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Biomedical subjects

H J Steiger

Publications and source records attributed to H J Steiger.

At least 19 recordsLinked to original sources
PubMed2006

New angiographic measurement tool for analysis of small cerebral vessels: application to a subarachnoid haemorrhage model in the rat.

INTRODUCTION: Exact quantification of vasospasm by angiography is known to be difficult especially in small vessels. The purpose of the study was to develop a new method for computerized analysis of small arteries and to demonstrate feasibility on cerebral angiographies of rats acquired on a clinical angiography unit. METHODS: A new software tool analysing grey values and subtracting background noise was validated on a vessel model. It was tested in practice in animals with subarachnoid haemorrhage (SAH). A total of 28 rats were divided into four groups: SAH untreated, SAH treated with local calcium antagonist, SAH treated with placebo, and sham-operated. The diameters of segments of the internal carotid, caudal cerebral, middle cerebral, rostral cerebral and the stapedial arteries were measured and compared to direct measurements of the diameters on magnified images. RESULTS: There was a direct correlation between the cross-sectional area of vessels measured in a phantom and the measurements acquired using the new image analysis method. The spread of repeated measurements with the new software was small compared to the spread of direct measurements of vessel diameters on magnified images. Application of the measurement tool to experimental SAH in rats showed a statistically significant reduction of vasospasm in the SAH groups treated with nimodipine-releasing pellets in comparison to all the other groups combined. CONCLUSION: The presented computerized method for analysis of small intracranial vessels is a new method allowing precise relative measurements. Nimodipine-releasing subarachnoidal pellets reduce vasospasm, but further testing with larger numbers is necessary. The tool can be applied to human angiography without modification and offers the promise of substantial progress in the diagnosis of vasospasm after SAH.

Animals↗
PubMed2005

Cranial and spinal dural arteriovenous malformations and fistulas: an update.

Awareness of a potential arteriovenous fistula is critical for diagnosis of cranial as well as spinal fistulas. The natural history of cranial and spinal dural arteriovenous fistulas has been clarified during the last decade and interdisciplinary therapies have experienced a substantial development recently. The classification of Cognard & Merland is now the most widely accepted one for cranial dural AVF. It is based on the degree of flow reversal in the sinuses and cortical veins and reflects well the natural history of the different lesions and serves as basis for therapeutic indications. Several studies have defined the annual bleeding risk of cranial dural fistulas between 1.8 and 15%, depending on the pattern of venous drainage and initial symptomatology. Surgical, endovascular and radiosurgical methods must be selectively chosen for the treatment. The risk associated with surgical or endovascular treatment of benign fistulas is higher than the risk of eliminating fistulas that have already led to cortical venous reflux. Transvenous endovascular occlusion or surgical disconnection of draining veins is the treatment of first choice for cranial and spinal dAVF with venous flow reversal. Benign cranial dural arteriovenous fistulas are a developing indication for radiosurgery.

Arteriovenous Fistula↗
PubMed2004

Congested residual nidus after preoperative intranidal embolization in midsize cerebral arteriovenous malformations of 3-6 cm in diameter.

