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Reconstructive surgery of skull base region after malignant tumor excision
Technology - SurgicalApproaches and Endoscopy
Monday, 7 July 1997
I0-7-951
Transpetrosal approach for craniobasal tumors. Experience of 220 cases
Detailsof technique and results will be discussedalong with a review of the literature.
Akira Hakuba, Kenji Ohata, Kenji Nagai,Michiharu Morino, Dept. of Neurosurgery, OsakaCity University, Osaka, Japan 1
Introduction: Since 1973, 220 transpetrosal approaches, for various craniobasal lesionsin the CP angle, clivus and suprasellar areas, have been performed. Method: Therewere 127 femaleand 93 maleswith agesranging between 2 and 73years (mean50.4 yrs).Thereare four kindsof transpetrosal approaches; 1) transmastoideal, 2) transzygomatic, 3) combined 1 and 2, 4) oticocondylar approaches. The selection of a particular approach will depend on the location and size of the lesion. Total removal of tumors in the transpetrosal approach was accomplished in 64% of 73 meningiomas, 95% of 64 neurinomas, 95% of 22 craniopharyngiomas, 74% of 19 pituitaryadenomas and 73% of 11 chordomas. The outcome was excellent in 31, good in 167, poor in 10 and death in 12 with operative mortalitys outot 220 (2.7%). Hearing waspreserved 41% in 171. The complications were CSF leakage in 8, cerebral contusion in 18, infarction in 5, and meningitis in 6, etc. Discussion and Conclusion: The transpetrosal approach can be useful to minimize brain retraction and achieve optimal exposure with the shortest possible distance and the most adequate view angle in the suprasellar, c1ival and petroclival regions. In this approach, hearing may be preserved because the middle ear vestibule and cochlear can be left intact during removal of the petrous bone.
10-7-961 The retrosigmoid intradural petrous apex approach (RIPA)to Meckel's cave and middle fossa M. Tatagiba, G.A. Carvalho, M. Samii. Department of Neurosurgery, Nordstadt Hospital, Hannover, Germany Introduction: The authorspresent a modification of the standard retrosigmoid intradural route to cerebellopontine (CPA) tumors which extend into Meckel's cave and the middle cranial fossa. This approach is called by the authors "Retrosigmoid Intradural PetrousApexApproach" (RIPA). Thesurgical anatomy of the RIPAis presented along with clinical examples. Methods: Main steps for the RIPA include a standard retrosigmoid craniotomy, intradural exposure of CPA,drilling the petrous apex portion to expose the Vthnervewithinthe Meckel'scave,andopening the tentorium upto Meckel's cave. The RIPA has been routinelyused in our Department since 1994.A total of 16 patients harboring meningiomas and trigeminal schwannomas which affected the middle and posteriorfossae and Meckel'scave have been operated on usingthis approach. The surgicalanatomyis described by cadaveric dissection, and the 16 clinical cases are reviewed. Clinicaland operative records, as well as radiological findings and postoperative outcome are presented. ReSUlts: Total tumor resection with preservation of the cranial nerves V, VII, VIII was achieved in the majority of the cases. No mortality and minimal morbidity characterized this series. Conclusion: The RIPAallowed for resection of large tumors from the posteriorfossa up to the middlefossa usinga simpleapproach withoutnecessity of extensive transpetrosal exposures. Facial and cochlearnervesare well visualized and preservedin the majorityof the cases.
I0-7-971
Reappraisal of the infratentorial supracerebellar approach
Y.Yonekawa, 1.E. Kwak, E. Taub. Department of Neurosurgery, Neurosurgical University Clinic, Zurich, Switzerland The infratentorial supracerebellar approach (ISCLA) is suitablefor the removal of tumorsin the pineal region. It can also be usedfor pathology of the thalamic, midbrain-tectal, tegmento-pontine and cerebellar regions. During the last 3 years, 29 patients underwent this approach in the sitting position: 22 usual medianISCLAand 7 paramedian ISCLA(Yasargil). Total removal of pathology was accomplished in 20 cases and partial or subtotal removal in 9 cases. No mortality and two cases of neurological deterioration were observed: one hemiparesis with 'thalamic hand" in one patient, and persistent Parinaud's syndrome in one patient. The followingprincipal observations can be madefrom our experience: (1) Pineal and thalamic pathology should be submitted to the usual median ISCLA. (2) Unilateral colliculo-midbrain pathology and tegmento-pontine pathology shouldbe submittedto paramedian ISeA. (3) Removal of a colliculussuperioron one side does not seemto produce any disturbance of occular movement. (4) Neither procedure gives adequate access to pathology of the floor of the third ventricle, so that an invasiveprocedure such as divisionof the colliculi in the midline mightbe taken into consideration.
