Biomedical subjects

K Ungersböck

Publications and source records attributed to K Ungersböck.

At least 19 recordsLinked to original sources

PubMed2005

Intraoperative evaluation of bone decompression in anterior cervical spine surgery by three-dimensional fluoroscopy.

Sufficient bone decompression of osteophytes is essential for functional long-term outcome in surgery for spondylotic cervical myelopathy. Postoperative CT scans clearly show that decompression is sometimes insufficient. Intraoperative CT scanning has been used to monitor sufficient decompression. Instead of standard intraoperative fluoroscopy, we used an isocentered three-dimensional (3D) fluoroscopy with 3D image reconstruction to evaluate the extent of bone decompression. From October 2003 to April 2004, we have used intraoperative 3D fluoroscopy on seven patients with anterior cervical spine surgery due to cervical spondylotic myelopathy. Five patients were operated on in one level, two patients had surgery in two segments. If surgery was performed in two levels or preoperative cinetic MRT showed cervical instability, internal plate fixation was done additionally. All patients were positioned on a radiolucent operating table, made of carbon fibers. Three-dimensional fluoroscopy was always performed before wound closure to evaluate sufficient bone removal. The scanning time was 120 s and the whole procedure from scanning to evaluation is approximately 5 min. In all patients we were able to evaluate the extent of bone decompression. Additionally, placement of cage, plates and screws can be evaluated intraoperatively. In one patient, 3D fluoroscopy showed insufficient decompression, especially on the right side. Further bone removal was performed before the end of the procedure. Intraoperative 3D fluoroscopy is a valuable tool for imaging bone decompression and implant location in anterior cervical spine surgery. The technique is safe, reliable and should help us to avoid incomplete decompression or misplacement of implants and therefore improve long-term functional outcome in cervical spine surgery in the future.

Aged↗

PubMed2003

Survival with dacarbazine and fotemustine in newly diagnosed glioblastoma multiforme.

A total of 55 patients with histologically proven glioblastoma multiforme (total gross resection: n=24, subtotal resection: n=20, stereotactic biopsy: n=11) were treated with the combination of dacarbazine (D) (200 mg m(-2)) and fotemustine (F) (100 mg m(-2)) and concomitant radiotherapy (2 Gy day(-1), 5 days per week using limited fields up to 60 Gy) to assess efficacy and toxicity of this regimen. Survival (median survival, 12-, 18- and 24-month survival rates) and time to progression (median time to progression (TTP), 6-month progression-free survival) were analysed by Kaplan-Meier's method. A total of 268 (range 1-8, median: 5) cycles were administered. Median survival is 14.5+ (range: 0.5-40+) months, and the 12-, 18- and 24-month survival rates are 58, 29 and 23%, respectively. Median TTP from the start of D/F therapy is 9.5+ (range: 0.5-33+) months. The 6-month progression-free survival is 54%. Partial remissions were observed in 3.6%. Main toxicity was thrombocytopenia. Five patients were excluded from further D/F application, four patients because of prolonged thrombocytopenia NCI-CTC grades 3 and 4 and one patient because of whole body erythrodermia. One patient died because of septic fever during thrombocytopenia and leukopenia NCI-CTC grade 4 after the first cycle. No other toxicities of NCI-CTC grade 3 or 4 occurred. The treatment is feasible in a complete outpatient setting and the results of the D/F regimen justify further investigations with these compounds.

Adolescent↗

PubMed2002

Anatomical landmarks for image registration in frameless stereotactic neuronavigation.

OBJECTIVE: Frameless stereotactic navigation devices require preoperative application of skin markers (SM) and planning radiography, which limits their even wider use. Therefore, we prospectively studied the applicability and accuracy of anatomic "natural" markers (NM) for image registration. METHODS: The accuracy of NM was evaluated in 26 patients operated on in the supine (n=24) or sitting (n=2) position, either by comparison to our standard navigation protocol using SM and planning radiography or by the deviation of anatomic landmarks using a routine diagnostic radiograph. In 21 cases, NM were compared to SM with planning radiography (computed tomography, or CT, in nine cases and magnetic resonance imaging, or MRI, in 12). The root mean square error (RMSE) of the registered volume was calculated by the Philips EasyGuide Neuro frameless stereotactic navigation system and compared between the two registration modalities. RESULTS: The mean RMSE was 3.2 mm+/-1.0 mm standard deviation using NM vs 2.9+/-1.0 mm using self-adhesive SM (P=0.13, Student's t-test). Computed tomography was slightly more accurate than MRI planning (mean RMSE 3.2 mm vs 3.3 mm). In three cases, diagnostic radiography (MRI) was used with a mean RMSE of 5.3 mm but acceptable intraoperative landmark correlation. CONCLUSION: Our pilot study demonstrates insignificant loss of registration accuracy using NM compared to SM. Additionally, the radiologic planning investigation and accuracy loss due to SM movement may be avoided.

