Objetivos A estimulação magnética transcraniana (TMS, do inglês: Transcranial Magnetic Stimulation) e as imagens funcionais por ressonância magnética (fMRI, do inglês: functinal Magnetic Resonance Imaging) são duas técnicas não invasivas de investigação de atividade do sistema nervoso central. Porém essas duas técnicas utilizam estratégias diferentes para mensurar a atividade cerebral, sendo que a TMS avalia a resposta elétrica enquanto que a fMRI a resposta hemodinâmica. Nosso intuito nesse trabalho foi criar ferramentas para a comparação dessas duas técnicas no mapeamento do córtex motor, bem como utilizando as ferramentas desenvolvidas, fazer uma comparação dos mapas motores de pacientes com AVC com sujeitos assintomáticos, e nesses dois grupos, também realizar uma avaliação nos efeitos no córtex motor da eletroestimulação sensorial (SES, do inglês: Sensory Electric Stimulation) pelas técnicas de TMS e fMRI. Métodos Paro o mapeamento vetorial do campo magnético produzido pela bobina de TMS utilizamos fantomas que simulavam o tecido cerebral e realizamos medidas de imagens de ressonância magnética (MRI, do inglês: Magnetic Resonance Imaging) de fase em três direções para a construção do mapa vetorial. Uma vez dominada a técnica de mapeamento por imagens de fase, a utilizamos para auxiliar na construção de bobinas para estimulação periférica e pequenos animais. Para realização do mapeamento do córtex motor com TMS desenvolvemos um sistema de neuronavegação (Neuronavegador InVesalius) e um programa para análise dos sinais de eletromiografia (MEPHunter), bem como um segundo programa para fazer o corregistro dos mapas de produzidos pela TMS com os mapas de fMRI (TMSProjection). Em posse dessas ferramentas, pudemos realizar o mapeamento do córtex motor de pacientes com AVCi crônicos. Para tanto estimulamos uma área quadrada de 25cm2 do escalpo sobre o córtex motor e coletamos o potencial evocado nos músculos abdutor curto do polegar ipsi e contralateral à TMS, e nos músculos flexor e extensor radial do carpo, contralaterais à TMS. Para a realização das fMRIs realizamos um paradigma evento-relacionada com um protocolo de abrir e fechar a mão. Por fim avaliamos os efeitos da SES à 3Hz com um única sessão de 30 minutos, realizando medidas de potencial evocado e fMRI imediatamente antes e imediatamente após à SES. Resultados O sistema de neuronavegação juntamente com o conjunto de programas computacionais possibilitou a realização dos estudos clínicos. Nossos dados mostraram uma correlação maior entre os mapas de MEP e os mapas de fMRI nos sujeitos normais do que nos pacientes com AVC, principalmente no hemisfério afetado. Nossos resultados também sugerem que a SES pode provocar modulação na excitabilidade cortical, causando redução da excitabilidade cortical das regiões motoras, quando aplicados na frequência e duração utilizadas nesse estudo. Conclusão O mapeamento de campo magnético por MRI é uma boa alternativa para medir campos complexos e pode ser utilizado no desenvolvimento de novas bobinas de estimulação magética. O neuronavegador Invesalius, o MEPHunter e o TMSProjection são ferramentas poderosas para estudos em neuroimagens podendo ser ampliado seu uso para outras áreas como neurologia e fisioterapia. Quanto aos estudos clínicos acreditamos que o fator que mais colabora para a pior correlação dos mapas dos pacientes é a redução de fibras corticoespinhais e a plasticidade, e que a SES aplicada a 3Hz em uma única sessão tem um efeito agudo de redução da excitabilidade do córtex motor. / Background and Purpose - Transcranial magnetic stimulation (TMS) and functional magnetic resonance images (fMRI) are two noninvasive techniques to investigate the central nervous system activity. These two techniques use different strategies to measure brain activity, once the TMS evaluates the electrical response while the fMRI studies hemodynamic response. Our purpose in this study was to create tools for the comparison of these two techniques for mapping the motor cortex. Latter, using these tools, we compared the motor maps of stroke patients and healthy subjects. Furthermore, we evaluated the effects of electrical stimulation in the sensory motor cortex (SES) by TMS and fMRI techniques. Methods - In order to map the magnetic field vector produced by the TMS coil, we used phantoms that simulated brain tissue and performed measurements of magnetic resonance phase images in three directions, in this way, composing the vector map. Then, we used this technique for helping to build small coils for peripheral and small animals stimulation. For the TMS mapping, we developed a neuronavigation system (InVesalius neuronavigator) and a program to analyze the electromyogram responses (MEPHunter). Secondly, a program to co-register the TMS and fMRI maps (TMSProjection) was created. Using these tools, we mapped the motor cortex of the chronic ischemic stroke patients. For this, we stimulated a square scalp area of 25cm2 over the motor cortex and collected the motor evoked potential (MEP) in the abductor pollicis brevis, ipsilateral and contralateral to TMS, and the flexor and extensor carpi radialis, contralateral to TMS. FMRI was also acquired using an event-related paradigm where the volunteers were asked to open and close their hand. Finally, we evaluated the effects of 3Hz SES in a single 30-minute session, performing measurements of TMS and fMRI before and immediately after the SES. Results - The neuronavigation system and the developed softwares made possible clinical studies. We also found a higher correlation between the MEP and fMRI maps in normal subjects than in stroke patients, especially in the affected hemisphere. Additionally, Our results suggested that SES may cause reduction in cortical excitability of motor regions, when applied with the frequency and duration used in this study. Conclusion - The magnetic field MRI mapping is an efficient alternative for complex fields measuring and can be utilized in the development of new TMS coils geometry. The neuronavigator InVesalius, MEPHunter and TMSProjection are powerful tools for neuroimaging studies and other areas as neurology and physiotherapy. We believe that the most important factor that contributes to the correlation decrease between the MEP and fMRI maps of the patients is the reduction of functional corticospinal fibers and the plasticity of motor areas. In this sense, the 3 Hz SES showed to be a potential technique as therapy in spastic patients.

