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Biomedical subjects

D Stolke

Publications and source records attributed to D Stolke.

At least 91 records · Page 5Linked to original sources
PubMed1990

[Cerebrospinal fluid dynamics in experimental subarachnoid hemorrhage].

To investigate the acute effects on intracerebral pressure, intracranial reserve capacity and CSF absorption resistance, a subarachnoidal haemorrhage was induced experimentally in a cat by bolus injection or continuous infusion of autologous blood into the cisterna magna. Intracisternal bolus injection resulted in a brief steep increase in intracranial pressure. 30 or 60 minutes after the haemorrhage the median intracranial pressure is slightly increased, the reserve capacity markedly reduced and the CSF absorption resistance considerably enhanced. During intracisternal blood infusion there is a continuous intracerebral pressure rise that persists to the end of the infusion and decrease again within a short time. This intracranial pressure behaviour is due to the simultaneous reduction of intracranial reserve capacity and the increase in CSF absorption resistance during the blood infusion.

Animals↗
PubMed1990

[Microsurgery, laser-assisted cranial nerve anastomosis. An experimental study].

Recently the milliwatt-CO2-laser has been introduced into the armentarium of experimental microsurgery for performing coaptation in peripheral nerves using the thermal effect of laser energy in order to achieve an atraumatic and reliable tissue bond. Experimental studies have shown that laser-assisted nerve coaptation are equal if not superior to conventional techniques in the reduced incidence of neuroma formation as well as the regenerative capacity. In this experimental study we have investigated if the CO2-laser working in the milliwatt range can be successfully applied for performing anastomosis of cranial nerves. The right oculomotor nerve in cats was microsurgically explored along the lateral temporal fossa from its exit at the brain stem to its entrance into the rudimentary cavernous sinus. Following division of the nerve with microscissors the nerve ends were loosely approximated. Thereafter welding of the cut nerves was performed with the CO2-laser (Cooper Laser Sonics, Model 860) using a power of 80-90 milliwatts, a spot-size of 150 microns and single bursts of laser energy. Complete welding of the cut nerve ends took about one to two minutes after which the surgical wound was closed. All experimental animals were observed for a period of 12 weeks after which they were sacrificed and the welded oculomotor nerve was removed for histological examination. Functional recovery of the III. nerve during the observation period was demonstrated by examination of the resting diameter of the pupil as well as by its reaction to direct stimulation with light. Morphological regeneration of the operated nerves could be demonstrated by histological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1989

Complement-derived polypeptide C3adesArg as a mediator of inflammation at the blood-brain barrier in a new experimental cat model.

The effect of the complement-derived polypeptide C3adesArg as a mediator of inflammation in the central nervous system was examined. Twenty-five anesthetized cats received 4 mg of this polypeptide by intraventricular injection, 20 cats who served as controls received saline. Cerebrospinal fluid (CSF) was sampled 3 h after intraventricular injection and the brains were removed. For assessment of the permeability of the blood-brain barrier the CSF penetration of four antibiotics, which were given intravenously was measured. Five control animals were employed for each antibiotic (tobramycin, ampicillin, imipenem, fosfomycin), whereas six C3adesArg-treated animals were used for each antibiotic and seven for tobramycin. Besides CSF levels of glucose, the prostanoids 6-keto-prostaglandin F1 alpha, thromboxane B2 and prostaglandin E2 were measured. The morphological examinations in the CSF sediments and histological brain sections in the C3adesArg-treated animals disclosed a distinct inflammation with leptomeningeal and perivascular infiltration of polymorphonuclear granulocytes compared to normal findings in the controls. The CSF/serum ratios of all of the antibiotics were markedly elevated compared to controls, indicating a blood-brain barrier disruption. The levels of all prostanoids were significantly higher in the treatment group than in the control group, whereas the glucose levels were lower. These findings are in accordance with a granulocytic meningitis as seen in some infections at the acute stage. It is concluded that C3adesArg acts as a mediator of inflammation in the central nervous system.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Ultrastructural changes of the basilar artery following experimental subarachnoid haemorrhage. A morphological study on the pathogenesis of delayed cerebral vasospasm.

