Endoscopy in aneurysm surgery.

BACKGROUND: Surgical clipping with complete occlusion of the aneurysm and preservation of parent, branching, and perforating vessels remains the most definitive treatment for intracranial aneurysms. OBJECTIVE: To evaluate the benefit of endoscopic application during microsurgical procedures in a retrospective study. METHODS: One hundred eighty aneurysms were microsurgically treated in 124 operations. Three different applications of endoscopic visualization were used, depending on the respective requirements: inspection before clipping, clipping under endoscopic view, and postclipping evaluation. RESULTS: Of 1380 aneurysms, 292 procedures were done with application of the endoscope. Of these 292, a complete data set, including video recording of the procedures for retrospective evaluation, was available in 180 cases. In these, the endoscope provided a favorable enhancement of the visual field, particularly in complex or deep-seated lesions. No adverse effects were observed. Before clipping, the endoscope was used to gain additional topographic information in 150 of 180 cases (83%). Clipping under endoscopic view was performed in 4 cases. After clipping, endoscopic inspection was performed in 130 of 180 procedures. Depending on the endoscopic findings, rearrangement of the applied clip or additional clipping was found to be necessary in 26 of 130 cases (20.0%). CONCLUSION: Endoscopic enhancement of the visual field provided by the endoscope before, during, and after microsurgical aneurysm occlusion may be a safe and effective application to increase the quality of treatment. Although unexpected findings concerning completeness of aneurysm occlusion and compromise of involved vessels could be diminished by endoscopic assessment, total prevention was not accomplished.

The keyhole concept in aneurysm surgery: results of the past 20 years.

BACKGROUND: Improvements in preoperative imaging and intraoperative visualization have led to a refinement in surgical techniques. OBJECTIVE: Report of a 20-year experience with application of the keyhole technique as a contribution to the ongoing debate on the impact of limited craniotomies in aneurysm surgery. METHODS: Over a 20-year period, 1000 consecutive patients with 1297 aneurysms were surgically treated in 1062 operations: 651 in the acute stage after SAH and 411 with unruptured aneurysms. The outcome was assessed with the modified Rankin scale and approach-related complications. RESULTS: The majority of the cases were treated by 4 different keyhole approaches: The supraorbital approach was used in 793 patients for 989 aneurysms, the subtemporal in 48 patients for 50 aneurysms, the interhemispheric in 46 patients for 51 aneurysms, and the retromastoidal in 55 patients for 55 aneurysms. In 120 patients, the classic pterional approach was applied to treat 152 aneurysms. The results of unruptured aneurysms were good (modified Rankin scale ≤ 2) in 96.52%. The complication rates of the keyhole approaches were less than in the pterional group, although the difference did not reach statistical significance. CONCLUSION: The overall outcome, rate of retreatment, and approach-related complications with keyhole approaches for the management of ruptured and unruptured aneurysms are comparable to recently published conventional surgical aneurysm series. In addition to the common benefits of limited-exposure approaches, this series demonstrates appropriate safety and applicability of the keyhole technique in aneurysm surgery.

Surgical complications after endoscopic transsphenoidal pituitary surgery.

Between January 2004 and June 2007 we conducted a retrospective analysis to assess post-operative complications related to endoscopic pituitary surgery in a series of 150 patients. Patients were treated with an endoscopic endonasal transsphenoidal approach to the sellar region for removal of pathological sellar and suprasellar lesions. We analysed the complications in groups according to the anatomical structures of the approach and the functional systems of the pituitary gland (anterior and posterior endocrine systems), and compared them to a large historical series using the traditional microsurgical transsphenoidal approach. Overall, we observed a decreased incidence of complications with respect to the surgical trauma, the functionality of the pituitary gland and post-operative patient comfort. We believe that the reduction of the complication rate observed in this study was mainly due to the wide structural overview offered by the endoscope as well as the anatomically direct, and therefore minimally invasive, character of the procedure. Successful endoscopic pituitary surgery requires extensive training in the use of an endoscope and careful planning of the surgery. Furthermore, close cooperation between a multidisciplinary team consisting of endocrinologists, neurosurgeons, ear, nose and throat surgeons, radiologists, and radiation oncologists is of utmost importance.

Mesencephalic ependymal cysts: treatment under pure endoscopic or endoscope-assisted keyhole conditions.