Este trabalho teve como objetivo o desenvolvimento de um phantom de cabeça, com características acústicas e magnéticas equivalentes à do cérebro humano, para a formação de imagens, tanto por ultrasom quanto em ressonância magnética, para uso de treinamento clínico em neuronavegação. Geralmente, nos procedimentos de neurocirurgia, são usadas ambas as modalidades de imagens, sendo a ressonância comumente usada durante o processo préoperatório e, o ultrasom usado durante o procedimento cirúrgico, a fim de localizar a lesão e guiar o ato cirúrgico. Para tanto, o material que mimetiza o tecido cerebral foi desenvolvido a base de gelatina animal e vegetal. Pó de vidro e outras substâncias químicas foram adicionados à gelatina de modo que a atenuação acústica, espalhamento da onda e velocidade acústica ficassem equivalentes ao observado no tecido humano. Para mimetizar o sinal de ressonância magnética, material paramagnético foi adicionado à gelatina de modo que os valores dos tempos de relaxação transversal (T2) e longitudinal (T1) ficassem equivalentes aos observados nos tecidos do cérebro humano. Testes de neuronavegação foram realizados com um sistema desenvolvido no próprio laboratório. Para simular um processo cirúrgico, uma janela de acesso ao tecido cerebral foi criada no lado esquerdo da cabeça. As propriedades acústicas e magnéticas do tecido mimetizador proporcionaram contraste nas imagens de ultrasom e ressonância magnética equivalentes aos observados no tecido do cérebro humano. A morfologia e o tamanho do phantom são equivalentes ao de um cérebro de uma criança de aproximadamente cinco anos. Para avaliar o potencial do phantom como uma ferramenta para treinamento de um processo précirúrgico, foi realizada o préprocessamento e reconstrução 3D do phantom a partir das imagens de ressonância magnética, utilizando um software comercial Brainvoyeger® . / The goal of this work was to make a head phantom that can be used either in Ultrasonography (US) or Magnetic Resonance Imaging (MRI) to be applied as guided training for head surgery in a neuronavigation system. Generally, for neurosurgery procedures, both images modality (US and MRI) are used as guide. MRI images are used for previous evaluation of surgery, for localization of the tumor, choice of window on the head for craniotomy and path into the brain to access the tumor. The ultrasonography of the brain is used during the surgery procedure to guide and control the removal of the tumor. The phantom was developed with mimickingtissue material to generate contrast and intensity in the MRI and US image equivalent to that one obtained in human brain. The base material was made of pork gelatin (Bloom 250). The acoustic properties of this material (velocity, attenuation and Speckle) were controlled adding formaldehyde and glass bids. The magnetic properties (T1 and T2 relaxation) were controlled by adding sodiumEDTA and cupric chloride (CuCl2). The morphology and size of the brain were modeled into a head shell of rubber with size and geometry equivalent to a head of a child of approximately 5 years old. The evaluation of the phantom as tools for neuronavigation training was done simulating a surgery procedure. First, a volume of MRI image of the phantom was acquired using a tomography of 1.5 T (Siemens Vision®). After, using a 3D special sensor coupled to micro convex ultrasound transducer, the ultrasound and MRI image, of a same region, was showed simultaneously using a navigator software developed in the own lab by another student. For this evaluation, a craniotomy was done in the right side of the phantom. The 3D reconstruction of the phantom from MRI images volume was evaluated using commercial software Brainvoyeger®. The size, morphology of the head and the US and MRI image quality 12 of the simulated brain were very close to those ones observed in the brain of a young person. This product is very useful as a tool for training neurosurgeons and for calibration of neuronavegator system.