Recent experimental studies have shown, that the endothelium of cerebral vessels undergoes significant changes after subarachnoid haemorrhage which may lead to biochemical changes at the endothelial surface with disturbance of the delicate homeostasis of vasodilating and vasoconstricting mechanisms which are thought to be responsible for preservation of the tones of the cerebral vasculature. Ultrastructural studies incorporating different forms of microscopic observations of the endothelium after SAH representing a prerequisite for further investigations on the pathogenesis of cerebral vasospasm are scarce. The experimental study was performed in order to investigate and define more precisely the pathomorphological changes at the endothelial surface of the basilar artery of dogs after experimental SAH. Two separate injections of autologous blood into the cisterna magna within 72 hours resulted in extensive angiographic narrowing of the diameter of the basilar artery of all animals. Histological studies of the basilar artery including light microscopic, transmission electron microscopic, scanning electron microscopic and freeze cracking microscopic examinations demonstrated severe pathomorphological changes at the endothelial surface. These consisted mainly of infolding and corrugation of the endothelium, disorientation and desquamation of endothelial cells as well as of vacuolation and ingrowth of fibrous tissue between the endothelial and muscular layer. No pathomorphological changes could be observed in the muscular layer. As the described post-haemorrhagic ultrastructural changes of the endothelium cerebral vessels in spasm are likely to represent the morphological basis of the delayed form of cerebral vasospasm future research on its pathogenesis should primarily focus on the structural and biochemical taking place at the endothelial surface of the cerebral vasculature after SAH.

Animals↗
PubMed1989

[Clinical use of a new method in microsurgical transplantation of peripheral nerves].

Due to its biophysical properties the CO2-laser has been mainly used for atraumatic incision of neural tissue or for ablative procedures like vaporisation of poorly vascularized tumors of the CNS. The possibility to use the thermal effect of laser energy to bond organic tissue, especially when a low energy CO2 laser working in the milliwatt range is employed, has emerged from recent experimental studies. The concept of laser assisted reconstructive procedures like anastomosis of vessels and nerves has been summarized under the concept of tissue welding. After extensive experimental studies incorporating peripheral and cranial nerves the technique of laser nerve welding has been used in a patient with a traumatically sectioned median nerve. A sural nerve graft consisting of 5 fasciles was used for interposition. Each fascicle was microsurgically welded to the distal and proximal median nerve stump using low power energy of 75 to 100 milliwatt in the continuous application mode. The postoperative course was uneventful. Electrophysiological as well as clinical examination at follow up 6 months post surgery revealed already satisfactory nerve regeneration with nerve conduction velocities measurable across the anastomotic side and positive Hoffmann-Tinel sign. It is suggested that laser assisted nerve anastomosis using the CO2 milliwattlaser might be a promising technique for microsurgical reconstruction of sectioned nerves.

Adult↗
PubMed1989

Efficacy of single intracisternal bolus injection of recombinant tissue plasminogen activator to prevent delayed cerebral vasospasm after experimental subarachnoid hemorrhage.

Premature lysis of subarachnoid blood clots by thrombolytic substances such as urokinase and plasmin has been shown to be efficacious in preventing cerebral vasospasm in clinical and experimental investigations. Recently, tissue plasminogen activator (rtPA) derived from recombinant deoxyribonucleic (DNA) technology has been introduced as a new thrombolytic substance. With its high affinity for fibrin-bound plasminogen and low affinity for circulating plasminogen by which a clot-selective fibrinolysis can be achieved without the danger of inducing systemic fibrinogenolysis, rtPA might be the ideal substance for the postoperative lysis of cisternal blood accumulations after subarachnoid hemorrhage. The efficacy of rtPA in preventing delayed cerebral vasospasm after experimental subarachnoid hemorrhage using a single intracisternal bolus injection of this agent was investigated. With a single injection of 25 micrograms of rtPA into the cisterna magna 48 hours after the first and 6 hours after the second injection of blood in the two-hemorrhage model of cerebral vasospasm, angiographic spasm of the basilar artery was completely prevented in all animals so treated whereas in the control group severe vasospasm occurred. Autopsy studies of the experimental animals demonstrated that the subarachnoid blood clots were almost completely removed by intracisternal rtPA application. Additionally the pathomorphological signs of proliferative vasculopathy present in all animals of the control group were not demonstrable in the rtPA group. As intracisternal bolus injection of rtPA is highly efficacious in preventing angiographic as well as pathomorphological vasospasm, it is concluded that use of this thrombolytic substance might be a promising approach for pharmacological blood clot removal.

Animals↗
PubMed1989

Intra- and postoperative complications in lumbar disc surgery.

In a prospective study, 412 primary and 69 reoperations for herniated lumbar disc were observed and intra- and postoperative complications compiled. Only surgeons with the experience of more than 100 surgical procedures on lumbar discs entered this study. The complication rates of the micro- and macrosurgical techniques are compared. Intraoperative complications range from 7.8% in the microdiskectomies and 13.7% in the macrodiskectomies to 27.5% in the reoperations. Postoperative complications range from 1.4% in reoperation, 3.9% in the microdiskectomies up to 4.2% in the macrodiskectomies. The risk of complications correlates with the age of the patient and the operating time.

Adult↗
PubMed1989

[Chronic subdural hematoma following spinal anesthesia].

