Image guided surgery versus conventional brain tumor and craniotomy localization.

BACKGROUND: Accurate brain lesion and craniotomy localization is an essential step in neurosurgical procedures. Image guided techniques transfer the information of neuroimaging about brain lesion localization to the patient. A critical view is necessary to find out how safe and reliable it is to transfer this information to the patient's head without using image guided systems. The aim of this study was to investigate the value of image guided brain lesion and craniotomy localization compared to conventional methods. METHODS: A new developed test was performed with 10 neurosurgeons from different clinics. The first task was to perform the conventional tumor localization, planning of craniotomy and skin incision using the MRI dataset of a patient with a left temporal brain tumor. Second, the neurosurgeons were asked to plan the craniotomy and skin incision using MRI based 3D visualization with the exact localization of the segmented brain tumor. Both plans of each neurosurgeon were compared and analyzed according to the calculated brain tumor localization, location, shape and size of craniotomy. RESULTS: All neurosurgeons changed the craniotomy localization and skin incision in the second part of the task using the image guided tumor visualization. The mean error (±standard deviation) of tumor localization of the conventional planning was 11.45±5.09 mm in the anterior-posterior (AP) and 12±7.91 mm in the superior-inferior (SI) direction. The mean error of the craniotomy localization using conventional planning was 10.18±6.09 mm in the AP and 10.75±8.18 mm in the SI direction. The craniotomy size was significantly larger using conventional planning of the craniotomy (P=0.035). CONCLUSIONS: Conventional brain tumor and craniotomy localization leads more frequently to errors and oversized craniotomy. Image guided surgery can reduce these errors and increase the safety and orientation for preoperative planning.

Augmented reality-guided neurosurgery: accuracy and intraoperative application of an image projection technique.

OBJECT: An augmented reality system has been developed for image-guided neurosurgery to project images with regions of interest onto the patient's head, skull, or brain surface in real time. The aim of this study was to evaluate system accuracy and to perform the first intraoperative application. METHODS: Images of segmented brain tumors in different localizations and sizes were created in 10 cases and were projected to a head phantom using a video projector. Registration was performed using 5 fiducial markers. After each registration, the distance of the 5 fiducial markers from the visualized tumor borders was measured on the virtual image and on the phantom. The difference was considered a projection error. Moreover, the image projection technique was intraoperatively applied in 5 patients and was compared with a standard navigation system. RESULTS: Augmented reality visualization of the tumors succeeded in all cases. The mean time for registration was 3.8 minutes (range 2-7 minutes). The mean projection error was 0.8 ± 0.25 mm. There were no significant differences in accuracy according to the localization and size of the tumor. Clinical feasibility and reliability of the augmented reality system could be proved intraoperatively in 5 patients (projection error 1.2 ± 0.54 mm). CONCLUSIONS: The augmented reality system is accurate and reliable for the intraoperative projection of images to the head, skull, and brain surface. The ergonomic advantage of this technique improves the planning of neurosurgical procedures and enables the surgeon to use direct visualization for image-guided neurosurgery.

The value of intraoperative sonography in low grade glioma surgery.

OBJECTIVE: There is a number of different methods to localize a glioma intraoperatively. Neuronavigation, intraoperative MRI, 5-aminolevulinic acid, as well as intraoperative sonography. Every method has its advantages and disadvantages. Low grade gliomas do not show a specific signal with 5-aminolevulinic acid and are difficult to distinguish macroscopically from normal tissue. In the present study we stress out the importance of intraoperative diagnostic ultrasound for localization of low grade gliomas. METHODS: We retrospectively evaluated the charts and MRIs of 34 patients with low grade gliomas operated in our department from 2011 until December 2014. The efficacy of ultrasound as an intraoperative navigational tool was assessed. In 15 patients ultrasound was used and in 19 not. Only histologically proven low grades gliomas (astrocytomas grade II) were evaluated. RESULTS: In none of the patients where ultrasound (combined with neuronavigation) was used (N=15) to find the tumors, the target was missed, whereas the exclusive use of neuronavigation missed the target in 5 of 19 cases of small subcortical low grade gliomas. CONCLUSIONS: Intraoperative ultrasound is an excellent tool in localizing low grade gliomas intraoperatively. It is an inexpensive, real time neuronavigational tool, which overcomes brain shift. Even when identifying the tumors with ultrasound is very reliable, the extend of resection and the decision to remove any residual tumor with the help of ultrasound is at the moment unreliable.

