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Biomedical subjects

H J Steiger

Publications and source records attributed to H J Steiger.

At least 19 recordsLinked to original sources
PubMed1995

Determination of cognitive hemispheric dominance by "stereo" transcranial Doppler sonography.

BACKGROUND AND PURPOSE: Transcranial Doppler sonography (TCD) can assess blood flow velocity changes induced by focal brain activation. Therefore, TCD may have the potential to identify hemispheric dominance for cognitive tasks. METHODS: Using a system with two TCD probes ("stereo" TCD), we monitored simultaneously both middle cerebral arteries (MCAs) of 14 healthy right-handed volunteers while they performed cognitive tasks. The averaged blood flow velocity ratio of the two MCAs and the hemispheric blood flow velocity shift induced by the cognitive task were calculated. RESULTS: In every subject, language tasks resulted in blood flow velocity shift to the left compared with visuospatial tasks. Mean MCA blood flow velocity shift to the left was 1.67%, 2.01%, and 2.31% in three language tasks. Mean blood flow velocity shift to the right was 1.67% and 2.31% in two visuospatial tasks. CONCLUSIONS: Bilateral simultaneous MCA blood flow velocity monitoring and averaging during cognitive tasks can help to identify hemispheric dominance for cognitive tasks in individuals.

Adult↗
PubMed1994

Current pattern of in-hospital aneurysmal rebleeds. Analysis of a series treated with individually timed surgery and intravenous nimodipine.

The management of aneurysmal subarachnoid haemorrhage has recently changed considerably. Emergency admission to specialized centres and early surgery have become common practice. In addition, the use of nimodipine has gained widespread acceptance. Little data are available concerning the frequency and temporal profile of reruptures under the current policies. The case histories of 387 patients treated for aneurysmal subarachnoid haemorrhage between January 1984 and March 1992 were reviewed with regard to the incidence of in-hospital reruptures. All patients were managed according to the same protocol including a policy of individually timed early surgery and intravenous nimodipine. A total of 44 first in-hospital rebleeds were observed during the waiting period. Two percent of the patients admitted on the day of haemorrhage had a rebleed on the same day after admission to the hospital. No rebleeds were observed on the day after subarachnoid haemorrhage. Rebleed rates on day 2 and 3 were also low with 0.6 and 0.8% of the population with an unclipped aneurysm. For the following 10 days, the daily rate of rerupture increased. A further peak was observed during the 4th week. Using life-table methods, the cumulative rate of rebleeds was calculated as 23% within 2 weeks and 42% within 4 weeks. Although patients suffering rebleeds differed in several respects from patients without rebleeds, most of the differences could be identified to be a consequence of a selection bias resulting in a longer period of exposure to the risk of rerupture for certain subgroups. Only patients suffering a loss of consciousness after the initial subarachnoid haemorrhage were definitively exposed to a higher daily risk of rerupture.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Transcranial Doppler monitoring in head injury: relations between type of injury, flow velocities, vasoreactivity, and outcome.

Eighty-six patients with head injuries with an admission Glasgow Coma Scale score between 3 and 12 were studied sequentially by transcranial and cervical Doppler sonography. On a subset of 26 patients, sequential autoregulation and CO2 reactivity testing was also performed. Patient characteristics and hemodynamic data were correlated and analyzed with respect to the final outcome. The internal carotid artery (ICA) and middle cerebral artery flow velocities followed a typical pattern. Both were depressed during the first 3 days after the trauma and then increased to a maximum between Days 5 and 7. The increase of the middle cerebral artery flow velocities was more pronounced than the increase of the ICA flow velocities, thus indicating some degree of vasospasm. The amount of subarachnoid hemorrhage on the initial computed tomography correlated with the average middle cerebral artery/ICA flow velocity ratio (r = 0.5). Subarachnoid hemorrhages on computed tomography and, to a lesser degree, subdural and intracerebral hematomas were correlated with an unfavorable outcome. Vasospasm remained subcritical, and no negative relationship to outcome could be identified. Hyperperfusion, as based on ICA flow velocities, and vasospasm were correlated with diminished vasoreactivity. However, disturbed vasoreactivities, particularly during the first days, were common and did not necessarily predict an unfavorable outcome.

Adolescent↗
PubMed1992

[Assessment and treatment of minor cranio-cerebral injuries].