S23
0-7-981 Pericollicular surgical approaches to pons and medulla oblongata
·C.Strauss, J. Romstock, R. Fahlbusch. Department of Neurosurgery, University of Erlangen-Nuremberg, 91054Erlangen, Germany Introduction: Safe surgical approaches into the floor of the IVth ventricle in brainstem lesionsare basedon detailedknowledge of rhomboid fossa anatomy and intraoperative localisation of superficial nuclei andfibers. Methods: For morphometric analysis 12 brainstem specimens were investigated in conventional axial and sagittal histological slices. Motor nuclei and fibers of the rhomboid fossa were measured in all 3 dimensions with consideration of shrinkage factors. During surgery electrical stimulation of superficial cranial nerve nuclei V-XII was performed in 40 patientswith intraaxial lesions and lesionsinfiltrating the brainstem. Results: Morphometric analysisof rhomboid fossa anatomydefinesa paramedian infracollicular approach of 9.2 mm locatedbetween the facial colliculus and the upperpole of the Nucleus N. hypoglossi. A paramedian supracollicular approach betweenfacialcolliculus and the fibers of the Vlth cranialnerve within the medullary velum measures 13.8 mm. Morphometric data were transferred to the surgical field by direct electrical stimulation of cranial motor nuclei and fibersV-XII in a total of 40 patients. Localisation of facial colliculusand trigonum hypoglossi was achieved in all cases. No side effectswere observed. Discussion: Morphometric investigation of histological anatomydefinestwo operative approaches intothe rhomboid fossa. Morphometric data can be transferred to surgeryusingadvanced neurophysiological methods. Direct electrical stimulation is a reliable, fast and safe methodto localizefunctionally important landmarks, thusprovidinq a safeapproach for lesionswithinthe rhomboid fossa. [1] Langet al: Acta Neurochir 113,84-90,1991 [2] Strauss et al~ J Neurosurg 79, 393--399, 1993
10-7-991 Tec.hnicalaspects ofthe IV ventricle mapping during bratnstem surgery G.A. Schekutiev, V.1. Lukianov, A.Y. Lubnin. N.N. Burdenko Neurosurgical Institute, Moscow, Russia Themoderntechnique of brainstem tumorsurgeryis basedon approachthrough safe entry zones via the floor of the IV ventricle. These zones can be identified by electrical stimulation of the floor and evokedelectromyographic (EMG) recordings of muscles of the head. In 20 patients with glioma and cavemoma of the caudal brain stem we studied technical aspectsof this IV ventricle mapping. Stimulating techniques: constant current versusconstantvoltage; types of electrodes: bipolar forceps, monopolar probe, coaxial electrode; types of insulationof the electrode: flush tip versus bare tip were compared. EMG electrodes from muscles supplied by the VII, IX, X, XII cranialnervesof both sides wereconnected simultaneously to the two channel amplifier. It allowed us to find EMG response free areas of the floor of the IV ventricle, that is the safe entry zone. Howevera variant of mixed EMGrecording does not allowto attributeany EMG response to definite motor structure of the brain stem. The results that the best technique for mapping of motor structures of the brain stem is constant current stimulation by flush tip coaxial electrode with a bipolar regime. In 14 patients we could get EMG response during stimulation of the hypoglossal and facial triangles of the rhomboid fossa from both left and right sides. In the other 6 cases identification of motor structures was partiallysuccessful. In 4 cases of them it probablydepended on displacement of motor structures and in 2 cases there was severe preoperative deficit of the corresponding motorfunctions.
I0-7-100 I malignant Rec.onstructive surg~ry of skull base region after tumor excision Igor V. Reshetov 1, ValeryI. Chissov1 , Alexander M. Sdvizkov 1 , Sergey A. Kravtzov j, Oleg V. Matorin1, SergeyV.Tanyashin 2, Vasiliy A. Tcherekaev 2. 1 p.A. Hertzen CancerResearch Institute, Moscow, Russia, 2 Burdenko Neurosurgical Institute, Moscow, Russia We haveoperated 38 patientsfor spread(T3-T4) tumorswith reconstruction of craniomaxillofacial region. There were epidermoid and basal cell carcinomas, sarcomas andsomeothermalignancies. Inall the caseswe used rotatedor vascularized free tissue flaps: in 21 cases fascilocutaneous (from forearm, parascapular region or forehead), in 12 cases musculofascial (m. latissimus dorsi, m. serratus anterior and m. trapezium), in remaining 5 cases - vascularized omental flap. Complication rate was 30%, in 2 caseswe observed insufficiency of vascularanastomoses. Therewas no postoperative mortality. 3-yearmortality
524
Technology - Surgical Approaches and Endoscopy
rate was 61.5%. The methods of craniofacial reconstruction with use of rotated and especially vascularized tissue lIaps with costal fragments permit restoration of the lacial skeleton and provide good cosmetic results.
