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B Schaller

Publications and source records attributed to B Schaller.

At least 37 records · Page 2Linked to original sources
PubMed2003

[Neuroprotection in brain tumors. Good sense or nonsense from the pathophysiological viewpoint?].

The hemodynamic and metabolic state of peritumoral brain tissue is not well understood, especially with subtotal or total, extraluminal compression of the carotid artery or other main intracranial vessels of the central nervous system. Possibly, parallels can be drawn from the knowledge in chronically malperfused brain tissue of atherosclerotic disease in sub- or nearly total stenosis of the internal carotid artery. From this point of view, it seems that the CBF/CBV quotient and oxygen extraction rate represent an additional diagnostic method-if needed in combination with the well-established balloon occlusion test-to help to better characterize the grade of still viable peritumoral brain tissue. The therapeutic strategy for possible pharmacological neuroprotection should be related to these parameters. It remains a matter of debate whether this clinical phenomenon will be one of the therapeutic domains influenced by ischemic preconditioning in the near-future.

Brain↗
PubMed2003

Effects of cerebral perfusion pressure and increased fraction of inspired oxygen on brain tissue oxygen, lactate and glucose in patients with severe head injury.

OBJECTIVE: The purpose of the study was to measure the effects of increased inspired oxygen on patients suffering severe head injury and consequent influences on the correlations between CPP and brain tissue oxygen (PtiO2) and the effects on brain microdialysate glucose and lactate. METHODS: In a prospective, observational study 20 patients suffering severe head injury (GCS< or =8) were studied between January 2000 and December 2001. Each patient received an intraparenchymal ICP device and an oxygen sensor and, in 17 patients brain microdialysis was performed at the cortical-subcortical junction. A 6 h 100% oxygen challenge (F IO2 1.0) ( Period A) was performed as early as possible in the first 24 hours after injury and compared with a similar 6 hour period following the challenge ( Period B). Statistics were performed using the linear correlation analysis, one sample t-test, as well as the Lorentzian peak correlation analysis. RESULTS: F IO2 was positively correlated with PtiO2 (p < 0.0001) over the whole study period. PtiO2 was significantly higher (p < 0.001) during Period A compared to Period B. CPP was positively correlated with PtiO2 (p < 0.001) during the whole study. PtiO2 peaked at a CPP value of 78 mmHg performing a Lorentzian peak correlation analysis of all patients over the whole study. During Period A the brain microdialysate lactate was significantly lower (p = 0.015) compared with Period B. However the brain microdialysate glucose remained unchanged. CONCLUSION: PtiO2 is significantly positively correlated with F IO2, meaning that PtiO2 can be improved by the simple manipulation of increasing F IO2 and ABGAO2. PtiO2 is positively correlated with CPP, peaking at a CPP value of 78 mmHg. Brain microdialysate lactate can be lowered by increasing PtiO2 values, as observed during the oxygen challenge, whereas microdialysate glucose is unchanged during this procedure. Extension of the oxygen challenge time and measurement of the intermediate energy metabolite pyruvate may clarify the metabolic effects of the intervention. Prospective comparative studies, including analysis of outcome on a larger multicenter basis, are necessary to assess the long term clinical benefits of this procedure.

Adolescent↗
PubMed2003

Hypothermia and stroke: the pathophysiological background.

Hypothermia to mitigate ischemic brain tissue damage has a history of about six decades. Both in clinical and experimental studies of hypothermia, two principal arbitrary patterns of core temperature lowering have been defined: mild (32-35 degrees C) and moderate hypothermia (30-33 degrees C). The neuroprotective effectiveness of postischemic hypothermia is typically viewed with skepticism because of conflicting experimental data. The questions to be resolved include the: (i) postischemic delay; (ii) depth; and (iii) duration of hypothermia. However, more recent experimental data have revealed that a protected reduction in brain temperature can provide sustained behavioral and histological neuroprotection, especially when thermoregulatory responses are suppressed by sedation or anesthesia. Conversely, brief or very mild hypothermia may only delay neuronal damage. Accordingly, protracted hypothermia of 32-34 degrees C may be beneficial following acute cerebral ischemia. But the pathophysiological mechanism of this protection remains yet unclear. Although reduction of metabolism could explain protection by deep hypothermia, it does not explain the robust protection connected with mild hypothermia. A thorough understanding of the experimental data of postischemic hypothermia would lead to a more selective and effective clinical therapy. For this reason, we here summarize recent experimental data on the application of hypothermia in cerebral ischemia, discuss problems to be solved in the experimental field, and try to draw parallels to therapeutic potentials and limitations.