BACKGROUND: Modern delicate microcatheters allow intranidal embolization of cerebral arteriovenous malformations (AVM). The aim of the current analysis was to assess effects of preoperative intranidal deployment of embolic material on surgical time and blood loss in cerebral arteriovenous malformations of 3-6 cm in diameter. METHODS: The case records of 38 cerebral AVM between 3 and 6 cm in maximum diameter were reviewed, that had been embolized intranidally with N-butyl 2-cyanoacrylate (Histacryl) and subsequently operated on. Surgical time and blood loss as well as particular intraoperative findings such as a congested nidus and thrombosis of draining veins were registered and correlated with the extent of embolization and the time interval between embolization and surgery. FINDINGS: Preoperative embolization occluded an estimated range of 10 to 90% of the nidus. Minor embolization related bleeding without clinical relevance occurred in 5 patients. Significant embolization related bleeding resulting in earlier than planned surgery occurred in another 5 patients. All embolization related haemorrhages occurred within 24 hours. Average total operating time was 343+/-106 min and average blood loss was 684+/-858 ml. Unequivocal bleeding difficulty from the nidus and a total blood loss of more than 1000 ml were encountered in 7 instances and dissection was tedious due to a bleeding AVM core in 5 other cases. A congested AVM core was the source of bleeding in 11 patients and paraventricular neovascularization in one. 6 of the 11 cases with a congested AVM core had suffered minor or substantial haemorrhage after a preoperative endovascular procedure. Intraoperative nidus congestion was noted in this series after an interval as long as 2 weeks after the last embolization. Combined management resulted in permanent morbidity in 6 of the 38 cases. In 4 of them the neurological deficit was associated with an intraoperative bleeding problem, in all due to congested nidus. Morbidity had to be correlated with major haemorrhage resulting from preoperative embolization in 2 instances. CONCLUSIONS: Intranidal embolization prior to surgical removal of AVM can lead to a congested residual nidus and intraoperative bleeding. Minor leakage after preoperative embolization is an inconsistent warning sign of nidus congestion. Nidus outflow after intranidal embolization appears to require a few weeks for normalization. Delay of surgery after embolization should be considered in cases of suspected congested residual nidus. The danger of major haemorrhage or arterial revascularization during this waiting period appears small.

Blood Loss, Surgical↗
PubMed2004

Paraparesis due to pressure erosion of the thoracic spine by an aortic aneurysm: remission of symptoms following resection of the aneurysm and vertebral reconstruction.

BACKGROUND: There are only a few descriptions in the literature of thoraco-abdominal aortic aneurysms responsible for erosion of the vertebral column and compression of the spinal cord. This case is therefore presented to provide an opportunity to discuss the pathomechanic aspects and to demonstrate the feasibility of total surgical repair by an interdisciplinary approach. METHODS: A thoraco-abdominal aortic aneurysm caused extensive erosion of vertebral bodies T5-8, leading to invasion of the spinal canal and compression of the cord. The clinical signs were paraparesis and chronic thoracolumbar pain. In a combined operation the aneurysm was replaced by a Dacron prosthesis. Corpectomy of T5-8 was carried out and a titanium mesh cage filled with autogenous bone tissue was inserted. The vertebral column was stabilized using dorsal and lateral instrumentation. FINDINGS: Clinical and imaging follow-up after three years showed remission of the patient's severe paraparesis and chronic pain and long-term technical success of the vertebral and aortic reconstruction. INTERPRETATION: Complete thoraco-abdominal aortic replacement and spinal column repair can be successfully accomplished with good clinical and neurological long-term results.

Aortic Aneurysm, Abdominal↗
PubMed2004

Prospective documentation and analysis of the pre- and early clinical management in severe head injury in southern Bavaria at a population based level.

Treatment of patients suffering from severe head injury is so far restricted to general procedures, whereas specific pharmacological agents of neuroprotection including hypothermia have not been found to improve the outcome in clinical trials. Albeit effective, symptomatic measures of the preclinical rescue of patients (i.e. stabilization or reestablishment of the circulatory and respiratory system) or of the early clinical care (e.g. prompt diagnosis and treatment of an intracranial space occupying mass, maintenance of a competent circulatory and respiratory system, and others) by and large constitute the current treatment based on considerable organizational and logistical efforts. These and other components of the head injury treatment are certainly worthwhile of a systematic analysis as to their efficacy or remaining deficiencies, respectively. Deficits could be associated with delays of providing preclinical rescue procedures (e.g. until intubation of the patient or administration of fluid). Delays could also be associated in the hospital with the diagnostic establishment of intracranial lesions requiring prompt neurosurgical intervention. By support of the Federal Ministry of Education and Research and under the auspices of the Forschungsverbund Neurotraumatology, University of Munich, a prospective system analysis was carried out on major aspects of the pre- and early clinical management at a population based level in patients with traumatic brain injury. Documentation of pertinent data was made from August 1998 to July 1999 covering a catchment area of Southern Bavaria (5.6 mio inhabitants). Altogether 528 cases identified to suffer from severe head injury (GCS < or = 8 or deteriorating to that level within 48 hrs) were enrolled following admission to the hospital and establishment of the diagnosis. Further, patients dying on the scene or during transport to the hospital were also documented, particularly as to the frequency of severe head injury as underlying cause of mortality. The analysis included also cases with additional peripheral trauma (polytrauma). The efficacy of the logistics and organization of the management was studied by documentation of prognosis-relevant time intervals, as for example until arrival of the rescue squad at the scene of an accident, until intubation and administration of fluid, or upon hospital admission until establishment of the CT-diagnosis and commencement of surgery or transfer to the intensive care unit, respectively. The severity of cases studied in the present analysis is evident from a mortality of far above 40% of cases admitted to the hospital, which was increased by about 20% when including prehospital mortality. The outcome data notwithstanding, the emerging results demonstrate a high efficacy of the pre- and early clinical management, as indicated by a prompt arrival of the rescue squad at the scene, a competent prehospital and early clinical management and care, indicative of a low rate of avoidable complications. It is tentatively concluded on the basis of these findings that the patient prognosis is increasingly determined by the manifestations of primary brain damage vs. the development of secondary complications.

