Biomedical subjects

J M Gilsbach

Publications and source records attributed to J M Gilsbach.

At least 91 records · Page 5Linked to original sources

PubMed1999

Fibrinolytic treatment of intraventricular haemorrhage preceding surgical repair of ruptured aneurysms and arteriovenous malformations.

Previous studies have indicated that intraventricular administration of tissue-type plasminogen activator (TPA) might improve the prognosis of patients with intraventricular haemorrhage (IVH). In aneurysmal IVH, fibrinolytic treatment was always preceded by surgical repair of the aneurysm, since the risk of recurrent haemorrhage from a non-occluded aneurysm was estimated to be high. We reviewed a series of patients with IVH secondary to ruptured aneurysms (n = 4) or arteriovenous malformation (AVM; n = 1) who underwent emergency intraventricular administration of TPA before repair of the bleeding source. Fibrinolysis resulted in rapid decrease of haematoma volume and of ventricular dilatation, and prevented ventricular catheters from becoming obstructed. No intracranial haemorrhages or other complications occurred. The results suggest that the presence of recently ruptured aneurysms or AVM is not necessarily a contraindication for intraventricular administration of TPA. The potentially life saving benefits might outweigh the inherent risks of recurrent haemorrhage in carefully selected patients with massive IVH, in whom ventricular distension, periventricular brain compression, obstruction of CSF flow, and elevated ICP appear to be major determinants for the outcome.

Adult↗

PubMed1999

Biomechanical modeling of the human head for physically based, nonrigid image registration.

The accuracy of image-guided neurosurgery generally suffers from brain deformations due to intraoperative changes. These deformations cause significant changes of the anatomical geometry (organ shape and spatial interorgan relations), thus making intraoperative navigation based on preoperative images error prone. In order to improve the navigation accuracy, we developed a biomechanical model of the human head based on the finite element method, which can be employed for the correction of preoperative images to cope with the deformations occurring during surgical interventions. At the current stage of development, the two-dimensional (2-D) implementation of the model comprises two different materials, though the theory holds for the three-dimensional (3-D) case and is capable of dealing with an arbitrary number of different materials. For the correction of a preoperative image, a set of homologous landmarks must be specified which determine correspondences. These correspondences can be easily integrated into the model and are maintained throughout the computation of the deformation of the preoperative image. The necessary material parameter values have been determined through a comprehensive literature study. Our approach has been tested for the case of synthetic images and yields physically plausible deformation results. Additionally, we carried out registration experiments with a preoperative MR image of the human head and a corresponding postoperative image simulating an intraoperative image. We found that our approach yields good prediction results, even in the case when correspondences are given in a relatively small area of the image only.

Biomechanical Phenomena↗

PubMed1999

Primary intradural pontocerebellar chordoma metastasizing in the subarachnoid spinal canal.

Chordomas that are entirely extraosseous and intradural are rare. Additionally subarachnoid spinal implantation from such a cranial, intradural chordoma has never been reported before. The authors present a case of a widespread primary intradural chordoma in the basal cisterns of a 48-year-old woman which shows seeding of neoplastic cells to the spinal leptomeninges. It is concluded that also in cases of intradural and intracranial chordomas a tumor staging should include the search for spinal subarachnoid metastases.

Biopsy↗

PubMed1998

Intraoperative localization of functional regions in the sensorimotor cortex by neuronavigation and cortical mapping.

Surgery of lesions within the central region requires exact intraoperative anatomical orientation and knowledge of the position of functional cortical regions to minimize the surgical trauma and to avoid postoperative neurological deficits. We combined somatosensory evoked potential (SSEP) phase reversal and/or cortical electrical stimulation with neuronavigation in 26 patients for localization and visualization of functional cortical areas and their anatomical site in relation to the lesion. After location of the central sulcus by means of SSEP phase reversal, the precentral gyrus was electrically stimulated to detect functional motor regions. Electrode position was documented, and the functional regions were related to the site of the lesion using a specially developed neuronavigation system. In 11 of 15 patients the central fissure was located with SSEP phase reversal. Electrical stimulation yielded motor evoked potentials in 23 of the total 26 patients. The anatomical site of these functional regions and their relation to the lesion were evaluated with the neuronavigation system. The precentral gyrus, central sulcus, and postcentral gyrus could be identified in all 23 cases. The combination of intraoperative electrophysiological mapping and neuronavigation provides safe and reliable localization of the sensorimotor cortex. This technique is a promising tool to minimize the risk of surgically caused sensory and motor deficits.

Adult↗

PubMed1998

Functional magnetic resonance mapping of sensory motor cortex for image-guided neurosurgical intervention.

