[Outpatient treatment of acute injuries of upper extremities with axillary plexus anesthesia in the emergency department-Is that possible without continuous anesthesia attendance?] / Ambulante Versorgung akuter Verletzungen der oberen Extremität in der Notfallambulanz in axillärer Plexusanästhesie ­ Ist das ohne durchgehende Anästhesiebegleitung machbar?

BACKGROUND: The incorporation into the routine operating procedure of patients with small but acute hand and forearm injuries requiring surgery who present in the emergency admission department, represents a challenge due to limited resources. The prompt treatment in the emergency admission department represents an alternative. This article retrospectively reports the authors' experiences with a treatment algorithm in which emergency patients were treated by ultrasound-guided axillary brachial plexus blocks (ABPB) and surgery carried out in the emergency department without further anesthesia attendance. METHODS: Patients were preselected by the surgeon if they were suitable for a standardized treatment without anesthesia attendance during surgery. If there were no anesthesiological or surgical contraindications patients received an ABPB in the holding area of the operating room (OR) under standard monitoring. Blocks were performed as a multi-injection, ultrasound-guided technique which is anatomically described in detail. Patients >60 kg received a total volume of 30 ml of a mixture of 10 ml 1% ropivacaine (100 mg) and 20 ml 2% prilocaine (400 mg). Patients <60 kg received the same mixture with a reduced volume of 25 ml corresponding to 82.5 mg ropivacaine and 332.5 mg prilocaine. After controlling for block success patients were admitted to the emergency department and the surgical procedure was carried out under supervision by the surgeon without further anesthesia attendance. At discharge patients were explicitly instructed that in the case of any complications or a continuation of the block for more than 24 h they should contact the emergency department. RESULTS: Between January 2013 and November 2017 a total of 566 patients (46.4 years, range 11-88 years, 174.9 cm, range 140-211cm, 80.8 kg, range 42-178kg, ASA 1/2/3, 190/338/38, respectively) were treated according to a standardized protocol. The ABPBs were performed by 74 anesthetists. In 5% of the patients the initial block was incomplete and rescue blocks were performed with a maximum of 2­3ml 1% prilocaine per corresponding nerve. After completion the block was ensured and all patients underwent surgery without further analgesics or local anesthetic infiltration by the surgeon. Complications related to the ABPB and readmissions were not observed. CONCLUSION: It could be demonstrated that minor surgery could be carried out safely and effectively with a defined algorithm using ABPB in selected patients outside the OR without permanent anesthesia attendance: however, indispensable prerequisites for such procedures are careful patient selection, patient compliance, the safe and effective performance of the ABPB and reliable agreement with the surgeon.

[Lumbar CT-guided radiofrequency ablation of the medial branch of the dorsal ramus of the spinal nerve : Anatomic study and description of a new technique]. / Lumbale CT-gezielte Radiofrequenzablationen des Ramus medialis rami dorsalis nervi spinalis : Anatomische Untersuchung und Beschreibung einer neuen Technik.

BACKGROUND: The success of radiofrequency ablation (RF) of the medial branch of the dorsal ramus in patients with facet joint pain depends on the effective coagulation distance. To date, computed tomography(CT)-guided techniques do not reach the nerve in parallel but rather than punctually. We report a new CT-guided technique to enhance parallelism and proximity of the RF needle to the nerve. MATERIALS AND METHODS: Two examiners with different experience with CT-guided procedures in corpses performed all punctures at the lumbar spine on 10 corpses. A RF needle was inserted 1 cm lateral to the spinous process of the vertebra located caudal to the target nerve. The needle was advanced under CT guidance at a flat angle between the superior articular process and the base of the costal or transverse process of the cranial vertebra. The position was verified by dissection. Needle position was judged successful provided the needle could be positioned in the first attempt with no more than one angle correction. RESULTS: In 86 out of 100 possible cases (50 per side) at the 5 lumbar segments, the RF needle could be depicted by CT in the target area with no more than one correction of the needle position. Anatomical dissections revealed that 47 out of 86 needles (54.6%) fulfilled the requirements of parallelism and proximity to the nerve. The dorsal ramus was never reached by the RF needle. Higher success rates were obtained in the middle segments compared to the border segments of L1-L2 and L5-S1. CONCLUSIONS: We could demonstrate that the principle of parallelism and proximity of the needle to the nerve could be fulfilled with this new technique; however, needle positioning requires practice due to the oblique puncture direction.