Craniocerebral Trauma↗
PubMed2004

Internal regulations and general guidelines of a neurosurgical department and training programme.

It is strongly recommended that general guidelines and internal regulations be laid down in written form by the department. The guidelines regulate the general workflow and related trainee duties and responsibilities, education and research, special procedures for particular diseases and conditions (standards of care). Regarding general workflow of the department, the following items should be laid down once in written form: time table of department, working hours, admission procedures, medical records directives, responsibilities on wards and in the emergency unit, patient information, discharge procedures, outpatient consultations, call schedule and on-call duty plan, as well as week-end and holiday regulations for rounds on wards and ICU. Regarding education and research, the following items should be written down: conferences and teaching rounds, policies on presentations and publications, policies regarding meetings and courses, research leave and vacation plan. The written definition of standards of care is still considered optional in neurosurgery at the present time.

Certification↗
PubMed2004

Principles of teaching in a structured training programme, the rotations, and the surgical training plan.

The present paper is divided into two parts. In the first part it summarises the essentials of transfer of knowledge and personality from trainer to trainee. The training capacity of a programme should be identified first since the number of residents in training has implications on the structure of the programme. The capacity is limited by the number of surgical "resident cases", which should at least amount to 70 per year and resident. For the future, more emphasis should be laid on the acquirement of methods of self-teaching and continuous self-education, in order to provide the trainees with the ability to cope with changes during their later career more easily. In part two the organisation of rotations as well as the structured surgical training plan are discussed. Teaching can be organised either as a gradual exposure to more and more complex procedures or as a sequence of speciality rotations. Structured teaching of theoretical contents should accompany practical teaching and in academic programmes a scientific rotation should be integrated. The ongoing subspecialisation is currently exceeding the limits of complete coverage during a six-year-programme.

Certification↗
PubMed2003

Molecular genetic investigations in the CCM1 gene in sporadic cerebral cavernomas.

OBJECTIVE: Cerebral cavernous malformations (CCM) occur in familial and sporadic forms that cannot be distinguished by phenotype. Mutations in Krit1, a gene located at the CCM1 locus on chromosome 7q21, account for the majority of familial CCM cases. The authors investigated the role that mutations at the CCM1 locus play in sporadic cavernomas and the prevalence of occult familial forms among symptomatic cavernomas. METHODS: The authors screened the DNA of cavernomas and adjacent normal brain tissue of 72 consecutive patients treated at the Neurosurgical Department/Ludwig-Maximilian University for mutations in Krit1. Eight of the patients had been suspected to have a mutation at CCM1, as they showed multiple cavernomas or clinically familial forms. RESULTS: None of the patients showed a mutation at the CCM1 site, either in cavernomas or in normal brain tissue. CONCLUSION: Mutations in Krit1 are seldom a cause of sporadic cavernomas.

Adolescent↗
PubMed2001

[Proper diagnosis and treatment of carotid stenoses. Recommending surgery, when is it too risky?].