PURPOSE: This paper describes the potentials of functional magnetic resonance imaging (fMRI) to map sensory motor cortex in patients with mass lesions near primary motor cortex and to guide neurosurgical procedures located close to eloquent brain regions. MATERIAL AND METHODS: 7 patients with mass lesions near the central sulcus and 10 healthy volunteers were studied using a blood oxygenation level dependent 2D multislice multishot T2* weighted gradient echo EPI sequence on a 1.5T Phillips Gyroscan during alternating epochs of rest and motor activation of hand, foot and tongue. Sites of neuronal activation were identified by statistical analysis of the signal time course using Kolmogorov Smirnov statistics. RESULTS: Neuronal activation following motor tasks consistently localised to the contralateral precentral gyrus and the supplementary motor area, even in the presence of local brain pathology. Additionally we could observe activation in primary sensory areas (post-central gyrus) and supplementary motor area (SMA) in some cases. CONCLUSION: fMRI is capable of mapping sensory motor cortex even in the presence of distorting brain lesions. Since this information will provide valuable information to the neurosurgeon during pre-operative planning, we consider this method for neurosurgical navigation a valuable tool in the routine diagnostic of intracerebral interventions.

Adult↗

PubMed1998

Four-year experience with the routine use of the programmable Hakim valve in the management of children with hydrocephalus.

OBJECTIVE: Cerebrospinal fluid (CSF) over- and underdrainage symptoms are frequent sequelae of shunt placement in patients with hydrocephalus, sometimes requiring repeated operations. To achieve more adequate CSF drainage, the non-invasively programmable Hakim valve has been developed. Because the clinical experiences with this valve so far are confined to adults, we describe our experiences with the routine use of the programmable Hakim valve in childhood hydrocephalus. METHOD: Sixty children (mean age of 3.4 years) with hydrocephalus of various aetiologies have been shunted with the programmable Hakim valve. In the majority of cases, initial opening pressures of between 100 and 120 mm H2O were selected. The mean follow-up period was 2.1 years. RESULTS: Thirty-three readjustment of the pressure setting of the valve were performed in 20 children because of CSF overdrainage (low intracranial pressure syndrome n = 13, slit ventricle syndrome n = 2, hygroma n = 1), CSF underdrainage (n = 3) and CSF leakage through the operation wound (n = 1). The symptoms of inadequate CSF drainage were cured in 18 of the 20 children. The necessity for valve readjustments was independent of the aetiology of the hydrocephalus. Thirty-one complications requiring repeated operation occurred during the follow-up period, accounting for an annual complication rate of 24.6%. Three complications were valve-related. CONCLUSION: In the majority of cases, the programmable Hakim valve allows the successful management of symptoms related to CSF over- and underdrainage by non-invasive change of the initial pressure setting of the valve. Therefore, the programmable Hakim valve should be considered as an alternative to non-programmable valves of advanced design.

Adolescent↗

PubMed1998

Endovascular coil embolization of microsurgically produced experimental bifurcation aneurysms in rabbits.

BACKGROUND: Endovascular treatment of cerebral aneurysms is a relatively new method, since only a few animal models and data are available. The present experimental study was performed in order to establish an appropriate aneurysm animal model, to determine the rate of permanent occlusion, and to correlate radiologic and morphologic findings. METHODS: End-to-side anastomoses of both common carotid arteries were performed microsurgically in 53 chinchilla rabbits. Venous pouches were adapted into the newly created bifurcation, resulting in berry-shaped aneurysms comparable to those in humans with regard to size and hemodynamics. Platinum and tungsten coils were used for endovascular embolization. The embolized aneurysms were investigated radiologically and morphologically. RESULTS: Twenty-three carotid bifurcation aneurysms remained for testing endovascular therapeutic approaches. The morphologic examinations of 13 embolized aneurysms revealed in no instance a complete obliteration, even in the three cases that were considered completely embolized according to angiographic criteria. CONCLUSIONS: The present animal model is an optimal tool for endovascular research. Analysis of the results of coil obliteration revealed a considerable discrepancy between radiologic and pathologic findings. The radiologic degree of aneurysm occlusion was overestimated.

Animals↗

PubMed1998

The supracondylar approach to the jugular tubercle and hypoglossal canal.

