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Biomedical subjects

D Stolke

Publications and source records attributed to D Stolke.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Reconstruction of the frontobasal skull after tumor operations and trauma. Transplant selection and functional outcome].

Defects of the frontoorbital complex subsequent to extensive tumor surgery or severe trauma often result in aesthetic and functional disharmonies. The long-term results of rehabilitation related to different materials and techniques are the subject of this study. From 1974 to 1996 altogether 127 patients with bony defects of the orbit and/or the skull base underwent surgery. All patients' data were documented prospectively from 1984 onwards. The results following reconstruction with autologous calvarian transplants in 52 patients were compared to those of a control group which received iliac bone or PMMA implants. Eighty-one bony defects (64%) resulted from tumor resection; 37 patients (29%) suffered from the effects of trauma. In 67 cases (53%) reconstruction was performed primarily, in 51 cases (40%) secondarily. Free or pedicled soft-tissue transplants were necessary in order to separate the orbit and the neurocranium in 26% of the defects. On the other hand, small, isolated defects of the orbital roof (7%) were left without any reconstructive procedure. Contrary to the iliac bone grafts, the calvarian transplants resisted secondary resorption. Postoperative infections appeared in two cases; loss of transplants was avoided entirely in the group of calvarian reconstructions in contrast to the alloplasts. The selection of a suitable donor site area and rigid fixation with microplates led to excellent esthetic results even in cases with large defects.

Adolescent↗
PubMed1998

A comparison of patient-controlled analgesia with lornoxicam versus morphine in patients undergoing lumbar disk surgery.

UNLABELLED: The analgesic efficacy and tolerability of lornoxicam (Xefo; Nycomed Pharma A/S, Roskilde, Denmark), a new nonsteroidal antiinflammatory drug, was compared with that of morphine in a double-blind, randomized, parallel-group study of 96 patients with at least moderate pain after lumbar microsurgical discectomy. Both drugs were administered i.v. via a patient-controlled analgesia (PCA) for up to 24 h postoperatively. Efficacy was assessed by comparing mean hourly pain intensity differences, mean hourly pain relief, and total pain relief (TOTPAR) values derived from a 5-point verbal rating scores of pain intensity and pain relief at several time points over 24 h. Of 79 patients included in a per-protocol analysis, statistically significant equivalence of lornoxicam and morphine was shown by TOTPAR values of 31.6 and 28.9, respectively (P = 0.048). Trends toward slightly faster onset of analgesia with morphine and slightly greater PCA demands with lornoxicam were observed initially, which may partly have been due to a higher baseline pain intensity in the lornoxicam group. Lornoxicam caused fewer adverse events than morphine (21.7% vs 38.0% of patients, respectively), most of which were mild or moderate in severity. These results suggest that lornoxicam is an alternative to morphine when administered by PCA for the treatment of moderate to severe postoperative pain. IMPLICATIONS: After surgery for lumbar disk disease, patients obtained statistically equivalent pain relief with lornoxicam and morphine when administered by patient-controlled analgesia. However, lornoxicam was associated with a lower incidence of adverse events. This study suggests that lornoxicam provides an alternative to morphine for the treatment of postoperative pain.

Adolescent↗
PubMed1997

[Post-traumatic cerebrospinal rhinorrhea].

PURPOSE: Since frontobasal fractures after severe head trauma may cause serious late-term complications such as meningitis, their recognition and operative treatment are essential. Therefore, we analysed the importance of rhinoliquorrhoea as an early symptom of such fractures by comparison with neuroradiological methods. MATERIAL AND METHODS: In all patients undergoing operative revision of frontobasal fractures during a 7-year period, the clinical symptoms, results of neuroradiological examinations, concomitant injuries, as well as operative results, were studied retrospectively. RESULTS: 45 patients out of 688 with severe head injury showed frontobasal fractures (6.5%). The most common cause of these injuries were traffic accidents (55%) and precipitated falls or plunges (35%). Posttraumatic rhinoliquorrhoea was seen in 41 of 45 patients (91%), and 30 showed external periorbital injuries (66%). In 8 patients (18%) the frontobasal fractures could not be visualised by facultatively performed neuroradiological methods (coronary CT-scan, CT-cisternography, subarachnoid space scintigraphy). 15 patients (33%) were secondarily transferred to our institution, two of them more than two years after the causative injury. All patients were operated on successfully within 14 days after admission. CONCLUSION: Traffic accidents and precipitated falls or plunges are the main causes of head injuries with frontobasal fractures and about 2/3 of these patients show external periorbital injuries. Rhinoliquorrhoea as an early symptom allows diagnosis of frontobasal fractures in 90% of all cases rather than neuroradiological methods which failed to demonstrate frontobasal fractures in about 20% of our patients. Therefore, recognition of rhinoliquorrhoea in patients with severe head injury is essential.

