncoforaminotomy (uncoforaminotomy) is an operative method intended to preserve the functional motion segment of the cervical spine while removing the underlying pathology. Controversy exists concerning the patients best suited for this treatment modality. Furthermore, no long-term outcome analyses have been published. METHODS: Between November 2002 and June 2004, 96 patients underwent single-level uncoforaminotomy in our neurosurgical department for the treatment of cervical radiculopathy. The patients were divided into three groups: A, soft disc; B, hard disc; C, hard and soft disc. Follow-up was performed 2 years after surgery. Clinical outcome was classified according to Odom et al. and to the cervical Oswestry and 11-point box scales for arm and neck pain. RESULTS: Ninety patients (92%) underwent intermediate follow-up examinations at an average of 33 months after surgery. Forty-nine patients were in group A, 24 in group B, and 17 in group C. At discharge, 98% of those in group A, 96% in group B, and 94% in group C showed excellent or good results. In two patients revision surgery was performed within 4 weeks due to recurrent disc herniation. In one patient revision was carried out due to a subcutaneous hematoma. In group B one case of vertebral artery injury occurred. Additionally in one patient of this group revision surgery was performed due to inadequate decompression of the neural foramen. At follow-up 94% of the patients in group A, 89% in group B, and 87% in group C had excellent or good results. The scores on the cervical Oswestry scale and the 11-point-box scale showed no significant differences among the groups. CONCLUSION: Uncoforaminotomy, especially in patients with soft-disc pathologies, is a good operative method for the treatment of radicular pain.

Computed tomographic angiography in the evaluation of clip placement for intracranial aneurysm.

BACKGROUND: Computed tomographic angiography (CTA) has been shown to reliably detect aneurysms pre-operatively. The aim of this study was to compare the ability of post-operative CTA to detect aneurysmal remnants in connection with clip placement compared with digital subtraction angiography (DSA). Furthermore, special attention was paid to identifying factors influencing the image quality of CTA. METHOD: Between January 2005 and January 2006 a total of 76 patients with intracranial aneurysms were treated in our department. Thirty-two patients with a total of 33 clipped aneurysm were included in this study. All patients underwent CTA and DSA after surgery. Two investigators, each blinded to the classifications of the other, assessed image quality and clip placement. FINDINGS: In three patients aneurysmal remnants could be detected with CTA and DSA. One 2-mm aneurysmal remnant was not clearly identified on CTA; two small (<2-mm) aneurysmal remnants were definitely not seen on CTA. A single titanium clip was used for aneurysmal clipping in 26 patients, two clips were needed in six patients and one aneurysm required three clips being used. Overall, use of one titanium clip tended to result in better image quality. In addition, clip-gantry angles between 30 degrees and 60 degrees tended to yield better image quality. CONCLUSION: Post-operatively, CTA can be recommended as a reliable non-invasive diagnostic tool only with optimal image quality and with this criterion up to 66% of the aneurysms can be evaluated. Titanium artefacts, especially in the important zone (<2 mm) around the clip in which small aneurysmal remnants can occur, can render adequate evaluation impossible. CTA image quality depends on the number of titanium clips used, but clip-gantry-angle does not significantly influence the image quality.

Microsurgically induced aneurysm models in rats, part I: techniques and histological examination.

INTRODUCTION: The percentage of aneurysms treated surgically has steadily decreased since the results of the ISAT study were published in 2002. The aim of this study was to develop different reliable and reproducible aneurysm models for microsurgical training and further research to guarantee effective instruction in microsurgery for young neurosurgeons with comparable aneurysms like in humans. METHODS: Arterial and venous pouch aneurysm models were created microsurgically using 22 Wistar rats. The femoral and the proximal iliac vessels and the bifurcation of the common carotid artery were exposed for induction. For histological examination every aneurysm was dissected out and analysed. RESULTS: A total of 39 microaneurysms was created in three different regions. During the creation four complications occurred: 4 bleedings and 1 defect were observed and immediately treated. Linear regression curves of the microsurgical evaluation showed a significant advancement in the course of the study. The volumes of the different models were: 2.58+/-1.01 mm (3) for the carotid, 6.49+/-3.36 mm (3) for the iliac and 10.41+/-4.13 mm (3) for the femoral aneurysms. The aspect ratios were 1.86+/-0.45 at the iliac, 1.62+/-0.3 at the femoral and 1.21+/-0.29 for the carotid aneurysms. In 89.7% of the cases the aneurysm sac was thrombosed accentuated at the aneurysm tip while the central zone of blood inflow revealed no thrombus formation. The proportion of endothelial cells displayed a reduction in relation to the total number per cross-section in all aneurysm types. CONCLUSIONS: The presented aneurysm models in rats are reliably and immediately available for further training or scientific histological investigations. Despite the fact that these are not bifurcation aneurysms, basic techniques such as suturing and microtechniques used for the dissection and repair of vessels can be taught.