Orientador: Helder Tedeschi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T16:36:45Z (GMT). No. of bitstreams: 1 Sarmento_StenioAbrantes_D.pdf: 8005225 bytes, checksum: 536dc762dc674f3a764c2acd713848f5 (MD5) Previous issue date: 2009 / Resumo: Nos últimos anos, consideráveis avanços tecnológicos, principalmente métodos de localização funcional do córtex cerebral, têm surgido no sentido de melhorar os resultados cirúrgicos no tratamento de lesões em áreas eloqüentes. O objetivo deste estudo é avaliar os resultados pós-operatórios em 74 pacientes submetidos à ressecção de lesões em área motora ou adjacente, utilizando-se de planejamento com exames de neuroimagem, conhecimento anatômico, técnica microcirúrgica adequada e métodos auxiliares a exemplo da estimulação intra-operatória. Glioma foi o diagnóstico histopatológico em 32 pacientes (43,2%), seguido de meningeoma em 19 pacientes (25,6%), metástase em 11 pacientes (14,8%) %), cavernoma em 5 (6,8%), linfoma primário em 02 pacientes, cisticercose em 2, displasia em 2 (2,7%) e processo inflamatório inespecífico em 1 paciente (1,4%). A ressecção cirúrgica foi considerada total em 68 (93,1%) pacientes e subtotal em 05 (6,84%). 54 pacientes (73,9%) apresentavam força muscular normal (grau 5) no préoperatório. Destes, 20 (37,3%) apresentaram déficit no pós-operatório imediato, sendo que 17 (85%) recuperaram completamente o déficit em até 3 meses e 3 pacientes apresentaram melhora parcial. 19 pacientes apresentavam déficit no pré-operatório. Destes, 05 apresentaram piora do déficit no pós-operatório imediato (sendo que 04 (80%) tiveram melhora no pós-operatório tardio) e 02 melhoraram já no pós- operatório imediato. A estimulação intra-operatória foi utilizada em 65% dos casos, principalmente nos gliomas, e, estereotaxia nos pacientes com cavernomas. Concluímos que a morbidade em pacientes operados de lesões em área motora é bastante aceitável e justifica a indicação cirúrgica com tentativa de ressecção máxima. As lesões extrínsecas (meningeomas e metástases) podem ser completamente ressecadas com baixa morbidade, sem nenhum método adicional, apenas conhecimento anatômico e técnica cirúrgica adequada. A estimulação intra-operatória foi fundamental para guiar a ressecção em grande parte dos gliomas. Não houve diferença na morbidade e nem no grau de ressecção quando comparamos os nossos resultados com aqueles da literatura em que usam métodos funcionais de imagem, neuronavegação ou outros métodos como a ressonância intraoperatória. Lesões subcorticais, como por exemplo, cavernomas podem ser tratadas utilizando apenas estereotaxia. / Abstract: In recent years considerable technological advances have been made with the purpose of improving the surgical results in the treatment of eloquent lesions. The overall aim of this study is to evaluate the postoperative surgical outcome in 74 patients who underwent surgery to remove lesions around the motor area, in which preoperative planning by using neuroimaging exams, anatomical study, appropriate microsurgery technique and auxiliary methods such as intraoperative stimulation were performed. Glioma was the histological diagnosis in thirty two patients (43,2%) follow by meningeoma in nineteen patients (25,6%), metastasis in eleven patients (14,8%), cavernoma in five (6,8%), primary linfoma in two patients, cisticercus in two, cortical dysplasia in two (2,7%) and inflammatory lesion in one patient (1,4%). Gross total removal was achieved in sixty-eight (93,1%) patients and subtotal in five (6,84%). Fifty-four patients (73,9%) presented a normal motor function in the preoperative period. Of these, twenty (37,3%) developed transitory deficit, nevertheless 85% of these presented a complete recovery later and three evolved with partial improvement. Nineteen patients presented a motor deficit preoperatively. Of these, five presented deterioration, but four patients improved later and two patients recovery in the early post-operative. The intraoperative stimulation was used in 65% of the patients, mainly in gliomas. Stereotaxy was used in patients with cavernoma. We concluded that the resection of lesions in motor areas is feasible. Lesions such as meningeomas and metastasis can be safely operated on without the necessity of auxiliary methods by using anatomic knowledge and appropriate surgical technique only. Intraoperative stimulation was very important to guide the resection in many cases of gliomas. There was no difference in the morbidity and resection grade when we compared our results with those who use image functional methods, neuronavegation system or other methods such as intraoperative magnetic resonance image in surgery around the motor area. Subcortical small lesions such as cavernoma can be treated by using stereotaxy techniques. / Doutorado / Neurologia / Doutor em Ciências Médicas

The identification of eloquent areas is of utmost importance in the surgery of tumors located near speech-eloquent brain areas, since the classical concept of a constant localization was proven to be untrue and the spatial localization of these areas may show large interindividual differences. Some neurosurgical centers apply intraoperative electrophysiological methods that, however, necessitate the performance of surgery in the awake patient. This might be a severe burden both for the patient and the operating team in a procedure that lasts several hours; in addition, electrical stimulation may generate epileptic seizures. Alternatively, methods of functional brain imaging (e.g., PET, fMRI, MEG) may be applied, which allow individual localization of speech-eloquent areas. Matching of these image data with a conventional 3D-CT or MRI now allows the exact transfer of this information into the surgical field by neuronavigation. Whereas standards concerning electrophysiological stimulation techniques that could prevent a permanent postoperative worsening of language are available, until now it remains unclear whether the resection of regions shown to be active in functional brain