Thermocoagulation of the Medial Branch of the Dorsal Branch of the Lumbal Spinal Nerve: Flouroscopy Versus CT.

Objective: For radiofrequency neurotomy of the medial branch of the lumbar dorsal rami, physicians use techniques guided either by fluoroscopy or computerized tomography (CT), and advocate for their respective techniques. Crucial to the choice of technique is how well each can capture the target nerve. The present study was, therefore, undertaken to assess in cadavers the accuracy of fluoroscopic-guided and CT-guided techniques. Design: In10 cadavers preserved with Thiel's method, electrodes with 10mm active tips were placed in supine position on the right using a fluoroscopic-guided technique, and on the left using a CT-guided technique. Using a special dissection approach, the relationship between the target nerve and the tip of the electrode was revealed. The displacement between electrode and the nerve, and the extent to which the electrode was parallel to the nerve, were measured with callipers. Results: Under fluoroscopy guidance, electrodes were placed accurately beside the nerve, and were parallel to it for 9 ±1.9 mm. In only two cases did the electrode pass too deeply. Under CT guidance, electrodes often failed to reach the nerve, but when they did they were parallel to it for only 3.2 ± 3.2 mm. In seven cases, the electrode passed too deeply beyond the target nerve. Conclusion: The fluoroscopy-guided technique can be relied upon to achieve optimal placement of electrodes on the lumbar medial branches. The CT-guided technique fails to do so, and should not be used in practice until a modified version has been developed and validated.

Susceptibility of the genitofemoral and lateral femoral cutaneous nerves to complications from lumbar sympathetic blocks: is there a morphological reason?

BACKGROUND: Interference with the function of the genitofemoral nerve (GFN) and lateral femoral cutaneous nerve (LFCN) represents a significant complication of lumbar sympathetic blocks (LSBs). The nerve topography of the lumbar sympathetic trunk (LST) was investigated to find a possible morphological reason for this. METHODS: A total of 118 cadavers embalmed by Thiel's method were investigated. The nerves were dissected from their innervation area to their paravertebral origins. Distances of the GFN and the LFCN to the LST were measured at levels L2/3, L3/4, and L4/5, which are the most common levels for LSB. RESULTS: Two hundred and thirteen sides were assessable for the GFN and 151 sides for the LFCN. In 186 cases, the whole GFN (in 20 cases, its femoral branch only) approached the medial margin of the psoas major (PM) and passed the LST laterally at the level of L3/4 and a distance of 0-28 mm (mean distance 8.5 mm; sd 6.7 mm) and ran dorsally between the PM and the vertebral body of L3, reaching the intervertebral foramen L2/3. In three cases, the GFN fused with the LFCN. In 55 cases, the GFN-LST distance was 0-13 mm at L4/5 and in 19 cases, 9-19 mm at L2/3. The LFCN approached the lateral margin of the PM and entered the intervertebral foramen at L2/3 in 141 cases. CONCLUSIONS: There is a higher risk of LSB affecting the GFN at L3/4 or L4/5 during neurolysis of the LST due to its topography. The LFCN rarely shows a strong relation to the LST and only when fused with the GFN.

Topography of the lumbar sympathetic trunk in normal lumbar spines and spines with spondylophytes.

