Advanced Neuronavigation in Skull Base Tumors and Vascular Lesions

Comparative Anatomic Analysis of Neuronavigated Transmastoid-Infralabyrinthine Approaches for Jugular Fossa Pathologies: Short Anterior Rerouting Versus Nonrerouting and Tailored Nonrerouting Techniques

BACKGROUND AND OBJECTIVES

Access to the jugular fossa pathologies (JFPs) via the transmastoid infralabyrinthine approach (TI-A) using the nonrerouting technique (removing the bone anterior and posterior to the facial nerve while leaving the nerve protected within the fallopian canal) or with the short-rerouting technique (rerouting the mastoid segment of the facial nerve anteriorly) has been described in previous studies. The objective of this study is to compare the access to Fisch class C lesions (JFPs extending or destroying the infralabyrinthine and apical compartment of the temporal bone with or without involving the carotid canal) between the nonrerouting and the short-rerouting techniques. Also, some tailored steps to the nonrerouting technique (NR-T) were outlined to enhance access to the jugular fossa (JF) as an alternative to the short-rerouting technique.

METHODS

Neuronavigated TI-A was performed using the nonrerouting, tailored nonrerouting, and short-rerouting techniques on both sides of 10 human head specimens. Exposed area, horizontal distance, surgical freedom, and horizontal angle were calculated using vector coordinates for nonrerouting and short-rerouting techniques.

RESULTS

The short-rerouting technique had significantly higher values than the NR-T ( P < .01) for the exposed area (169.1 ± SD 11.5 mm 2 vs 151.0 ± SD 12.4 mm 2 ), horizontal distance (15.9 ± SD 0.6 mm vs 10.6 ± SD 0.5 mm 2 ), surgical freedom (19 650.2 ± SD 722.5 mm 2 vs 17 233.8 ± SD 631.7 mm 2 ), and horizontal angle (75.2 ± SD 5.1° vs 61.7 ± SD 4.6°). However, adding some tailored steps to the NR-T permitted comparable access to the JF.

CONCLUSION

Neuronavigated TI-A with the short-rerouting technique permits wider access to the JF compared with the NR-T. However, the tailored NR-T provides comparable access to the JF and may be a better option for class C1 and selected class C2 and C3 JFPs.

Exoscopic Microsurgery: A Change of Paradigm in Brain Tumor Surgery? Comparison with Standard Operative Microscope

BACKGROUND

The exoscope is a high-definition telescope recently introduced in neurosurgery. In the past few years, several reports have described the advantages and disadvantages of such technology. No studies have compared results of surgery with standard microscope and exoscope in patients with glioblastoma multiforme (GBM).

METHODS

Our retrospective study encompassed 177 patients operated on for GBM (WHO 2021) between February 2017 and August 2022. A total of 144 patients were operated on with a microscope only and the others with a 3D4K exoscope only. All clinical and radiological data were collected. Progression-free survival (PFS) and overall survival (OS) have been estimated in the two groups and compared by the Cox model adjusting for potential confounders (e.g., sex, age, Karnofsky performance status, gross total resection, MGMT methylated promoter, and operator's experience).

RESULTS

IDH was mutated in 9 (5.2%) patients and MGMT was methylated in 76 (44.4%). Overall, 122 patients received a gross total resection, 14 patients received a subtotal resection, and 41 patients received a partial resection. During follow-up, 139 (73.5%) patients experienced tumor recurrence and 18.7% of them received a second surgery. After truncation to 12 months, the median PFS for patients operated on with the microscope was 8.82 months, while for patients operated on with the exoscope it was >12 months. Instead, the OS was comparable in the two groups. The multivariable Cox model showed that the use of microscope compared to the exoscope was associated with lower progression-free survival (hazard ratio = 3.55, 95%CI = 1.66-7.56, p = 0.001).