imaging will cause a permanent postoperative deficit. / Die Identifikation sprachaktiver Areale ist von höchster Bedeutung bei der Operation von Tumoren in der Nähe des vermuteten Sprachzentrums, da das klassische Konzept einer konstanten Lokalisation des Sprachzentrums sich als unrichtig erwiesen hat und die räumliche Ausdehnung dieser Areale eine hohe interindividuelle Varianz aufweisen kann. Einige neurochirurgische Zentren benutzen deshalb intraoperativ elektrophysiologische Methoden, die jedoch eine Operation am wachen Patienten voraussetzen. Dies kann sowohl für den Patienten als auch das Operations-Team eine schwere Belastung bei diesem mehrstündigen Eingriff darstellen, zusätzlich können epileptische Anfälle durch die elektrische Stimulation generiert werden. Alternativ können Modalitäten des «functional brain imaging» (PET, fMRT, MEG usw.) eingesetzt werden, die die individuelle Lokalisation sprachaktiver Areale gestatten. Die Bildfusion dieser Daten mit einem konventionellen 3D-CT oder MRT erlaubt den exakten Transfer dieser Daten in den OP-Situs mittels Neuronavigation. Während Standards bei elektrophysiologischen Stimulationstechniken existieren, die eine permanente postoperative Verschlechterung der Sprachfunktion weitgehend verhindern, bleibt die Relevanz sprachaktiver Areale bei den neuesten bildgebenden Techniken bezüglich einer Operations-bedingten Verschlechterung der Sprachfunktion bisher noch unklar. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Background: Advancement in diagnosis and treatment of various cancer entities led to an increasing incidence of brain metastases in the last decades. Surgical excision of single and multiple brain metastases is one of the central treatment options beside radiotherapy, radiosurgery and chemotherapy. To evaluate the benefit of surgery with/without whole-brain radiation therapy (WBRT) in single brain metastases and the influence of image guidance for brain metastases resection, 104 patients were retrospectively evaluated for post-operative outcome. Patients and Methods: Between January 1994 and December 1999 150 patients were surgically treated for brain metastases at the Department of Neurosurgery at the Technical University of Dresden. Outcome could be evaluated in 104 patients with respect to special treatment strategies and survival time (69 patients with single and 35 patients with multiple lesions). Results: Most metastases originated from primary lung and breast tumours. Karnofsky performance score improved on average by 10 after surgery. The extent of the extracerebral tumour burden was the main influence on survival time. Patients’ age below 70 years was combined with prolonged survival time (median survival time, MST: 4.5 months vs. 7 months). Patients with solitary cerebral metastasis had a MST of 16 months, whereas patients with singular lesions had a MST of 7 and 4 months, depending on the extent of the extracerebral tumour growth. Additional post-operative WBRT with 30 Gy was combined with an increase in MST in patients with single brain metastasis (surgery + WBRT: MST 13 months; surgery only: MST 8 months). In addition, the rate of recurrent cerebral tumour growth was distinctly higher in the non-WBRT group. Neuronavigation did not significantly improve post-operative survival time. In 80% of patients extracerebral tumour growth limited patients’ survival. Conclusion: Surgery is an initial treatment option in patients with single and multiple brain metastases especially with large tumours (> 3 cm). Post-operative WBRT seems to prolong survival time in patients with single brain metastasis by decreasing local and distant tumour recurrence. Neuronavigational devices permit a targeted approach. Multiple processes can be extirpated in one session without prolonging the hospitalisation time for the patient. However, neuronavigational devices cannot assure complete tumour resection. / Hintergrund: Fortschritte in der Diagnostik und Therapie von Krebserkrankungen haben in den letzten Jahrzehnten zu einer steigenden Inzidenz von Hirnmetastasen geführt. Die chirurgische Entfernung singulärer und multipler Hirnmetastasen stellt neben Strahlentherapie, Radiochirurgie und Chemotherapie eine zentrale Therapieoption dar. Um die Wertigkeit der chirurgischen Behandlung von singulären Hirnmetastasen mit/ohne Ganzhirnbestrahlung (WBRT) und den Einfluss der Neuronavigation zu untersuchen, wurden 104 Patienten retrospektiv bezüglich ihres postoperativen «Outcomes» untersucht. Patienten und Methoden: Zwischen Januar 1994 und Dezember 1999 wurden 150 Patienten mit Hirnmetastasen in der Klinik für Neurochirurgie der Technischen Universität Dresden operiert. Das «Outcome » von 104 Patienten konnte bezüglich der verschiedenen Behandlungsstrategien und Überlebenszeit ausgewertet werden (69 Patienten mit singulären und 35 Patienten mit multiplen Läsionen). Ergebnisse: Die meisten Metastasen stammen von Lungen- und Mammakarzinomen. Nach operativer Behandlung verbesserte sich der Karnofsky-Index um durchschnittlich 10. Das Ausmaß der extrazerebralen Tumormasse stellte die Haupteinflussgröße für die Überlebenszeit dar. Ein Lebensalter unter 70 Jahren war mit einer verlängerten Überlebenszeit verbunden (mittlere Überlebenszeit, MÜZ: 4,5 Monate vs. 7 Monate). Patienten mit solitären Metastasen hatten eine MÜZ von 16 Monaten, während Patienten mit singulären Läsionen, abhängig vom Ausmaß des extrazerebralen Tumorwachstums, eine MÜZ von 7 bzw. 4 Monaten aufweisen. Eine zusätzliche postoperative WBRT mit 30 Gy zeigte eine Verbesserung der MÜZ bei Patienten mit singulären Hirnmetastasen (OP + WBRT: MÜZ 13 Monate; OP allein: MÜZ 8 Monate). Gleichzeitig war die Rate der zerebralen Tumorrezidive in der Nicht-WBRT Gruppe deutlich höher. Die postoperative Überlebenszeit wurde durch Verwendung der Neuronavigation nicht signifikant verbessert. In 80% der Patienten limitierte das extrazerebrale Tumorwachstum die Überlebenszeit. Fazit: Bei Patienten mit singulären und multiplen Metastasen stellt die initiale chirurgische Tumorentfernung eine Therapiealternative insbesondere bei großen Tumoren (> 3 cm) dar. Eine postoperative WBRT scheint die ÜLZ der Patienten mit singulären Hirnmetastasen durch Begrenzung des Auftretens von Rezidivtumoren zu verlängern. Die Neuronavigation erlaubt eine gezielte Zugangsplanung. Multiple Prozesse können einzeitig operiert werden, ohne dass die postoperative stationäre Verweildauer verlängert wird. Hingegen wird eine radikale Tumorentfernung durch Verwendung der Neuronavigation nicht gewährleistet. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Frameless neuronavigational systems are a recent novelty for a precise approach to intracerebral tumours in open surgery. In this study 66 patients with a variety of intracranial tumours in various locations underwent surgical resection with neuronavigational guidance. Two different neuronavigational systems – the arm- and pointer-based ISG viewing wand and the miroscope-based MKM system – were compared for four different indications. Neuronavigation was used (a) in multiple tumours, e. g. brain metastases, (b) in solitary cortical or subcortical tumours located in eloquent brain areas, e. g. motor cortex or speech region, (c) in deep-situated brain tumours, including brain stem neoplasms, and (d) in infiltratively growing tumours to define the borders of the lesion. Using taped skin markers (MKM system) and a surface-fit algorithm (viewing wand) for registration, an accuracy of 1 to 2 mm deviation was achieved, which was sufficient for removal of all of the intracranial neoplasms investigated. Both systems proved to be safe and useful surgical tools regardless of the patient`s age, positioning of the patient during surgery or the location of the lesion. When these two systems were compared, the viewing wand was found to be preferable for resection of multiple brain tumours located in distant operative sides and solitary tumours in eloquent brain areas; this was because of the wide range of movement of the pointing device and the possibility of 3D reconstruction of the brain surface. As the MKM system provided the option of stereotactical guidance during the operative procedure, it was found to be superior in approaching small and deep-situated lesions. In certain cases brain shifting due to early drainage of the CSF led to minor underestimation of the real depth. For the precise definement of tumour borders of intraparenchymal neoplasms both system were equally suitable. However, intrusion of brain parenchyma into the resection cavity led to minor overestimation of the real tumour size in certain large intraparenchymal tumours. / Rahmenfreie Neuronavigationssysteme stellen eine Neuerung in der offenen operativen Behandlung intrazerebraler Tumoren dar. In dieser Studie wurden 66 Patienten mit verschiedenen intrakraniellen Tumoren in unterschiedlichen Lokalisationen mit Hilfe der Neuronavigation operiert. Hierbei wurden zwei verschiedene Navigationssysteme – ein Arm- und Pointer-basierendes System (ISG Viewing Wand) und ein Mikroskop-basierendes System (MKM) – für vier verschiedene Indikationen miteinander verglichen. Die Neuronavigation wurde verwendet (a) bei multiplen Tumoren, wie z.B. Hirnmetastasen, (b) bei solitären kortikalen oder subkortikalen Prozessen in eloquenten Hirnarealen, wie z.B. Motorkortex oder Sprachregion, (c) bei tiefgelegenen Hirntumoren einschließlich Hirnstammtumoren und (d) bei infiltrativ wachsenden Tumoren zur Bestimmung der Tumorgrenzen. Die Verwendung von Hautklebemarkern (MKM-System) und eines Oberflächen-Anpassungsalgorithmus (Viewing Wand) zur Registrierung war mit einer Genauigkeit von 1 bis 2 mm Abweichung für die operative Entfernung aller intrakraniellen Tumoren ausreichend. Beide Systeme bestätigten sich als sichere und geeignete chirurgische Hilfsmittel unabhängig vom Alter der Patienten, der Lagerung des Patienten unter dem chirurgischen Eingriff und der Lokalisation der Raumforderung. Im Systemvergleich zeigte die Viewing Wand durch einen weiten Bewegungsraum des Pointers und der Möglichkeit einer dreidimensionalen Rekonstruktion der Hirnoberfläche Vorteile in der Entfernung von multiplen, in entfernten Hirnregionen gelegenen Tumoren sowie von solitären Prozessen in eloquenter Lokalisation. Das MKM-System war durch die Bereitstellung einer stereotaktischen Führung während des operativen Eingriffes in der Ansteuerung kleiner tiefgelegener Prozesse zu bevorzugen. Eine frühzeitige Liquordrainage führte zu einem brain shifting mit einer diskreten Unterschätzung der wirklichen Tiefe. Für eine genaue Festlegung der Tumorgrenzen von intraparenchymalen Tumoren waren beide Systeme vergleichbar geeignet. Das Relabieren von Hirngewebe in die Resektionshöhle führte jedoch in einigen Fällen von großen intraparenchymalen Tumoren bei beiden Systemen zu einer geringen Überschätzung der wirklichen Tumorgrenzen. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

The identification of eloquent areas is of utmost importance in the surgery of tumors located near speech-eloquent brain areas, since the classical concept of a constant localization was proven to be untrue and the spatial localization of these areas may show large interindividual differences. Some neurosurgical centers apply intraoperative electrophysiological methods that, however, necessitate the performance of surgery in the awake patient. This might be a severe burden both for the patient and the operating team in a procedure that lasts several hours; in addition, electrical stimulation may generate epileptic seizures. Alternatively, methods of functional brain imaging (e.g., PET, fMRI, MEG) may be applied, which allow individual localization of speech-eloquent areas. Matching of these image data with a conventional 3D-CT or MRI now allows the exact transfer of this information into the surgical field by neuronavigation. Whereas standards concerning electrophysiological stimulation techniques that could prevent a permanent postoperative worsening of language are available, until now it remains unclear