BACKGROUND: Degenerative processes of the lumbar spine may change the position of the sympathetic trunk which might cause failure of sympathetic blocks owing to inadequate distribution of local anaesthetic. METHODS: The retroperitoneal spaces of 56 cadavers [24 males and 32 females; 79 (10) yr] embalmed with Thiel's method were investigated by dissection. The course of the lumbar sympathetic trunk (LST) was documented from the diaphragmatic level to the linea terminalis. Topography of the large vessels and the psoas muscle was documented. In the case of spondylophytes, the location or direction of displacement of the trunk was regarded with special interest. RESULTS: The LST entered the retroperitoneal space at the level of the vertebral body of L2 in 70 of the 112 sides and showed the most consistent relationship with the medial margin of the psoas muscle at intervertebral disc level L2/3. On 11 spines with spondylophytes, the sympathetic trunk was dislocated to the most ventrolateral point of the spondylophyte in 12 cases, in six cases dorsolaterally, and in one case ventromedially. The more the sympathetic chain departed at the vertebral body level, the more the body developed a concavity by loss of height. CONCLUSIONS: Spondylophytes influenced the location of the LST and the distribution of the local anaesthetic. The local anaesthetic should wash around the spondylophyte to reach all possible locations of the chain. The medial margin of the psoas muscle was confirmed to be a consistent reference point at intervertebral disc level L2/3.

Dorsal minimally invasive plate osteosynthesis of the distal tibia with regard to adjacent anatomical characteristics.

INTRODUCTION: The aim of this study was to perform MIPO of the distal tibia from a dorsomedial and dorsolateral approach and to evaluate their feasibility and risk of injury to adjacent anatomical structures. MATERIAL & METHODS: A total of 18 extremities from 9 adult human cadavers was included in the study. In each cadaver, one lower leg underwent application of a 12-hole 3.5 LCP metaphyseal plate from the medial and the further one from the lateral approach. For the medial approach, a 4 cm skin incision was performed at the tibial border of the Achilles tendon, starting from 1 cm proximal to its insertion point at the calcaneal tuberosity. Entrance was gained between the medial border of the flexor hallucis longus tendon and the medial neurovascular bundle. Regarding the lateral approach, the skin was incised over a length of about 4 cm at the lateral border of the Achilles tendon, approximately 1 cm proximal to its insertion point. Entrance was gained between the Achilles tendon and the peroneus brevis muscle. The plates were inserted in direct bone contact in a proximal direction and the proximal and distal ends were fixed. During dissection, the proximal and distal holes beneath the crossing points of the neurovascular bundle and the plate were noted. The distal and proximal intersection points of the neurovascular bundle and the plate were measured with reference to the distal border of the plate. RESULTS: Concerning the medial approach, the neurovascular bundle was on median located between the 6th and 11th plate holes starting from distal. The bundle intersected the plate distally at a mean height of 65.8 mm and proximally at 156.8 mm on average. For the lateral approach, the neurovascular bundle was situated between the 6th and the 12th plate hole from distal. It crossed the plate distally at a mean of 61.0 mm and proximal at a mean height of 153.9 mm. In none of the cases, lacerations of the neurovascular bundle were observed. CONCLUSION: In conclusion, MIPO from the dorsomedial and dorsolateral approach are both safe procedures as indicated by our study.

Anatomical investigation of a new vertical obturator nerve block technique.

BACKGROUND: We evaluated a vertical obturator nerve block (VOB) using a single morphological landmark and no additional distance measurement or obligatory changes of the needle's direction. MATERIALS AND METHOD: A total of 88 cadavers (176 lower limbs), prepared using Thiel's embalming method, were examined. The index finger was placed lateral to the palpable pubic tubercle and the needle inserted laterally to the distal part of the fingernail at the tubercle's level and advanced strictly perpendicular to the table's surface. If bone contact was made, the needle was slightly turned to pass the bone distally. Colored latex (5 ml) was then injected. The injection depth was documented, then followed by dissection and nerve exposition. The real skin-nerve distance and the degree of difficulty in orientation and of palpation were measured. Additionally, the dissemination around the nerve or its branches and the intrapelvic spread were documented. RESULTS: The nerve was colored completely in 93.75%, partially in 1.71%, and not colored in 4.54% of cases. The mean injection depth was 3.9 cm (±0.7 SD) and real nerve depth was 3.8 cm (±0.69 SD). Bone contact necessitating the needle's redirection was found in 20 (11.4%) cases. Easy orientation and palpation of the tubercle was always found. In 40 cases, the latex spread via the obturator canal into the lesser pelvis. CONCLUSION: In this anatomical study, the VOB technique exhibits easy orientation without stimulation or ultrasound guidance. The nerve was located at a constant depth. The injection offered a high percentage of colored nerves.