Adolescent↗
PubMed1997

[Hemangioblastoma: description of a disease picture and report of 41 cases].

Hemangioblastomas are benign tumors of the central nervous system (CNS) with a predominance of the cerebellar hemispheres. They are one of the most frequent tumors of the posterior fossa in adults. In this retrospective study the data of 41 operated patients (23 men and 18 women) with a hemangioblastoma of the CNS are demonstrated. The mean age of the patients was 42.2 years (Range 4-70 years). 76% of the hemangioblastomas were located in the cerebellum, 9% in the cerebral hemispheres, 7% in the spinal canal and 5% in the brain stem. Signs of increased intracranial pressure and cerebellar dysfunction were the most frequent symptoms. Complete tumor removal was achieved in 90% of all operated cases. 82% of the hemangioblastomas were cystic and 18% solid. The mean diameter of the tumor cysts was 36 mm (Range 20-60 mm) and 18 mm (Range 2-40 mm) of the solid tumors. In 7% of the cases tumor recurrence was seen with a mean time interval of 5.7 years.

Adolescent↗
PubMed1996

Surgical treatment of pituitary adenomas in elderly patients.

Partly due to increased life expectancy, more and more patients over 60 years of age present with neurosurgical problems. In each case you have to decide to operate a patient or not. Describing the management in pituitary adenomas we conclude that also in elderly people operative therapy via the transsphenoidal approach can be done with a low risk in most cases.

Adenoma↗
PubMed1996

Combined surgery and radiotherapy of invasive pituitary adenomas--problems of radiogenic encephalopathy.

The aim of the present study was to find out: can combined modality of surgery and local irradiation in case of invasive pituitary adenomas prevent tumour relapse and develop radiogenic late damage after this therapy. Thirty-three patients suffered from primary hypophysomas and twenty-three patients had pituitary tumour recurrences. In all cases combined therapy was performed. The long term results of 56 patients showed a recurrence rate of 5.4% (3 cases). The median follow-up time was 152 months, ranging from 101 to 197 months. Clinical and neuroradiological signs of radiogenic encephalopathy developed in 16 cases (28%). Because of slow progression, the exact beginning of the neurological symptoms was difficult to determine and varied from 7 to 11 years. The extent of the cerebral and endocrinological disturbances was very different but a marked effect of the optic nerve was not seen. It seems that the usual X-ray therapy with single doses of 1.8 Gy and total doses of 45-50 Gy have a high risk of radiogenic morbidity.

Adenoma↗
PubMed1996

[Intradiscal pressure forces on cervical intervertebral discs in physiologic and pathologic conditions. In vitro study].

Clinical and experimental studies concerning intradiscal pressure have mainly been carried out using the lumbar spine. It has been shown that degenerative changes in the intervertebral disc and external loads can significantly influence intradiscal pressure. To see if these findings are also relevant for cervical discs, we carried out an in vitro study using human cervical spine specimens. The specimens were tested biomechanically under various conditions with simultaneous recording of intradiscal pressure in two cervical discs. We were able to confirm in vivo measurements of intradiscal pressure reported in the literature. Simulation of muscle force led to a marked increase in intradiscal pressure. Moreover, it was demonstrated that ventral cervical fusion has a significant influence on intradiscal pressure in both adjacent segments. In general, the results improve our understanding of the basic biomechanics of the cervical spine. The experiments with fused specimens could help to explain why degeneration is accelerated in adjacent motion segments after ventral cervical fusion.

Biomechanical Phenomena↗
PubMed1996

The dual-switch valve. A new hydrostatic valve for the treatment of hydrocephalus.