Endoscope-assisted keyhole surgery via an eyebrow incision for removal of large meningiomas of the anterior and middle cranial fossa.

BACKGROUND: Conventional open surgery of large meningiomas has proven to be challenging even in experienced hands. Intense retraction and dissection around neurovascular structures increase morbidity and mortality. In the present study, we retrospectively analyzed the surgical technique, and outcome in 40 patients with large anterior cranial fossa meningiomas extending to the middle fossa. All patients were approached via a supraorbital mini craniotomy. METHODS: It is a retrospective study of 40 patients (12 males, 28 females) who underwent surgery for large anterior cranial fossa meningiomas (diameter >5 cm) extending to the middle fossa in four different neurosurgical centers within 6 years. Depending on the localization of the tumor, the skin incision was between 2.5 and 3 cm long and was made without shaving the patient's eyebrow hair. Subsequently, a keyhole craniotomy was performed of approximately 0.8×1.2-1.4 cm in diameter. Preoperative and postoperative clinical and radiological data were analyzed and discussed. RESULTS: Headache and psycho-organic syndrome were the most common presenting symptom in all patients. Presenting symptoms were associated with psychological changes in 23 cases, visual impairment in 19 patients, and anosmia in 17 patients. In overall, 36 of 40 patients (90%) showed a good outcome and returned at long-term follow-up to their previous occupations. The elderly patients returned to their daily routine. CONCLUSION: With the appropriate keyhole approach as a refinement of the classic keyhole craniotomy to a smaller key"burr"hole, and with use of modern and new designed equipment, it is possible to perform complete resection of large anterior and middle fossa meningiomas with the same safety, efficiency and with less complication rates as described in the literature for large meningiomas even performed with classic keyhole craniotomies.

Visualization of small veins with susceptibility-weighted imaging for stereotactic trajectory planning in deep brain stimulation.

Intracerebral hemorrhage (ICH) is the most significant complication of Deep Brain Stimulation (DBS). To prevent ICH, stereotactic contrast enhanced T1-weighted images are used to visualize vessels as source of hemorrhage. Susceptibility-Weighted Imaging (SWI) is an MRI sequence with improved visualization of susceptibility differences between tissues, particularly sensitive for brain veins. The aim of this prospective study was to analyze the utility of SWI compared to contrast enhanced stereotactic T1-weighted images for trajectory planning of DBS. Preoperative SWI was performed in 33 patients undergoing DBS and was compared to the T1-weighted images. Vessels identified only with SWI in relation to the bilateral planned trajectory were analyzed. In all patients vessels were depicted on SWI only within the planned trajectory (range 1-4 vessels, for each trajectory, mean: 2.4). In 6 patients vessels were identified on SWI adjacent to the target (up to 5mm distal from target). In 11 patients SWI visualized additional cortical veins adjacent to the entry point of the trajectory. The apparent diameter of these vessels ranged between 0.8 and 2.1mm (mean: 1.2mm). Postoperative MRI was compared with preoperative SWI and revealed in two patients small (<3 mm) T2 hyperintense lesions along electrodes without correlation with visualized veins. SWI facilitates the visualization of small veins superior to T1-weighted images. However, cerebral veins within the trajectory were not found to be a significant source of ICH after DBS. Potential sources of ICH are mesencephal veins at the endpoint of electrodes which can cause fatal hemorrhage and are visualized with SWI reliably.

Functional magnetic resonance imaging of motor and language for preoperative planning of neurosurgical procedures adjacent to functional areas.