The superficial palmar arch and median artery as an example of misleading results due to a small number of investigated specimens or the use of different classifications.

BACKGROUND: Small numbers of investigated specimens might lead to misinterpretations. Different classifications can change results dramatically. This is demonstrated by an investigation of the superficial palmar arch and the palmar median artery. MATERIALS AND METHODS: A total of 702 upper limbs were investigated. Data were collected during eight dissection courses for advanced medical students and one workshop of hand surgery (number of investigated limbs per course between 52 and 111). The variations of superficial palmar arches were documented according to the classification of Lippert and Pabst as well as the occurrence of a palmar median artery. The results of each course were compared among each other, to the total result and compared to allocation according Jaschtschinski's classification. RESULTS: In total, the results show complete arches in 52.15%. Incomplete arches with the ulnar artery supplying the thumb in 15.38%, reaching the index in 22.15% and the middle finger in 10.32%. Median arteries were documented in 4.5%. Individual course results varied concerning complete arches from 41.1% (37 out of 90) and 65% (35 out of 55), median arteries were found between 0 (0 of 69 hands) and 9.1% (5 of 55 hands). Classifying our total result with Jaschtschinski's classification there would have been complete arches in 67.8% (individual course result: 43.3-81.8%). CONCLUSIONS: Small numbers of investigated specimens can lead to confounding results. The classification used has to be precisely determined. Both classifications need to be known to interpret results correctly. A repetition of investigation might be performed to confirm results.

Levetiracetam compared to phenytoin for the prevention of postoperative seizures after craniotomy for intracranial tumours in patients without epilepsy.

Anticonvulsant drugs are frequently given after craniotomy. Phenytoin (PHT) is the most commonly used agent; levetiracetam (LEV) is a new anticonvulsant drug with fewer side effects. To compare the incidence of seizures in patients receiving either prophylactic PHT or LEV perioperatively, 971 patients undergoing a craniotomy were analysed retrospectively during a 2-year period. PHT was used routinely and LEV was administered when PHT was contraindicated. Seizures documented during the first 7 days after craniotomy were considered. A total of 235 patients were treated with an antiepileptic drug: 81 patients received LEV, and 154 patients, PHT. Two patients receiving LEV (2.5%) and seven receiving PHT (4.5%) had a seizure despite this treatment. No patient had a documented side effect or drug interaction. The data show that LEV may be an alternative option in patients with contraindications to PHT.

Hypericin for visualization of high grade gliomas: first clinical experience.

AIMS: We aimed to demonstrate that Hypericin, a component of St. Johns Wort, selectively visualizes malignant gliomas. Hypericin is known as one of the most powerful photosensitizers in nature with excellent fluorescent properties. METHODS: In five patients with a recurrence of a malignant glioma a newly developed water soluble formulation of hypericin was given intravenously (0.1 mg/kg body weight) 6 h before the surgical procedure. Tumor resection was performed under white light and fluorescence mode. The intensity grade of the tissue fluorescence was categorisized by the surgeon in three grades, highly fluorescent, weakly fluorescent and not fluorescent. In these areas tissue samples were taken and investigated by two blinded independent neuropathologists. Tissue samples were histologically classified differentiating between tumor tissue, tumor necrosis, tissue with scattered tumor cells and normal brain tissue. RESULTS: In all patients tumor tissue was clearly distinguishable by its typically red fluorescence color from normal brain tissue which was colored blue under a special fluorescent filter. Histological evaluation of the 110 tissue samples showed a specificity of 100% and sensitivity of 91% for one of the two neuropathologists, whereas specificity for second pathologist was 90% and sensitivity 94%. The i.v. application of Hypericin proofed to be safe in all cases and there were no side effects observed. CONCLUSION: Hypericin in its water soluble form is a well tolerated drug. In addition to its high photosensitizing properties hypericin will open up interesting new therapeutic possibilities especially when used in combination with fluorescence detection and simultaneously photodynamic therapy.