I0-7-1 01 I Computer-aided reconstruction of large skull defects M. Lorenz, G. Graubner, H. Schumann 1, U. Hustedt". M. Samii. Klinik, Zentrale Forschungswerkstatten, 2 AbteilungfUr Neuroradiologie, Medizinische HochschuleHannover, 0-30623 Hannover, Germany
1 Neurochirurgische
Introduction: Large bony skull defects usually occur after decompressive craniectomy. Typically, the shape contains different curvatures. The indication for a plastic reconstruction is to facilitate a normalization of the ICP-dynamtcs, and cosmetical reasons. A freehand reconstruction will fulfill the physical requirements but often misses a sufficient cosmetical result. Patients and Method: A new procedure of an anatomically exact reconstruction was developed and is under further improvement: 1. Skull-data were sampled by 3D-CT. 2. These data were converted into commands that control a milling machine to produce a laminar accumulated model. 3. Thereafter, a Palacosv-lrnplant was made. Initially, a positive form showing the defect was used. In the last time, the lacking surface could be calculated by mirroing the data of the other side. This is of valuable help in modelling the implant and opens the possibility for a direct manufacturing of the lIap. First resultsare very satisfying. However, the production has to be improved because it is still too time consuming to establish it as a routine-process. Results and Conclusion: In 19 patients a new designed way of an anatomically correct reconstruction of large skull delects was used and relined. This procedure was chosen especially in alert persons wrth the demand of an optimal result. The produced models matched the anatomical form very good and the patients were very satisfied with the cosmetical result. The effort and costs will be justified in those patients who will recover full social activities. A Palaces'[- implant will allow subsequent MR-imaging. The lurther development of a primary implant-production may lead to implants at other places, such as for the closure of basal defects after removal of huge tumors.
I0-7-102 1 Ventricular lavage system Newton Paes. Universidade de Santo Amaro, Sao Paulo, Brazil The management of patients at risk lor cranial hypertension continues to be a controversial subject. O'Sullivan, et at, have concluded that even severely head injured patients whose initial CT scan is normal or does not show a mass lesion, midline shift, or effaced cisterns nevertheless remain at risk lor developing significant secondary cerebral insults due to elevated ICP, reduced CPP, and hypotensiondespite aggressiveintensive care. Ischemiabeginswhen cerebral perfusion pressure lalls below 50 mmHg, and when CPP is below 30 mmHg severe, irreversible ischemia occurs. Since CPP is equal to mean arterial pressure minus ICP, the monitoring of ICP has proved to be a useful tool in the management 01 these patients. ICP can be lowered with diuretics, hyperventilation or barbiturate therapy. In addition, the drainage of CSF can be particularly useful in lowering IC? Currently ICP moniloring and drainage are independent 01 each other. The author presents the design theory and initial animal studies of a new microprocessor based device designed to both monitor and control ICP by automatic extraction of micro volumes 01 CSF. The system consists of a double lumen catheter connected to an extemal double pump system with pressure monitor and micro-processor based controller. ICP is monitored through the catheter and ICP is controlled by the extraction 01 small volumes of CSF.The software and microprocessor controller permit the control of ICP to avoid hypertension. In addition, software permits the determination of brain compliance to trend the progress of the patient. The system may also be used for infusion and extraction of physiologic solutions to aid in the eliminationof blood clots. It is anticipated that this device may proveto be uselul in preventing intracranial hypertension in cases of intraventricular hemorrhage, subarachnoid hemorrhage, post surgical tumor removal, hydrocephalUS and traumatic brain edema.
10 -7-103 1 EndC?scopy-assisted microsurgery of cramopharyngeomas Erik Van Lindert, Axel Pemeczky, Christoph Busert. Department of Neurosurgery, Universityof Mainz, Mainz, Germany Introduction: With the intention to reduce the surgical trauma in skull base surgery, we gradually reduced the size of our surgical approaches. This change has been made possible by individual approach planning and by intraoperative useof endoscopy.This study should evaluate the resultsof endoscopy-assisted keyhole approacheslor craniopharyngeomas.