Microsurgically induced aneurysm models in rats, Part II: clipping, shrinking and micro-Doppler sonography.

INTRODUCTION: To adapt to the changed approach in the treatment of aneurysms, the authors have developed three different experimental aneurysm models for teaching clipping, microvascular Doppler sonography and shrinking. METHODS: 39 microaneurysms were created in 22 animals in three different locations at the carotid, femoral and iliac arteries and treated by neurosurgical clipping. Additionally, shrinking was accomplished in selected cases. Microvascular Doppler sonography with a 20-MHz microprobe was performed prior to and after clipping to assess the achieved result of the clipping manoeuvre. Multiple clip applications in different techniques were performed for optimisation of clip placement and additional training. RESULTS: All created aneurysms could be clipped successfully. The mean duration for clipping and control of clipping results by the micro-Doppler was 8:51+/-4:41 minutes at all aneurysms. The aneurysm clip was repositioned in 16 of 39 (41%) cases, on the basis of the Doppler findings in 14 aneurysms (36%). A relevant stenosis was detected in 10 (25.7%) and incomplete occlusion in 4 (10.2%) attempts. In one aneurysm vasospasm was detected at the distal part of the parent artery. Complete clipping was achieved in all cases. During the entire procedure three unexpected complications involving rupture and bleeding impeded the training. CONCLUSION: Surgically induced aneurysms in rats allow the possibility of multiple clipping, shrinking and micro-Doppler sonography for the simulation of aneurysm treatment.

Deep venous thrombosis after lumbar disc surgery due to compression of the vena cava caused by a retroperitoneal haematoma.

The case of a 46-year-old Arabian male complaining of low back pain due to congenital lumbar spinal canal stenosis with additional disc herniation is presented. Following CT scan and MRI, bilateral enlarged partial hemilaminectomy was performed in L5/S1 with removal of herniated disc material. Intraoperatively, no complication was encountered. In the postoperative course, the patient had persistent low back pain and developed deep venous thrombosis in the left leg. Phlebography revealed thrombosis in the deep veins of the left leg extending into the pelvic region. The source of this high obstruction of the venous outflow was a retroperitoneal haematoma, visible on CT scan, compressing the vena cava at the level of L5/S1, the most probable cause of which was accidental perforation of the anterior spinal ligament. This case demonstrates that injury to the retroperitoneal vessels during lumbar disc surgery can also present as deep venous thrombosis due to obstruction of venous outflow.

Current status of intraoperative real-time vibrography in neurosurgery.

PURPOSE: Intracranial lesions are often characterized by different elasticities. The aim of the present study was to test the application of vibrography during brain tumor surgery. MATERIALS AND METHODS: The real-time vibrography system consisted of a conventional ultrasound system (Siemens Sonoline Omnia) with a custom-designed RF interface and a 6.5-MHz endocavity curved array (Siemens 6.5EC10). The RF data were digitized using a 50-MHz, 12-bit PCI analog/digital (A/D) converter for real-time or offline processing. Static compression was replaced by low-frequency axial vibration of the probe. A special applicator equipped with a stepping motor moved the ultrasonic probe and produced a low frequency mechanical vibration of 5-10 Hz with a vibration amplitude of 0.3 mm and slight preliminary compression (total<1 mm). The maximum application time was 60 sec. A pneumatic holding device (Unitrac, Aesculap, Tuttlingen, Germany) was used. RESULTS: Brain tissue is normally color coded between red and orange. In this study 41 out of 45 tumors could be detected via vibrography. Two tumors could not be detected with this imaging technique: a glioblastoma at a depth of 2 cm and a metastasis at a depth of 3 cm. Two additional tumors were not recognized because of technical problems. In 4 cases tumors with strain values identical to those in brain tissue (coded red or orange) but easily identified by a peripheral zone of high strain (yellow) were found. Tumors with strain values higher than those measured in brain tissue coded yellow and were softer than brain during surgical intervention. Higher strain was found in 23 tumors. Tumors with strain values lower than those in cerebral tissue were found to be harder during surgery and coded brown or black. Lower strain was found in 10 cases. Four tumors were inhomogeneous and could not be assigned to one of the above groups. Mortality was 0%, morbidity 2.3%. One patient displayed transient paresis of the lower extremity due to microsurgical difficulties during the approach. In one patient minimal bleeding of the cortical surface occurred in a frontobasal tumor; however, no postoperative deficits were noted. CONCLUSION: Vibrography is a new low-risk technique for intraoperative imaging. In low-grade astrocytomas and oligodendrogliomas, this additional technique can be used to control resection. In other cortical and subcortical tumors (e. g. metastases), it can provide an impression of the intratumoral elasticities.