The currently available hydrocephalus valves are still far from perfect. Whereas the design principles of differential pressure valves and adjustable devices involve the danger of overdrainage, hydrostatic valves have a tendency to clog. The new dual-switch valve (DSV) avoids overdrainage-related problems such as subdural hygromas/hematomas or slit-like ventricles with the high risk of proximal catheter obstruction by means of two parallel chambers in a titanium casing: one for the the horizontal and the other for the vertical position. The control chamber for the horizontal position is closed by a gravity-activated tantalum ball as soon as the patient moves into an upright position. Now the drainage of CSF is directed into the appropriate controller for the erect position. Thus, the hydrostatic differential pressure between ventricles and peritoneal cavity is counterbalanced and the intraventricular pressure (IVP) remains within physiological values independently of the CSF flow and the position of the patient. To avoid the problem of clogging, the newly designed valve introduces large-area diaphragms to create extensive acting forces. The forces generated in this way are able to overcome sticking forces set up as a result of high protein content or cellular debris. By this mechanism the IVP is maintained in physiological ranges regardless of the CSF composition. The new valve has been investigated with a computer controlled test apparatus especially designed to simulate different positions of the body. The in vitro test results according to ASTM standards document a superior performance in comparison with other valves. When the new device was interposed in external drainage systems precision of its function was confirmed even in the presence of elevated protein content and high CSF flow. Simulation of the upright position of the patient allowed documentation of the valve's reliability in maintaining the IVP within physiological ranges. A clinical trial with implantation of the new dual-switch valve was started at the beginning of 1995; so far follow up has been short. Clinical and computer tomographic monitoring has provided evidence of the valve's capacity to avoid the problems of overdrainage and early clogging.

Adult↗
PubMed1996

Indications for surgery in upper cervical spine injury.

20% of all spine injuries are cervical spine injuries. Surgical treatment of these injuries must take into account the great mobility of this part of the spinal column. Therefore, biomechanical aspects must be considered, especially in the upper cervical spine-C1 and C2. Describing our own therapeutical regimen in 35 patients with unstable upper cervical spine injuries we explain the biomechanical back-ground and review the literature. It becomes evident that ventral approaches are superior to dorsal techniques for decompression, reposition, and stabilization with minimal loss of mobility.

Adolescent↗
PubMed1996

Long-term evaluation of EC-IC bypass patency.

The EC-IC Bypass Study Group could not detect any benefit from surgery compared to medical management in the prevention of stroke in 1985 [15]. During the past years surgical revascularization was re-evaluated and considered as an appropriate treatment for a small subgroup of patients with recurrent focal cerebral ischaemia and impaired haemodynamics. This retrospective study examines the long-term benefit and patency rate of bypass. We present a follow-up of 5.6 years of 47 patients, all of whom underwent bypass surgery after 1985. Forty patients suffered recurring transient ischaemic attacks due to uni- or bilateral internal carotid artery occlusion. Examination included neurologic status, TCD with CO2 or Diamox challenge, angiography, CT and SPECT scans. Neurological improvement was seen in 23% of patients with better results after early surgery, a worsening in 22% suffering further ischaemic events on a postoperative average of 2.8 years. Patency rate for vein graft material was 50%, for the STA-MCA procedure 91%. Occlusion of the vein graft occurred on an average after 1.4 years, other anastomosis after 2.7 years. We conclude that only few patients derived long-term benefit from EC-IC bypasses. Functioning of the bypass worsens over time, suggesting a role for surgery predominantly in the first year of ischaemic events due to insufficient collateral supply. Actual indications for bypass surgery may be patients with failure of maximal medical therapy and progressive ischaemia and haemodynamic compromise.

Adult↗
PubMed1996

[Craniocerebral trauma--new pathophysiologic aspects].

In the last two decades our understanding of the pathophysiology of severe head injury has significantly increased. It has become evident that secondary neuronal damage may occur and should be prevented. It is ischemia, similar to that seen with stroke and aneurysmal subarachnoid hemorrhage, that causes secondary brain damage. Therefore, careful monitoring of blood pressure is indicated, and the treatment of arterial hypotension/hypertension should begin as soon as possible. Moreover, there are some new pharmacological concepts for changing the threshold for ischemia in brain tissue. At the present time, however, valid data concerning clinical use are still not available. Therefore, mild hyperventilation and sedation during the initial post-traumatic phase and lowering of intracranial pressure by osmotherapeutics remain the most important treatment modalities, as they were 20 years ago.

Blood Pressure↗
PubMed1996

Prevention of cerebral vasospasm after experimental subarachnoid hemorrhage by RO 47-0203, a newly developed orally active endothelin receptor antagonist.