Analysis of risk factors influencing the development of severe dizziness in patients with vestibular schwannomas in the immediate postoperative phase.

OBJECTIVE: Dizziness, a common postoperative symptom in patients with vestibular schwannomas (VSs) has a negative effect on the course of recovery, particularly in patients with severe symptoms. Reports on incidence and possible risk factors contributing to these symptoms are inconsistent and sometimes even contradictory. In order to establish a profile of patients at risk of severe symptoms in the immediate postoperative phase we retrospectively analyzed data of patients with unilateral VSs focusing on the incidence of severe dizziness and nausea during the immediate postoperative period and up to 1 year after surgery. METHODS: In a retrospective study data of 104 consecutive patients with VSs were analyzed. All patients underwent microsurgical tumor resection via a lateral-suboccipital approach. Factors that were assumed to affect the development of severe dizziness, such as age, gender, tumor size, tumor side, and cranial nerve function, were analyzed by means of univariate and multivariate logistic regression analyses. A three step grading system was used to describe symptoms of patients included in this study: 0=no symptoms of dizziness, 1=slight dizziness including light-headedness or feeling of disequilibrium and 2=severe dizziness with nausea including imbalance or insecurity when walking, requiring antiemetic treatment. RESULTS: Data of 92 patients, 41 men and 51 women, were available for analyses. Mean age of treated patients was 53 years (range 17-81). There was no predilection of side (52.2% right/47.8% left). Before surgery 39 patients (42.4%) were symptom free (grade 0), 13 patients (14.1%) had slight symptoms (grade 1) and 40 patients (43.5%) suffered from severe symptoms (grade 2). Immediately after surgery two patients (2.2%) where symptom free (grade 0), 19 patients (20.7%) had slight symptoms (grade 1) and 71 patients (77.2%) suffered from severe symptoms (grade 2). All patients with grade 2 symptoms required antiemetic treatment ranging between 1 and 10 days (mean 4 days). Logistic regression analyses showed young age, large tumor size (T3/T4), female gender, and severe preoperative symptoms to be main factors increasing the odds for patients to develop severe symptoms postoperatively. CONCLUSION: Patients at risk to develop severe symptoms should receive antiemetic treatment even before surgery. If in doubt about the actual risk for a specific patient with a large tumor (T3 or T4) available data suggests that patients will benefit if antiemetic treatment is started early, even before surgery.

Broadening horizons of neuroendoscopy with a variable-view rigid endoscope: an anatomical study.

AIM: To test the versatility and usefulness of a prototype rigid endoscope with a continuously variable-view-angle tip (Endochamaeleon, Karl Storz, Tuttlingen, Germany) with regard to field of vision and applicability for endoscopic assisted neurosurgery. METHODS: In five formaldehyde fixed specimens frontolateral and retrosigmoid approaches were prepared on both sides and five target positions of the endoscopes tip were defined. A rigid 4mm endoscope, which offers in one plane a viewing range of approximately -10 degrees to +120 degrees by turning a proximal knob coupled to fine distal optomechanics was compared to 0 degrees , 45 degrees , and 70 degrees rigid endoscopes. The visualizable neuroanatomical structures were assessed for each position, endoscope angle, and plane of view as well as the over-all visibility of neuroanatomical structures and the time factor. RESULTS: 1905 recorded images of 1800 different views were analyzed. The EC offers a variable angle of view in one plane without need to change the endoscope position. This feature is well suited for inspection of functionally delicate areas at the skull base. The maximum number of visible structures for each position was only seen with the EC. Endoscopic exploration was significantly less time consuming with the EC than with the other endoscopes. CONCLUSION: The EC provided superior usability and visualization potential compared to standard rigid endoscopes with fixed angulation. It combines the ergonomic and safety advantage of not having to insert endoscopes with different angles with the opportunity to "scan" the surgical field with a variable angle of 0 degrees -120 degrees within one plane of view.