Monda); 7 July 1997
Methods: We retrospectively studied the clinical files of 14 palients (M:F
=6:8) operated on between 1993 and 1996. Patient ages ranged from 14-63
yrs (average; 40 yrs). Seven patients presented with recurrent tumors, 5 of them operated on elsewhere. The approaches that were used were: supraorbital (8), transventricular/transforaminal (2), transcaliosaVtransventricular (2), presigmoidal (1), subtrontal interhemispheric (1). Results: In 5 cases tumor resectionwas performed truly endoscopy-assisted (so-called videosurgery). In 9 cases endoscopy was used for inspection after completed microsurgical tumor exstirpation. In three of these cases tumor remnants were lound endoscopically, which then could be removed under endoscopic control. In all 14 patients gross total removal could be achieved. Ten patients had a good result, however most 01 them with hormonal substitution. Two patients had a moderate outcome, one 01 them with amnestic syndrome, the other with a psychosyndrome and an oculomotor nerve palsy. Two patients died: one patient six weeks after surgery of pulmonary embolism and sepsis, the other 5 months after surgery due to electrolyte disturbances. There was no tumor recurrence after a mean follow-up of 28 months in the other 12 patients. Conclusion: We conclude that intraoperative endoscopy is an adequate tool that helps to achieve radical tumor removal in craniopharyngeoma surgery, even for recurrent tumors. The combination 01 individual approach planning by the keyhole conceptand intraoperative endoscopy is benelicial to a patient with a craniopharyngeoma by reducing surgical traumatization.
I0-7-1041 Image-directed neuroendoscopy N.L. Dorward" O. Alberti 1 , J. Zha0 2 , D. Hawkes 2 , J. Buurrnan-', A. Dijkstra, D.G.T. Thomas 1. ' Institute of Neurology. London, UK, 2 Radiological Sciences, Guy s Hospital, London, UK, 3 Philips Medical Systems, Best, Netherlands Introduction: Both minimallyinvasive surgery and image guidancecan improve outcome and reduce hospital stay. Until now they have largely been approached as altemative not complementary techniques. Our aimwas to combinethe power of navigation with the minimally invasive qualities of neuroendoscopy. Methods: We have Easy Guide Neuro (Philips Medical Systems) for navigation and a rigid 24 cm 4 channel neuroendoscope (Aesculap AG). An array of light emitting diodes was produced for attachment to the endoscope, enabling the guidance system to track the tip. Live orthogonal reformats of the pre-operative MRI showed the tip position. Such reformats were also produced at a known distance ahead 01 the endoscope tip through Virtual elongation of the endoscope, chosen to correspond with the field 01 view. Results: The ability 01 the system to accurately localise the endoscope tip and the accuracy 01 virtual tip elongation reformatting have been verified through phantom studies. These revealed a mean localisation error for the standardpointer of 0.63 mm with a standard deviation of 0.58 mm and with the endoscope of 0.67 and 0.53 mm respectively. The system has been tested in the clinical setting and proven to be 01considerable value. Discussion: This work has resulted not only in image-guidance of the endoscope but also in interactive endoscopy. The former enables the surgeon to preciselytailor the incision,burr hole(s) and approach to the individualpatient, to guide the normally blind insertion of the endoscope and provide orientation at all times. The latter is the novel ability to display the wider anatomy beyond the endoscope view and beyond the CSF spaces in an iterative manner. This is a powerful 1001with real clinical potential. Research funded by EEC Telematics in Surgery Project.
I0 -7-1051 Endoscopy-assisted skull base surgery Yong Ko, Kwang-Myung Kim, Suck-Jun Oh. Hanyang University Hospitsl, Seoul, Korea Wide skin and bony exposure including the lace is current policy in the management of skull base tumors. Even though this aggressive surgery saved many lives, it did not result in a better quality 01 lile. In the present series miniature craniotomy near the skull base and endoscopy were used to reduce morbidity. In a period of3 years 13 patients were operated with the diagnosis of skull base meningioma,chordoma, rhabdomyosarcoma, metastaticadenocarcinoma and neurilemmoma. Small superolateral orbital roof craniotomy was done to operate anterior and middle cranial base tumors. Retromastoid craniectomy with or without removal of C1 arch sufficed for posterior fossa tumors. Most of tumors could be removed through a mini-window. Remnant tumors behind the petrous bone and at the contralateral side were effectively removed under endoscopic visualization. Good anatomical relationship between tumor and brain could be observed with zero and thirty degree endoscopes. However, endoscopic surgery had limitations in the dissection 01 highly vascular tumors since it could not control massive bleeding. A rigid endoscope was usually used during surgery and a flexible endoscope was additionally used to see hidden areas. Our technique resulted in less scar, facial deformity and morbidity. Endoscopic surgery can satisfactorily help neurosurgeons to control skull base tumors with a small incision, and restricted craniotomy.