Since their discovery in 1988, endothelins have attracted scientific interest because of their extremely potent and long-lasting vasoconstrictive effects, similar to cerebral vasospasm in humans. In this study, the efficacy of the orally active endothelin receptor antagonist RO 47-0203 for prevention of cerebral vasospasm after experimental subarachnoid hemorrhage, using the two-hemorrhage dog model, was investigated. Twenty-eight beagle dogs were used in this laboratory experiment. Fourteen animals each were assigned to the treatment and control groups. In the treatment group, each dog received two single doses of 30 mg/kg RO 47-0203 orally per day. The diameter of the basilar artery decreased from 1.36 +/- 0.17 mm on Day 1 to 1.19 +/- 0.23 mm on Day 8 in the treatment group, whereas in the control group, the vessel diameter decreased from 1.48 +/- 0.19 mm on Day 1 to 1.02 +/- 0.22 mm on Day 8. These results corresponded to a decrease of vessel diameter of 13.1% +/- 11.2% in the treatment group and a decrease of vessel diameter of 30.7% +/- 12.4% in the control group (P < 0.001). Concentrations of endothelin-1 in cerebrospinal fluid significantly increased with time after subarachnoid hemorrhage. These results emphasize the important role of endothelin in the development of cerebral vasospasm and present first-time evidence that prevention of cerebral vasospasm can be achieved by the endothelin receptor antagonist RO 47-0203.

Administration, Oral↗
PubMed1996

Posterior transpetrosal approach to aneurysms of the basilar trunk and vertebrobasilar junction.

Aneurysms of the basilar trunk and vertebrobasilar junction represent an exceptional challenge to the neurosurgeon. Surgical access to these deep and confined lesions is hampered by the direct proximity of highly vulnerable neural structures such as the brainstem and cranial nerves, as well as by the structure of the petrous bone, which blocks direct surgical approach to these aneurysms. A number of surgical tactics consisting of different supra- and infratentorial approaches have been applied over the years to gain access to these treacherous lesions. Only recently have lateral approaches, such as the anterior transpetrosal, the retrolabyrinthine-transsigmoidal, and the combined supra/infratentorial-posterior transpetrosal approaches, directed through parts of the petrous bone, been reported for surgery of basilar trunk and vertebrobasilar junction aneurysms. Because detailed reports of direct operative intervention using the transpetrosal route for these rare and difficult lesions are scarce, the authors present their surgical experiences in nine patients with basilar trunk and vertebrobasilar junction aneurysms, in whom they operated via the supra/infratentorial-posterior transpetrosal approach. In eight patients, including one with a giant partially thrombosed basilar trunk aneurysm, direct clipping of the aneurysm via the transpetrosal route was possible. In one patient with a giant vertebrobasilar junction aneurysm, the completely calcified aneurysm sac was resected after occlusion of the vertebral artery. In total, one patient died and another experienced postoperative accentuation of preexisting cranial nerve deficits. Two patients had transient cerebrospinal fluid leakage, and the postoperative course was uneventful in the remaining seven. Postoperative angiography demonstrated complete aneurysm clipping in eight patients and relief of preoperative brainstem compression in the patient with the giant vertebrobasilar junction aneurysm. It is concluded that the supra/infratentorial-posterior transpetrosal approach allows excellent access to the basilar artery trunk and vertebrobasilar junction and can be considered the approach of choice to selected aneurysms located in this area.

Adult↗
PubMed1995

Epidural scar tissue formation after spinal surgery: an experimental study.

Extensive epidural scar formation is a well-known complication after spine surgery. Fibrous adhesions around nerve roots are a major reason for recurrent neurological symptoms following lumbar discectomy. A large variety of materials, implanted onto the dura, have been used to prevent or reduce laminectomy membrane, with conflicting results. We therefore carried out an experimental study in dogs to compare those materials that seemed to be most suitable. In each of 30 adult beagles, three lumbar laminectomies were performed. Each level was covered with a different material--free autologous fat graft, cellulose mesh, Gelfoam or triamcinolone suspension. In a control group nothing was implanted. After 7 days or 1, 3 or 6 months the animals were killed. The lumbar vertebral columns were harvested and prepared for further histological examination. To compare the results, we designed a new classification scheme (scar index). The data were obtained without knowledge of implanted material or time since operation. We found that free autologous fat grafts are able to reduce epidural scar formation in a high proportion of cases, especially after 3 and 6 months; cellulose mesh showed the worst results. We conclude that free autologous fat grafts are superior to other materials because of simple operative handling, good compatibility and effective prevention of laminectomy membrane.