Association of the Jun dimerization protein 2 gene with intracranial aneurysms in Japanese and Korean cohorts as compared to a Dutch cohort.

In a previous study a linkage region for association to IA patients was found on chromosome 14q22. In this study, we report the findings of a positional candidate gene, Jun dimerization Protein 2 (JDP2), and single nucleotide polymorphisms (SNP) of that gene that are associated with intracranial aneurysms in different ethnic populations. We screened the linkage region around chromosome 14q22 and narrowed it down to JDP2. We then genotyped case and control groups of three different ethnic populations: 403 Japanese intracranial aneurysm (IA) cases and 412 controls, 181 Korean IA cases and 181 controls, 379 Dutch cases and 642 Dutch controls. Genotyping was performed using polymerase chain reaction and direct sequencing technology. The allele distribution of three SNPs (two intronic: rs741846; P=0.0041 and rs175646; P=0.0014, and one in the untranslated region: rs8215; P=0.019) and their genotype distribution showed significant association in the Japanese IA patients. The allelic and genotypic frequency of one intronic SNP (rs175646; P=0.0135 and P=0.0137, respectively) and the genotypic frequency for the SNP in the UTR region (rs8215; P=0.049) was also significantly different between cases and controls of the Korean cohort. There was no difference in allelic or genotypic frequencies in the Dutch population. These SNPs in JDP2 are associated with intracranial aneurysms, suggesting that variation in or near JDP2 play a role in susceptibility to IAs in East Asian populations.

Real-time 3T fMRI data of brain tumour patients for intra-operative localization of primary motor areas.

INTRODUCTION: In patients with tumours in or near the motor cortex reliable intra-operative identification of the precentral gyrus can be difficult due to anatomical dislocation. Maps of functional magnetic resonance imaging (fMRI) based on the blood oxygen level dependent (BOLD) effect are used to localize eloquent functional areas of the brain but require postprocessing for reduction of false positive activations. We set the focus of this study on the evaluation of feasibility and clinical usefulness of using real-time fMRI t-maps without postprocessing for pre-operative planning and intra-operative localization of functional motor areas. METHODS: Real-time fMRI t-maps from a 3-T MRI scanner were co-registered with MRI data. Ten patients were operated under general anaesthesia using 3D neuronavigation with integrated real-time fMRI t-maps. Surgical and functional outcome was compared to results of 12 patients who previously underwent wake surgeries. RESULTS: Good neurological outcome was achieved in all treated patients. Main activation clusters on fMRI real-time maps were easily identified. Co-registered real-time fMRI data without additional postprocessing were useful in planning the surgical approach. However, due to brain shift and large voxel size of BOLD contrast signals on t-maps exact localization of borders between tumours and functional areas was not possible intra-operatively. CONCLUSION: Our method is very simple to use and effective in guiding the neurosurgeon safely through minimally invasive craniotomies to tumours in eloquent areas without setting lesions to functional areas. Furthermore, the neurosurgeon is more independent when tumour location requires acquisition of fMRI data for pre-operative planning and intra-operative navigation.

The use of high-frequency electromagnetics in brain tumour surgery.