Monday, 7 July 1997
I0-7-951
Transpetrosal approach for craniobasal tumors. Experience of 220 cases
Detailsof technique and results will be discussedalong with a review of the literature.
Akira Hakuba, Kenji Ohata, Kenji Nagai,Michiharu Morino, Dept. of Neurosurgery, OsakaCity University, Osaka, Japan 1
Introduction: Since 1973, 220 transpetrosal approaches, for various craniobasal lesionsin the CP angle, clivus and suprasellar areas, have been performed. Method: Therewere 127 femaleand 93 maleswith agesranging between 2 and 73years (mean50.4 yrs).Thereare four kindsof transpetrosal approaches; 1) transmastoideal, 2) transzygomatic, 3) combined 1 and 2, 4) oticocondylar approaches. The selection of a particular approach will depend on the location and size of the lesion. Total removal of tumors in the transpetrosal approach was accomplished in 64% of 73 meningiomas, 95% of 64 neurinomas, 95% of 22 craniopharyngiomas, 74% of 19 pituitaryadenomas and 73% of 11 chordomas. The outcome was excellent in 31, good in 167, poor in 10 and death in 12 with operative mortalitys outot 220 (2.7%). Hearing waspreserved 41% in 171. The complications were CSF leakage in 8, cerebral contusion in 18, infarction in 5, and meningitis in 6, etc. Discussion and Conclusion: The transpetrosal approach can be useful to minimize brain retraction and achieve optimal exposure with the shortest possible distance and the most adequate view angle in the suprasellar, c1ival and petroclival regions. In this approach, hearing may be preserved because the middle ear vestibule and cochlear can be left intact during removal of the petrous bone.
10-7-961 The retrosigmoid intradural petrous apex approach (RIPA)to Meckel's cave and middle fossa M. Tatagiba, G.A. Carvalho, M. Samii. Department of Neurosurgery, Nordstadt Hospital, Hannover, Germany Introduction: The authorspresent a modification of the standard retrosigmoid intradural route to cerebellopontine (CPA) tumors which extend into Meckel's cave and the middle cranial fossa. This approach is called by the authors "Retrosigmoid Intradural PetrousApexApproach" (RIPA). Thesurgical anatomy of the RIPAis presented along with clinical examples. Methods: Main steps for the RIPA include a standard retrosigmoid craniotomy, intradural exposure of CPA,drilling the petrous apex portion to expose the Vthnervewithinthe Meckel'scave,andopening the tentorium upto Meckel's cave. The RIPA has been routinelyused in our Department since 1994.A total of 16 patients harboring meningiomas and trigeminal schwannomas which affected the middle and posteriorfossae and Meckel'scave have been operated on usingthis approach. The surgicalanatomyis described by cadaveric dissection, and the 16 clinical cases are reviewed. Clinicaland operative records, as well as radiological findings and postoperative outcome are presented. ReSUlts: Total tumor resection with preservation of the cranial nerves V, VII, VIII was achieved in the majority of the cases. No mortality and minimal morbidity characterized this series. Conclusion: The RIPAallowed for resection of large tumors from the posteriorfossa up to the middlefossa usinga simpleapproach withoutnecessity of extensive transpetrosal exposures. Facial and cochlearnervesare well visualized and preservedin the majorityof the cases.
I0-7-971
Reappraisal of the infratentorial supracerebellar approach
Y.Yonekawa, 1.E. Kwak, E. Taub. Department of Neurosurgery, Neurosurgical University Clinic, Zurich, Switzerland The infratentorial supracerebellar approach (ISCLA) is suitablefor the removal of tumorsin the pineal region. It can also be usedfor pathology of the thalamic, midbrain-tectal, tegmento-pontine and cerebellar regions. During the last 3 years, 29 patients underwent this approach in the sitting position: 22 usual medianISCLAand 7 paramedian ISCLA(Yasargil). Total removal of pathology was accomplished in 20 cases and partial or subtotal removal in 9 cases. No mortality and two cases of neurological deterioration were observed: one hemiparesis with 'thalamic hand" in one patient, and persistent Parinaud's syndrome in one patient. The followingprincipal observations can be madefrom our experience: (1) Pineal and thalamic pathology should be submitted to the usual median ISCLA. (2) Unilateral colliculo-midbrain pathology and tegmento-pontine pathology shouldbe submittedto paramedian ISeA. (3) Removal of a colliculussuperioron one side does not seemto produce any disturbance of occular movement. (4) Neither procedure gives adequate access to pathology of the floor of the third ventricle, so that an invasiveprocedure such as divisionof the colliculi in the midline mightbe taken into consideration.