OBJECT: Primary intracranial ependymal cysts are extremely rare. Similar to congenital intraparenchymal cysts in the mesencephalon they usually occur with symptoms of an occlusive hydrocephalus or symptoms like Parinaud syndrome, dizziness, or gait disturbance. The objective of this study was to evaluate the surgical methods for the treatment of these cysts and the clinical outcome of the patients. METHODS: The authors present the clinical records of 8 patients who were treated in their department for symptomatic mesencephalic ependymal cysts in the past 10 years. The patient age ranged from 22 to 60 years with a mean age of 44 years. In 4 cases the authors performed a suboccipital infratentorial supracerebellar approach by using endoscope-assisted microsurgery. The other 4 patients underwent a pure endoscopic procedure over a frontal bur hole trepanation. RESULTS: Four patients became symptom free, and the remaining 4 improved significantly after a mean follow-up duration of 38.5 months (range 5-119 months). One patient underwent 2 operations: first a ventriculocystostomy and 4 months later endoscopic third ventriculostomy because of recurrent hydrocephalus. In 1 case a second surgery was necessary because of a wound infection. In all of the patients an adequate fenestration of the cyst was achieved. CONCLUSIONS: A symptomatic mesencephalic ependymal cyst is an indication for neurosurgical intervention. These cysts can be treated successfully and most likely definitively by a pure endoscopic or endoscope-assisted keyhole neurosurgical technique. There were no morbid conditions or death due to the procedures in this group of 8 patients. Therefore, the authors regard these surgical procedures to be good alternatives to treatments such as shunt placement or stereotactic aspiration of the cysts.

Tumors of the lateral and third ventricle: removal under endoscope-assisted keyhole conditions.

OBJECTIVE: Intraventricular tumors usually are managed by approaches and microsurgical techniques that need retraction and dissection of important brain structures. Minimally invasive endoscopic procedures achieve a remarkable alternative to conventional microneurosurgical techniques. Endoscope-assisted microneurosurgery may be a minimally invasive technique with maximally effective treatment. Using the keyhole concept for planning the surgical strategy, the reduction of the brain retraction is achieved, which is one of the main benefits of this technique. METHODS: We treated 35 patients (16 female patients and 19 male patients) with tumors in the lateral (n = 8) and the third (n = 27) ventricle. Patient age at the date of surgery ranged from 5 to 73 years. The follow-up period ranged from 6 to 83 months. The tumors were operated on using transcortical, transcallosal, or suboccipital transtentorial or infratentorial supracerebellar approaches after precise planning of the skin incision, the trephination, and the trajectory to the center of the tumor, performed earlier with a magnetic resonance imaging scan. RESULTS: Total removal of the tumor was achieved in 28 patients (78.5%). In 2 patients (6.5%), recurrent tumor occurred. In 5 patients (15%), parts of the tumors remained because of infiltration of eloquent areas. Overall clinical improvement was achieved in 31 patients (87%). Three patients (10%) were unchanged and 1 patient (3%) deteriorated. CONCLUSION: Endoscope-assisted keyhole neurosurgery seems to be a safe method of removing tumors in all regions inside the ventricular system with a low risk of permanent neurological deficits. The exact surgical corridor planning on the basis of the keyhole strategy offers less traumatic exposure of even deep-seated endoventricular tumors.

New method of bone reconstruction designed for skull base surgery.

The direct endonasal or transoral transclival approaches to the skull base permit effective, minimally invasive surgery along the clivus. Developing long-term, effective techniques to prevent cerebrospinal fluid (CSF) leaks and their consequences (infection and delayed healing) remains a major challenge. In this study we describe a method of bone reconstruction newly developed by us, which uses a custom designed silicone plug for bone replacement after minimally invasive skull base surgery with a low incidence of postoperative CSF leaks. German Landrace pigs were used to test the efficiency of the new technique. Twelve craniotomies were performed in six pigs using a subtemporal approach and subsequently the dura was opened. After these preparations the craniotomy defects were occluded with a silicone ball, which had a near spherical shape. The ball elastically adapts to the bone defect. Each pig also received an intracranial pressure (ICP) catheter and a subdural catheter for later fluorescein injection. Then we increased ICP by infusion of artificial CSF and detected fluorescein leaks from the craniotomy using ultraviolet illumination and a photomacroscope equipped with appropriate filters and a charge-coupled device camera. In all pigs we increased ICP to 75-80 mmHg by infusing 25-30 mL saline containing 0.05% sodium fluorescein. For the first four craniotomies infusions were interrupted after CSF leaks occurred due to technical failures, which were subsequently rectified. The following eight craniotomies were watertight without CSF leakage. This novel medical device allows a leak-proof closure of bone defects after minimally invasive craniotomies; no additional surgery or other therapies were necessary. The application of the silicone plug, which is made of a cost-effective and biocompatible material, is easy and fast, making use of a specially developed toolkit.