CONCLUSIONS

The exoscope has proven efficacy in terms of surgical resection, which was not different to that of the microscope. Furthermore, patients operated on with the exoscope had a longer PFS. A comparable OS was observed between microscope and exoscope, but further prospective studies with longer follow-up are needed.

Skull-Base Surgery-A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon's capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

Assessment of necessity of neuronavigation in localization of calvarial extra-axial lesions in the setting of limited resources

Background

Neuronavigation is a very beneficial tool in modern neurosurgical practice. However, the neuronavigation is not available in most of the hospitals in our country raising the question about its importance in localizing the calvarial extra-axial lesions and to what extent it is safe to operate without it.

Methods

We studied twenty patients with calvarial extra-axial lesions who underwent surgical interventions. All lesions were preoperatively located with both neuronavigation and the usual linear measurements. Both methods were compared regarding the time consumed to localize the tumor and the accuracy of each method to anticipate the actual center of the tumor.

Results

The mean error of distance between the planned center of the tumor and the actual was 6.50 ± 1.762 mm in conventional method, whereas the error was 3.85 ± 1.309 mm in IGS method. Much more time was consumed during the neuronavigation method including booting, registration, and positioning. A statistically significant difference was found between the mean time passed in the conventional method and IGS method (2.05 ± 0.826, 24.90 ± 1.334, respectively), P-value < 0.001.

Conclusion

In the setting of limited resources, the linear measurement localization method seems to have an accepted accuracy in the localization of calvarial extra-axial lesions and it saves more time than neuronavigation method.

Image-guided surgery in otolaryngology: A review of current applications and future directions in head and neck surgery

Image-guided surgery (IGS) has become a widely adopted technology in otolaryngology. Since its introduction nearly three decades ago, IGS technology has developed rapidly and improved real-time intraoperative visualization for a diverse array of clinical indications. As usability, accessibility, and clinical experiences with IGS increase, its potential applications as an adjunct in many surgical procedures continue to expand. Here, we describe the basic components of IGS and review both the current state and future directions of IGS in otolaryngology, with attention to current challenges to its application in surgery of the nonrigid upper aerodigestive tract.

Advanced Magnetic Resonance Imaging of the Skull Base

Magnetic resonance (MR) imaging is a crucial tool for evaluation of the skull base, enabling characterization of complex anatomy by utilizing multiple image contrasts. Recent technical MR advances have greatly enhanced radiologists' capability to diagnose skull base pathology and help direct management. In this paper, we will summarize cutting-edge clinical and emerging research MR techniques for the skull base, including high-resolution, phase-contrast, diffusion, perfusion, vascular, zero echo-time, elastography, spectroscopy, chemical exchange saturation transfer, PET/MR, ultra-high-field, and 3D visualization. For each imaging technique, we provide a high-level summary of underlying technical principles accompanied by relevant literature review and clinical imaging examples.

Optimization of radiation settings for angiography using 3D fluoroscopy for imaging of intracranial aneurysms

Mobile 3D fluoroscopes have become increasingly available in neurosurgical operating rooms. We recently reported its use for imaging cerebral vascular malformations and aneurysms. This study was conducted to evaluate various radiation settings for the imaging of cerebral aneurysms before and after surgical occlusion. Eighteen patients with cerebral aneurysms with the indication for surgical clipping were included in this prospective analysis. Before surgery the patients were randomized into one of three different scan protocols according (default settings of the 3D fluoroscope): Group 1: 110 kV, 80 mA (enhanced cranial mode), group 2: 120 kV, 64 mA (lumbar spine mode), group 3: 120 kV, 25 mA (head/neck settings). Prior to surgery, a rotational fluoroscopy scan (duration 24 s) was performed without contrast agent followed by another scan with 50 ml of intravenous iodine contrast agent. The image files of both scans were transferred to an Apple PowerMac^® workstation, subtracted and reconstructed using OsiriX^® MD 10.0 software. The procedure was repeated after clip placement. The image quality regarding preoperative aneurysm configuration and postoperative assessment of aneurysm occlusion and vessel patency was analyzed by 2 independent reviewers using a 6-grade scale. This technique quickly supplies images of adequate quality to depict intracranial aneurysms and distal vessel patency after aneurysm clipping. Regarding these features, a further optimization to our previous protocol seems possible lowering the voltage and increasing tube current. For quick intraoperative assessment, image subtraction seems not necessary. Thus, a native scan without a contrast agent is not necessary. Further optimization may be possible using a different contrast injection protocol.

