Walter Saringer

A clinical study of a fibrinogen-based collagen fleece for dural repair in neurosurgery.

Summary.Summary. Background: There is frequently a need for dural grafts to cover defects resulting from retraction, shrinkage, or excision following neurosurgical procedures. Many substances have been tried as possible dural substitution, and different tissues and materials have been evaluated for use in dural repair. Method: The authors performed a retrospective review of 288 consecutive neurosurgical procedures using a fibrinogen based collagen fleece (TachoComb®), a resorbable mesh of collagen from horse tendons, coated with human fibrinogen, bovine thrombin, bovine aprotinin and riboflavin (for marking the coated side), for dural substitution. The fibrinogen and thrombin imitate the last step of the coagulation cascade. On contact with bleeding wounds or other body fluids the coagulation factors dissolve and a link is formed between the collagen carrier and the wound surface. Thrombin converts fibrinogen into fibrin by splitting off peptides. Aprotinin prevents premature lysis of the fibrin clot by plasmin. Findings: Neither superficial or deep wound infections nor aseptic meningitis were noted. We found good fibrous incorporation of TachoComb® into the surrounding normal dura. Postoperative cerebrospinal-fluid (CSF) leaks developed in only five cases, who had to be re-operated, upon as well as one patient with a rebleeding. In another four cases, there was notable subcutaneous cerebrospinal-fluid accumulation without CSF-leak. They required a lumbar cerebrospinal-fluid drainage. Interpretation: We conclude that TachoComb® is a valuable alternative to the patients fibrous tissues for dural repair in cases in which autogenous tissues are either unavailable or insufficient for proper reconstruction.

Gamma-Knife Radiosurgery for Brain Metastases of Renal Cell Carcinoma: Results in 23 Patients

Summary From Jan. 1993 to Sept. 1995 23 patients suffering from brain metastases from renal cell carcinoma were treated with the Leksell Gamma Knife at the University of Vienna. At the time of diagnosis 13 patients had single and 10 patients presented with multiple metastatic lesions with a total of 44 metastases in MRI scans. Median tumour volume was 5500 cmm (range 100–24000 cmm). Predominant neurological symptoms and signs were different forms of hemiparesis, focal and generalized seizures, cognitive deficit, headache, dizziness, ataxia and CN XII paresis. Fourteen patients received Gamma Knife Radiosurgery (GKRS) with a median dose of 22 Gy (range 8–30 Gy) at the tumour margin. Nine patients underwent a combined treatment of a radiosurgical boost with a median dose of 18 Gy (range 10–22 Gy) at the tumour margin followed by Whole Brain Radiotherapy (total dose 30 Gy/2 weeks). In 20 patients tumour volume reduction up to 30% of the primary tumour volume was found after 4 weeks, evaluated on CT or MRI. A total remission was seen in 4 cases 3 months after GKRS. We achieved a local tumour control of 96%. Rapid neurological improvement after GKRS was seen in 17 patients. The median survival time was 11 months; the one-year actual survival in this unselected group was 48%. Five long term survivors were still alive, 18 patients had subsequently died, 15 of them of general tumour progression. GKRS induces a significant tumour remission accompanied by rapid neurological improvement and therefore provides the opportunity for extended high quality survival. Neither local tumour control was improved nor CNS relapse free survival was prolonged significantly by additional WBRT.

Cranioplasty with individual carbon fibre reinforced polymere (CFRP) medical grade implants based on CAD/CAM technique.

Summary. Background: The authors present a new method for the reconstruction of large or complex-formed cranial bone defects using prefabricated, computer-generated, individual CFRP (carbon fibre reinforced plastics) medical grade implants. Method: CFRP is a composite material containing carbon fibres embedded in an epoxy resin matrix. It is radiolucent, heat-resistant, extremely strong and light (its weight is 20% that of steel), has a modulus of elasticity close to that of bone, and an established biocompatibility. The utilisation of a CAD/CAM (computer aided design/computer aided manufacture) technique based on digitised computed tomography (CT) data, with stereolithographic modelling as intermediate step, enabled the production of individual, prefabricated CFRP medical grade implants with an arithmetical maximum aberration in extension of less than ±0.25 mm. Between 1995 and February 2002, 29 patients (15 men and 14 women; mean age, 39.9 years; range, 16 to 67 years) underwent cranioplasty with CFRP medical grade implants at the neurosurgical department of the University of Vienna. Twenty-four patients were repaired secondarily (delayed cranioplasty) while 5 were repaired immediately following craniectomy (single stage cranioplasty). All cases were assessed for the accuracy of the intra-operative fit of the implant, restoration of the natural skull contour and aesthetics and adverse symptoms. Findings: The intra-operative fit was excellent in 93.1% and good in 6.9% of the implants. In two cases minor adjustments of the bony margin of the defect were required. The operating time for insertion ranged from 16 to 38 minutes, median 21 minutes. Postoperatively, 86.2% of the patients graded the restoration of their natural skull shape and symmetry as excellent while 13.8% termed it good. In one patient a non-space occupying subdural hygroma was found at the follow-up, but required no intervention. Two patients experienced atrophy of the frontal portion of the temporal muscle while one patient had a transient palsy of the frontal branch of the facial nerve. Over the mean follow-up period of 3.3 years (range, 0.08 to 6.8 years), there were no adverse reactions and no plate had to be removed. Interpretation: Individual, prefabricated CFRP medical grade implants may be considered as an alternative to conventionally utilised materials for cranioplasty, in particular in the challenging group of patients with extensive cranial defects or more complex-formed defects of the fronto-orbital or temporo-zygomatic region, guaranteeing short operating times and excellent functional and aesthetic results, which justifies the expense of their production.