BACKGROUND: Circumscribed lesions of the hypoglossal canal and of the jugular tubercle still remain a surgical challenge. So far, transpetrosal, transcondylar suboccipital, and extreme lateral approaches have been used to access this region. These surgical procedures bear a high risk for neurological deficits. Therefore, we introduce a new minimally invasive extradural approach to the hypoglossal canal that also allows access to the lateral aspects of the jugular tubercle. METHODS: After a paramedian retromastoid skin incision, a basal suboccipital craniectomy lateral to the foramen magnum toward the jugular tubercle is performed. With this approach the occipital condyle and the lateral osseous circumference of the foramen magnum are preserved. Drilling extradurally, the dorsal parts of the jugular tubercle are removed. The exposure is extended downward to the posterior margins of the hypoglossal canal and laterally to the jugular bulb, enabling a minimally invasive exposure of the hypoglossal canal, the lateral aspects of the jugular tubercle, and medial aspects of the jugular bulb. RESULTS: Using this supracondylar approach, surgical interventions were performed in three patients suffering from a hypoglossal neurinoma, a cholesterol granuloma extending into the jugular tubercle, and a cyst of the hypoglossal canal, respectively. No additional postoperative neurological deficits were seen. CONCLUSIONS: The supracondylar approach seems to be useful to gain access to benign lesions of the hypoglossal canal and of the jugular tubercle to decompress tumors or cysts. In contrast to previously reported techniques this approach has a low risk of morbidity. The surgical field, however, is restricted laterally by the jugular bulb, medially and basally by the residual occipital condyle and dorsally by the dura. Therefore, this approach is useful to remove small lesions or to perform extended biopsies. Radical removal of large tumors seems to be problematic using this approach.

Adult↗

PubMed1998

Minimally invasive bedside craniotomy using a self-controlling pre-adjustable mechanical twist drill trephine.

BACKGROUND: Craniotomy with a mechanical twist drill is a standard, minimally invasive procedure in neurosurgery, widely used for the drainage of chronic subdural hematomas and the placement of ventricular drains. Nevertheless, the use of a standard twist drill trephine bears the risk of causing cerebral lesions. METHOD: A commercially available mechanical twist drill system has been modified by a special self-controlling drill and a pre-adjustable distance holder that limits intracerebral penetration. After initial cadaver testing, the modified trephine has been used for 65 trephinations in patients (37 chronic subdural hematomas, 21 external ventricular drains, 6 frontal hygromas, 1 tumor cyst). RESULTS: There were no complications related to the modified trephine; cerebral lesions caused by drilling too deeply or by uncontrolled penetration were safely prevented. In our series no procedure related infections occurred, and the drilling time was reduced significantly. CONCLUSION: The described modified mechanical twist drill enables fast, easy, and safe craniotomy without jeopardizing the advantages of a mechanical twist drill. Therefore, it can be recommended particularly for difficult emergency conditions.

Brain Injuries↗

PubMed1998

Experience with a new multifunctional articulated instrument holder in minimally invasive navigated neurosurgery.

A new multifunctional articulated instrument holder for use in minimally invasive navigated neurosurgery is presented. The instrument holder is secured to the Mayfield clamp, yielding permanent fixation and guidance of instruments. Thus, surgical conditions with the advantages of both conventional and frameless stereotaxic neurosurgery are created without sacrificing the relevant advantages of both methods. Accuracy testing of the instrument holder in combination with the neuronavigation system EasyGuide Neuro demonstrated an error of 0.0 to 2.4 (mean 1.6) mm. In clinical testing, the device has been used for guided catheter insertions, pointer fixation for continuous intraoperative guidance and trajectory planning, navigated endoscopic procedures, and navigated intracerebral biopsies in totally 53 patients.

Equipment Design↗

PubMed1998

The combined use of image-guided frameless stereotaxy and neuroendoscopy for the surgical management of occlusive hydrocephalus and intracranial cysts.

The objective of the study was to report the initial experiences with the combined use of an infrared-based frameless stereotactic navigation device and neuroendoscopy. Ten hydrocephalic patients underwent endoscopic third ventriculostomy and two patients with intracranial cysts underwent cystoventriculostomy. The trajectory of the rigid endoscope and target point were planned by frameless stereotaxy. An articulated arm served to maintain the predetermined trajectory during the surgery and to guide the endoscope. Endoscopic surgery was successfully performed in 11 of the 12 patients. In one patient with a small third ventricle the ventriculostomy had to be abandoned. We observed no surgical morbidity. In none of the cases was it necessary to correct the predetermined trajectory of the endoscope to reach the planned target area. The planning of the trajectory and the target area, as well as the maintenance of the trajectory during endoscopy reduce the risk of inadvertent damage to vital structures. The combined use of frameless stereotaxy and neuroendoscopy might contribute to a decrease of procedure-related morbidity.

Adolescent↗

PubMed1998

Cognitive deficits in the acute stage after subarachnoid hemorrhage.