The use of intraoperative computed tomography navigation in pituitary surgery promises a better intraoperative orientation in special cases

OBJECTIVE

The safety of endoscopic skull base surgery can be enhanced by accurate navigation in preoperative computed tomography (CT) and magnetic resonance imaging (MRI). Here, we report our initial experience of real-time intraoperative CT-guided navigation surgery for pituitary tumors in childhood.

MATERIALS AND METHODS

We report the case of a 15-year-old girl with a huge growth hormone-secreting pituitary adenoma with supra- and perisellar extension. Furthermore, the skull base was infiltrated. In this case, we performed an endonasal transsphenoidal approach for debulking the adenoma and for chiasma decompression. We used an MRI neuronavigation (Medtronic Stealth Air System) which was registered via intraoperative CT scan (Siemens CT Somatom). Preexisting MRI studies (navigation protocol) were fused with the intraoperative CT scans to enable three-dimensional navigation based on MR and CT imaging data. Intraoperatively, we did a further CT scan for resection control.

RESULTS

The intraoperative accuracy of the neuronavigation was excellent. There was an adjustment of <1 mm. The navigation was very helpful for orientation on the destroyed skull base in the sphenoid sinus. After opening the sellar region and tumor debulking, we did a CT scan for resection control because the extent of resection was not credible evaluable in this huge infiltrating adenoma. Thereby, we were able to demonstrate a sufficient decompression of the chiasma and complete resection of the medial part of the adenoma in the intraoperative CT images.

CONCLUSIONS

The use of intraoperative CT/MRI-guided neuronavigation for transsphenoidal surgery is a time-effective, safe, and technically beneficial technique for special cases.

Utility of Neuronavigation in Intracranial Meningioma Resection: A Single-Center Retrospective Study

OBJECTIVE

In this study, we validate the utility of navigation in intracranial meningioma excision and evaluate the effectiveness of image guidance surgery based on clinical outcome, extent of resection, and recurrence-free survival (RFS).

METHODS

Information related to clinical history, use of neuronavigation, neuroimaging, microsurgical dissection, and outcomes of 517 consecutive cases with meningiomas between January 1995 and June 2015 was collected retrospectively. A Cox proportional hazards regression model was used to determine independent predictors of RFS.

RESULTS

In this study, overall recurrence rate after tumor excision with or without neuronavigation was 17.7% and 31.2%, respectively (P = 0.03). Based on neuronavigation use, RFS of the patients with meningiomas in different locations also varied significantly (skull base; with, 110 months vs. without, 157 months; P = 0.02). The median RFS for patients operated on with or without use of neuronavigation during resection of tumors was 167 and 97 months, respectively, (log-rank P =0.0001). In Cox regression multivariate analysis, use of neuronavigation (P = 0.0001), gross total resection (Simpson grade I-II; P = 0.001), and World Health Organization grade I tumor (P = 0.0001) were revealed as significant predictors of RFS. In addition, mean blood loss (P = 0.005) and average length of stay (P = 0.008) in the hospital were significantly reduced and performance status was improved using neuronavigation during resection of meningiomas.

CONCLUSIONS

Interactive surgical navigation is a useful tool in the operative management of intracranial meningiomas to decrease recurrence rate, blood loss, and length of stay, and to improve RFS and performance status. Therefore, use of neuronavigation should be ensured during resection of intracranial meningiomas.