OBJECTIVE: Functional magnetic resonance imaging (fMRI) for motor and language mapping is used for presurgical planning. This study aimed to evaluate the value of fMRI in clinical routine for preoperative planning of brain surgery adjacent to functional brain areas. METHODS: Thirty-seven consecutive patients with brain lesions adjacent to sensomotor and/or language functional areas underwent fMRI prior to planned brain surgery on a 3T MRI scanner for identification of motor in all and language functional areas in 29 patients. Analysis software installed on the MRI console was used for rapid image analysis and direct visualization. All fMRI results were analyzed according to the use for preoperative planning. RESULTS: fMRI data analysis and visualization was possible in less than 10min. In 35 patients fMRI of motor cortex and in 25 patients fMRI of language could be performed due to the patient's compliance. In 34 patients motor activity could be clearly identified in the precentral gyrus. The dominant hemisphere could be identified clearly in 22 cases. In 18 patients direct anatomical correlation of the activity maps to the speech area of Broca and/or Wernicke could be made. Resection surgery was performed in all patients. 11 patients underwent awake surgery with intraoperative cortical stimulation. CONCLUSION: fMRI for clinical routine is a reliable and rapid method for identification of functional brain areas prior to brain surgery adjacent to functional areas. This method allows direct monitoring of the data quality and visualization without being time consuming. Knowledge about the relation of functional areas to the brain lesions improves the preoperative planning, the operation strategy and decision making with patients.

Intracranial basal cell carcinoma with extensive invasion of the skull base.

Intracranial invasion of basal cell carcinoma is very rare. A case of a 71-year-old male patient is presented with extensive invasion of middle and posterior fossae, with nearly complete destruction of the petrous bone, involving cerebellopontine angle and cranial nerves by recurrent basal cell carcinoma of the auricular region on the right side. The clinical manifestation was cerebrospinal fluid otorrhoea, facial nerve palsy and trigeminal nerve impairment with hypoesthesia. The patient underwent surgery by combined retroauricular and temporal approach to the skull base. Adjuvant radiation of residual tumor and former tumor recurrence region was performed. MRI studies performed annually show no progress of the tumor. Our patient reports a good quality of life without new neurological deficits 6 years after surgery. Attention should be paid to the malignant nature of basal cell carcinoma making follow up care necessary. In indicated cases in which incomplete excision cannot be excepted and risk factors exist, follow up with CT or/and MRI should be performed to evaluate the infiltrative and invasive character of aggressive basal cell carcinoma and to rule out bone or cerebral infiltration.

Endoscopic endonasal transsphenoidal approach for resection of a coexistent pituitary macroadenoma and a tuberculum sellae meningioma.

The coexistence of a pituitary macroadenoma and a tuberculum sellae meningioma is very rare. This article demonstrates the surgical technique of the simultaneous resection of a pituitary macroadenoma and a tuberculum sellae meningioma using an endoscopic, endonasal, biportal, transsphenoidal approach. A 36-year-old woman presented with frontal headache and extended visual field loss of the right eye. She underwent cranial magnetic resonance imaging (MRI) revealing a 2 × 2 × 2.5 mm contrast-enhancing intrasellar and suprasellar lesion with compression of the optic chiasma. The coexistence of a pituitary macroadenoma and meningioma was suggested. A biportal endoscopic endonasal transsphenoidal approach was performed to remove both lesions. The histological results confirmed the coexistence of the pituitary macroadenoma and meningioma, World Health Organization (WHO) grade I. The endoscopic, endonasal, transsphenoidal approach is a safe and reliable minimal invasive surgical alternative for resection of the intra-, supra- and parasellar lesions, avoiding additional craniotomy.

Extensive growth of an anaplastic meningioma.