An optical evaluation of the phenomenon of red out in neuroendoscopic surgery: what is the physical background?

BACKGROUND: The loss of visualization in neuroendoscopy due to intraoperative bleeding is called "red out". Although red out is a well-known problem during endoscopy, clear physical descriptions of this phenomenon are lacking. OBJECTIVE: The aim of this study was to investigate the optical properties of red out. In particular, the attenuation coefficient, comprising scattering, and absorption, of various blood/Ringer solutions was quantified and measured spectrally resolved. Small amounts of blood virtually preclude neuroendoscopic visualization. In blood/Ringer solutions with a dilution of 1:101, it was not possible to distinguish characters (font size 10, Arial) at a distance of 5 mm. We have concluded, from our physical investigations, that the problem of red out is dominated by scattering rather than by absorption. Accordingly, technical developments aimed at increasing information acquisition under red out conditions should be based on optical measurement concepts for scattering media.

Chronic subdural haematoma in patients with Huntington's disease.

We studied the frequency of patients who had chronic subdural haematomas (CSDH) and Huntington's disease (HD) in a 1-year study period. In our department a total of 58 patients with CSDH were treated. Four patients (6.9% of them) had HD. Surgical evacuation of the haematoma was performed in all four cases with the use of a twist drill trepanation without a drainage system.

Analysis of surgical management of calvarial tumours and first results of a newly designed robotic trepanation system.

This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.

Dynamic cerebral autoregulation in patients with ruptured and unruptured aneurysms after induction of general anesthesia.

INTRODUCTION: Blood pressure management in patients undergoing surgery for clipping of aneurysms is demanding. More information about the ability of cerebral vessels to normally regulate cerebral blood flow may have a direct influence on the intraoperative management. In patients with subarachnoid hemorrhage (SAH) a disturbance of cerebral autoregulation has been reported and it correlated with the severity of the bleeding in these studies. The impairment of autoregulation was demonstrated using static measurements of cerebral pressure autoregulation. However, the dynamic component of the autoregulatory capacity seems to be of importance in the acute setting after SAH. The aim of this study was to evaluate dynamic pressure autoregulation in patients undergoing surgery for intracranial aneurysms. PATIENTS/MATERIAL AND METHODS: 36 patients with a mean age of 45 years were evaluated, 26 patients with acute SAH, 10 patients with unruptured aneurysms. Cerebral autoregulation in normocapnia was tested using thigh cuffs to alter arterial blood pressure and continuous registration of the blood flow velocities with transcranial Doppler sonography. After the induction of general anesthesia under normocapnia the autoregulatory index (ARI) was calculated (values between 0-9). Patient groups were compared using Wilcoxon- and Spearman's rank test. RESULTS: The two patient groups were comparable with regard to gender, age, PaCO(2), blood flow velocities and blood pressure. In patients with SAH mean ARI was 3.1/3.3 (right/left side) compared to 4.7/4.6 (right/left side) in patients without SAH. The difference was statistically significant (Wilcoxon p = 0.0399). The degree of impairment of the autoregulatory capacity increased significantly (p = 0.006) with the severity of the SAH (Hunt&Hess and Fisher scale). CONCLUSION: Dynamic pressure autoregulation is impaired in patients after SAH compared to patients without SAH and correlates with the severity of the SAH. We propose that autoregulation should be measured in all patients with SAH or that an impaired autoregulation should be taken into account in patients with SAH undergoing surgery in the acute phase.