Intraoperative cerebral angiography by intravenous contrast administration with 3-dimensional rotational fluoroscopy in patients with intracranial aneurysms: a feasibility study

BACKGROUND

Intraoperative imaging of cerebral aneurysms may be desirable in emergency situations with large space-occupying hematomas or to visualize vessels after clip placement. Mobile 3-dimensional fluoroscopes are available in a number of neurosurgical departments and may be useful in combination with simple image postprocessing to depict cerebral vessels.

OBJECTIVE

To assess whether intracranial aneurysms are detectable with appropriate image quality with intraoperative 3-dimensional fluoroscopy with intravenous contrast administration.

METHODS

Eight patients were included in the study. The patients' heads were fixed in a radiolucent Mayfield clamp. First, a rotational fluoroscopy scan was performed without contrast agent. Then, a second scan with 50 mL iodine contrast agent was performed. The DICOM (digital imaging and communications in medicine) data of both scans were transferred to an Apple PowerMac workstation, subtracted, and reconstructed with OsiriX imaging software. The images were compared with preoperative angiograms.

RESULTS

No adverse effects were observed during contrast administration. The entire procedure from fluoroscope positioning to the production of usable 3-dimensional images took 5 to 6 minutes with an image acquisition time of 2 × 24 seconds. The configuration of the aneurysm and the vessel anatomy were assessable. Previous coiling limited image quality in 1 patient.

CONCLUSION

This technique quickly provides images of adequate quality to assess the configuration of intracranial aneurysms, which may be helpful when immediate intraoperative information about intracranial vessel pathologies is required. The positioning of the fluoroscope, image acquisition, and processing can be completely integrated into the surgical workflow.

Intraoperative Navigated Angiosonography for Skull Base Tumor Surgery

BACKGROUND

One of the main challenges during skull base tumor surgery is identifying the relationships between the lesion and the principal intracranial vessels. To this end, neuronavigation systems based on preoperative imaging lack accuracy because of brain shift and brain deformation. Intraoperative navigated B-mode ultrasonography is useful in defining the extent of brain tumor. Doppler imaging adds information regarding flow entity in neighboring vessels. Second-generation ultrasound contrast agents improve the signal-to-noise ratio of B-mode imaging and permit the study of the vessel's course, blood flow, and perfusion characteristics of focal lesions. We report our experience using intraoperative navigated contrast-enhanced ultrasound to perform a navigated angiosonography (N-ASG) for the visualization of vessels in a series of 18 skull base tumors.

METHODS

We performed N-ASG in a series of 18 skull base tumors (10 meningiomas, 3 craniopharyngiomas, 2 giant pituitary adenomas, 1 posterior fossa epidermoid, 2 dermoid cysts). N-ASG was obtained after craniotomy before resecting each lesion and during tumor removal, after intravenous injection of ultrasound contrast agent.

RESULTS

In all 18 cases, major vessels and their branches were simultaneously identified (both high and low flow) using N-ASG, which allowed to visualize the whole length of each vessels. N-ASG was also useful in highlighting the lesion, compared with standard B-mode imaging, and showing its perfusion patterns.

CONCLUSIONS

N-ASG can be applied to skull base tumor surgery, providing helpful information about the relationship between principal intracranial vessels and tumors. This technique could be of assistance in approaching the tumor and avoiding vascular damages.

From Grey Scale B-Mode to Elastosonography: Multimodal Ultrasound Imaging in Meningioma Surgery-Pictorial Essay and Literature Review

The main goal in meningioma surgery is to achieve complete tumor removal, when possible, while improving or preserving patient neurological functions. Intraoperative imaging guidance is one fundamental tool for such achievement. In this regard, intra-operative ultrasound (ioUS) is a reliable solution to obtain real-time information during surgery and it has been applied in many different aspect of neurosurgery. In the last years, different ioUS modalities have been described: B-mode, Fusion Imaging with pre-operative acquired MRI, Doppler, contrast enhanced ultrasound (CEUS), and elastosonography. In this paper, we present our US based multimodal approach in meningioma surgery. We describe all the most relevant ioUS modalities and their intraoperative application to obtain precise and specific information regarding the lesion for a tailored approach in meningioma surgery. For each modality, we perform a review of the literature accompanied by a pictorial essay based on our routinely use of ioUS for meningioma resection.