whether the resection of regions shown to be active in functional brain imaging will cause a permanent postoperative deficit. / Die Identifikation sprachaktiver Areale ist von höchster Bedeutung bei der Operation von Tumoren in der Nähe des vermuteten Sprachzentrums, da das klassische Konzept einer konstanten Lokalisation des Sprachzentrums sich als unrichtig erwiesen hat und die räumliche Ausdehnung dieser Areale eine hohe interindividuelle Varianz aufweisen kann. Einige neurochirurgische Zentren benutzen deshalb intraoperativ elektrophysiologische Methoden, die jedoch eine Operation am wachen Patienten voraussetzen. Dies kann sowohl für den Patienten als auch das Operations-Team eine schwere Belastung bei diesem mehrstündigen Eingriff darstellen, zusätzlich können epileptische Anfälle durch die elektrische Stimulation generiert werden. Alternativ können Modalitäten des «functional brain imaging» (PET, fMRT, MEG usw.) eingesetzt werden, die die individuelle Lokalisation sprachaktiver Areale gestatten. Die Bildfusion dieser Daten mit einem konventionellen 3D-CT oder MRT erlaubt den exakten Transfer dieser Daten in den OP-Situs mittels Neuronavigation. Während Standards bei elektrophysiologischen Stimulationstechniken existieren, die eine permanente postoperative Verschlechterung der Sprachfunktion weitgehend verhindern, bleibt die Relevanz sprachaktiver Areale bei den neuesten bildgebenden Techniken bezüglich einer Operations-bedingten Verschlechterung der Sprachfunktion bisher noch unklar. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Frameless neuronavigational systems are a recent novelty for a precise approach to intracerebral tumours in open surgery. In this study 66 patients with a variety of intracranial tumours in various locations underwent surgical resection with neuronavigational guidance. Two different neuronavigational systems – the arm- and pointer-based ISG viewing wand and the miroscope-based MKM system – were compared for four different indications. Neuronavigation was used (a) in multiple tumours, e. g. brain metastases, (b) in solitary cortical or subcortical tumours located in eloquent brain areas, e. g. motor cortex or speech region, (c) in deep-situated brain tumours, including brain stem neoplasms, and (d) in infiltratively growing tumours to define the borders of the lesion. Using taped skin markers (MKM system) and a surface-fit algorithm (viewing wand) for registration, an accuracy of 1 to 2 mm deviation was achieved, which was sufficient for removal of all of the intracranial neoplasms investigated. Both systems proved to be safe and useful surgical tools regardless of the patient`s age, positioning of the patient during surgery or the location of the lesion. When these two systems were compared, the viewing wand was found to be preferable for resection of multiple brain tumours located in distant operative sides and solitary tumours in eloquent brain areas; this was because of the wide range of movement of the pointing device and the possibility of 3D reconstruction of the brain surface. As the MKM system provided the option of stereotactical guidance during the operative procedure, it was found to be superior in approaching small and deep-situated lesions. In certain cases brain shifting due to early drainage of the CSF led to minor underestimation of the real depth. For the precise definement of tumour borders of intraparenchymal neoplasms both system were equally suitable. However, intrusion of brain parenchyma into the resection cavity led to minor overestimation of the real tumour size in certain large intraparenchymal tumours. / Rahmenfreie Neuronavigationssysteme stellen eine Neuerung in der offenen operativen Behandlung intrazerebraler Tumoren dar. In dieser Studie wurden 66 Patienten mit verschiedenen intrakraniellen Tumoren in unterschiedlichen Lokalisationen mit Hilfe der Neuronavigation operiert. Hierbei wurden zwei verschiedene Navigationssysteme – ein Arm- und Pointer-basierendes System (ISG Viewing Wand) und ein Mikroskop-basierendes System (MKM) – für vier verschiedene Indikationen miteinander verglichen. Die Neuronavigation wurde verwendet (a) bei multiplen Tumoren, wie z.B. Hirnmetastasen, (b) bei solitären kortikalen oder subkortikalen Prozessen in eloquenten Hirnarealen, wie z.B. Motorkortex oder Sprachregion, (c) bei tiefgelegenen Hirntumoren einschließlich Hirnstammtumoren und (d) bei infiltrativ wachsenden Tumoren zur Bestimmung der Tumorgrenzen. Die Verwendung von Hautklebemarkern (MKM-System) und eines Oberflächen-Anpassungsalgorithmus (Viewing Wand) zur Registrierung war mit einer Genauigkeit von 1 bis 2 mm Abweichung für die operative Entfernung aller intrakraniellen Tumoren ausreichend. Beide Systeme bestätigten sich als sichere und geeignete chirurgische Hilfsmittel unabhängig vom Alter der Patienten, der Lagerung des Patienten unter dem chirurgischen Eingriff und der Lokalisation der Raumforderung. Im Systemvergleich zeigte die Viewing Wand durch einen weiten Bewegungsraum des Pointers und der Möglichkeit einer dreidimensionalen Rekonstruktion der Hirnoberfläche Vorteile in der Entfernung von multiplen, in entfernten Hirnregionen gelegenen Tumoren sowie von solitären Prozessen in eloquenter Lokalisation. Das MKM-System war durch die Bereitstellung einer stereotaktischen Führung während des operativen Eingriffes in der Ansteuerung kleiner tiefgelegener Prozesse zu bevorzugen. Eine frühzeitige Liquordrainage führte zu einem brain shifting mit einer diskreten Unterschätzung der wirklichen Tiefe. Für eine genaue Festlegung der Tumorgrenzen von intraparenchymalen Tumoren waren beide Systeme vergleichbar geeignet. Das Relabieren von Hirngewebe in die Resektionshöhle führte jedoch in einigen Fällen von großen intraparenchymalen Tumoren bei beiden Systemen zu einer geringen Überschätzung der wirklichen Tumorgrenzen. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