Despite the usually uncomplicated course, minor head injury has a major economic impact because of its high frequency. The traditional evaluation and management using plain skull x-rays and subsequent surveillance has recently been questioned due to the wide-spread availability of CT and MRI. Indication and value of these diagnostic methods, however, are still ill-defined. The resulting uncertainty leads to increasing pressure on the smaller hospitals to transfer patients with minor head injury to specialized centres. This trend causes further financial escalation and the capacity of the specialized centres is not large enough to admit all minor injuries. The present review is focused on the initial risk estimation after minor head injury with the aim to derive guidelines for safe and efficient patient management. Adequately communicating patients without history of loss of consciousness have only a minimum risk of an intracranial haemorrhage and need not routinely be submitted to x-ray studies or in-hospital surveillance. Patients with a history of change of consciousness carry a risk of a few percent to develop intracranial haemorrhage and need therefore be admitted for 24 hours. A skull fracture increases the risk of haemorrhage to approximately 10%. An initially unsuspicious CT-scan is no absolute guarantee against subsequent intracranial haemorrhage. Patients who are disoriented and/or somnolent upon emergency room admission or who display a focal neurological deficit have a high risk of intracranial haemorrhage and emergency CT-scan is therefore recommended. The expensive MRI technique is not justified for initial diagnostic work up of head injuries. However, this technique represents a sensitive means to define organic lesions in cases of persistent neurological or neuropsychological deficits.

Brain Injuries↗
PubMed1992

[Results of percutaneous chemonucleolysis in lumbar disk hernia].

The percutaneous interventions have gained widespread acceptance for operative treatment of certain lumbar disc herniations. During recent years, percutaneous nucleotomy and laser discolysis replaced more and more the older technique of chemonucleolysis. Reports of anaphylactic shocks and severe neurological complications as well as unsatisfaction with the results of chemonucleolysis were responsible for this change. The basic mechanical concept of reduction of the intradiscal pressure remains the same with the newer methods. At the Inselspital percutaneous nucleotomy replaced chemonucleolysis in 1990. The results of chemonucleolysis were analysed with the aim of quantifying the efficiency of the percutaneous approach among our patient population. A total of 111 patients underwent chemonucleolysis between 1984 and 1989. The indication for the intervention was based on a several month history of lumbosciatica and a correlating radiological finding of disc protrusion or limited herniation. One case of anaphylaxis was the only serious perioperative complication. Upon follow-up examination approximately 2 months later, 54% of the patients were satisfied with the result, 27% reported an unchanged condition, and 19% had more pain than prior to the intervention. These results appear insufficient for an intervention associated with a non-negligible risk. Reduction of the nucleus pulposus appears often not to be an efficient mechanical concept for the treatment of disc protrusions and herniations.

Adult↗
PubMed1991

Outcome of acute supratentorial cerebral infarction in patients under 60. Development of a prognostic grading system.

Thirty-five patients under the age of 60 were admitted to the Neurosurgical Department of the Inselspital with acute supratentorial ischaemic strokes between February 1985 and June 1990. The mean delay from the onset of the symptoms until emergency room admission was 10 hours. CT scan, Doppler sonography, and angiography were done routinely at the time of admission and CT was repeated 24 hours later. Initial treatment consisted of mannitol, low-molecular dextran and prednisolone. Intravenous nimodipine was added to the protocol in 1987. Intensive care including hyperventilation and intracranial pressure monitoring was instituted in cases of deteriorating level of consciousness and considerable oedema as visualized on the primary or repeat CT scan. Eight patients developing severe intracranial hypertension and/or unilateral mydriasis despite hyperventilation and osmotherapy underwent decompressive craniectomy. A total of 9 patients died in the acute stage, all but one due to a cerebral cause. At 6 months, only 6 patients were without significant neurological or neuropsychological deficits. Fourteen patients were moderately disabled and 6 were severely disabled. There were no vegetative survivors. A number of demographic, clinical and radiological variables were investigated for a possible prognostic significance. A grading scale was developed for each variable. Of the initial neurological deficits, degree of motor paralysis, gaze deviation, and decreased level of consciousness correlated with an unfavourable result. While the prognostic significance of each of these individual variables was only moderate, the combined score of these 3 variables correlated better with outcome (r = 0.62). More advanced age was found to correlate with a less favourable prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Prognostic factors in the treatment of trigeminal neuralgia. Analysis of a differential therapeutic approach.