Adolescent↗

PubMed2001

Extraforaminal, thoracic, epidural cavernous haemangioma: case report with analysis of magnetic resonance imaging characteristics and review of the literature.

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.

Diagnosis, Differential↗

PubMed2000

Defining the role of stereotactic radiosurgery versus microsurgery in the treatment of single brain metastases.

Stereotactic radiosurgery (RS) and surgery have proved to be effective treatment modalities for brain metastasis. We followed 133 patients whose treatment for intracranial disease was either RS or a single surgical resection at the University of Vienna from August 1992 through October 1996. All patients who received additional Whole Brain Radiotherapy were included. This was a retrospective, case-control study comparing these treatment modalities. Sixty-seven patients were treated by RS and 66 patients were treated by microsurgery. The median size of the treated lesions for RS patients was 7800 mm3, and 12500 mm3 for microsurgery patients, respectively. The median dose delivered to the tumour margin for RS patients was 17 gray. The median survival for patients after RS was 12 months, and 9 months for patients after microsurgery. This difference was not statistically significant (p = 0.19). Comparison of local tumour control, defined as absence of regrowth of a treated lesion, showed that tumours following RS had a preferred local control rate (p < 0.05). Univariate and multivariate analysis showed that this fact was due to a greater response rate of "radioresistant" metastasis to RS (p < 0.005). Postradiosurgical complications included the onset of peritumoural oedema (n = 5) and radiation necrosis (n = 1). Two patients after microsurgery experienced local wound infection. One postoperative death occurred due to pulmonary embolism in this group. On the basis of our data we conclude that RS and microsurgery combined with Whole Brain Radiotherapy are comparable modalities in treating single brain metastasis. Concerning morbidity and local tumour control, in particular in cases of "radioresistant" primary tumours, RS is superior. Therefore we advocate RS except for cases of large tumours (> 3 cm in maximum diameter) and for those with mass effect.

Brain Neoplasms↗

PubMed2000

Spinal dural arteriovenous fistula associated with syringomyelia.

The previously undescribed association of a spinal dural arteriovenous fistula with syringomyelia was found in a 60-year-old male, who developed increasing paresis, numbness of both lower extremities and sphincteric dysfunction. Symptoms and signs were attributed to a syringomyelia at T5-L1 and an arteriovenous spinal dural fistula at L1. The fistula was successfully immobilised with N-butyl-cyano-acrylate. Six months after the procedure, all abnormalities had nearly disappeared. Whether the relation between the fistula and the syringomyelia was coincidental or causative could not be determined.

Angiography↗

PubMed1999

[Acute symptom transverse laminectomy for a benign osteoclastoma of thethoracic spine--case report and review of the literature].

Benign osteoclastomas of the spine above the sacrum are uncommon lesions. Acute paraparesis as the presenting sign of disease is unusual and rarely described in the literature. We report on the case of a 41 yrs old male who underwent acute T3-5 laminectomy for spinal cord decompression from a T4 expansive mass lesion with locally destructive growth. Although a malignant lesion was suspected, definitive histologic examination disclosed a benign osteoclastoma. Therefore, elective trans-thoracic total vertebrectomy T4 with ventral stabilization was performed to allow for marginal total resection of the tumor and reconstruction of the spine. Twenty-four months after the procedure the patient has made a good neurologic recovery with no evidence of tumor recurrence.

Acute Disease↗

PubMed1998

Evaluation of cerebral vasospasm after early surgical and endovascular treatment of ruptured intracranial aneurysms.

OBJECTIVE: To document the influence of the treatment modality (early surgery versus early endovascular treatment) on measures of cerebral vasospasm in a nonrandomized series of 156 patients treated within 72 hours of aneurysmal subarachnoid hemorrhage. METHODS: The following parameters were prospectively collected in a computerized data base and retrospectively analyzed for association with vasospasm-related ischemic infarctions: 1) Hunt and Hess (H&H) grade, 2) Fisher grade, 3) highest mean cerebral blood flow velocity (CBFVMAX) and maximum percent change in mean CBFV (%deltaCBFV) as recorded by transcranial Doppler ultrasound, 4) incidence of repeat subarachnoid hemorrhage, 5) incidence of delayed ischemic neurological deficits, 6) incidence of delayed ischemic infarctions, and 7) Glasgow Outcome Scale score. RESULTS: Forty-one patients (26.3%) suffered ischemic infarctions. The ischemic infarction rate was correlated with higher H&H grade (P = 0.002), higher Fisher grade (P = 0.05), higher CBFVMAX (P < 0.001) and %deltaCBFV (P = 0.01), occurrence of repeat subarachnoid hemorrhage, occurrence of delayed ischemic neurological deficits, and endovascular treatment (P = 0.02). CONCLUSION: The infarction rate was higher with endovascular treatment versus surgery (37.7 versus 21.6%), as a result of a skewed Fisher Grade 4 infarction pattern in the endovascular treatment group versus the surgery treatment group (66.7 versus 24.5%). We suspect that unremoved subarachnoid/intracerebral clots contributed to the higher infarction rate with endovascular treatment. When patients with Fisher Grade 4 and H&H Grade V were excluded from analysis, the difference in infarct incidence between the treatment groups no longer reached statistical significance (Fisher Grades 1-3, P = 0.49; H&H Grades I-IV, P = 0.96).