OBJECTIVE: In spite of fundamentally improved medical management of subarachnoid hemorrhage (SAH), many patients remain mentally impaired. However, the causes of these disturbances are unclear. The present study was performed to elucidate the significance of the hemorrhage itself and related events in the neuropsychological performance of patients in the acute stage after SAH. METHODS: A series of 51 patients were examined, by means of a battery of cognitive tests, 1 to 13 days (mean, 5.9 d) after SAH. Thirty-three patients had experienced ruptured aneurysms, and 18 had sustained SAH of unknown origin. Furthermore, 25 patients who had undergone surgical treatment (a mean of 5.0 d earlier) of prolapsed lumbar discs served as a control group. RESULTS: The cognitive deficits of the patients after aneurysmal SAH proved to be comparable to those after spontaneous SAH of unknown origin, with the single exception of a significantly worse (P = 0.003) concentration capacity in the surgically treated group. The severity of SAH in computed tomographic scans correlated (up to r = 0.57, P < 0.001) with poor performance on tests of memory, concentration, divided attention, and perseveration. Frontal intracerebral hemorrhage led to significantly more errors in an aphasia screening test (P < 0.001) and a test of perseveration (P < 0.001). If acute hydrocephalus was present, the patients exhibited worse long-term memory (P < 0.001), showed slower reaction times (P = 0.01), and made more errors in the perseveration test (P = 0.004). Patients with intraventricular blood performed at significantly lower levels in the concentration (P = 0.001), divided attention (P = 0.01), long-term memory (P < 0.001), and perseveration (P = 0.003) tests. CONCLUSION: The results emphasize that the severity of SAH (Fisher score) is the most important factor related to cognitive dysfunction, but frontal hematoma, intraventricular hemorrhage, and acute hydrocephalus were also associated with cognitive deficits, compared with patients with SAH without these findings.

Adult↗

PubMed1998

Treatment strategies and results in spinal vascular malformations.

We report the treatment strategies and results of 70 patients with spinal vascular malformations. Forty-six had dural arteriovenous fistulas, 12 spinal cavernous angiomas, nine intramedullary angiomas, and three intradural arteriovenous fistulas. The diagnosis was established for cavernomas by magnetic resonance images only and in the other cases by selective spinal angiography in patients whose neurological deficits, myelograms or magnetic resonance images suggested the presence of a spinal vascular malformation. All patients had symptomatic vascular malformations and were treated microsurgically. Intramedullary angiomas were operated when embolization seemed too dangerous or impossible and when they had a contact to the dorsal or lateral surface of the spinal cord. All but one were completely resected. In one angioma a small ventral residual fistula area was left. Complete obliteration of all fistulas was achieved. The cavernomas were primarily resected. Apart from one postoperative permanent deterioration with a paresis of the left arm in a patient with an intramedullary angioma, 16 cases presented only a transitory worsening of their neurological status after surgery. The long-term outcome of all these patients was good. Five patients had to be operated on again: three patients showed difficult localizations of dural fistulas which were still visible in the postoperative angiograms, one patient suffered a spinal epidural hematoma, and another patient showed a cerebrospinal fluid accumulation. We conclude that spinal dural arteriovenous fistulas, small intradural fistulas, spinal cavernomas, and symptomatic spinal angiomas with contact to the lateral or dorsal surface can be treated microsurgically with low perioperative morbidity.

Adult↗

PubMed1998

Management of aneurysms of the vertebral artery-posterior inferior cerebellar artery complex.

Aneurysms of the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) account for only about 3% of all diagnosed intracranial aneurysms. The surgical therapy of these aneurysms is complex and difficult due to the close topographical relationship between the neurovascular structures. Here, we report upon 27 patients with 29 such aneurysms. Of these, 22 patients (81%) were hospitalized because of a subarachnoid hemorrhage. Sixteen of these patients (72%) had an additional intraventricular hemorrhage. Twenty-one patients (78%) were surgically treated for their aneurysms, three of them also for an associated arteriovenous malformation. Aneurysms of the VA and the proximal PICA were exposed via a transcondylar (n = 11) or lateral suboccipital (n = 3) approach, those originating from the distal PICA via a paramedian suboccipital (n = 7) route. Endovascular therapy was used in three patients. A patient with a fusiform aneurysm of the vertebrobasilar junction was treated with a ventriculoperitoneal shunt only. Three aneurysms with a complex morphology were not treated. Of the patients operated upon, two died postoperatively due to vasospasm. Two other patients developed an incomplete dorsolateral medullary syndrome. One individual was lost for follow-up. The median follow-up period was 4.6 years (range 3-86 months). Both, the overall mortality (2/27) and morbidity (2/27) were 7.5%, respectively. Our results show that even complex vascular lesions of the posterior fossa can be treated with a satisfactory long-term outcome in the majority of our patients (85%). The multimodal management and an individually tailored microsurgical approach are key issues for the treatment of such aneurysms.

