Biomedical subjects

V Seifert

Publications and source records attributed to V Seifert.

At least 91 records · Page 5Linked to original sources

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↗

PubMed1997

[Neurosurgical therapy of subarachnoid hemorrhage].

Annually, there are about 12,000 cases of aneurysmal subarachnoid hemorrhage (SAH) in the Federal Republic of Germany. The clinical signs are usually highly indicative and the definite diagnosis is usually made with a CT-scan. The high morbidity and mortality has led to the development of rather immediate definitive management strategies. Presently most aneurysms are proven by digital subtraction angiography but modern cross-sectional techniques approach a level of equal sensitivity. The major element of the treatment of aneurysmal SAH is the triple-h therapy with hemodilution, hypertension and hypervolemia. Prerequisite for this regimen is the early, definitive occlusion of the aneurysm. In most cases this will be accomplished by surgical clipping. As a complement, endovascular techniques are being developed and constantly refined. An early operation may be inappropriate in patients with poor Hunt and Hess grade or in whom a difficult anatomical situation is present. This limitation does not apply to the endovascular occlusion. The course of SAH is characterized by a high incidence of secondary ischemic complication due to vasospasm which met with intraoperative rinsing of the basal cisterns, lysis of the clot with intracisternal rTPA, application of calcium antagonists as either causative or antagonistic treatment. Despite significant advances, the morbidity and mortality of SAH remains high, leaving sufficient space for further improvements.

Aneurysm, Ruptured↗

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↗

PubMed1996

[Prevention of cerebral vasospasms after experimental subarachnoid hemorrhage by the endothelin receptor antagonist RO 47-0203].

Endothelins have attracted scientific interest because of their extremely potent and long lasting vasoconstrictive effects, similar to cerebral vasospasm in man. In this study the efficacy of the orally active endothelin-receptor-antagonist RO 47-0203 for prevention and treatment of cerebral vasospasm after experimental subarachnoid hemorrhage (SAH), using the canine two-hemorrhage model, was investigated. In the preventive study 28 beagle dogs were used. Fourteen animals each were assigned to the treatment and to the control group. 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 at day one to 1.19 +/- 0.23 mm at day eight in the treatment group while in the control group the vessel diameter decreased from 1.48 +/- 0.19 mm at day one to 1.02 +/- 0.22 mm at day eight. 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). In the therapeutic study the intraarterial infusion of 15.0 mg/kg RO 47-0203, at day 8 after experimental subarachnoid hemorrhage, caused no significant increase of the vessel diameter after 10 min., 20 min. or 30 min. These results underline the important role of endothelin in the development of cerebral vasospasm, and give for the first time evidence that prevention of cerebral vasospasm can be achieved by the endothelin-receptor-antagonist RO 47-0203.

Animals↗

PubMed1995

Anterior decompressive microsurgery and osteosynthesis for the treatment of multi-segmental cervical spondylosis. Pathophysiological considerations, surgical indication, results and complications: a survey.

Surgical treatment of cervical myelopathy due to multi-segmental cervical spondylosis (MSCS) is currently performed by either anterior or posterior approaches. Considering the complex nature of the underlying disease involving more than one cervical segment, as well as the patho-biomechanical features of the spondylotic cervical spine, adequate decompression of the spinal cord and correction of hypermobility should be achieved by surgery in one stage, in order to achieve positive immediate and long-term benefit for the patient suffering from progressive myelopathy. Recently, anterior decompressive surgery, consisting of single or multi-level vertebrectomy, microsurgical epidural decompression and osteo-synthesis has emerged as an aggressive therapeutic approach for the treatment of MSCS. Based on the experience of a series of 92 patients with progressive cervical myelopathy due to MSCS operated on using the above described combined techniques, as well as the results from a limited number of clinical studies of anterior decompressive surgery in MSCS patients from the literature, the pathophysiological considerations, surgical indications, surgical technique as well as clinical results and complications of anterior surgery in patients with MSCS are reviewed and discussed.

Cervical Vertebrae↗

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

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↗

PubMed1994

Microsurgery of the cervical spine in elderly patients. Part 1: Surgery of degenerative disease.