A number of multicentric randomized studies have been able to demonstrate a benefit from surgery in high-grade asymptomatic and symptomatic carotid artery stenosis. The benefits of carotid artery endarterectomy are greater in symptomatic than in asymptomatic patients. This means that, in the case of the latter, the benefits and risks of surgery must be considered with special care. The gold standard of the preoperative diagnostic work-up is selective angiography. Since this examination modality is associated with a complication rate of > 1% in this group of patients, there is an increasing tendency to content oneself with such noninvasive procedures as duplex sonography used in combination with cranial and cervical MRI. The life expectancy of patients undergoing carotid artery end-arterectomy is determined mainly by their concomitant cardiac problems. Constant surveillance and optimal treatment of vascular risk factors is therefore essential in these patients.

Carotid Stenosis↗
PubMed2001

[Brain protective interstitial laser thermotherapy. Therapy of brain tumors without secondary damage].

The purpose of interstitial radiosurgery is to deliver a necrotizing dose of heat to an accurately defined focal area without damaging adjacent healthy brain tissue. To achieve this, heat at a temperature of 60-100 degrees C is applied via a laser fiber placed stereotactically in the center of the tumor. With the aid of thermosensitive magnetic resonance imaging (MRI), not only can the heat distribution within and around the tumor be measured during treatment, but also the extent of the lesion produced assessed. Interstitial laser thermotherapy (ILTT) performed under MRI monitoring, could become an important interdisciplinary minimally invasive treatment option for patients with brain tumors. Experimental data on the biological effects of interstitial laser therapy on normal brain tissue are not yet available, and only preliminary clinical studies investigating the effects of laser energy on brain tumors have so far been carried out. This overview presents a description of our own initial results, discusses the present state of our knowledge and current possibilities and limitations of this new treatment modality.

Brain↗
PubMed2001

Standards of neurosurgical procedures.

Written specifications with regard to procedures performed, equipment used, and training of the involved personnel are widely used in the industry and aviation to guarantee constant quality. Similar systems are progressively being introduced to medicine. We have made an effort to standardize surgical procedures by introducing step-by-step guidelines and checklists. The current experience shows that a system of written standards is applicable to neurosurgery and that the use of checklists contributes to the prevention of forgetting essential details. Written standards and checklists are also a useful training tool within a university hospital and facilitate communication of essentials to the residents. Comparison with aviation suggests that standardization leads to a remarkable but nonetheless limited reduction of adverse incidents.

Germany↗
PubMed2001

How to control the risk of novel surgical procedures.

Novel surgical procedures impose particular problems in addition to the general issues of clinical research [1, 7]. Surgical procedures are usually highly technical and therefore difficult to judge by the institutional ethics committee. The ethics committee has therefore to rely on external experts and a relatively large responsibility remains with the surgeon in charge. There are no generally valid regulations regarding new surgical procedures. At our institution, informed consent by the patient, a detailed risk analysis, testing and training in the anatomy/animal lab are required, and in addition a formation/training visit if know-how is available elsewhere. In emergency situations, if during a procedure circumstances call for a new surgical procedure, all the above preconditions cannot be met. A suggested minimum requirement in such a situation is that the decision for a new procedure is achieved by agreement of two board certified specialists. A problem that has to be solved in the future is how to make the negative experiences with new surgical procedures generally available in order to prevent that the same mistakes are repeated in other institutions.

Animals↗
PubMed2001

Meningiomas of the sellar region presenting with visual impairment: impact of various prognostic factors on surgical outcome in 62 patients.