We present the case of a 30-year-old male patient with an almost complete destruction of the calvarial bone through an anaplastic meningioma diagnosed in line with dizziness. Neuroimaging revealed an extensive growing, contrast enhancing lesion expanding at the supra- and infratentorial convexity, infiltrating and destroying large parts of the skull, and infiltrating the skin. Due to progressive ataxia and dysarthria with proven tumor growth in the posterior fossa in the continuing course, parts of the tumor were resected. A surgical procedure with the aim of complete tumor resection in a curative manner was not possible. Six months after the first operation, due to a new tumor progression, most extensive tumor resection was performed. Due to the aggressive and destructive growth with a high rate of recurrence and tendency of metastases, anaplastic meningiomas can be termed as malignant tumors. The extrinsic growth masks the tumor until they reach a size, which makes these tumors almost unresectable. In the best case scenarios, the five-year survival is about 50%. With the presented case, we would like to show the aggressive behavior of anaplastic meningiomas in a very illustrative way. Chemotherapy, radiotherapy, and surgery reach their limits in this tumor entity.

A novel augmented reality system of image projection for image-guided neurosurgery.

BACKGROUND: Augmented reality systems combine virtual images with a real environment. OBJECTIVE: To design and develop an augmented reality system for image-guided surgery of brain tumors using image projection. METHODS: A virtual image was created in two ways: (1) MRI-based 3D model of the head matched with the segmented lesion of a patient using MRIcro software (version 1.4, freeware, Chris Rorden) and (2) Digital photograph based model in which the tumor region was drawn using image-editing software. The real environment was simulated with a head phantom. For direct projection of the virtual image to the head phantom, a commercially available video projector (PicoPix 1020, Philips) was used. The position and size of the virtual image was adjusted manually for registration, which was performed using anatomical landmarks and fiducial markers position. RESULTS: An augmented reality system for image-guided neurosurgery using direct image projection has been designed successfully and implemented in first evaluation with promising results. The virtual image could be projected to the head phantom and was registered manually. Accurate registration (mean projection error: 0.3 mm) was performed using anatomical landmarks and fiducial markers position. CONCLUSIONS: The direct projection of a virtual image to the patients head, skull, or brain surface in real time is an augmented reality system that can be used for image-guided neurosurgery. In this paper, the first evaluation of the system is presented. The encouraging first visualization results indicate that the presented augmented reality system might be an important enhancement of image-guided neurosurgery.

Optimal invasive key-hole neurosurgery with a miniaturized 3D chip on the tip: Microendoscopic device.

OBJECTIVE: The goal of the performed study was to evaluate the possibility of a three-dimensional endoscope to become a combined microscope-endoscope device in one. We analyzed the ergonomy of the device, the implementation into the surgical workflow, the image quality, and the future perspectives such devices could have for the next generation of neurosurgeons. MATERIALS AND METHODS: Within 6 months, 22 patients (10 male, 12 female, 20-65 age) underwent surgery in neuroaxis using the new 3D-microendoscope (ME). The new 3D-ME has (a) the ability to visualize the surgical field from out- to inside with all advantages offered by a microscope, and in the same moment, (b) its design is like a small diameter endoscope that allows stereoscopic views extracorporal, intracorporal, and panoramic "para-side" of the lesion. RESULTS: In general, transcranial 3D-"microendoscopy" was performed in all patients with high-resolution 3D quality. No severe complications were observed intra- or postoperatively. With the addition of depth perception, the anatomic structures were well seen and observed. CONCLUSION: The 3D-microendoscopy is a very promising surgical concept associated with new technological developments. The surgeon is able to switch to a modern visualization instrument reaching the most optimal surgical approach without compromising safety, effectiveness, and visual information.

Glioblastoma multiforme in children: report of 13 cases and review of the literature.