Microsurgical anterior cervical foraminotomy (uncoforaminotomy) for unilateral radiculopathy: clinical results of a new technique.

Summary.Summary. Background: The authors report the clinical application of a new microsurgical technique. The cervical anterior foraminotomy (uncoforaminotomy), which is used for the surgical treatment of unilateral cervical radiculopathy secondary to posterolateral disc herniations or spondylotic foraminal stenoses. Method: Between June 2000 and May 2001, 34 patients (16 men and 18 women with a mean age of 43.8 years, range 29 to 80 years) underwent anterior cervical foraminotomy (uncoforaminotomy) for the treatment of cervical radiculopathy at one or two adjacent levels in the Neurosurgical Department of the University of Vienna. This surgical technique was devised to accomplish direct anterior decompression of the affected nerve root by removing an offending posterolateral sponylotic spur or disc fragment. The nerve root is decompressed from its origin in the spinal cord to the point were it passes behind the vertebral artery laterally. The intervertebral disc of the affected level is maintained in its form and function. Thus, the functioning motion segment is preserved and fusion related sequelae, including graft related complications, graft site complications and the adjacent level disease, are avoided. Prior to its clinical application, anatomical features of the anterior cervical spine were reviewed, and an anatomical morphometric analysis and work-up of the technique was performed in 4 cervical specimens. Findings: The follow-up period varied from two to 17 months with a mean of 8.2 months. The large majority (97%) of patients were pleased with the results of their operation. The relief of neck pain and redicular pain in the affected dermatome was immediate in all patients. Motor-weakness and sensory deficit improved dramatically immediately postoperatively, and improved to normalisation in the majority of patients within 3 to 6 months. Two of the patients sustained an incomplete transient recurrent laryngeal nerve palsy, which fully resolved within two to 4 weeks. One of the patients had a repeat herniation on the second postoperative day, but recovered completely after re-operation and continued to do well at the 6-month follow-up. No permanent surgery related morbidity or associated complications were encountered. Interpretation: The results indicate that this new microsurgical technique is an attractive treatment option for adequate anterior decompression of the cervical nerve root via a minimized approach. It was associated with excellent clinical outcome and a less painful postoperative course, allowing patients an almost immediate return to unrestricted full activity.

Extraforaminal, Thoracic, Epidural Cavernous Haemangioma: Case Report with Analysis of Magnetic Resonance Imaging Characteristics and Review of the Literature

Summary.Background: A case of a solitary, thoracic, extradural, extraforaminal cavernous haemangioma causing a chronic neuralgia syndrome is presented. In the spectrum of spinal axis cavernous malformations, extradural lesions are exceedingly rare. A purely extraforaminal, paraspinal cavernous haemangioma has never been previously reported. Method: A 56-year-old woman suffered from a chronic neuralgia syndrome at the right D3 dermatome. Conservative treatment was ineffective. MRI revealed an extraforaminal mass at T3–4 which homogeneously enhanced after Gadolinium administration mimicking a schwannoma. The lesion was completely removed via an extraforaminal approach. Findings: Histopathological investigation revealed a cavernous haemangioma. The patient recovered completely within 4 weeks after surgery. Interpretation: Cavernous haemangiomas are developmental vascular hamartomas representing a single entity regardless of their location. As purely epidural lesions are rare, their clinical and radiological presentation could be confusing if located foraminally or extraforaminally. Thus, their signal characteristics providing valuable information will facilitate diagnosis and treatment.

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.

Susceptibility-weighted imaging at 7 T: Improved diagnosis of cerebral cavernous malformations and associated developmental venous anomalies

Background and aim In the diagnosis of cerebral cavernous malformations (CCMs) magnetic resonance imaging is established as the gold standard. Conventional MRI techniques have their drawbacks in the diagnosis of CCMs and associated venous malformations (DVAs). The aim of our study was to evaluate susceptibility weighted imaging SWI for the detection of CCM and associated DVAs at 7 T in comparison with 3 T. Patients and methods 24 patients (14 female, 10 male; median age: 38.3 y (21.1 y–69.1 y) were included in the study. Patients enrolled in the study received a 3 T and a 7 T MRI on the same day. The following sequences were applied on both field strengths: a T1 weighted 3D GRE sequence (MP-RAGE) and a SWI sequence. After obtaining the study MRIs, eleven patients underwent surgery and 13 patients were followed conservatively or were treated radio-surgically. Results Patients initially presented with haemorrhage (n = 4, 16.7%), seizures (n = 2, 8.3%) or other neurology (n = 18, 75.0%). For surgical resected lesions histopathological findings verified the diagnosis of CCMs. A significantly higher number of CCMs was diagnosed at 7 T SWI sequences compared with 3 T SWI (p < 0.05). Additionally diagnosed lesions on 7 T MRI were significantly smaller compared to the initial lesions on 3 T MRIs (p < 0.001). Further, more associated DVAs were diagnosed at 7 T MRI compared to 3 T MRI. Conclusion SWI sequences at ultra-high-field MRI improve the diagnosis of CCMs and associated DVAs and therefore add important pre-operative information.