Adult↗

PubMed1997

Cavernous malformations: from frame-based to frameless stereotactic localization.

An exact surgical approach to cavernous malformations, in particular those located in areas of critical brain function, is important for their microsurgical resection without putting too much strain on the patient. During a two-year period, 29 cavernoma resections were performed. Stereotactic guidance was performed in 16 cases (55.2%). Nine cavernomas located in the supratentorial region were resected using the stereotactic operating microscope "MKM", which represents 21.6% of a total of 51 MKM-navigated operations; in one further case system referencing failed. The experience gathered with this frameless stereotactic system is compared to a retrospective analysis of 5 frame-based stereotactic cavernoma localizations. Frameless stereotactic localization has been shown to be sufficiently accurate but more advantageous than frame-based techniques in terms of utility, ease of integration, and detailed image-guided anatomical information. Software improvements have resulted in a high stability of the frameless stereotactic system.

Adult↗

PubMed1996

Monitoring of cortical blood flow: clinical relevance of experimental laser Doppler studies.

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve as a measure of cortical blood flow. For clinical application instead of single fiber probes a multispot measurement approach will provide a reliable cortical blood flow monitoring. The use of continuous techniques will lead to a better understanding of cerebral hemodynamics under pathological conditions.

Animals↗

PubMed1995

The preoperative assessment of stroke risk in lesions involving the internal carotid artery.

Patients with vascular or tumourous lesions involving the internal carotid artery are at risk of damage or occlusion of this vessel during surgical or endovascular procedures. To assess the stroke risk transcranial Doppler aided carotid compression tests were performed in 82 patients. Based on changes of blood flow velocity (BFV), pulsatility index, systolic/diastolic ratio and length of transient hyperaemic response three groups could be differentiated. Patients in group A (31%) showed only a slight reaction of BFV and were at minimal risk in case of carotid occlusion. Patients in group B (52%) underwent a distinct decrease of Doppler readings with partial improvement and were considered to have moderate to high stroke risk. In group C patients (17%) trial occlusion caused a dramatic reduction of BFV with no recovery (p < 0.01), which denotes a very high stroke risk. Transcranial Doppler aided carotid occlusion manoeuvres provide useful information on cerebrovascular collateral capacity and prognosis of stroke risk.

Adolescent↗

PubMed1995

Transcranial Doppler and cortical microcirculation at increased intracranial pressure and during the Cushing response: an experimental study on rabbits.

The effect of increased intracranial pressure on the flow velocity of the basilar artery was measured with transcranial ultrasonic Doppler in New Zealand White rabbits under alpha-chloralose anesthesia and artificial respiration. Laser Doppler flowmetry served to study changes of the cortical microcirculation. The results confirm a high inverse correlation of the diastolic flow velocity, the pulsatility index, and the resistance index with the cerebral perfusion pressure (CPP). During acute intracranial hypertension, however, these parameters do not show a good correlation with the local cortical blood flow. The absence of a correlation was evident over a wide CPP range down to values of 35 mm Hg. Only at CPP values below this critical threshold is the microcirculation impaired. The threshold is reached at pulsatility index values of more than 2.0 and at resistance index values of more than 0.8. Therefore, transcranial Doppler indices permit the detection of critical reductions of microcirculatory blood flow. The Cushing reaction occurred with a constant time lag of 5.5 +/- 0.7 seconds after the loss of CPP. The Cushing reaction did not establish systolic blood flow, which remained below the functional threshold, as concluded from the temporary loss of somatosensory evoked potentials.

Animals↗

PubMed1994

Results of 200 intracranial stereotactic biopsies.