The results of microsurgery for degenerative disease of the cervical spine are reported in 84 consecutive patients being 65 years of age or older at the time of surgery. Patients were suffering from either soft or hard disc disease or from advanced forms of cervical myelopathy. In 60 patients microsurgical resection of the involved cervical disc and posterior osteophytes was performed followed by anterior fusion. Spondylectomy, microsurgical decompression and osteosynthesis was performed in 24 patients with multi-level cervical stenosis. A multitude of accompanying systemic diseases was present in almost all patients. Evaluation of the peri-operative risk profile of the patients was performed using the American Society of Anesthesiology (ASA) Grading of Physical Status Score. In 82 patients a complete follow-up was available. Two patients died within seven days after surgery from heart attack and pulmonary embolism. Three patients died during the observation period from causes unrelated to their cervical disease or to surgery. Overall surgical results were as follows: 66 patients (79%) were improved by surgery, 14 patients (17%) were unchanged, two patients (2%) became worse, and two patients (2%) died. Postoperative recovery was significantly correlated to the pre-operative neurological status. Neither age, nor the pre-operative ASA score had a significant influence on the postoperative outcome. The incidence of peri-operative systemic complications was significantly correlated to the pre-operative physical status of the patients according to the ASA score. No significant correlation towards an increase of peri-operative complications with higher grades of pre-operative neurological deficits or with increasing age of the patients could be found.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Microsurgery of the cervical spine in elderly patients. Part 2: Surgery of malignant tumourous disease.

In this retrospective study, the results of surgery were examined in 25 patients, 65 years of age or older, suffering from malignant tumour growth along the cervical spine. The group consisted of 17 men and 8 women. The mean age was 73 years, ranging from 66 to 88 years. The pathology identified was metastasis in 23 patients, and plasmocytoma in two. The tumour localization involved a single segment of the cervical spine in 12 patients, two segments in 8 patients, three segments in 4 patients, and four segments in one patient. Pre-operatively, 8 patients (32%) suffered solely from severe pain. 6 patients (24%) showed severe pain and radicular nerve compression. 5 patients (20%) had incomplete para- or tetraparesis but were able to walk, and again 6 patients (24%) had incomplete para- or tetraparesis, and were unable to walk. A multitude of accompanying systemic diseases was present in the majority of patients. Evaluation of the peri-operative risk profile was performed using the American Society of Anaesthesiology (ASA) Grading of Physical Status Score. Operation consisted of microsurgical tumour removal, usually incorporating a single- or multi-level vertebrectomy, with radical epidural decompression, and grafting with bone cement followed by an appropriate osteosynthesis. Of the whole cohort of patients treated, four patients were still alive at the time of the last follow-up evaluation. 21 patients died. Four patients died within seven days after surgery. The remaining 17 patients died during the follow-up period. All of these patients died from systemic spread of their primary cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗

PubMed1994

Intrathecal fibrinolysis using recombinant tissue plasminogen activator (rTPA) for prevention of cerebral vasospasm and delayed ischaemic deficits after aneurysmal subarachnoid haemorrhage. Experimental and clinical data.

Cerebral vasospasm and delayed ischaemic neurological deficits (DIND) remain the leading cause of death and major disability after aneurysmal subarachnoid haemorrhage (SAH). Experimental and clinico-radiological studies have clearly demonstrated the relationship between the volume of blood accumulated in the basal cisterns after aneurysm rupture and SAH, and the incidence and severity of vasospasm and DIND. Recently intrathecal thrombolysis using recombinant tissue plasminogen activator (rTPA) has been introduced as an innovative pharmacological method for the removal of subarachnoid blood accumulations, in order to prevent the development of cerebral vasospasm. In this survey a number of experimental and clinical studies which have been performed recently by the neurovascular research group of the author on the possible use of rTPA during SAH will be presented and discussed in the light of other experimental investigations as well as other recently performed pilot studies on the use of rTPA.

Aneurysm, Ruptured↗

PubMed1994

Clinical and radiological evaluation of long-term results of stereotactic proton beam radiosurgery in patients with cerebral arteriovenous malformations.

