Ch. Matula

Frameless stereotactic guided neurosurgery: Clinical experience with an infrared based pointer device navigation system

SummaryAn infrared based frameless stereotactic navigation device (Easy Guide Neuro) was investigated for its clinical applicability, registration/application accuracy and limitations in a standard operating room set-up.In a five-month period 40 frameless stereotactic procedures (23 female, 17 male, mean age 46.4, yrs range 10–83) including 36 craniotomies and 4 spinal surgery procedures were performed. Image registration, data transfer and operation planning using skin fixed fiducials (between 5–10, mean 6.6) and CCT in 12 patients/MRI in 28 patients, generally was done the day before surgery.Clinical applicability was proven in all procedures with an additional time for pre-operative imaging and system application in the OR of 50 min mean (35–120 range). A useful registration was achieved in 39/40 patients (97.5%) with a registration accuracy of 3.4 mm (range 1.8–6.7) for brain surgery cases and 14.4 mm (6.8–25) for spine cases. This resulted in intra-operative application accuracy values for brain surgery of 4.2 mm mean (range 1–12). Enhanced registration/application accuracy values over the test period from 4.2/3.8 mm mean (Cases 1–20) up to 3.2/2 mm mean (Cases 21–40) was observed. In spinal surgery an application accuracy of 11.3 mm mean (range 5–20) was found. An intra-operative re-calibration because of system-head drift was necessary in none of the patients, nevertheless, application accuracy degradation due to brain shift was detected in every case.In conclusion, the system allowed a time sufficient accurate frameless intra-operative localisation guidance in cavernoma, meningioma, glioma, and brain metastasis surgery. In spinal surgery, the application accuracy exceeded clinical usefulness due to high registration inaccuracy using skin markers.

Cavernous sinus surgery

SummaryThe cavernous sinus is divided from the surgical point of view into three parts. The middle part consists of the lateral sinus wall, the cranial nerves III, IV, V, VI and the posterior siphonknee of the internal carotid artery. Lesions of this region, vascular as well as tumorous, can be exposed by approaching the lateral sinus wall. The surgical dissection through the sinus wall is based on some important anatomical details, which are described here. As a consequence a modified transcavernous approach will be introduced and demonstrated by 35 clinical cases.

Endoscopically assisted microneurosurgery.

SummaryTechnological developments in neuroendoscopy are leading to an expansion of applications into the realm of microneurosurgical procedures. The new dimension that using an endoscope provides requires insight into different neuroanatomical aspects and a new kind of strategy in planning a microneurosurgical procedure. To gain some new insights into these exciting aspects of neurosurgery we have explored the sellar, parasellar, and posterior fossa regions in 50 fresh anatomical specimens and used various types of endoscopes to observe the surgically relevant neurotopographical details. We then utilized this experience in 33 clinical cases during microsurgical approaches for various lesions (posterior fossa tumors — 12 cases, sellar and parasellar tumors — 8 cases, transsphenoidal procedures for pituitary adenoma — 7 cases, transventricular procedures — 6 cases). In the laboratory we found that familiar neuroanatomical structures are seen in a completely different aspect from what we are accustomed. Orientation is at times difficult, which requires rehearsal and special handling of the endoscope for complex clinical procedures. We found that certain structures that are hardly noticed in routine anatomical views become very important when utilizing the endoscope (i.e., different arachnoid membranes and trabeculae). Importantly, the dimensions of a microsurgical approach can be greatly enlarged with the endoscope, making it possible to look behind structures and “around corners”. We present our findings with respect to important anatomical details relevant to utilizing the endoscope as an adjunct to microneurosurgical procedures and our clinical data. We have concluded that the neuroendoscope can be a safe and helpful adjunct in many microneurosurgical procedures.

Long-term results of different treatment modalities in 37 patients with glomus jugulare tumors.

Abstract The results of different forms of treatment of 37 patients with previously untreated glomus jugulare tumors were compared retrospectively. According to the Fisch classification system, 6 patients presented with class B tumors, 19 class C and 12 patients with class D. Twenty-eight patients underwent surgery and 9 patients had primary radiation therapy (to 50 Gy). In 20 of the surgical cases (71%), radical tumor removal could be achieved and required no further treatment over a follow-up period of 8.6 years (range 2–15 years). Incomplete tumor resection with postoperative radiation therapy resulted in progressive tumor growth in three cases. One patient in this group experienced subarachnoid bleeding that had to be managed by salvage surgery. After primary radiation therapy, glomus jugulare tumors were still evident on magnetic resonance imaging scans, but showed no signs of disease progression. As a result of our experience, we found that a one-stage radical tumor resection performed in collaboration by otologic surgeons and neurosurgeons was the best treatment for patients with large glomus jugulare tumors.

Contour-guided brain tumor surgery using a stereotactic navigating microscope.

OBJECTIVE The benefit of intraoperative radiological data integration in approach planning and resection of brain tumors using a computer navigating microscope (MKM Zeiss) was investigated. METHODS Since February 1995, out of 86 MKM-guided surgical procedures, 53 contour-guided tumor cases (24 females, 29 males, mean age 51.6) including 16 metastasis, 14 glioblastomas, 10 low-grade gliomas, 6 anaplastic gliomas, 3 meningiomas and 4 others were performed. The preoperative planning was based on CT in 42 cases and Magnetic Resonance Tomography (MRT) in 11 cases using skin markers (4-9, mean 6). Neuroradiologically defined tumor contours were transferred into the ocular of the microscope and projected into the operating field during the procedure. RESULTS The advantages of the system were: (1) preoperative approach planning; (2) minimal, accurate skin incision and craniotomy; (3) intraoperative detection of deep seated lesions or lesion components; (4) determination of lesion boundaries; (5) minimized traumatization in/near eloquent areas. Mean registration accuracy improved from 5.3 mm for the first 10 cases up to 2 mm for the last 18 cases. In glioma surgery, the system provided exact definition of radiologically planned resection borders. In meningioma surgery, it allowed a tailored craniotomy, dura opening and resection, lowering the risk of recurrence. In metastasis surgery, it provided a safe approach to deep and eloquent located lesions. CONCLUSION Contour-guided operation planning and resection guidance using the investigated navigating microscope provides additional security to avoid some potential risks in brain tumor surgery.