Virtual reality system for planning minimally invasive neurosurgery. Technical note.

OBJECT: The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. METHODS: Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. RESULTS: After a short period of acclimatization, the system proved easy to operate and is currently used routinely for preoperative planning of difficult cases at the authors' institution. It was felt that working with a virtual reality multimodal model of the patient significantly improved surgical planning. The pathoanatomy in individual patients could easily be understood in great detail, enabling the authors to determine the surgical trajectory precisely and in the most minimally invasive way. CONCLUSIONS: The authors found the preoperative 3D model to be in high concordance with intraoperative conditions; the resulting intraoperative "déjà-vu" feeling enhanced surgical confidence. In all procedures planned with the Dextroscope, the chosen surgical strategy proved to be the correct choice. Three-dimensional virtual reality models of a patient allow quick and easy understanding of complex intracranial lesions.

MGMT in primary and recurrent human glioblastomas after radiation and chemotherapy and comparison with p53 status and clinical outcome.

The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) plays a pivotal role in alkylating drug resistance. Here, we determined MGMT activity in primary and recurrent glioblastomas (GBM, WHO grade IV) of patients who received radiation therapy (RT) or RT plus chemotherapy with alkylating agents (temozolomide, chloroethylnitrosoureas). The mean MGMT activity of untreated GBM was 37 +/- 45 (range 0-205) fmol/mg proteins. In the 1st, 2nd and 3rd recurrences, MGMT activity increased from 66 +/- 50 (13-194) to 68 +/- 44 (14-143) and 182 +/- 163 (64-423) fmol/mg protein, respectively. Comparing patients who received RT only with RT plus chemotherapy, a significant increase of MGMT in 1st recurrences was only found after treatment with RT plus chemotherapy, indicating either selection of MGMT expressing cells or induction of the MGMT gene by alkylating agents. The p53 status was not significantly related to the MGMT expression level, although a trend for lower MGMT activity in p53 positively stained tumors was observed. Patients expressing MGMT activity of

Unilateral multilevel interlaminar fenestration instead of laminectomy or hemilaminectomy: an alternative surgical approach to intraspinal space-occupying lesions. Technical note.

Laminectomy is the most conventional dorsal approach to intraspinal space-occupying lesions and may result in gradually increasing instability or deformity of the vertebral column. Less invasive procedures such as hemilaminectomy and osteoplastic laminotomy have been described by other authors, but an approach that interferes with spinal stability to an even lesser extent seems desirable. In an attempt to further reduce the need for bone removal, the authors used interlaminar fenestration (mostly unilateral) at one or more spinal levels to remove intramedullary, extramedullary, or extradural lesions, and even some lesions that extended over several spine segments. The authors present their experiences with this surgical approach in 78 patients harboring different intraspinal lesions. Up to 16 segments were fenestrated in one patient. Complete removal of the lesion was possible in most patients, and no postoperative spinal instabilities were observed in up to 8 years of follow up. Multilevel interlaminar fenestration, also called "multiple spinal keyhole surgery," is a feasible, safe, and effective approach to intraspinal lesions.

Differentiation of fibroblastic meningiomas from other benign subtypes using diffusion tensor imaging.

PURPOSE: To differentiate fibroblastic meningiomas, usually considered to be of a hard consistency, from other benign subtypes using diffusion tensor imaging (DTI). MATERIALS AND METHODS: From DTI data sets of 30 patients with benign meningiomas, we calculated diffusion tensors and mean diffusivity (MD) and fractional anisotropy (FA) maps as well as barycentric maps representing the geometrical shape of the tensors. The findings were compared to postoperative histology. The study was approved by the local ethics committee, and informed consent was given by the patients. RESULTS: According to one-way analysis of variance (ANOVA), FA was the best parameter to differentiate between the subtypes (F=32.2; p<0.0001). Regarding tensor shape, endothelial meningiomas were represented by spherical tensors (80%) corresponding to isotropic diffusion, whereas the fibroblastic meningiomas showed a high percentage (43%) of nonspherical tensors, indicating planar or longitudinal diffusion. The difference was highly significant (F=28.4; p<0.0001) and may be due to the fascicular arrangement of long spindle-shaped tumor cells and the high content of intra- and interfascicular fibers as shown in the histology. In addition, a capsule-like rim of the in-plane diffusion surrounded most meningiomas irrespective of their histological type. CONCLUSION: If these results correlate to the intraoperative findings of meningioma consistency, DTI-based measurement of FA and analysis of the shape of the diffusion tensor is a promising method to differentiate between fibroblastic and other subtypes of benign meningiomas in order to get information about their "hard" or "soft" consistency prior to removal.