144 patients operated on for trigeminal neuralgia between June 1982 and May 1990 were followed for up to 8 years. 122 patients were treated by retrogasserian glycerol rhizolysis and 22 by posterior fossa exploration. The average age was 65 years. 89 patients were women and 55 men. The 1st branch was principally involved in 9 patients, the 2nd in 92 and the 3rd in 43. 32 patients had prior procedures. 102 of the 122 patients submitted to glycerol injection were rendered pain-free (84%). An additional 7 patients were relieved by a supplemental radiofrequency procedure, thus achieving an 89% success rate with the percutaneous approach. All 22 posterior fossa explorations were initially successful. 65 patients of the group treated percutaneously had some new postoperative objective and/or subjective sensory deficit as well as 13 of the patients operated on by posterior fossa exploration. Corneal sensation was decreased after 19 glycerol procedures including 3 who had a supplemental radiofrequency coagulation. No corneal hypaesthesia was seen after posterior fossa explorations. Kaplan-Meier analysis showed that at 5 years 59% of the percutaneous rhizolysis group were free of neuralgia and 68% of the patients treated by posterior fossa exploration. A number of patient characteristics and surgical factors were analysed for a possible correlation with outcome. Intact preoperative facial sensation was the most important prognostic factor for an initially successful operative result. Some degree of postoperative sensory deficit was the most important factor for long-term remission of neuralgia. However, of the 54 patients with a postoperative new sensory deficit who were available for long-term follow-up, 13 complained of persistent disturbing disaesthesias.

Aged↗
PubMed1990

Early prognosis of supratentorial grade 2 astrocytomas in adult patients after resection or stereotactic biopsy. An analysis of 50 cases operated on between 1984 and 1988.

50 adult supratentorial low-grade astrocytomas operated upon between 1984 and 1988 were analysed retrospectively with respect to postoperative condition and progression-free survival. Pilocytic lesions were excluded. In 32 instances the tumour was macroscopically completely removed and partially in 4. In 14 cases a stereotactic biopsy was performed only. 10 patients received postoperative radiotherapy with 55 to 65 Gy. 1 patient died perioperatively from pulmonary embolism. 39 patients could resume their previous activities after discharge from the hospital, 10 were significantly disabled by neurological deficit, reduced neuropsychological performance or medically intractable epilepsy. Postoperatively, most patients required continuous anti-epileptic medication, 10 recurrences or tumour progressions of incompletely removed or merely biopsied lesions were observed within the mean follow-up period of 22 months. All recurrences after gross total removal, that were reoperated, had progressed to a malignant glioma. Of the prognostic tumour characteristics analysed, a histologically well-delineated tumour demarcation was most clearly associated with a favourable prognosis. Concerning treatment modalities, gross total resection was associated with a favourable prognosis. Radiotherapy was associated with an unfavourable outcome but this is probably due to selection of otherwise unfavourable cases.

Adolescent↗
PubMed1990

[Anemia-induced focal cerebral symptoms in carotid stenoses. Observations of pathophysiology].

Four patients with cerebral ischemic events related to anemia or therapeutic hemodilution were observed within a 10-month period. Upper gastro-intestinal hemorrhage was responsible in 2 patients. The 3rd suffered from chronic polyarthritis and erosive gastritis, and in the 4th instance, the decrease of hematocrit was the result of a therapeutic hemodilution for polycythemia. A significant carotid stenosis corresponding to the symptoms was diagnosed in all patients. Passage of emboli in the middle cerebral or ophthalmic artery respectively was detected in two patients during the transcranial Doppler exam. Analysis of the effect of a decrease of hematocrit on arterial stenoses suggests that cerebral ischemic events related to blood loss are partially due to induced embolism.

Aged↗
PubMed1990

[Stereotaxic brain puncture. Indications and results].

228 stereotactic biopsies for the diagnosis of brain lesions were evaluated. In 98.2% a diagnosis could be established. The diagnosis was made of brain tumor in 79.3%, of brain abscess in 7.5% and of encephalitis in 3.5% of cases. In 2.2% of the patients a pathological finding was obtained without a clear histological definition. No histological diagnosis could be made in 1.8% of the patients. A severe complication of brain biopsy occurred in 2.2% of the patients (1 death, 1 abscess, 3 increased impairments). The stereotactic procedure appears to have a low mortality and morbidity, and to be highly accurate.

AIDS Dementia Complex↗
PubMed1989

[Results in microsurgical carotid artery endarterectomy].

100 consecutive carotid endarterectomies were performed by a microscopic technique with monitoring of cerebral perfusion by transcranial Doppler sonography and EEG. No additional cerebral deficits occurred in this series. Perioperative mortality due to medical complications occurred in 2 instances. During the average follow-up period of 15 months, 1 patient suffered a lethal cerebral infarction ipsilateral to the operated carotid artery and 1 patient a contralateral minor stroke. 2 patients died from unrelated causes during follow-up.

Aged↗
PubMed1989

Radical resection of superior sagittal sinus meningioma with venous interposition graft and reimplantation of the rolandic veins. Case report.