S23
0-7-981 Pericollicular surgical approaches to pons and medulla oblongata
·C.Strauss, J. Romstock, R. Fahlbusch. Department of Neurosurgery, University of Erlangen-Nuremberg, 91054Erlangen, Germany Introduction: Safe surgical approaches into the floor of the IVth ventricle in brainstem lesionsare basedon detailedknowledge of rhomboid fossa anatomy and intraoperative localisation of superficial nuclei andfibers. Methods: For morphometric analysis 12 brainstem specimens were investigated in conventional axial and sagittal histological slices. Motor nuclei and fibers of the rhomboid fossa were measured in all 3 dimensions with consideration of shrinkage factors. During surgery electrical stimulation of superficial cranial nerve nuclei V-XII was performed in 40 patientswith intraaxial lesions and lesionsinfiltrating the brainstem. Results: Morphometric analysisof rhomboid fossa anatomydefinesa paramedian infracollicular approach of 9.2 mm locatedbetween the facial colliculus and the upperpole of the Nucleus N. hypoglossi. A paramedian supracollicular approach betweenfacialcolliculus and the fibers of the Vlth cranialnerve within the medullary velum measures 13.8 mm. Morphometric data were transferred to the surgical field by direct electrical stimulation of cranial motor nuclei and fibersV-XII in a total of 40 patients. Localisation of facial colliculusand trigonum hypoglossi was achieved in all cases. No side effectswere observed. Discussion: Morphometric investigation of histological anatomydefinestwo operative approaches intothe rhomboid fossa. Morphometric data can be transferred to surgeryusingadvanced neurophysiological methods. Direct electrical stimulation is a reliable, fast and safe methodto localizefunctionally important landmarks, thusprovidinq a safeapproach for lesionswithinthe rhomboid fossa. [1] Langet al: Acta Neurochir 113,84-90,1991 [2] Strauss et al~ J Neurosurg 79, 393--399, 1993
10-7-991 Tec.hnicalaspects ofthe IV ventricle mapping during bratnstem surgery G.A. Schekutiev, V.1. Lukianov, A.Y. Lubnin. N.N. Burdenko Neurosurgical Institute, Moscow, Russia Themoderntechnique of brainstem tumorsurgeryis basedon approachthrough safe entry zones via the floor of the IV ventricle. These zones can be identified by electrical stimulation of the floor and evokedelectromyographic (EMG) recordings of muscles of the head. In 20 patients with glioma and cavemoma of the caudal brain stem we studied technical aspectsof this IV ventricle mapping. Stimulating techniques: constant current versusconstantvoltage; types of electrodes: bipolar forceps, monopolar probe, coaxial electrode; types of insulationof the electrode: flush tip versus bare tip were compared. EMG electrodes from muscles supplied by the VII, IX, X, XII cranialnervesof both sides wereconnected simultaneously to the two channel amplifier. It allowed us to find EMG response free areas of the floor of the IV ventricle, that is the safe entry zone. Howevera variant of mixed EMGrecording does not allowto attributeany EMG response to definite motor structure of the brain stem. The results that the best technique for mapping of motor structures of the brain stem is constant current stimulation by flush tip coaxial electrode with a bipolar regime. In 14 patients we could get EMG response during stimulation of the hypoglossal and facial triangles of the rhomboid fossa from both left and right sides. In the other 6 cases identification of motor structures was partiallysuccessful. In 4 cases of them it probablydepended on displacement of motor structures and in 2 cases there was severe preoperative deficit of the corresponding motorfunctions.
I0-7-100 I malignant Rec.onstructive surg~ry of skull base region after tumor excision Igor V. Reshetov 1, ValeryI. Chissov1 , Alexander M. Sdvizkov 1 , Sergey A. Kravtzov j, Oleg V. Matorin1, SergeyV.Tanyashin 2, Vasiliy A. Tcherekaev 2. 1 p.A. Hertzen CancerResearch Institute, Moscow, Russia, 2 Burdenko Neurosurgical Institute, Moscow, Russia We haveoperated 38 patientsfor spread(T3-T4) tumorswith reconstruction of craniomaxillofacial region. There were epidermoid and basal cell carcinomas, sarcomas andsomeothermalignancies. Inall the caseswe used rotatedor vascularized free tissue flaps: in 21 cases fascilocutaneous (from forearm, parascapular region or forehead), in 12 cases musculofascial (m. latissimus dorsi, m. serratus anterior and m. trapezium), in remaining 5 cases - vascularized omental flap. Complication rate was 30%, in 2 caseswe observed insufficiency of vascularanastomoses. Therewas no postoperative mortality. 3-yearmortality
524
Technology - Surgical Approaches and Endoscopy
rate was 61.5%. The methods of craniofacial reconstruction with use of rotated and especially vascularized tissue lIaps with costal fragments permit restoration of the lacial skeleton and provide good cosmetic results.