BACKGROUND: Meningiomas of the supra- and parasellar region can cause insidious visual loss by optic nerve compression. 62 cases with such tumours affecting the anterior optic pathways were analysed to assess the surgical results and prognostic factors with particular attention to visual outcome. METHOD: In all patients, visual deterioration was the first clinical manifestation. Eleven lesions had their origin at the anterior clinoid process, 24 at the tuberculum sellae, 10 at the planum sphenoidale, two in the optic canal, 10 in the medial sphenoidal wing, and five in the olfactory groove. All patients underwent microsurgical tumour resection. Median age at the time of operation was 54 years, median duration of symptoms seven months. The mean follow-up time was 5.2 years (range 2 to 8 years). Statistical analysis of prognostic factors (gender, age, tumour location, tumour size, duration of symptoms, brain tumour interface, resection grade, preoperative visual loss, Glascow Outcome Score) was performed using univariate and multivariate analysis. FINDINGS: The severe morbidity rate was 6.4%. Two patients died within the first 30 postoperative days. Overall, vision improved in 39 (65%) patients, in 11 (18%) it was unchanged, and worse in 10 (17%). Visual prognosis was favourably affected by age under 54 years (p < 0.025), duration of symptoms of less than seven months (p < 0.037), and the presence of an intact arachnoid membrane around the lesion (p < 0.001). Severe preoperative loss of visual acuity (<0.02) appeared to be an unfavourable prognostic factor (p < 0.047). INTERPRETATION: Possible difficulties and surgical outcome in such patients can be predicted successfully. These facts in connection with new therapeutic modalities (radiosurgery, adjuvant therapies) will demand a careful risk assessment and should influence the treatment strategies and the degree of operative aggressiveness in the future.

Adult↗
PubMed2001

Transorbital keyhole approach to anterior communicating artery aneurysms.

OBJECTIVE: The transorbital keyhole approach to anterior communicating artery aneurysms was developed as a minimally invasive method for safe control of the anterior communicating artery complex. This approach does not necessitate resection of the gyrus rectus. METHODS: The technique is described in detail. The transorbital keyhole approach provides more ventral access than the supraorbital approaches, and the anterior communicating artery complex can be controlled by splitting the basal aspect of the interhemispheric fissure. RESULTS: Since late 1998, the authors have used the transorbital keyhole approach routinely. During the initial experience with 33 patients, the only observed complication specific to this approach was transient diplopia in one patient. At follow-up examinations 2 to 15 months after surgery, the cosmetic results were favorable as compared with those of standard pterional craniotomy. CONCLUSION: We have designed a small, custom-tailored approach to the anterior communicating artery complex for routine use. The small orbitocranial approach is a step toward the ideal of purely extra-axial safe control of anterior communicating artery aneurysms. The orbitocranial keyhole approach seems to be substantially better than the craniotomy, although it requires additional effort and time.

Esthetics↗
PubMed2001

M2/M2 side-to-side rescue anastomosis for accidental M2 trunk occlusion during middle cerebral artery aneurysm clipping: technical note.

OBJECTIVE: A technically feasible and rapid technique for revascularizing the main branches of the middle cerebral artery (MCA) is described. This technique is applied mainly when clipping of an MCA aneurysm is complicated and occlusion of the origin of an MCA main branch results. METHODS: M2/M2 side-to-side anastomosis was applied in two patients in whom unplanned M2 occlusion occurred during the course of complicated MCA aneurysm clipping. The first patient underwent an emergency procedure after temporoparietal intracerebral hemorrhage. Unilateral mydriasis precluded preoperative angiographic workup, and a complex large MCA aneurysm was found as the source of hemorrhage. Shaping of the aneurysm neck by bipolar coagulation and clipping resulted in accidental occlusion of the superior trunk, and patency could not be regained despite multiple clip corrections. The second patient had an unruptured multilobulated aneurysm 8 mm in maximum diameter. Continuity of the inferior trunk was lost during clipping because of a tear at the origin. In both instances, side-to-side anastomosis was placed approximately 15 mm from the bifurcation, where the MCA main trunks ran side by side for a length of approximately 5 mm. RESULTS: After intracerebral hemorrhage, the first patient recovered to a level of moderate disability within 2 months. Substantial hemiparesis and expressive dysphasia remained as sequelae of the intracerebral hemorrhage. Digital subtraction angiography 2 months after the emergency procedure confirmed patency of the side-to-side anastomosis. The second patient was neurologically intact after recovery from anesthesia. Before discharge from the hospital on postoperative Day 8, digital subtraction angiography confirmed patency of the anastomosis. CONCLUSION: The MCA main branches usually run in close proximity for a short segment at the bottleneck entrance to the insular cistern. M2/M2 side-to-side anastomosis at this site is a rapid and feasible mode of revascularization of an M2 trunk accidentally occluded during complicated MCA aneurysm clipping.

Adult↗