Volume assessment of intracranial large meningiomas and considerations about their microsurgical and clinical management

OBJECTIVE

To assess the volume of large intracranial meningiomas and analyse their different microsurgical and clinical managements.

METHOD

The volume of 45 large meningiomas treated in our department during the last 9.5 years was retrospectively assessed using recorded neuronavigation data. The seven most employed microsurgical strategies and five important factors influencing the patient's outcome (tumor location, grade of peritumoral brain swelling, grade of brain atrophy, entrapment of neurovascular structures and the management of the vascular infused fluid volume) were individually analysed. The follow-up ranged from 14 to 84 months.

RESULTS

The assessed volumes exceed 100 cm(3) in 38 supratentorial and 45 cm(3) in seven infratentorial tumors. The highest averaged volume in this series was assessed by tuberculum sellae and olfactory meningiomas (174 cc). A complete resection was achieved in 39 patients and was not influenced by the tumor volume. However, an averaged volume difference of 60 cc was observed between anterior skull base tumors in which their averaged greatest diameter variation was only 1.5 cm. Twelve of 24 patients with deep located tumors and entrapped neurovascular structures presented accentuated brain swelling. A new permanent post-operative neurological deficit was observed only in two patients. In the other patients, cranial nerve deficits, pre-operative hemiparesis and superior cerebral functions improved to varying degrees. Four cases with subtotal resection showed stable residual volumes after 4.5 year follow-up. Three cases underwent additional radiosurgery.

CONCLUSION

Tumor volume assessment allows an improved meningioma size differentiation. Despite the large volume of the tumors in this series, satisfactory resection was still possible using single-stage procedures. Individual microsurgical strategies and fluids management contributed to reducing patient's morbi-mortality.

Endovascular treatment of AICA flow dependent aneurysms. A report of three cases and review of the literature

Peripheral anterior inferior cerebellar artery (AICA) aneurysms are rare, accounting for less than 1% of all cerebral aneurysms. To our knowledge 34 flow-related cases including the present study have been reported in the literature. Three patients harbouring four flow dependent aneurysms were referred to our institution. Two patients presented with subarachnoid hemorrhage, one presented with cerebellar manifestations. They were all treated by endovascular embolization of the aneurysm as well as the parent artery using liquid embolic material. Two cases were embolized using NBCA, Onyx was used in the third case. No bleeding or rebleeding were encountered during the follow-up period which ranged from five to nine months. One patient developed facial palsy, cerebellar symptoms and sensorineural hearing loss. The remaining two cases did not develop any post treatment neurological complications. Endovascular management of flow-dependent AICA aneurysms by parent artery occlusion is feasible and efficient in terms of rebleeding prevention. Post embolization neurological complications are unpredictable. This depends upon the adequacy of collaterals from other cerebellar arteries.

Intraoperative image guidance in neurosurgery: development, current indications, and future trends

Introduction. As minimally invasive surgery becomes the standard of care in neurosurgery, it is imperative that surgeons become skilled in the use of image-guided techniques. The development of image-guided neurosurgery represents a substantial improvement in the microsurgical treatment of tumors, vascular malformations, and other intracranial lesions. Objective. There have been numerous advances in neurosurgery which have aided the neurosurgeon to achieve accurate removal of pathological tissue with minimal disruption of surrounding healthy neuronal matter including the development of microsurgical, endoscopic, and endovascular techniques. Neuronavigation systems and intraoperative imaging should improve success in cranial neurosurgery. Additional functional imaging modalities such as PET, SPECT, DTI (for fiber tracking), and fMRI can now be used in order to reduce neurological deficits resulting from surgery; however the positive long-term effect remains questionable for many indications. Method. PubMed database search using the search term "image guided neurosurgery." More than 1400 articles were published during the last 25 years. The abstracts were scanned for prospective comparative trials. Results and Conclusion. 14 comparative trials are published. To date significant data amount show advantages in intraoperative accuracy influencing the perioperative morbidity and long-term outcome only for cerebral glioma surgery.