INTRODUÇÃO: Embora a craniotomia pterional e suas variantes sejam os acessos mais utilizados em neurocirurgia, poucos estudos analisaram de forma quantitativa a exposição fornecida em cada uma delas. OBJETIVOS: Neste estudo, realizou-se avaliação comparativa das exposições cirúrgicas fornecidas pelas craniotomias pterional (PT), pré-temporal (PreT) e orbitozigomática (OZ) por meio de medidas quantitativas da área de exposição cirúrgica ao redor círculo arterial do cérebro, exposição angular e exposição linear da artéria basilar na fossa interpeduncular e cisterna pré-pontina. MÉTODOS: Oito cadáveres adultos frescos, com tempo máximo de 24 horas após a morte, foram utilizados no estudo. As craniotomias foram realizadas sequencialmente no mesmo cadáver, em um único lado, iniciando-se com a PT, seguido da PreT e terminando com a OZ. Após cada craniotomia, calculou-se a área de exposição cirúrgica, delimitada pelos seguintes pontos: (1) ponto mais lateral da fissura orbitária superior ipsilateral; (2) bifurcação da artéria cerebral média (ACM) ipsilateral; (3) ponto mais distal da artéria cerebral posterior (ACP) ipsilateral; (4) ponto mais distal da ACP contralateral; (5) ponto mais distal da ACM contralateral; (6) ponto mais lateral na asa menor do esfenoide contralateral. Calculou-se ainda, após cada craniotomia, a exposição angular nos eixos horizontal e vertical das seguintes estruturas vasculares: (1) bifurcação da ACM ipsilateral; (2) bifurcação da artéria carótida interna (ACI) ipsilateral; (3) topo da artéria basilar; (4) ponto médio da artéria comunicante anterior; (5) bifurcação da ACI contralateral; (6) ponto mais distal da ACM contralateral. Por fim, após cada craniotomia, mediu-se a exposição linear da artéria basilar na fossa interpeduncular e cisterna pré-pontina. Todas as aferições foram feitas utilizando-se um sistema de neuronavegação computadorizado. RESULTADOS: A OZ apresentou maior exposição cirúrgica em torno do círculo arterial do cérebro (PT = 844,7 ± 233,3 mm2; PreT = 1.134 ± 223,3 mm2; OZ = 1.301,3 ± 215,9 mm2) com aumento de 456,7 mm2 em relação à PT (p < 0,01) e de 167,4 mm2 comparado com a PreT (p < 0,05). A exposição linear da artéria basilar aumentou significativamente com a extensão da craniotomia PT para a PreT e sequencialmente para a OZ. A extensão da PT para PreT e OZ aumentou a exposição angular em todas as medições. Ao compararmos as craniotomias PreT e OZ encontramos um aumento na exposição angular horizontal do topo da artéria basilar (p = 0,02) e bifurcação da artéria carótida interna contralateral (p = 0,048). CONCLUSÕES: A craniotomia OZ oferece vantagens cirúrgicas significativas em relação à PT e PreT, no que diz respeito à área de exposição cirúrgica e exposição linear da artéria basilar. A remoção de parte da margem orbital e do arco zigomático forneceu aumento significativo da exposição angular, proporcionando maior liberdade cirúrgica para acessar estruturas da fossa interpeduncular, cisterna pré-pontina e cisternas subaracnóideas contralaterais. Os dados apresentados no estudo, somados à experiência do cirurgião podem auxiliar na escolha do melhor acesso cirúrgico para cada lesão a ser tratada / INTRODUCTION: Although pterional craniotomy and its variants are the most used approaches in neurosurgery, few studies have analyzed quantitatively the exposure provided by each of them. OBJECTIVES: In this study we compared the surgical exposures provided by pterional (PT), pretemporal (PreT) and orbitozygomatic (OZ) approaches through quantitative measurements of area of surgical exposure around the circle of Willis, angular exposures, and linear exposure of basilar artery in the interpeduncular fossa and prepontine cistern. METHODS: Eight adult fresh cadavers were used within 24 hours after death. The craniotomies were sequentially performed in the same cadaver, first starting with the PT, followed by the PreT, ending up with the OZ. After each craniotomy the area of surgical exposure was calculated, delimited by the following points: (1) lateral aspect of the superior orbital fissure in the ipsilateral sphenoid wing; (2) bifurcation of ipsilateral middle cerebral artery (MCA); (3) most posterior visible point of the ipsilateral posterior cerebral artery (PCA); (4) most posterior visible point of the contralateral PCA; (5) most distal visible point of the contralateral MCA; (6) most lateral visible point of the contralateral lesser sphenoid wing. After each craniotomy, the angular exposure in the horizontal and vertical axes of the following vascular structures was calculated: (1) bifurcation of the ipsilateral MCA; (2) bifurcation of the ipsilateral internal carotid artery (ICA); (3) basilar artery tip; (4) middle point of anterior communicating artery; (5) bifurcation of the contralateral ICA; (6) most distal point of the contralateral MCA. Finally, after each craniotomy, linear exposure of the basilar artery was measured in the interpeduncular fossa and prepontine cistern. All measurements were performed using a computerized neuronavigation system. RESULTS: OZ presented a wider surgical exposure of the circle of Willis (PT = 844.7 ± 233.3 mm2; PreT = 1134 ± 223.3 mm2; OZ = 1301.3 ± 215.9 mm2) with an increase of 456.7 mm2 in relation to the PT (p < 0.01) and of 167.4 mm2 to the PreT (p < 0.05). The linear exposure of the basilar artery significantly increased with the craniotomy extension to the PreT and then to OZ. The extension from PT to PreT and OZ increases angles in all measurements. When comparing the PreT and OZ we found an increase in the horizontal angular exposure to the basilar tip (p = 0.02) and contralateral ICA bifurcation (p = 0.048). CONCLUSIONS: The OZ approach offered significant surgical advantages compared to the traditional PT and PreT regarding to the area of exposure and linear exposure to basilar artery. With regards to the angular exposure, the orbital rim and zygomatic arch removal provided greater surgical freedom to access structures of the interpeduncular fossa, prepontine cistern, and contralateral subarachnoid cisterns. The data presented in the study added to the experience of the surgeon can help in choosing the best individualized surgical approach