A chronic subdural hematoma was observed 4 weeks after spinal anesthesia. The 70-year-old patient complained of severe, long-lasting headache soon after lumbar puncture. The later symptoms of hemiparesis and aphasia were first misinterpreted as a cerebral vascular accident. After evacuation of the hematoma the patient recovered. Long-lasting, severe headaches after lumbar puncture may be caused by a chronic subdural hematoma, a very rare complication. Risk groups are elderly patients and alcoholics, but every age group can be affected, including parturient women who deliver under spinal anesthesia. The diagnostic procedure of choice is computerized tomography (CAT). The application of contrast medium might be necessary if the CAT scan appears suspicious for a hematoma with the same density as the brain tissue. Because this complication is so rare informing the patient before spinal anesthesia does not seem to be necessary. According to expert opinions, a connection between lumbar puncture and subdural hematoma should be possible. In elderly patients and alcoholics, a pre-existing subdural hematoma may be possibly present.

Aged↗
PubMed1989

Laser-assisted reconstruction of the oculomotor nerve: experimental study on the feasibility of cranial nerve repair.

In this experimental study the feasibility of microsurgical laser-assisted repair of the oculomotor nerve in the cat was investigated. The 3rd cranial nerve was explored after a temporobasal craniectomy from its exit at the brain stem to its entrance into the cavernous sinus and transected. The cut nerve ends were loosely reapproximated and welded together with a CO2 milliwatt laser using a power setting of 80 to 90 mW and a spot size of 150 mu. Regeneration of the oculomotor nerve within an observation period of 12 months as assessed by weekly examination of the pupil diameter was excellent in 4 animals and satisfactory in 2. In the two control groups consisting of 6 animals in which the nerve reconstruction had been performed with fibrin glue or by simple nerve reapproximation minimal nerve regeneration could be observed only in one animal. The histomorphological examinations revealed good regeneration across the laser anastomosis including new formation of a perineural sheath without any significant scarring effect or constriction at the anastomotic site. It is concluded that the CO2 milliwatt laser might be a useful tool for the microsurgical repair of cranial nerves and should possibly be incorporated into the neurosurgical armamentarium of reconstructive cranial nerve surgery.

Animals↗
PubMed1988

Timing of aneurysm surgery. Comparison of results of early and delayed surgical intervention.

In a retrospective study covering a period of 8 years and 403 surgically treated patients the results of microsurgical aneurysm treatment were compared between two groups. One group received surgical treatment within 72 h and the second were treated surgically after this time interval. The data indicated that patients receiving delayed surgery had a better outcome at 6 months as compared to patients receiving immediate surgical intervention. The location of the aneurysm and the preoperative neurological status imparted the most significant impact on the subsequent outcome and on the incidence of rebleeding. High risk patients with poor neurological status on admission seemed to have a considerable chance of gaining satisfactory functional recovery, especially with a more delayed surgical approach. Despite its superior results delayed surgery was burdened with a rebleeding rate and an incidence of ischemic deficits due to cerebral vasospasm twice as high as in patients receiving early surgery. The implications of these results on surgical timing are discussed and it is concluded that despite the fact that late surgery yields better results than early surgery, the considerable reduction of recurrent hemorrhage and additional possibility of aggressive treatment of incipient vasospasm makes early surgery a promising alternative for the treatment of patients with aneurysmal subarachnoid hemorrhage.

Carotid Artery Diseases↗
PubMed1988

Intraspinal lipomas in infancy and childhood causing a tethered cord syndrome.

The authors report on a series of 26 children with spina bifida occulta in combination with intraspinal lipoma and clinical signs of tethered cord syndrome. The age of the children at presentation ranged from 1 month to 12 years. The typical signs and symptoms consisted of skin lesions in the lumbar-sacral region, neurogenic foot deformities, and bladder and bowel disturbances. The diagnosis was confirmed by neuroradiological investigations including lumbar myelography, computerized tomography, and only recently magnetic resonance imaging. Indications for surgery were based on the radiological evidence of intraspinal lipoma and tethered cord and especially on the clinical signs of neurological deterioration. The results of the operative treatment are presented and the role of surgery before onset of symptoms as well as during the symptom-free interval is discussed.

Child↗
PubMed1988

Diagnostic and therapeutic problems with an unusual congenital cystic hygroma of the orbit.

A case of an extensive congenital cystic hygroma in an unusual situation in the orbit is presented. The lesion occurred as an ulcerative, rapidly--growing and repeatedly--bleeding tumour with destruction of the left orbit, parts of the middle face, the nose and the base of skull. Despite X-ray investigation, computed tomography, nuclear magnetic resonance imaging and angiography it was impossible to give a reliable diagnosis. Because of the rapid growth of the tumour and its uncertain nature a radical resection with exenteration of the orbit, resection of the zygoma, the soft tissues of the cheek and parts of the nose and skull base was performed. One year after the resection there was no sign of recurrence.

Facial Neoplasms↗
PubMed1988

[Intraspinal lipoma with tethered cord syndrome in childhood].