A Comparative Study of Digital and Anatomical Techniques in Skull Base Measurement

This study compared the accuracy of measurements of the skull base made using computed tomography (CT) images and an image-guided surgery system with those made using scientific callipers in order to evaluate the practicability of replacing conventional direct anatomical measurements with digitized techniques in skull base surgery. Important bony landmarks and parameters were measured using the three different methods in 25 cadaver skull bases. No statistically significant differences were observed between the methods. Coefficient of variation calculations indicated that data obtained from CT images was the most stable. Digital methods of navigation have the potential to reflect individual skull base anatomical features more accurately than traditional group-based data, but it is important to assess their accuracy. This study demonstrated that CT imageology and image-guided surgery systems can provide accurate anatomical measurements. Digital methods are also more flexible and less variable, and may have wide applications in this field. Though not perfect, digital imaging is a promising tool for skull base surgery.

A case of ruptured peripheral aneurysm of the anterior inferior cerebellar artery associated with an arteriovenous malformation : a less invasive image-guided transcortical approach

A 47-year-old man presented with a subarachnoid hemorrhage (SAH) and right cerebellar hematoma was referred for evaluation. Cerebral angiography revealed a distal anterior inferior cerebellar artery (AICA) aneurysm associated with an arteriovenous malformation (AVM). Successful obliteration and complete removal of the aneurysm and AVM were obtained using transcortical approach under the guidance of neuronavigation system. The association of a peripheral AICA aneurysm and a cerebellar AVM by the same artery is unique. The reported cases of conventional surgery for this disease complex are not common and their results are variable. Less invasive surgery using image-guided neuronavigation system would be helpful and feasible for a peripheral aneurysm combining an AVM of the posterior fossa in selective cases.

Navigated resection of giant intracranial meningiomas based on intraoperative 3D ultrasound

BACKGROUND

Surgical resection of giant meningiomas may pose different challenges. Normal brain tissue is often compressed to the limit and is vulnerable to further traction. In addition, severe intraoperative bleeding may be a problem as many giant meningiomas are vascularised with deep feeding vessels entering from the skull base. Neuronavigation based on preoperative imaging can be of limited use as there may be extensive brain shifts during surgery.

METHOD

We have retrospectively evaluated navigated resection based on intraoperative 3D ultrasound in a series of 15 giant meningiomas with a diameter of more than 5 cm. A pre- and postoperative MRI was preformed in all patients. Preoperative and postoperative neurological function was assessed.

FINDINGS

We were able to safely perform ultrasound-guided intracapsular gross total resection of tumour tissue in all patients. Twelve out of 15 patients were radically operated (Simpson grade I and II). Major feeding arteries and adjacent normal arteries could be identified by ultrasound power Doppler angiography. In one patient we were not able to indentify important venous structures. All patients experienced postoperative improvement of their symptoms. Postoperative MRIs did not reveal significant ischemic changes in adjacent normal brain tissue. The mean duration of hospitalisation after surgery was 4.9 days.

CONCLUSION

We present a method of ultrasound-guided resection of giant meningiomas. The method enables image-guided resection through narrow approaches that minimise traction. Power Doppler angiography allows the identification of feeding vessels that may be coagulated to limit bleeding. Likewise, normal arteries can be avoided during surgery. The tumour capsule is often surprisingly easy to remove from the arachnoid membrane after gross intracapsular tumour reduction.