I0-7-1 01 I Computer-aided reconstruction of large skull defects M. Lorenz, G. Graubner, H. Schumann 1, U. Hustedt". M. Samii. Klinik, Zentrale Forschungswerkstatten, 2 AbteilungfUr Neuroradiologie, Medizinische HochschuleHannover, 0-30623 Hannover, Germany
1 Neurochirurgische
Introduction: Large bony skull defects usually occur after decompressive craniectomy. Typically, the shape contains different curvatures. The indication for a plastic reconstruction is to facilitate a normalization of the ICP-dynamtcs, and cosmetical reasons. A freehand reconstruction will fulfill the physical requirements but often misses a sufficient cosmetical result. Patients and Method: A new procedure of an anatomically exact reconstruction was developed and is under further improvement: 1. Skull-data were sampled by 3D-CT. 2. These data were converted into commands that control a milling machine to produce a laminar accumulated model. 3. Thereafter, a Palacosv-lrnplant was made. Initially, a positive form showing the defect was used. In the last time, the lacking surface could be calculated by mirroing the data of the other side. This is of valuable help in modelling the implant and opens the possibility for a direct manufacturing of the lIap. First resultsare very satisfying. However, the production has to be improved because it is still too time consuming to establish it as a routine-process. Results and Conclusion: In 19 patients a new designed way of an anatomically correct reconstruction of large skull delects was used and relined. This procedure was chosen especially in alert persons wrth the demand of an optimal result. The produced models matched the anatomical form very good and the patients were very satisfied with the cosmetical result. The effort and costs will be justified in those patients who will recover full social activities. A Palaces'[- implant will allow subsequent MR-imaging. The lurther development of a primary implant-production may lead to implants at other places, such as for the closure of basal defects after removal of huge tumors.
I0-7-102 1 Ventricular lavage system Newton Paes. Universidade de Santo Amaro, Sao Paulo, Brazil The management of patients at risk lor cranial hypertension continues to be a controversial subject. O'Sullivan, et at, have concluded that even severely head injured patients whose initial CT scan is normal or does not show a mass lesion, midline shift, or effaced cisterns nevertheless remain at risk lor developing significant secondary cerebral insults due to elevated ICP, reduced CPP, and hypotensiondespite aggressiveintensive care. Ischemiabeginswhen cerebral perfusion pressure lalls below 50 mmHg, and when CPP is below 30 mmHg severe, irreversible ischemia occurs. Since CPP is equal to mean arterial pressure minus ICP, the monitoring of ICP has proved to be a useful tool in the management 01 these patients. ICP can be lowered with diuretics, hyperventilation or barbiturate therapy. In addition, the drainage of CSF can be particularly useful in lowering IC? Currently ICP moniloring and drainage are independent 01 each other. The author presents the design theory and initial animal studies of a new microprocessor based device designed to both monitor and control ICP by automatic extraction of micro volumes 01 CSF. The system consists of a double lumen catheter connected to an extemal double pump system with pressure monitor and micro-processor based controller. ICP is monitored through the catheter and ICP is controlled by the extraction 01 small volumes of CSF.The software and microprocessor controller permit the control of ICP to avoid hypertension. In addition, software permits the determination of brain compliance to trend the progress of the patient. The system may also be used for infusion and extraction of physiologic solutions to aid in the eliminationof blood clots. It is anticipated that this device may proveto be uselul in preventing intracranial hypertension in cases of intraventricular hemorrhage, subarachnoid hemorrhage, post surgical tumor removal, hydrocephalUS and traumatic brain edema.
10 -7-103 1 EndC?scopy-assisted microsurgery of cramopharyngeomas Erik Van Lindert, Axel Pemeczky, Christoph Busert. Department of Neurosurgery, Universityof Mainz, Mainz, Germany Introduction: With the intention to reduce the surgical trauma in skull base surgery, we gradually reduced the size of our surgical approaches. This change has been made possible by individual approach planning and by intraoperative useof endoscopy.This study should evaluate the resultsof endoscopy-assisted keyhole approacheslor craniopharyngeomas.