Adult↗

PubMed1997

Criteria to find qualified candidates--professional personnel recruitment methods adapted to neurosurgery.

A neurosurgeon has not received any special training in personnel recruitment at the time he becomes chief of a department. Consequently, a suboptimal personnel policy is most probable. Due to the rapid changes in social behaviour and style of leadership in postwar Europe, he might be ill advised to follow only the example of his successful predecessors, apart from the fact, that this would only be possible if the personalities (of the former and new chief) were similar. To save time and energy for optimal patient care, personnel recruitment can be improved and made more reproducible and reliable by adopting modern, professional non-medical principles. A typical stepwise process of personnel recruitment includes an analysis of the position and function, the definition of demands and offers, the choice of advertising and searching methods, the analysis of the application documents, the interview with the candidate including its re-evaluation and the ongoing evaluation process during the training. This election process is not only conducted by the chief of a department, but also by senior staff-members and even young, competing assistants. It aims to find the candidate who fits best in the requirements, who will be trained and educated with the least effort and who has the best potential to succeed in the long run. The only factors seemingly predicting a good development of a candidate are personality, energy (potential, motivation) and intelligence. Therefore, the search should especially aim to discover these-admittedly difficult to detect-qualities.

Achievement↗

PubMed1997

Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part I: Anatomical and surgical considerations.

A unilateral laminotomy for bilateral access to the lumbar spinal canal was investigated in human cadaver spine specimens to test its practicability in the treatment of spinal stenosis. Micro-surgical decompression was performed by partial resection of the ipsilateral facet, the medial portion of the laminar arch, the contralateral facet and by complete removal of the ligamentum flavum. Anatomical, radiological and morphometrical studies on 4 adult cadaver spine specimens have proved the feasibility of this unilateral approach. Complete bilateral flavectomy and partial bilateral facetectomy were the essential surgical steps for an adequate operative decompression.

Adult↗

PubMed1997

Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part II: Clinical experiences.

The surgical aim in the treatment of symptomatic lumbar spinal stenosis is the relief of the patient's complaints by an adequate neural decompression. Unilateral laminotomy and bilateral spinal canal decompression represents such a safe, effective and minimally invasive surgical method. This technique has been successfully used in the operative treatment of 29 patients with symptomatic mono- or multisegmental lumbar stenosis. There was no surgically induced neurological deterioration. In one patient, an inadvertent dural tear occurred, and due to unchanged symptoms another patient with a multisegmental stenosis had to be re-operated on at an additional level. Postoperatively, 25 of the 27 patients with neurogenic claudication (93%) demonstrated a marked improvement of the walking distance. The follow-up of 25 patients (mean follow-up time was 18 months) demonstrated an excellent result without pain in 7 patients (28%); a good outcome with mild residual pain, but a normal working capacity in 15 patients (60%); and a fair outcome with unchanged postoperative low-back pain but markedly improved working capacity and walking distance in 3 patients (12%). Postoperative morphometric evaluation as well as the clinical improvement of the patient's symptoms clearly demonstrated that bilateral ligamentectomy and recess decompression were adequately and successfully achieved via unilateral approach.

Adult↗

PubMed1997

Cytogenetic analysis of gliomas by in situ hybridization of stereotactic biopsy material.

Chromosome analysis of brain tumours can provide important pathobiological data; however, cytogenetic tools are so far not routinely applied for diagnosis. In the present study 25 paraffin embedded stereotactic biopsies from 19 glioma patients were studied using in situ hybridization of chromosome #10 and #15 using biotinylated pericentromeric probes. Numerical changes of chromosome #10 are frequent alterations in glioblastoma. Quantification of chromosome #15 served as a control in order to exclude artificial monosomies or nonspecific changes. The number of chromosomes in at least 200 cells were counted for each specimen. 18 of 25 biopsies could be evaluated quantitatively. The small volume of probes was not a limiting factor for analysis. Quantification of "nonspecific" chromosome #15 revealed single spots in 22-41% of all cells in the 18 biopsies. Chromosome #10 showed single spots in a range between 34 and 44% of counted nuclei in 13/18 biopsies. In 5 out of 18 biopsies 51-60% monosomies were found: in this subgroup were 4 high grade gliomas. These cases were interpreted as monosomy of chromosome #10. The results demonstrate feasibility and quantitative evaluability of cytogenetic analysis in stereotactic biopsy material using in situ hybridization.

Adolescent↗