In this article the authors report on a series of 26 children with spina bifida occulta in combination with intraspinal lipoma and clinical signs of tethered cord syndrome. The age of the children at presentation ranged from 1 month to 12 years. The typical signs and symptoms of the patients consisted of dermatological changes in the lumbosacral region, neurogenic foot deformities and genitourinary tract anomalies with disturbed bladder function. The diagnosis was confirmed by neuroradiological studies including lumbal myelography, spinal computerized tomography and only recently magnetic resonance imaging. Indications for surgery were based on the radiological evidence of intraspinal lipoma and tethered cord and especially on the clinical signs of neurological deterioration. The results of the operative treatment are presented and the role of surgery before onset of symptoms as well as during the symptom-free interval are discussed.

Child↗
PubMed1988

[Postoperative lumbar intervertebral discitis. A review of a 15-year period and 7,493 operations].

The incidence of postoperative discitis in a series of almost 7500 surgical interventions covering a period of 15 years is reported. Ninety patients (1.2%) were found to be suffering from typical symptoms, which are described and discussed. It is pointed out that above all radicular pain diminished, while on the other hand severe pain occurred in the lumbar spine, caused by movement and vibration, accompanied by a usually sharp rise in ESR, up to values of 100/200 mm. It is pointed out that conventional tomography is the diagnostic tool of choice, diagnosis being possible as of approx. three weeks postoperatively. The social implications of this important complication are pointed out, in particular the fact that only 50% of patients were able to return to full-time work in their old occupations, while the rest had to retire or accept a less strenuous job.

Adult↗
PubMed1988

[Early or late operation on the ruptured aneurysm? An analysis based on 356 cases].

From January 1979 to December 1985 356 patients underwent microsurgery for a ruptured intracranial aneurysm. 150 patients (42%) were operated on early, i.e. within 72 hours after subarachnoidal haemorrhage. 206 (58%) were operated on after this period. Both groups of patients were compared with one another in respect of preoperative staging (Hunt and Hess), localisation of the aneurysm, postoperative recovery (Glasgow-Outcome-Scale) and frequency of recurrent haemorrhages. 48% of the patients who were operated on early were preoperatively in stages I and II, 32% in stage III and 20% in stages IV and V. In the group of patients who were operated on late, 64.6% were in stages I and II, 17.5% in stage III and 17.9% in stages IV and V. 72.5% of the patients receiving early surgery in stages I to II showed a positive postoperative result (grades I and II of the Glasgow-Outcome-Scale = GOS) compared against 80.5% of those undergoing late surgery. 9.2% or 3.5% survived with considerable neurological deficits (GOS III). 18.3% or 15.4%, respectively, remained in the vegetative stage or died (GOS IV and V). A satisfactory postoperative result was obtained even in patients subjected to surgery in stages IV and V, in the following proportions: 40% if operated on early, and 48.6% if operated on late (GOS I and II). Aneurysms of the anterior communicating artery were most frequent, followed by aneurysms of the internal carotid artery and the middle cerebral artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Damage, Chronic↗
PubMed1988

Influence of blood volume on cerebrospinal fluid levels of arachidonic acid metabolites after subarachnoid hemorrhage: experimental study on the pathogenesis of cerebral vasospasm.

Based on accumulating data indicating the important role of arachidonic acid metabolites in the pathogenesis of cerebral vasospasm, we examined the influence of alterations in blood volume on the cerebrospinal fluid (CSF) level of the subarachnoid hemorrhage (SAH). Three separate injections of autologous blood into the cisterna magna of dogs within subarachnoid hemorrhage (SAH). Three separate injections of autologous blood into the cisterna magna of dogs within 72 hours were performed. Three experimental groups were formed, with an overall injected blood volume of 6, 9, and 12 ml. Arterial spasm was verified by comparison of the angiographic diameter of the basilar artery on Day 8 vs. Day 1. Additionally, light microscopic, scanning and transmission electron microscopic, and freeze cracking technique examinations of the basilar artery demonstrated the typical morphological features of proliferative vasculopathy. Increasing the volume of experimental SAH led to a linear decrease of the mean vessel diameter from 45% to 53% and finally to 75% of normal. Parallel to the reduction of angiographic vessel lumen, a volume-dependent significant increase of all three eicosanoids was demonstrated. A deficiency of prostacyclin concentration during the course of the experiment was not observed. Despite highly elevated CSF levels of vasodilating prostacyclin, however, severe angiographic constriction of the basilar artery occurred in the presence of high concentrations of TXA2 and PGE2. It is concluded that increasing volumes of SAH led to a concomitant release of arachidonic acid metabolites during posthemorrhagic clot lysis. From our data, it seems questionable whether a prostacyclin deficiency is an important underlying factor for the development of cerebral spasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