Neuronavigational guidance in craniofacial approaches for large (para)nasal tumors involving the anterior skull base and upper clival lesions

OBJECTIVE

Due to the destruction of osseous landmarks of the skull base or paranasal sinuses, the anatomical orientation during surgery of frontobasal or clival tumors with (para)nasal extension is often challenging. In this relation computer assisted surgical (CAS) guidance might be a useful tool. Here, we explored the use of CAS in an interdisciplinary setting.

METHODS

The surgical series consists of 13 patients who underwent a lateral rhinotomy combined with a subfrontal craniotomy in case of significant intracranial tumor extension. The procedures were planned and assisted by advanced CAS techniques with image fusion of CT and MRI. Tumors included carcinomas (one case associated with an olfactory groove meningioma), esthesioneuroblastoma, chordoma, chondrosarcoma and ganglioglioma.

RESULTS

The application of CAS in the combined approaches was both safe and reliable for delineation of tumors and identification of vital structures hidden or encased by the tumors. There was no perioperative 30-day mortality; however two patients died 5 weeks and 5 months after craniofacial tumor resection due to worsening medical conditions. The most common perioperative morbidity was postoperative wound complication in two cases. Tumors were either removed completely, or subtotal resection was achieved allowing targeted postoperative radiotherapy.

CONCLUSION

Craniofacial approaches with intraoperative neuronavigational guidance in a multidisciplinary setting allow safe resection of large tumors of the upper clivus and the paranasal sinuses involving the anterior skull base. Complex skull base surgery with the involvement of bony structures appears to be an ideal field for advanced navigation techniques given the lack of intraoperative shift of relevant structures.

Experiences in the management of brainstem hematomas

The purpose of this study was to present our experience in the management of spontaneous brainstem hematomas (BSH). Records of 58 consecutive patients were reviewed, including demographic data, symptoms, Glasgow Coma Scale, treatment, intraoperative findings (in surgical cases), and outcome according to the Glasgow Outcome Scale. Fifteen patients were comatose (GCS 4 or less): 11/15 patients were treated conservatively. Four patients with accompanying acute occlusive hydrocephalus were treated by placement of an external ventricular drainage. None survived. In nine patients (60%), arteriosclerosis and/or long-standing arterial hypertension were known and arteriopathic BSH was suspected. Forty-three patients were not comatose: 37 patients showed no impairment of consciousness (GCS 15), 6 patients presented with mild disturbance of conscious state (GCS 13), progressing to coma (GCS 8) in 1. In the majority (36/43) of the non-comatose patients (83.7%) cavernoma could be revealed and removed surgically. In six patients (14%), an atypically located arteriopathic BSH was assumed and treated medically. One patient had an underlying brainstem arteriovenous malformation and was treated radiosurgically. Many arteriopathic BSH cause immediate coma indicating direct and irreversible damage of midpontine structures. Thus, we suggest not to proceed to surgery, even if the bleeding is accompanied by acute hydrocephalus. The majority of BSH not resulting in immediate coma are caused by underlying cavernomas. In these cases surgery should be considered.

CT–MR image data fusion for computer assisted navigated neurosurgery of temporal bone tumors

PURPOSE

To demonstrate the value of multi detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative work up of temporal bone tumors and to present, especially, CT and MR image fusion for surgical planning and performance in computer assisted navigated neurosurgery of temporal bone tumors.

MATERIALS AND METHODS

Fifteen patients with temporal bone tumors underwent MDCT and MRI. MDCT was performed in high-resolution bone window level setting in axial plane. The reconstructed MDCT slice thickness was 0.8 mm. MRI was performed in axial and coronal plane with T2-weighted fast spin-echo (FSE) sequences, un-enhanced and contrast-enhanced T1-weighted spin-echo (SE) sequences, and coronal T1-weighted SE sequences with fat suppression and with 3D T1-weighted gradient-echo (GE) contrast-enhanced sequences in axial plane. The 3D T1-weighted GE sequence had a slice thickness of 1mm. Image data sets of CT and 3D T1-weighted GE sequences were merged utilizing a workstation to create CT-MR fusion images. MDCT and MR images were separately used to depict and characterize lesions. The fusion images were utilized for interventional planning and intraoperative image guidance. The intraoperative accuracy of the navigation unit was measured, defined as the deviation between the same landmark in the navigation image and the patient.