Watertightness and Effectiveness of a Fibrinogen-Based Collagen Fleece (TachoComb®) in Neurosurgery

SummaryBACKGROUND: Meningitis or cerebrospinal fluid rhinorrhoea can occur years or even decades after trauma or operation and can be the first indication of a previously unidentified dural lesion. Preventing cerebrospinal fluid (CSF) leakage with a fibrinogen-based collagen fleece (TachoComb®) was the interest of our clinical study. METHODS: In the present study, we examined the watertightness and effectiveness of TachoComb® following supratentorial/infratentorial as well as skull-base operations. The dura was closed primarily by sutures and covered with a fibrinogen-based collagen fleece to prevent CSF leakage. RESULTS: Twelve patients developed a subcutaneous CSF collection requiring no further treatment, seven patients were managed by lumbar CSF drainages, and three patients had to be reoperated. CONCLUSIONS: Based on these results, we proved the watertightness and effectiveness of this fibrinogen-based collagen fleece.ZusammenfassungGRUNDLAGEN: Eine Meningitis oder eine Liquorfistel kann Jahre bis Jahrzehnte nach einem Trauma oder einer neurochirurgischen Operation erstmalig auftreten. Als Prophylaxe gegen eine Liquorfistel haben wir ein resorbierbares Kollagenvlies, das mit Bestandteilen eines Fibrinklebers beschichtet ist (TachoComb®), klinisch getestet. METHODIK: In unserer vorliegenden Studie haben wir die Wasserdichtheit von TachoComb® in 421 Fällen getestet. Die primär vernähte Dura mater wurde mit einem beschichteten Kollagenvlies bedeckt, ebenso die Schädelbasis nach Schädelbasisoperationen. ERGEBNISSE: 12 Patienten entwickelten ein subcutanes Liquorkissen, welches keiner weiteren Therapie bedurfte. In 7 Fällen wurden die Patienten mit einer Lumbaldrainage behandelt und in 3 Fällen mußte reoperiert werden, um den Defekt zu decken. SCHLUSSFOLGERUNGEN: Basierend auf diesen Ergebnissen können wir die Verwendung von TachoComb® zum Erreichen eines wasserdichten Duraverschlusses empfehlen.

Microsurgical anterior decompression and internal fixation with Iliac bone graft and titanium plates for treatment of cervical intervertebral disc herniation

Summary42 cervical interbody fusions with iliac bone graft and titanium plate fixation were performed between October 1991 and March 1994. The mean follow up period in this study was 10.7 months. In 32 cases fusion was done for 1 and in 10 cases for 2 segments. 2 different types of plates were used. In 25 cases micro-osteosynthesis plates and screws with 2.7 mm diameter were used, and in 17 cases cervical H-plates and screws with 3.5mm diameter. A favourable outcome was achieved in 31 of 42 cases (74%). Satisfactory pain relief was achieved in 90%. For radicular motor deficit good results were obtained in 84% and for cervical myelopathy in 54%. The 2 different types of plates showed a remarkable difference in the clinical outcome. The results were regarded favourable in 15 of 25 microplate fusions (60%) and in 16 of 17 H-plate fusions (94%). Compression of the bone graft was seen in 5 patients of the micro plate group, however, radiological signs for fusion were present in all 42 cases at follow up. Major surgical complications, damage to neural structures or neurological deterioration did not occur in this study. Plate fixation in cervical interbody fusions seems to be a safe procedure and may reduce graft related complications at the fusion site if the plates and screws are sufficiently well proportioned. A favourable impact upon the results for cervical interbody fusion might be expected and should be further investigated in a long term follow up study.

Localization and System Integration Tests as Quality Assurance for the Leksell γ-Unit

Quality control in stereotactic radiotherapy of brain lesions with the Leksell γ-unit or the LINAC-facility is a must, as missing the target is the most serious error that can occur in that kind of treatment. We developed a quality assurance program to reduce this risk. To evaluate the accuracy of the procedure, which defines the target, including all possible errors of the therapy chain, irradiations of phantoms were performed, using the so-called “known” and “unknown” target method. Accuracy is defined by the deviation of the irradiated target from the calculated target with digital images used for therapy planning. GafChromic MD-55 films, which have been irradiated by means of a special author-developed phantom, were applied for measuring the precision of the radiation unit. The results obtained for isocentric accuracy of the Leksell γ-unit were in good agreement with the measurements of the manufacturing company. The deviation measured with the 4-mm collimator helmet was up to 0.3 mm, including the CT images and the stereotactic frame less than 0.85 mm, respectively. The phantom designed for this purpose is useful in quality assurance measurements of this stereotactic therapy chain.