Durante um procedimento cirúrgico cerebral existe o deslocamento das estruturas que é um problema tipicamente não-rígido e não-linear. A ultrassonografia intra-operatória é utilizada como guia cirúrgico e pode ser utilizada para correção das imagens pré- operatórias através do corregistro rígido entre estas e um sistema de rastreio. Isto torna possível a visualização do deslocamento das estruturas devida a remoção de parte delas durante o ato cirúrgico. O objetivo deste trabalho é um estudo do corregistro livre não-rígido a partir de um modelo in vitro experimental que simule uma situação cirúrgica de retirada de uma inclusão líquida, de forma controlada, para medir os deslocamentos das estruturas próximas, utilizando imagens de ultrassom. Alguns fantomas que simulam o tecido humano nas imagens de ultrassom, feitos de gelatina e parafina, foram escolhidos como modelo. Para realizar o corregistro foi escolhida a transformação geométrica por splines simples (B-Splines), o otimizador Limited- memory BroydenFletcherGoldfarbShanno (LBFGS) e a métrica de similaridade soma do quadrado das diferenças (SQD) e, utilizada a biblioteca Insight Segmentation and Registration Toolkit (ITK), assim como o estudo dos parâmetros adequados para a nossa tarefa. Foi demonstrado para as condições envolvidas que para as imagens em modo B as deformações até 5% e mapas de RF até 9%, sem nenhuma otimização dos parâmetros do corregistro, é factível sem uso excessivo de tempo computacional. Foi analisada a influência da grade em relação a dois tipos diferentes de deformação, ambas com valor de 2%. O tamanho da grade, levando em consideração o erro e o tempo, foram a 5x11 para as imagens em Modo B e 11x17 para os mapas de RF, independentemente do tipo de deformação. Os parâmetros do otimizador (Default Step Length, Gradient Convergence Tolerance e Line Search Accuraccy) também foram avaliados e os valores obtidos foram 1,6; 0,03 e 0,8 para as imagens modo B e 1,2; 0,05 e 1,0 para os mapas de RF. No entanto ao comparamos, utilizando os parâmetros propostos obtidos, os campos de deslocamentos esperados com os gerados pelo modo B e pelos mapas RF, foi demonstrado que os mapas de RF fornecem valores abaixo do esperado e que as imagens em modo B retratam mais fielmente os deslocamentos e isto se deve a escolha do conjunto de valores testados para o otimizador. Foram aplicados estes parâmetros em dois fantomas de parafina- gel e em dois de gelatina. Nos três primeiros fantomas foi retirada um inclusão líquida em várias etapas. Os deslocamentos das estruturas vizinhas foram avaliados durante as etapas de remoção para demonstrar os campos de sução e de torção. No último fantoma, que simula morfologicamente um cérebro humano, foram retiradas, em várias etapas, regiões sólidas, simulando a retirada de tecido e foram calculados os deslocamentos e demonstrados os campos provenientes deste tipo de intervenção. Os trabalhos futuros se concentrarão em utilizar os volumes para medir os movimentos das estruturas e em novos parâmetros do otimizador para os mapas de RF. / During a brain surgery there is the displacement of the structures that is a typical non- rigid and non-linear problem. Intraoperative ultrasound is used as a surgical guide and can be used for spatial correction of preoperative images through the rigid registration between these and a track system. This makes it possible to visualize the displacement of structures due to removal of some piece of them during surgery. This work is a study of the non-rigid free-from registration using an experimental in vitro model to simulate a surgical situation withdrawal of a fluid inclusion in a controlled manner, to measure the displacement of nearby structures, using ultrasound images. Some phantoms that simulate the human tissue in the ultrasound images made of gelatin and paraffin were chosen as a model. To perform the registration it was used the framework Insight Segmentation and Registration Toolkit (ITK) and were chosen a geometric transformation of simple splines (B-splines), the Limited-memory Broyden-Fletcher- Goldfarb-Shanno (LBFGS) optimizer and the similarity metric sum of the squared differences (SQD). The search for the suitable parameters for our task are done and it has been shown that for the conditions involved for B-mode images deformations up to 5% and RF maps up to 9% without any optimization of the parameters of registration, is feasible without excessive use of computational time. The influence of the grid was examined for two different types of deformation, both for 2%. The size of the grid, taking into account the error and time were the 5x11 for the images in B mode and 11x17 maps for RF, regardless of the type of deformation. The parameters of the optimizer (Default Step Length, Gradient Convergence Tolerance and Line Search Accuraccy) were also evaluated and the values obtained were 1.6, 0.03 and 0.8 for the B-mode images and 1.2, 0.05 and 1.0 for RF maps. However when comparing the expected displacement fields with the generated by B-mode images and the RF maps, using the obtained parameters, it have been shown that RF maps provide values are lower than expected and that the B-mode images portray more faithfully displacements. This is due to the choice set of values tested for the optimizer. Finally, image registration parameters for B-mode were applied in two paraffin-gel and two gelatin phantoms. In the first three phantoms the fluid inclusion was removed in several stages and the displacements of neighboring structures were evaluated during the removal steps to demonstrate the fields of suction and torsion. The last phantom, which morphologically mimics a human brain, a solid region was removed, also in several stages, simulating a surgery. The displacements were calculated and demonstrated the fields from this type of intervention. Future work will focus on using the volumes to measure the movements of the structures and new parameters test of the optimizer to RF maps.