RESULTS

Tumorous lesions of bone and soft tissue were well delineated and characterized by CT and MR images. The images played a crucial role in the differentiation of benign and malignant pathologies, which consisted of 13 benign and 2 malignant tumors. The CT-MR fusion images supported the surgeon in preoperative planning and improved surgical performance. The mean intraoperative accuracy of the navigation system was 1.25 mm.

CONCLUSION

CT and MRI are essential in the preoperative work up of temporal bone tumors. CT-MR image data fusion presents an accurate tool for planning the correct surgical procedure and is a benefit for the operational results in computer assisted navigated neurosurgery of temporal bone tumors.

Intraoperative navigated 3-dimensional ultrasound angiography in tumor surgery

BACKGROUND

Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumor surgery. Using angiographic image data in neuronavigation may be useful in cases where vascular anatomy is of special interest. Since 2003, we have routinely used 3D ultrasound angiography in tumor surgery, and between January 2003 and May 2005, 62 patients with different tumors have been operated using intraoperative 3D ultrasound angiography in neuronavigation.

METHODS

An ultrasound-based neuronavigation system was used. In addition to 3D ultrasound tissue image data, 3D ultrasound angiography (power Doppler) image data were acquired at different stages of the operation. The value and role of navigated 3D ultrasound angiography as judged by the surgeon were recorded.

RESULTS

We found that intraoperative ultrasound angiography was easy to acquire and interpret, and that image quality was sufficient for neuronavigation. In 26 of 62 cases, ultrasound angiography was found to be helpful by visualizing hidden vessels adjacent to and inside the tumor, facilitating tailored approaches and safe biopsy sampling.

CONCLUSIONS

Intraoperative 3D ultrasound angiography is straightforward to use, image quality is sufficient for image guidance, and it adds valuable information about hidden vessels, increasing safety and facilitating tailored approaches. Furthermore, with updated 3D ultrasound angiography imaging, accuracy of neuronavigation may be maintained in cases of brain shift.

Recent advances in surgical and intensive care management of subarachnoid hemorrhage

There have been considerable advancements in the medical and surgical management of subarachnoid hemorrhage (SAH) resulting from the rupture of the intracranial aneurysms in the past three decades. While developments in anesthesia and critical care management and recently introduced neuroprotective agents had a considerable effect on the improvement of the medical treatment strategies, advancements in the microsurgical techniques together with the evolvements in the field of interventional neuroradiology have improved surgical therapy. The aim of this paper is to review some of the recent advancements in the surgical and critical care management.

Computer-assisted 3D ultrasound-guided neurosurgery: technological contributions, including multimodal registration and advanced display, demonstrating future perspectives

BACKGROUND

Navigation systems are now frequently being used for guiding surgical procedures. Existing neuronavigation systems suffer from the lack of updated images when tissue changes during surgery as well as from user-friendly displays of all essential images for accurate and safe surgery guidance.

METHODS

We have developed various new technologies for improved neuronavigation. Using intraoperative 3D ultrasound (US) imaging, we have developed various registration algorithms for using and updating a complete multimodal and multivolume 3D map for navigation.

RESULTS

We experienced that advanced multimodal visualization makes it easy to interpret information from several image volumes and modalities simultaneously. Using high quality intraoperative 3D ultrasound, essential preoperative information could be corrected due to brain shift. fMRI and other important preoperative data could then be used together with intraoperative ultrasound imaging for more accurate, safer and improved guidance of therapy.

CONCLUSIONS

We claim that new features, as demonstrated in the present paper, using intraoperative 3D ultrasound in combination with advanced registration and display algorithms will represent important contributions towards more accurate, safer and more optimized future patient treatment.