Monda); 7 July 1997
Methods: We retrospectively studied the clinical files of 14 palients (M:F
=6:8) operated on between 1993 and 1996. Patient ages ranged from 14-63
yrs (average; 40 yrs). Seven patients presented with recurrent tumors, 5 of them operated on elsewhere. The approaches that were used were: supraorbital (8), transventricular/transforaminal (2), transcaliosaVtransventricular (2), presigmoidal (1), subtrontal interhemispheric (1). Results: In 5 cases tumor resectionwas performed truly endoscopy-assisted (so-called videosurgery). In 9 cases endoscopy was used for inspection after completed microsurgical tumor exstirpation. In three of these cases tumor remnants were lound endoscopically, which then could be removed under endoscopic control. In all 14 patients gross total removal could be achieved. Ten patients had a good result, however most 01 them with hormonal substitution. Two patients had a moderate outcome, one 01 them with amnestic syndrome, the other with a psychosyndrome and an oculomotor nerve palsy. Two patients died: one patient six weeks after surgery of pulmonary embolism and sepsis, the other 5 months after surgery due to electrolyte disturbances. There was no tumor recurrence after a mean follow-up of 28 months in the other 12 patients. Conclusion: We conclude that intraoperative endoscopy is an adequate tool that helps to achieve radical tumor removal in craniopharyngeoma surgery, even for recurrent tumors. The combination 01 individual approach planning by the keyhole conceptand intraoperative endoscopy is benelicial to a patient with a craniopharyngeoma by reducing surgical traumatization.
I0-7-1041 Image-directed neuroendoscopy N.L. Dorward" O. Alberti 1 , J. Zha0 2 , D. Hawkes 2 , J. Buurrnan-', A. Dijkstra, D.G.T. Thomas 1. ' Institute of Neurology. London, UK, 2 Radiological Sciences, Guy s Hospital, London, UK, 3 Philips Medical Systems, Best, Netherlands Introduction: Both minimallyinvasive surgery and image guidancecan improve outcome and reduce hospital stay. Until now they have largely been approached as altemative not complementary techniques. Our aimwas to combinethe power of navigation with the minimally invasive qualities of neuroendoscopy. Methods: We have Easy Guide Neuro (Philips Medical Systems) for navigation and a rigid 24 cm 4 channel neuroendoscope (Aesculap AG). An array of light emitting diodes was produced for attachment to the endoscope, enabling the guidance system to track the tip. Live orthogonal reformats of the pre-operative MRI showed the tip position. Such reformats were also produced at a known distance ahead 01 the endoscope tip through Virtual elongation of the endoscope, chosen to correspond with the field 01 view. Results: The ability 01 the system to accurately localise the endoscope tip and the accuracy 01 virtual tip elongation reformatting have been verified through phantom studies. These revealed a mean localisation error for the standardpointer of 0.63 mm with a standard deviation of 0.58 mm and with the endoscope of 0.67 and 0.53 mm respectively. The system has been tested in the clinical setting and proven to be 01considerable value. Discussion: This work has resulted not only in image-guidance of the endoscope but also in interactive endoscopy. The former enables the surgeon to preciselytailor the incision,burr hole(s) and approach to the individualpatient, to guide the normally blind insertion of the endoscope and provide orientation at all times. The latter is the novel ability to display the wider anatomy beyond the endoscope view and beyond the CSF spaces in an iterative manner. This is a powerful 1001with real clinical potential. Research funded by EEC Telematics in Surgery Project.
I0 -7-1051 Endoscopy-assisted skull base surgery Yong Ko, Kwang-Myung Kim, Suck-Jun Oh. Hanyang University Hospitsl, Seoul, Korea Wide skin and bony exposure including the lace is current policy in the management of skull base tumors. Even though this aggressive surgery saved many lives, it did not result in a better quality 01 lile. In the present series miniature craniotomy near the skull base and endoscopy were used to reduce morbidity. In a period of3 years 13 patients were operated with the diagnosis of skull base meningioma,chordoma, rhabdomyosarcoma, metastaticadenocarcinoma and neurilemmoma. Small superolateral orbital roof craniotomy was done to operate anterior and middle cranial base tumors. Retromastoid craniectomy with or without removal of C1 arch sufficed for posterior fossa tumors. Most of tumors could be removed through a mini-window. Remnant tumors behind the petrous bone and at the contralateral side were effectively removed under endoscopic visualization. Good anatomical relationship between tumor and brain could be observed with zero and thirty degree endoscopes. However, endoscopic surgery had limitations in the dissection 01 highly vascular tumors since it could not control massive bleeding. A rigid endoscope was usually used during surgery and a flexible endoscope was additionally used to see hidden areas. Our technique resulted in less scar, facial deformity and morbidity. Endoscopic surgery can satisfactorily help neurosurgeons to control skull base tumors with a small incision, and restricted craniotomy.