Within a period of nearly 10 years, from October, 1980, to May, 1990, a total of 68 patients with a cerebral arteriovenous malformation (AVM) were referred to a radiosurgical center in the United States for stereotactic Bragg peak proton beam therapy. Radiosurgery was chosen as an alternative treatment, either because the AVM was considered to be of high surgical risk due to its size and/or location, or because the patient refused surgery. In 63 patients (92.6%), complete clinical and radiological follow-up examinations were available. Clinical and radiological long-term results were correlated to size and to the Spetzler-Martin scale of the AVM. With increasing size or higher grade on the Spetzler-Martin scale, the clinical results of proton beam therapy became progressively worse. Of 37 patients with an AVM between 3 and 6 cm in diameter, only one-third showed amelioration of their clinical symptoms, and two-thirds remained the same or even deteriorated after radiation treatment. The same results apply to patients with very large AVM's, of whom only one-third profited from proton beam therapy. Although 85.7% of the patients in Spetzler-Martin Grades I and II showed postirradiation amelioration of their clinical symptoms, this compares to only 54.2% of the patients in Grade III, and only 24% in Grade IV. In regard to the radiological results of proton beam therapy, complete obliteration during long-term observation was only detectable in 10 patients or 15.9%, which is less than one-sixth of the whole group of 63 patients. All of these obliterated AVM's were smaller than 3 cm. Almost 85% of the patients treated using stereotactic proton beam therapy did not show any angiographic change in the radiological appearance of their AVM. The results reported here indicate that radiosurgery using stereotactic proton beam therapy is ineffective for the treatment of medium- or large-sized AVM's and should not be recommended for patients harboring an AVM larger than 3 cm. If proton beam treatment is contemplated, it should be restricted to AVM's that are less than 3 cm in size and whose location makes them easily accessible only for proton beam therapy.

Adolescent↗

PubMed1994

[Osteoplasty of osseous defects of the frontal bone and orbital roof--indications, technique and results].

From 1972 to 1992, 65 patients with traumatic or postoperative defects of the orbitocranial skeleton were operated on at the department for maxillofacial surgery, University of Essen. Until 1989 alloplastic reconstruction with PMMA implants or autogenous bone grafts of the iliac crest were preferred. Since 1989 we have utilized autogenous calvarial bone grafts (17 cases). CT based models of the defect helped to select calvarial donor sites of appropriate size and contour. The calvarial autografts provided high resistance against resorption. Until now, we have seen no major donor site morbidity. On the whole the results substantiate these autografts to be the superior material for orbitocranial reconstruction.

Bone Transplantation↗

PubMed1993

[Neurosurgical therapy of subarachnoid hemorrhage. Microsurgical techniques--early postoperative nimodipine administration].

With the increasing life expectancy of the general population, the number of geriatric patients with aneurysmatic subarachnoid bleeding consulting the neurosurgeon is also increasing. The possibilities of modern micro-neurosurgery have created a situation that permits craniotomy and aneurysmal clipping in the geriatric patient with an acceptably low level of risk and high probability of high post-operative quality of life. Although a definitive evaluation of perioperative administration of calcium channel blockers in geriatric patients with an aneurysm is not yet possible, experience so far gained points to their positive effect on a more rapid and more pronounced resolution of the post-hemorrhagic impairment of the cognitive performance.

Aged↗

PubMed1993

Advances in diagnosis and treatment of spinal hemangioblastomas.

Spinal hemangioblastoma usually leads to large intramedullary cysts. Until recently clinical and conventional radiological examination was often not able to detect single or multiple tumor niduses at the wall of a secondary syringomyelia cyst. Thus during surgical exploration the tumor not infrequently was missed, leading to misinterpretation of the pathological entity as syringomyelia, spinal gliosis or low grade spinal astrocytoma. This often resulted in explorative biopsy or decompressive laminectomy. Clinical deterioration postoperatively was not uncommon due to the remaining tumor and increasing spinal cord enlargement. Now magnetic resonance imaging allows the exact preoperative localization of the medullary lesion apart from the accompanying cysts and facilitates differential diagnosis of primary syringomyelia or other spinal cord neoplasms. Microsurgical techniques and laser-assisted resection have improved the outcome. We report on eight patients with spinal hemangioblastoma treated in our clinic since the installation of magnetic resonance imaging and laser-assisted microneurosurgery.