200 stereotactic biopsies were evaluated. The validity of the intraoperative histopathological results were compared with the final diagnosis using conventional embedding and staining techniques. Further comparison between the histology of the biopsy and the post mortem or open operative findings were possible in 41 cases. Discrepancy was found in one case regarding the tumor detection, and in three cases regarding the tumor grading. The mortality in our patients was 1% and the morbidity 3%. Stereotactical biopsy had a low risk even in deep brain regions such as basal ganglia, mesencephalon, and pons. At the same time the high histologic validity makes the CT-guided stereotactical biopsy recommendable in all lesions not operated by an open resection before any conservative or palliative therapy is started.

Adolescent↗

PubMed1994

Aneurysm surgery of patients in poor grade condition. Indications and experience.

Out of a total of 196 patients admitted with aneurysmal subarachnoid haemorrhage (SAH) to the neurological department in Mainz over a 42 month period, 48 patients (24.5%) were considered as grade IV or V on admission. Aneurysm surgery within 48 hours after SAH was performed in 56.3% of these patients, 2% were operated between day 3 and 7 and 16.6% were operated after day 7. 25% did not undergo operation because of severe neurological deficit and brain damage. The overall outcome according to the Glasgow outcome scale in the surgically treated group was full recovery in 11.1%, moderate disability in 16.7%, severe disability in 47.2%, vegetative state in 2.8% and death in 22.2%. All patients in the not operated group died. Good and moderate outcome was mainly seen in patients grade IV, which justify an aggressive strategy. Severe disability was mainly attributed to primary brain damage, while vasospasm played a minor role. Improvement may only be achieved by early referral of SAH patients to neurosurgical centres.

Adult↗

PubMed1993

Preserved cortical somatosensory evoked potentials in apnoeic coma with loss of brain-stem reflexes: case report.

A comatose patient suffering from diffuse cerebellar haemorrhage developed apnoea and brainstem areflexia, i.e. the clinical signs of brain death. However, median nerve somatosensory evoked potential testing 2.5 h and 22 h after the onset of this clinical syndrome showed cortical potentials partly preserved; these were abolished 46 h after the beginning of the clinical signs of brain death. This case report underlines the need for electrophysiological confirmation of brain death in patients with primarily infratentorial lesions.

Aged↗

PubMed1993

Cerebral blood flow alterations in a rat model of cerebral sinus thrombosis.

BACKGROUND AND PURPOSE: Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats. METHODS: Thrombosis was induced by slow injection of kaolin-cephalin suspension after frontal and caudal ligation of the sagittal sinus in rats. Local cerebral blood flow was measured by laser Doppler flowmetry and correlated with parenchymal damage found 24 hours after induction of thrombosis. RESULTS: Local cerebral blood flow 1 hour after sinus occlusion and induction of thrombosis had decreased to 60.92 +/- 29.05% (p < 0.01); however, there was a large variability among individual animals. Only five of 12 rats showed histological damage and intracerebral hemorrhages 24 hours after induction of thrombosis. A subgroup analysis revealed that parenchymal damage occurred in concurrence with reduced blood flow values after sinus ligation and injection of the thrombogenic material. Sinus thrombosis alone, without alteration of blood flow, did not cause tissue necrosis. CONCLUSIONS: The data support the contention that sinus vein thrombosis evolves gradually, with major symptoms occurring only if the thrombus expands from the sinus into bridging and cortical veins. Collateral venous outflow pathways are thereby occluded, and local blood flow may become reduced to and below the ischemic threshold.

Animals↗

PubMed1992

CT-guided stereotactic biopsy aided by Doppler ultrasonic vascular monitoring.

The use of a 20 MHz pulsed Doppler technique during stereotactic brain tumour biopsies is described. By means of a miniaturized ultrasonic probe the tissue planned for biopsy was investigated for vessel signals. Out of 41 patients, with this technique a flow-pulse curve in front of the biopsy cannula was registered in 14 cases. In 9 cases one pulse curve was determined and in 5 cases two or more flow curves were found, indicating the presence of arterial vessels. The depth of the vessels signal could be localized and this area avoided for biopsy sampling. In a series of 41 stereotactic biopsies carried out in this way there was no intra-operative haemorrhage or postoperative haematoma.

Adolescent↗

PubMed1991

Evaluation of collateral flow capacity in patients with vascular or tumorous lesions of the skull base by Doppler sonography.

In 12 patients with vascular or tumorous lesions of the skull base, the collateral flow capacity was examined by transcranial Doppler sonography and carotid compression studies. In four patients no cross flow mechanism was found, in two patients the test remained unclear, and in six patients the examination suggested a good collateral flow capacity. However, for this application of Doppler sonography no borderlines have yet been defined and thus interpretation is difficult. Intraoperative Doppler sonography was used in five patients and proved to be helpful for localisation of the internal carotid artery within skull base tumors.

Adult↗