OBJECTIVE: The first commercially available high-frequency electromagnetic field (EMF) system promises additional functionality for neurosurgical procedures. In a prospective study, we evaluated the optimal use as well as the limitations of this system designed for vaporizing tissue and for coagulation in brain tumour surgery. METHODS: For the microsurgical treatment of 63 consecutive patients with various intracranial tumours, the EMF system was used in addition to the standard neurosurgical instrumentarium. The system was assessed with respect to its compatibility with the operating room environment. Furthermore, attention was given to the particular techniques required to use the system most effectively. The efficiency of the investigated tool was monitored throughout the study. RESULTS: The EMF system functioned properly in all procedures and did not cause any complications. Specific handling techniques and electrode tip configurations could be defined for optimal use of high-frequency electromagnetics for vaporization and coagulation in different intraoperative settings. Thereby, the efficiency of the device could be increased throughout the study while ineffective use decreased from 7 to 2 cases. Although this tool is designed ergonomically and offers high tactile control, it cannot be used submerged in cerebrospinal fluid or under continuous irrigation, which makes it necessary to use it in tandem with suction devices to obtain a clear view on the surgical field. CONCLUSION: Maneuvering with the EMF system was substantially different to both monopolar and bipolar systems, clearly necessitating a learning curve for the surgeon. This device was found to be a valuable complementary tool to standard electrosurgical instruments when applied effectively and with elaborated techniques.

Image-guided craniotomy for frontal sinus preservation during meningioma surgery.

OBJECTIVE: Preservation of the frontal sinus (FS) during the frontolateral approach to the skull base reduces morbidity, enhances patient comfort, and speeds up the surgical procedure. Due to its irregular outline, mental reconstruction of the borders of FS from two-dimensional images is challenging during surgery. This study was designed to evaluate the impact of neuronavigation on identification and preservation of the FS during frontolateral craniotomies. METHODS: Forty-five patients with pathologies located in the anterior skull base and in the parasellar region were included. A standard computed tomography (CT) sequence was obtained from each patient and uploaded onto an image-guidance system for volumetric rendering of 3D images. The outline of the FS was visualized and the distance between its lateral border and the mid-pupillary line (MPL) was measured. The results were used for navigated craniotomies and compared to the intra-operative findings. RESULTS: The FS was located medial, on and lateral to the MPL in 32, 4 and 9 cases, respectively. The individual outline of the FS could be identified with a mean target registration error of 1.4mm (+/-0.7 mm). The craniotomy could be custom-tailored for each patient according to the individualized landmarks while visualizing the lesion and the surgical landmarks simultaneously. Unintended opening of the frontal sinus or orbit did not occur in any of these cases. CONCLUSION: Image-guided craniotomies based on 3D volumetric image rendering allow for fast and reliable demarcation of complex anatomical structures hidden from direct view in frontolateral approaches. The outline of the frontal sinus and the orbit can be appraised at a glance providing additional safety and precision during craniotomy.

Surgical planning for retrosigmoid craniotomies improved by 3D computed tomography venography.

OBJECTIVE: It is impossible to precisely anticipate the crooked course of the transverse and sigmoid sinuses and their individual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was designed to evaluate this anatomical relationship with the help of a surgical planning system and to analyze the impact of these in vivo findings on trepanation placement in retrosigmoid craniotomies. METHODS: In a consecutive series of 123 patients with pathologies located in the cerebellopontine angle, 72 patients underwent surgical planning for retrosigmoid craniotomies based on 3D volumetric renderings of computed tomography venography. By opacity modulation of surfaces in 3D images the position of the asterion was assessed in relationship to the transverse-sigmoid sinus transition (TST) and compared to its intraoperative localization. We evaluated the impact of this additional information on trepanation placement. RESULTS: The spatial relationship of the asterion and the underlying TST complex could be identified and recorded in 66 out of 72 cases. In the remaining 6 cases the sutures were ossified and not visible in the 3D CT reconstructions. The asterion was located on top of the TST in 51 cases, above the TST in 4 cases, and below the TST in 11 cases. The location of the trepanation was modified in 27 cases due to the preoperative imaging findings with major and minor modifications in 10 and 17 cases, respectively. CONCLUSION: Volume-rendered images provide reliable 3D visualization of complex and hidden anatomical structures in the posterior fossa and thereby increase the precision in retrosigmoid approaches.