Endoscopic endonasal pituitary surgery: surgical and outcome analysis of 50 cases.

OBJECTIVE: Microsurgical transsphenoidal surgery for pituitary tumors has been standard therapy for decades and was established by Harvey Cushing in the early twentieth century. Today, endoscopy is increasingly accepted in the therapy of pituitary lesions. In this retrospective study, we analysed the surgical technique and outcome of 50 patients with pituitary lesions treated with an endoscopic endonasal trans-sphenoidal approach. METHODS: Between January 2004 and July 2005, 50 patients (30 female and 20 male) with pituitary tumors were operated upon using an endoscopic endonasal trans-sphenoidal procedure without nasal speculum or postoperative nasal packing. The follow-up period ranged from 3 to 18 months. RESULTS: All patients had normal airways through both nostrils immediately after extubation. Postoperative discomfort was minimal and hospitalization was 4-5 days. Three patients developed postoperative transient diabetes insipidus, persisting in one for a further 2 months. Among the 50 patients, total tumor removal was achieved in 47 patients (94%), subtotal in two patients (4%). One patient died intraoperatively due to subarachnoid haemorrhage. CONCLUSION: The endoscopic endonasal transsphenoidal approach for removing pituitary lesions is a form of minimally invasive surgery offering excellent postoperative results.

White matter fiber tracking computation based on diffusion tensor imaging for clinical applications.

Fiber tracking allows the in vivo reconstruction of human brain white matter fiber trajectories based on magnetic resonance diffusion tensor imaging (MR-DTI), but its application in the clinical routine is still in its infancy. In this study, we present a new software for fiber tracking, developed on top of a general-purpose DICOM (digital imaging and communications in medicine) framework, which can be easily integrated into existing picture archiving and communication system (PACS) of radiological institutions. Images combining anatomical information and the localization of different fiber tract trajectories can be encoded and exported in DICOM and Analyze formats, which are valuable resources in the clinical applications of this method. Fiber tracking was implemented based on existing line propagation algorithms, but it includes a heuristic for fiber crossings in the case of disk-shaped diffusion tensors. We successfully performed fiber tracking on MR-DTI data sets from 26 patients with different types of brain lesions affecting the corticospinal tracts. In all cases, the trajectories of the central spinal tract (pyramidal tract) were reconstructed and could be applied at the planning phase of the surgery as well as in intraoperative neuronavigation.

A collaborative virtual reality environment for neurosurgical planning and training.

OBJECTIVE: We have developed a highly interactive virtual environment that enables collaborative examination of stereoscopic three-dimensional (3-D) medical imaging data for planning, discussing, or teaching neurosurgical approaches and strategies. MATERIALS AND METHODS: The system consists of an interactive console with which the user manipulates 3-D data using hand-held and tracked devices within a 3-D virtual workspace and a stereoscopic projection system. The projection system displays the 3-D data on a large screen while the user is working with it. This setup allows users to interact intuitively with complex 3-D data while sharing this information with a larger audience. RESULTS: We have been using this system on a routine clinical basis and during neurosurgical training courses to collaboratively plan and discuss neurosurgical procedures with 3-D reconstructions of patient-specific magnetic resonance and computed tomographic imaging data or with a virtual model of the temporal bone. Working collaboratively with the 3-D information of a large, interactive, stereoscopic projection provides an unambiguous way to analyze and understand the anatomic spatial relationships of different surgical corridors. In our experience, the system creates a unique forum for open and precise discussion of neurosurgical approaches. CONCLUSION: We believe the system provides a highly effective way to work with 3-D data in a group, and it significantly enhances teaching of neurosurgical anatomy and operative strategies.

Combined endo- and exoscopic semi-robotic manipulator system for image guided operations.

This paper describes the development of a robotic assistance system for image guided operations. To minimize operation time, a multimodal user interface enables freehand robotic manipulation of an extracorporeal stereoscopic digital camera (exoscope) and an endoscope. The surgeon thereby wears a head-mounted unit with a binocular display, a head tracker, a microphone and earphones. Different view positioning and adjustment modes can be selected by voice and controlled by head rotation while pressing a miniature confirmation button with a finger. Initial studies focused on the evaluation and optimization of the intuitiveness, comfort and precision of different modes of operation, including a user test with neurosurgeons in a virtual reality simulation. The first labtype of the system was then implemented and demonstrated in the operating room on a phantom together with the clinical partners.