Adipose Tissue↗
PubMed1995

Endothelin concentrations in patients with aneurysmal subarachnoid hemorrhage. Correlation with cerebral vasospasm, delayed ischemic neurological deficits, and volume of hematoma.

Plasma and cerebrospinal fluid (CSF) concentrations of endothelin (ET)-1, ET-3, and big ET-1 in patients with aneurysmal rupture were measured serially for 2 weeks after the onset of aneurysmal subarachnoid hemorrhage (SAH) and compared with levels of ETs in patients without SAH and the plasma concentrations of ETs in normal volunteers. Big ET-1 was the predominant peptide present in the CSF of SAH patients. The CSF concentrations of big ET-1, ET-1, and ET-3 were significantly higher in older patients than in younger patients. In SAH patients with cerebral vasospasm (CVS) documented by transcranial Doppler sonography and clinical signs, postoperative concentrations of ETs in the CSF remained at or were increased above levels measured before surgery. In SAH patients without CVS, the concentrations of ETs in the CSF decreased with time, whereas the time course of CVS coincided with the increase in concentrations of big ET-1 and ET-1. The temporal dependence of concentrations of big ET-1 and ET-1 in SAH patients with and without CVS were significantly different. The volume of hematoma in the basal cisterns as detected by computerized tomography was predictive of the concentrations of ETs in the CSF. Plasma concentrations of ETs were not correlated with CVS. The possible role of ETs in the pathogenesis of CVS associated with SAH and the controversial data reported to date are discussed.

Adolescent↗
PubMed1994

[The scar tissue protective effect of free autologous fatty tissue transplants. An animal experiment on spinal surgery].

All spinal operations can be followed by the formation of extensive epidural scar tissue. The development of fibrous adhesions around the nerve roots is known to be the main cause of recurrent symptoms after lumbar discectomy. In the past many materials have been used to prevent or to reduce postlaminectomy membrane, with very different results. They have to be implanted onto the dura at the end of the operation. Therefore, we carried out the following controlled experimental study in dogs to compare the materials that seemed to be most suitable. In 30 adult beagles three lumbar laminectomies were performed. For each level a different material was used--free autologous fat graft, cellulose mesh, gel foam, triamcinolone suspension. Animals were sacrificed after 7 days and 1, 3, and 6 months. The lumbar vertebral columns were prepared for further histological examination. We found that free autologous fat grafts reduce epidural scarring in a high percentage, especially after 3 and 6 months. Only in this group good or excellent results were found at all lumbar levels (n = 18). To compare the results with each other we used a newly developed classification scheme (I-IV). The consistency and extent of scar tissue, the kind of cellular infiltrations, and adhesions to the surrounding structures were estimated separately. Cellulose mesh yielded the worst results. We conclude that free autologous fat is superior to other materials, because of: (1) simple and uncomplicated operative handling, (2) good compatibility and (3) effective prevention of postlaminectomy membrane.

Adipose Tissue↗
PubMed1994

Prevention of delayed ischaemic deficits after aneurysmal subarachnoid haemorrhage by intrathecal bolus injection of tissue plasminogen activator (rTPA). A prospective study.

Among a series of 224 patients with aneurysmal subarachnoid haemorrhage (SAH) admitted over a period of three years, 52 patients were prospectively treated with intrathecal tissue plasminogen activator (rTPA). All of these patients were admitted and operated on within 72 h after SAH. SAH was confirmed by CT scan and the volume of blood accumulated in the basal cisterns was graded according to Fisher's scale. All patients had a SAH according to Fisher's grade III, as a prerequisite for inclusion into the study. In 21 patients additional intraventricular bleeding was detectable on CT scan. The diagnosis of a single intracerebral aneurysm as the bleeding source was established by pan-angiography, which also excluded additional cerebro-vascular malformations. The control group consisted of 68 patients, which were also treated within 72 h after SAH. Age and sex distribution as well as the clinical patterns were comparable to the rTPA group. In all patients the aneurysm was clipped using standard microsurgical techniques. After the aneurysm had been excluded from the parent vessel, 10 mg of rTPA, dissolved in 10 ml of its solution fluid, were slowly instilled into the basal cisterns in the treatment group. In patients with additional severe intraventricular bleeding, 5-10 mg of rTPA were injected into the ventricles via an intraventricular catheter at the end of the operation. Apart from the intrathecal application of the thrombolytic substance, the surgical protocol was identical in the patients of the control group. During the postoperative period, the patients in both groups were examined neurologically and by transcranial Doppler on a daily basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