Adolescent↗

PubMed1993

Spondylectomy, microsurgical decompression and osteosynthesis in the treatment of complex disorders of the cervical spine.

In 44 patients with complex degenerative, traumatic, neoplastic and infectious disorders of the cervical spine an aggressive surgical approach was used, consisting of spondylectomy, radical microsurgical decompression and osteosynthesis. The patient group consisted of 23 patients with multisegmental cervical spondylosis, 9 patients with primary or metastatic malignant tumour disease spread along the cervical spine, 6 patients with complex cervical trauma and 6 patients with infection affecting one or more cervical segments. Considering the heterogeneity of the group of patients treated, a multitude of neurological symptoms and signs were present. Excruciating pain was the predominant symptom in 84% of the patients, followed by sensory and motor signs of varying degrees in 77% and 65% respectively. Involvement of the long tracts was present in 51%, gait disturbance in 49% and bladder disfunction in 28%. Considering the nature of the underlying disease, in the group with multisegmental cervical spondylosis (MSCS), advanced cervical myelopathy was the predominant clinical symptom, whereas in those patients with trauma, tumour or infection, pain was the leading symptom, followed by disturbed motor and/or sensory function. Altogether 59 vertebrae have been removed in the 44 patients. In 28 patients spondylectomy was performed at one level, in 15 patients at two levels and in one female tumour patient at three levels. In 34 patients an iliac crest bone graft was used and in 10 patients bone cement. Within the observation period, solid fusion was achieved in all patients. In one tumour patient screw loosening was demonstrable at follow-up, but the fusion remained stable. 2 patients with infectious disease required re-operation due to significant loosening of screws and plates. However, after re-stabilization solid fusion was achieved. Considering amelioration of specific pre-operative symptoms and signs, excruciating pain responded best to the stabilizing procedure, with improvement in over 90% of the patients, followed by improvement of sensory and motor deficits in 85% and 82% respectively. Improvement in pre-operative gait disturbance could be achieved in 81% of the patients, while disturbance of bladder function is less likely to improve after surgery with a positive response in only 58%. None of the patients became neurologically worse after surgery. With regard to the underlying disease, patients with MSCS and tumour had the best results with overall improvement in 62% and 75% respectively. While in patients with infection improvement could be achieved in 58%, improvement in trauma patients was demonstrable in only 34% while in 66% the pre-operative clinical status remained unchanged.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

Cerebral blood flow and intracranial pressure during experimental subarachnoid haemorrhage.

The relationships of intracranial pressure (ICP), systemic blood pressure (SBP) and cerebral blood flow (CBF) during experimental subarachnoid haemorrhage were investigated in cats. Continuous monitoring of regional cerebral blood flow (rCBF) was done by a thermal diffusion method using a Peltier stack. During haemorrhage ICP rose within 5.4 +/- 0.97 minutes from 10.5 +/- 4.9 to 176.1 +/- 27.8 mmHg. This strong increase of ICP resulted in a temporary arrest of cerebral circulation. The Cushing response during the haemorrhage could not improve the cerebral circulation, but in contrast caused a further increase of ICP. After the haemorrhage the cerebral blood flow normalised within minutes. It is concluded, that the Cushing response during a subarachnoid haemorrhage should be regarded as a deleterious rather than a beneficial mechanism.

Animals↗

PubMed1992

Combined orbito-frontal, sub- and infratemporal fossa approach to skull base neoplasms. Surgical technique and clinical application.

Neoplasms located along the antero-lateral skull base, with probable involvement of the orbit and with extension into the pterygoid and/or infratemporal fossa can usually not be sufficiently exposed using standard neurosurgical or otosurgical approaches, which is why combined approaches to these skull base targets have been developed in the recent past. In this report we describe our experience, using a combined orbito-frontal, sub- and infratemporal fossa approach which, starting with a pre-auricular incision and a standard pterional craniotomy, is extended to an extensive osteoplastic enbloc resection of the orbito-zygomatic area allowing for direct visualisation of the antero-temporo-lateral skull base from the orbital cavity to the depth of the infratemporal and pterygoid fossa. The surgical technique as well as the clinical experiences accumulated with this approach are described.

Chordoma↗