Endoscopic aqueductoplasty through a tailored craniocervical approach.

OBJECT: Neuroendoscopy has an essential role in the management of occlusive hydrocephalus due to a membranous obstruction of the sylvian aqueduct. Well-known endoscopic methods include endoscopic third ventriculostomy (ETV) and endoscopic aqueductoplasty through a frontal burr hole. Building on their experience in the endoscopic management of hydrocephalus, the authors realized that not all of their patients with aqueductal obstruction were eligible for the aforementioned lines of treatment. Certain anatomical situations made it impossible to perform ETV or endoscopic aqueductoplasty through a frontal burr hole. Long-term complications of the shunt system led the authors to seek an alternative form of treatment for these patients. In this study, they present a new endoscopic approach to performing aqueductoplasty through the fourth ventricle. METHODS: Endoscopic aqueductoplasty was performed in five patients by using a tailored craniocervical approach. In all patients a caudally located membranous obstruction of the sylvian aqueduct was present, and the authors were able to relieve the membranous obstruction in all patients without complications. All patients experienced improvement, which was demonstrated clinically and on imaging studies. CONCLUSIONS: Caudal endoscopic aqueductoplasty is a safe and effective method of treatment in the management of a caudally located membranous obstruction of the sylvian aqueduct. This should be considered as an alternative endoscopic method when other endoscopic solutions are not suitable.

Ten-year experience with the supraorbital subfrontal approach through an eyebrow skin incision.

OBJECTIVE: More than ever before, the priority in contemporary neurosurgery is to achieve the greatest therapeutic effect while causing the least iatrogenic injury. The evolution of microsurgical techniques with refined instrumentation and illumination and the enormous development of preoperative and intraoperative diagnostic tools enable neurosurgeons to treat different lesions through limited and specific keyhole approaches. METHODS: Based on our surgical experience, the technique of supraorbital subfrontal craniotomy is described in detail in this article. After an eyebrow skin incision is made, a limited supraorbital craniotomy is performed with a width of 15 to 25 mm and a height of 10 to 15 mm. RESULTS: We have been using the supraorbital keyhole craniotomy since 1985 and have approached a variety of lesions within the anterior, middle, and posterior cranial fossae. During a 10-year period between July 1994 and June 2004, the lesions treated via the supraorbital approach in our department comprised 1125 intracranial tumors or cystic lesions, cerebral aneurysms, and other miscellaneous diseases, performed by 23 different surgeons and residents. Of these 1125 patients, we operated on 471 of them, and information obtained from 450 contributed to the follow-up data. Three months after surgery, the Glasgow Outcome Scale scores for this very heterogeneous group of patients were as follows: 5 in 387 patients (86.0%), 4 in 29 patients (6.4%), 3 in 16 patients (3.5%), 2 in 10 patients (2.2%), and 1 in 8 patients (1.8%). Of the 450 patients, 229 were treated for intracranial aneurysms, 93 for cranial base meningiomas, 39 for craniopharyngiomas, 23 for pituitary adenomas, 18 for deep-seated brainstem tumors, and 48 for other miscellaneous frontotemporal or suprasellar lesions. CONCLUSION: In our experience, the supraorbital craniotomy allows a wide, intracranial exposure for extended, bilaterally situated, or even deep-seated intracranial areas, according to the strategy of keyhole craniotomies. The supraorbital craniotomy offers equal surgical possibilities with less approach-related morbidity owing to limited exposure of the cerebral surface and minimal brain retraction. In addition, the short skin incision within the eyebrow and careful soft tissue dissection result in a pleasing cosmetic outcome.

Tumors of the lateral and third ventricle: removal under endoscope-assisted keyhole conditions.