A case of a 48 year old women is reported in whom a haemangiopericytic meningioma involving the middle third of the superior sagittal sinus was radically excised. The sinus was replaced by a saphenous vein graft and the Rolandic veins were reinserted. During clamping of the sinus the patient was heparinized and hypothermia, hypotension and barbiturates were used to prevent swelling of the brain. The postoperative course was uncomplicated and patency of the graft was demonstrated 2 weeks after the operation by Doppler sonography performed through a midline burr hole. The technical details of the operation and the pertinent physiology of cerebral venous flow are discussed.

Cranial Sinuses↗
PubMed1989

Results of microsurgical carotid endarterectomy. A prospective study with transcranial Doppler and EEG monitoring, and elective shunting.

100 consecutive carotid endarterectomies in a total of 93 patients were performed using the operative microscope. Cerebral perfusion and activity were monitored with simultaneous transcranial Doppler (TCD) and EEG. Thiopentone for cerebral protection was given prior to carotid clamping in 11 cases when an insufficient collateral circulation was suspected on the basis of the pre-operative TCD or angiography and if temporary intraluminal shunting was to be avoided because of a high bifurcation, long stenosis or associated carotid artery kinking. A temporary intraluminal shunt was inserted electively if the mean middle cerebral artery flow velocity fell after cross-clamping below 30-40%. Direct closure of the arteriotomy was preferred over a patch graft, which was performed only in cases with concomitant stricture of the arterial wall. No peri-operative strokes occurred in the present series. Two patients died due to medical complications in the post-operative period. During the mean follow-up of 15 months, 1 patient suffered a lethal stroke ipsilateral to the treated carotid artery and another patient had a minor contralateral stroke. Two patients died of unrelated causes during follow-up. Two patients suffered a single reversible neurologic deficit corresponding to the treated carotid territory. Four other patients had a single contralateral hemispheric or retinal reversible ischaemic attack during follow-up.

Adult↗
PubMed1989

Growth of aneurysms can be understood as passive yield to blood pressure. An experimental study.

The strength of aneurysm walls obtained intraoperatively or at autopsy immediately after death was evaluated by measurements of the force response to one-directional stretch and compared to the walls of intracranial arteries. The maximum stress that aneurysm tissue could tolerate was found slightly lower than in arteries, which is most probably due to the amount of immature forms of collagen. The stress resistance of aneurysms and arterial tissue decayed over a period of several hours. The relaxation curve could be approximated by the sum of 2 exponential terms. The half decay times of these terms were found identical in aneurysms and arteries, they appear to be collagen characteristics. The strength measured in vitro was compared to the stress in vivo, which was calculated on the basis of blood pressure and aneurysm radius. The stress tolerated by aneurysm walls over a period of 24 hours was found to be in the range of the stress that is imposed in vivo by the mean blood pressure. Arteries resisted stresses corresponding to pressures 10 to 20 times higher than physiological values. The thickness of the aneurysm walls correlated with the aneurysm radius in a linear fashion. It is suggested that aneurysm growth can be understood as passive yield to blood pressure, and reactive healing and thickening of the wall with increasing aneurysm diameter.

Biomechanical Phenomena↗
PubMed1989

Strength, elasticity and viscoelastic properties of cerebral aneurysms.

Tissue strength and stiffness of cerebral aneurysm walls obtained intraoperatively or at autopsy were evaluated by uniaxial strain/stress measurements. For comparison, corresponding measurements were also made on autopsy specimens of intracranial arteries. The maximum stress that the aneurysm tissue could tolerate, the yield stress, was found to be slightly lower than in arteries, which is likely due to the content of immature forms of collagen. The material stiffness, as determined by division of the yield stress by the corresponding strain, was also smaller in aneurysms than in arteries. The stress resistance of aneurysms and arterial tissue decreased over a period of several hours. The relaxation curves were found to be identical in aneurysms and arteries. The stress tolerated by aneurysm walls was found to be in the range of the stress that is imposed in vivo by the blood pressure. Arteries resisted stresses corresponding to pressures 5-10 times higher than physiological values. It is suggested that the balance of tissue strength and the stress imposed by the blood pressure is causally related to aneurysm growth.

Adult↗
PubMed1988

[Cerebral cavernoma as a cause of recurrent cerebral hemorrhage and epileptic insults].

Cerebral cavernous angiomas or cavernomas have been increasingly diagnosed in recent years as a cause of recurrent cerebral hemorrhage or epilepsy. Some cavernomas exhibit a tumorous growth tendency. On CT-scan, cavernomas appear as variably cystic lesions often with focal calcifications. The lesion may be masked by a surrounding hematoma. Seventeen cases were observed initially or on follow-up within 3 years. Examination of the surgical specimens allowed differentiation of the lesions into several subtypes correlating to the different clinical courses. The diagnosis of cavernomas is important since these lesions can be cured surgically. The spontaneous clinical course, however, is usually progressive.

Adolescent↗