We present clinical and histopathologic data from 13 children who underwent craniotomy for newly diagnosed glioblastoma multiforme. Clinical characteristics were compared to those in adult patients (n = 403). The mean age of the children was 10.4 years. The male/female ratio was 3.3:1. The localization was infratentorial in 6 cases (brainstem, n = 4; cerebellum, n = 2) and supratentorial in 7 cases (frontal, n = 2; parietal, n = 3; temporal, n = 2). Infratentorial localization was observed solely in children from 0-10 years, whereas supratentorial location was found in children between the age of 11 and 21 years. Surgical resection was followed by radiotherapy in 11 cases and additional chemotherapy in 8 cases. Giant cell glioblastoma multiforme was found in 2 cases (15%, vs 1-5% in adults). The mean Ki-67 proliferation index was 29.4% (vs 25.6% in adults). There were no significant differences in histologic morphology between children and adults. The total survival time was 90 weeks (vs 47 weeks in adults). One patient is still alive after 8 years. Predictive factors of prolonged survival were the extent of tumor resection and radio- and/or chemotherapy after resection. Multidisciplinary treatment of glioblastoma in childhood might lead to better median survival than in adults. Infratentorial tumor location was observed exclusively in children younger than 11 years old.

Post-traumatic extensive knee ganglion cyst.

A rare case of a posttraumatic extensive ganglion cyst of the anterolateral thigh with connection to the knee joint is presented. A 54-year-old man presented a palpable mass in the anterolateral region of his right thigh with a 15 months existing sense of fullness and tightness. He had an accident with his bicycle 21 months ago. Magnetic resonance imaging (MRI) was performed showing a cyst inside the quadriceps femoris muscle between vastus lateralis and intermedius with connection to recessus suprapatellaris and knee joint. In addition MRI detected a traumatic lesion in the quadriceps femoris tendon in the near of the knee joint. The ganglion cyst was 18 cm long and was excised completely. Intraoperatively, the knee joint connection was confirmed and excised as well. The ganglion cyst was filled with a gelatinous and viscous fluid.

The effect of lung-protective permissive hypercapnia in intracerebral pressure in patients with subarachnoid haemorrhage and ARDS. A retrospective study.

OBJECTIVE: Lung protective ventilation has a beneficial effect in treating patients with acute respiratory distress syndrome (ARDS). An effect of this ventilation modality is hypercapnia, which leads to increased cerebral blood flow. Since increased cerebral blood flow can induce brain oedema the question arises whether lung protective ventilation can be applied in patients with subarachnoid haemorrhage. METHODS: We retrospectively analysed 12 patients with subarachnoid haemorrhage who were ventilated with lung protective ventilation since they suffered of ARDS. Tidal volume was 5-8 ml/kg body weight, and positive end expiratory pressure was 10-15 cm H2O. Intracerebral pressure was continuously measured by intracerebral probe. RESULTS: Despite of hypercapnia (pCO2 50-60 mmHg) there was no increase of the intracerebral pressure. Lung protective ventilation could be safely performed in patients with subarachnoid haemorrhage. CONCLUSION: Patients with higher Hunt and Hess grades of subarachnoid haemorrhage who are predominantly intubated and ventilated and most of them suffer from ARDS can receive lung protective ventilation. In our small patient collective, the occurring hypercapnia did not influence (increase) the intracerebral pressure.

Glioblastoma of the cerebellum and brainstem.

Glioblastoma multiforme (GB) is the most common and most malignant primary intracranial tumor. Of the 577 patients who underwent surgery for newly diagnosed GB (World Health Organization grade IV) between January 1991 and March 2008 at our department, seven had infratentorial GB (iGB) (incidence 1.2%). Patients younger than 21years of age, as well as patients with gliomatosis cerebri, were excluded from the analysis. We concluded that iGB is rare in adults. Because of its rarity and the non-specific radiological features of iGB, it can easily be misdiagnosed as a brain metastasis, ependymoma or even as a benign lesion such as vestibular schwannoma or meningioma. Surgical removal, or at least stereotactic biopsy, is essential to establish the diagnosis. Postoperative adjuvant therapy similar to that for supratentorial glioblastoma is indicated. We analysed the clinical characteristics and therapy of our patients with iGB and reviewed the literature.

A case of rapid-growing anaplastic meningiomas.