OBJECTIVE: Intraventricular tumors usually are managed by approaches and microsurgical techniques that need retraction and dissection of important brain structures. Minimally invasive endoscopic procedures achieve a remarkable alternative to conventional microneurosurgical techniques. Endoscope-assisted microneurosurgery may be a minimally invasive technique with maximally effective treatment. Using the keyhole concept for planning the surgical strategy, the reduction of the brain retraction is achieved, which is one of the main benefits of this technique. METHODS: We treated 35 patients (16 female patients and 19 male patients) with tumors in the lateral (n = 8) and the third (n = 27) ventricle. Patient age at the date of surgery ranged from 5 to 73 years. The follow-up period ranged from 6 to 83 months. The tumors were operated on using transcortical, transcallosal, or suboccipital transtentorial or infratentorial supracerebellar approaches after precise planning of the skin incision, the trephination, and the trajectory to the center of the tumor, performed earlier with a magnetic resonance imaging scan. RESULTS: Total removal of the tumor was achieved in 28 patients (78.5%). In 2 patients (6.5%), recurrent tumor occurred. In 5 patients (15%), parts of the tumors remained because of infiltration of eloquent areas. Overall clinical improvement was achieved in 31 patients (87%). Three patients (10%) were unchanged and 1 patient (3%) deteriorated. CONCLUSION: Endoscope-assisted keyhole neurosurgery seems to be a safe method of removing tumors in all regions inside the ventricular system with a low risk of permanent neurological deficits. The exact surgical corridor planning on the basis of the keyhole strategy offers less traumatic exposure of even deep-seated endoventricular tumors.

Surgical technique of the supraorbital key-hole craniotomy.

BACKGROUND: The enormous development of microsurgical techniques and instrumentation together with preoperative planning using the excellent preoperative diagnostic facilities available, enables neurosurgeons to treat more complicated diseases through smaller and more specific approaches. METHODS: The technical details of the supraorbital key-hole craniotomy are described in this article as it has been evolving in our experience for more than 10 years. After an eyebrow skin incision with careful soft tissue dissection and single frontobasal burr-hole trephination, a supraorbital craniotomy is carried out with a diameter of about 1.5 x 2.5 cm. As a real frontolateral approach, the supraorbital craniotomy avoids removal of the orbital rim, the lesser sphenoid wing or the zygomatic arch. RESULTS AND CONCLUSIONS: The supraorbital craniotomy allows wide intracranial exposure of the deep-seated supra- and parasellar region, according to the concept of key-hole approaches. The limited craniotomy requires minimal brain retraction thus significantly decreasing approach-related morbidity. In addition, the short skin incision within the eyebrow, the careful soft tissue dissection, and the single burr hole trephination result in a pleasing cosmetic outcome.

[Biportal neuroendoscopy of the prepontine cisterns]. / A praepontin ciszternák biportalis neuroendoszkópiája.

INTRODUCTION: While bi- or multiportal approaches have been adopted in different fields of surgery including abdominal and spine surgery, the uniportal access into the skull is a traditional principle in neurosurgery. In this preclinical cadaver study the authors developed combinations of biportal endoneurosurgical dissections in the prepontine subarachnoid space to test the safety of this technique. METHODS: In 34 fresh post-mortem adult human cadavers and 14 formaldehyde-fixed adult human head specimen a total of 48 biportal endoscopical dissections were carried out. 0 degree, 30 degrees, and 70 degrees lens scopes with a diameter of 1.7 and 4.2 mm and trochars with a diameter of 5.0 to 6.5 mm were used. RESULTS: Six different endoscopic routes to the prepontine region and a total of 10 different combinations of this approaches could be described. Useful and safe biportal combinations were: 1. supraorbital on both sides, 2. supraorbital combined with ipsilateral anterior subtemporal, 3. supraorbital combined with contralateral anterior subtemporal, 4. supraorbital combined with ipsilateral posterior subtemporal, 5. supraorbital combined with ipsilateral frontal interhemispheric, 6. supraorbital combined with contralateral frontal interhemispheric, 7. anterior subtemporal combined with ipsilateral frontal interhemispheric, 8. anterior subtemporal combined with contralateral frontal interhemispheric. CONCLUSION: The biportal endomicrosurgical strategy offered effective and safe dissections within the prepontine subarachnoid space.

Primary myelomeningocele closure and consequences.

PURPOSE OF REVIEW: Myelomeningocele, the most frequently occurring open neural tube defect, requires lifelong care of the patient by medical professionals and by relatives. A basic understanding of the neurosurgical measures that have to be taken in the newborn, the infant, the child and the adult is important also for physicians of other disciplines involved in the treatment of patients with myelomeningocele. RECENT FINDINGS: The most recent topic broadly discussed in this context is the role of foetal neurosurgery for closure of the neural tube defect. There is ongoing debate as to whether the beneficial postnatal effects of a prenatal operation in the unborn foetus outweighs the possible complications for the mother as well as the child. SUMMARY: As some of the problems associated with myelomeningocele occur only later in life, it will still take many years until the beneficial, as well as the adverse, effects of prenatal neurosurgical procedures can be evaluated.