The retrosigmoid approach to acoustic neurinomas: technical, strategic, and future concepts

SummaryThe retrosigmoid approach continues to be the most widely employed strategy for the surgical resection of acoustic neuromas. The results with respect to facial nerve function are uniformly reported to be quite high. The great emphasis currently is upon improving results with regard to the conservation of useful hearing. This paper focuses on the anatomical and strategic surgical factors that we currently consider to be important to maximizing our current results. The future aspects of this trend toward improved success in conserving hearing in these patients is also discussed.

Paragangliomas of the Temporal Bone: Results of Different Treatment Modalities in 53 Patients

Summary. Background: The authors retrospectively compared the results of three different treatment modalities (surgery, conventional radiotherapy and gamma knife radiosurgery) in patients with paragangliomas of the temporal bone, in order to determine the optimal current treatment concept. Method: Between 1978 and August 2001, 53 patients (12 men and 41 women; mean age, 58.3 years; range, 17 to 84 years) with paragangliomas of the temporal bone were treated at the neurosurgery and ENT departments of the University of Vienna. According to the Fisch classification, 6 patients had class B tumours, 20 had class C, and 27 patients had class D tumours. Thirty-two patients (mean age, 57.0 years; 6 B, 14 C, 12 D) underwent surgery. In 17 cases the tumour was embolised prior to surgery. Nine patients (mean age, 73.9 years; 6 C, 3 D) received primary radiotherapy (median total dose, 46.8 Gy). Six patients (mean age, 73.5 years; 6 D) underwent primary radiosurgery (median centre dose 24, Gy) and 6 patients (6 D) admitted from other departments with recurrent tumours adjuvant radiosurgery (median centre dose, 25.5 Gy). Findings: In 20 of the surgical cases (62.5%) complete tumour resection was achieved and the patients required no further treatment over a mean follow-up period of 9.1 years. Of the 12 patients with incomplete tumour resection, 9 (5 C, 4 D) received postoperative adjuvant radiotherapy and three patients (3 D) adjuvant radiosurgery. In 15 (83.4%) of the 18 patients who underwent radiotherapy the tumours showed no signs of progression and the patients remained clinically unchanged over a mean period of 9.4 years. Three patients (16,6%) experienced progression of their tumour within an average period of 2.8 years. In the 15 patients who underwent primary radiosurgery, an objective 100% tumour control rate with no evidence of progression of disease was observed. Interpretation: The results indicate that the most effective current treatment option for patients with paragangliomas of the temporal bone is a single-stage radical tumour resection, performed in advanced tumours as an interdisciplinary neuro-otosurgical procedure. For subtotally resected or non-resectable tumours, gamma knife radiosurgery has proved to be a safe and effective treatment modality.

Cephaloceles - Experience with 42 Patients

SummaryForty-two patients with 44 cephaloceles treated between 1966 and 1993 are presented. Eighteen lesions were occipital, 2 parietal, 1 at the anterior fontanelle, 11 sincipital, and 12 basal. In recent years computerized tomography (CT) and magnetic resonance imaging (MRI) provided better information on the site and nature of the lesion as well as on associated malformations. Different malformations were associated more frequently with the cranial vault lesions. Cerebrospinal fluid (CSF)-rhinorrhea was the most frequent clinical sign in the basal lesions. Excision of the cele was performed in all but one case. The age at the time of surgical treatment ranged from 1 day to 11 years. Seven patients were shunted. Postoperative complications were persisting CSF-leaks in 5 patients needing operative revision and 2 infections. The outcome was good in the anterior lesions and in the occipital meningoceles.

Course of the arteria vertebralis in its segment V1 from the origin to its entry into the foramen processus transversi

The segment V1 of the arteria vertebralis (pathway from its origin from the a. subclavia to the entry into the respective foramen processus transversi) has a special significance in vascular surgery. Contrary to indications in the literature, we found 47.15% of the specimens to have a contorted course in this segment. The tortuosities carried by the respective vessels were found to be horizontal in 42.5%, in a sagittal direction in 30% and in the frontal plane in 27% of the cases. However, no significant difference was found between vessels carrying a tortuosity and those without, regarding the average lengths of the arteries concerned in the segment V1.

Modifications of Temporal Approaches: Anatomical Aspects of a Microneurosurgical Approach

All subtemporal approaches have in common the risk of temporal lobe damage. To reduce the retraction of the temporal lobe we combine two synergistic modifications of temporal approaches to reach the prepontine space. The first is the temporary resection of the zygomatic arch which allows to bring the temporalis muscle more caudally and subsequently allows an anterior subtemporal approach with only minimal temporal lobe retraction. The second modification is the resection of the apex of the petrous bone after incision of the tentorium. This provides an excellent view into the posterior fossa between the trigeminal nerve medially, the internal carotid artery caudally and the internal auditory canal laterally. The anatomical aspects of a microneurosurgical approach regarding these modifications are reported and discussed.