Meningiomas are tumours originating from the leptomeningeal covering of the brain and spinal cord and are generally benign and slow growing. Rarely, they show malignant anaplastic characteristics with a high recurrence rate. A number of factors have been reported to predict this high recurrence. Such factors are histopathological ones, such as necrosis and hypercellularity, the World Health Organization (WHO) grade, mitotic index, positivity of proliferation markers (Ki-67 or MIB-1), clinical parameters such as age, gender, localisation, cytogenetic factors and radiation treatment. The present case reports a patient with a giant meningioma over the right frontal lobe who had almost all possible negative prognostic parameters and showed an explosive multifocal recurrence in a timespan of about 5 months.

FLAIR-/T1-/T2-co-registration for image-guided diagnostic and resective epilepsy surgery.

OBJECTIVE: For technical reasons, T2-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) sequences do not allow morphological orientation with high anatomic resolution, but they may show small epileptogenic lesions. Considering the peculiarities of diagnostic and resective epilepsy surgery the present study focused on the co-registration of various magnetic resonance sequences for guided epilepsy surgery. METHODS: Fifty patients (24 men; 26 women) aged 2 to 74 years (mean, 32 yr), in whom epileptogenic lesions were not readily identifiable on three-dimensional T1-weighted MRI scans underwent additional two-dimensional T2-weighted and FLAIR sequences before diagnostic and/or resective epilepsy surgery. FLAIR and/or T2-weighted images were co-registered to the T1-weighted data set and were displayed on the navigation station on site for guided invasive diagnostics and for resection according to an individualized resection plan. Postoperative MRI scanning was routinely performed for assessment of resection extent. RESULTS: Co-registered T1- and FLAIR-/T2-images allowed for image-guided intraoperative identification of all lesions (n = 50). Control MRI scans revealed that complete resection was performed as planned before the operation in 49 patients and incomplete resection was performed in one patient. Preliminary seizure outcome with a mean follow up of 14 months (range, 7-24 mo) was assigned according to the Engel classification: Class I, 78%; Class II, 12%; Class III, 4%; Class IV, 6%. CONCLUSION: Image guidance on the basis of image fusion/co-registration of T1- and FLAIR-/T2-images allows for intraoperative identification of otherwise poorly visible lesions on standard MRI sequences in good spatial resolution. Recall of this information during surgery from the navigation system's screen assists in achieving the goal of precise electrode placement, or complete resection of the lesion as well as of the perilesional epileptogenic tissue and improves the surgeon's intraoperative orientation.

Coregistration of digital photography of the human cortex and cranial magnetic resonance imaging for visualization of subdural electrodes in epilepsy surgery.

OBJECTIVE: To develop a method for the coregistration of digital photographs of the human cortex with head magnetic resonance imaging (MRI) scans for invasive diagnostics and resective neocortical epilepsy surgery. METHODS: Six chronically epileptic patients (two women, four men; mean age, 34 yr; age range, 20-43 yr) underwent preoperative three-dimensional (3D) T1-weighted MRI scans. Digital photographs of the exposed cortex were taken during implantation of subdural grid electrodes. Rendering software (Analyze 3.1; Biomedical Imaging Resource, Mayo Foundation, Rochester, MN) was used to create an MRI-based 3D model of the brain surface. Digital photographs were manually coregistered with the brain surface MRI model using the registration tool in the Analyze software. By matching the digital photograph and the brain surface model, the position of the subdural electrodes was integrated into the coordinate system of the preoperatively acquired 3D MRI dataset. RESULTS: In all patients, the position of the labeled electrode contacts in relation to the cortical anatomy could be visualized on the 3D models of the cortical surface. At the time of resection, the resulting image of the coregistration process provides a realistic view of the cortex and the position of the subdural electrode. CONCLUSION: The coregistration of digital photographs of the brain cortex with the results of 3D MRI data sets is possible. This allows for identification of anatomic details underlying the subdural grid electrodes and enhances the orientation of the surgeon.