Journal Article↗
PubMed2002

[Cerebral ischemia tolerance].

Ischemic tolerance means a rapid adaptative cerebral reaction to one or more cycles of short ischemia and reperfusion, improving the tolerance to a subsequent longer ischemia. The basic molecular mechanisms of ischemic tolerance are largely unknown. The pathophysiological course can be divided in induction, transduction and tolerance. During induction NMDA- and adenosin receptors, free radicals and conservation of energy metabolism are required. Protein kinases, transcription factors, and immediate early genes play a role in transduction. Tolerance can be observed in different time windows. The early phase lasts for several hours after the preconditioning stimulus and can be related to adenosine receptors and ATP-dependent potassium channels. A delayed phase, after 1-7 days, is explained by genetic remodeling. Clinically, there is evidence for a protective effect of transient ischemic attacks occurring before stroke.

Cerebral Infarction↗
PubMed2002

Cerebral ischemic preconditioning. An experimental phenomenon or a clinical important entity of stroke prevention?

Neurons can be preconditioned by various procedures to resist ischemic events. The preconditioning mechanism induced is characterized by a brief episode of ischemia that renders the brain more resistant against subsequent longer ischemic events. This ischemic tolerance has been shown in numerous experimental models of cerebral ischemia. The basic molecular mechanisms of ischemic tolerance are largely unknown. During the induction phase N-methyl-O-aspartate and adenosine receptors and, possibly, oxygen free radicals and conservation of energy metabolism are required. Protein kinases, transcription factors, and immediate early genes appear to transduce the signal into a tolerant response. Although the mechanism of ischemic tolerance remains uncertain, its discovery provides the focus for further understanding of the mechanism of endogenous neuroprotection and the potential of novel therapeutic strategies for neuroprotection. Such neuroprotective strategies may extend beyond ischemic tolerance to include other brain injury states as well.

Animals↗
PubMed2002

[Craniocerebral trauma--new pathophysiological and therapeutic viewpoints].

AIM: The prognosis has markedly improved during the last years after mild and moderate head injuries. After severe head trauma, this evolution could not be observed so far. This requires a better understanding of pathophysiological interaction, especially in the subacute and late phase of trauma. METHODS: Review article. DISCUSSION: Causes for the development of secondary brain damage are the intracranial space demand after traumatic injury and edema formation which max result in ischemia, as well as inflammatory processes. Both isolated severe head trauma and polytrauma with or without brain damage may result in a systemic inflammatory response syndrome due to the synthesis of cytokines and other inflammatory mediators which may cause a single or multiple organ failure. The hypermetabolism after severe head trauma is often regarded as an interaction between the central nervous system and the whole organism by the activation of the neuroendocrine axis. Moreover, coagulation, metabolism and fracture healing are influenced by the onset of SIRS as well. CONCLUSION: Our knowledge about the bidirectional inflammatory interaction between brain and whole organism is still limited. It is generally accepted that extracranial complications are highly influential in determining the outcome from severe head injury.

Brain Damage, Chronic↗
PubMed2001

[Anterior spinal artery syndrome: an important differential diagnosis of acute non-traumatic transverse spinal cord syndrome].

We report on a 77-year-old man who was suffering from pain in the chest, which was initially circumferential, along with paresthesia in his left leg, a fluctuating spastic paraparesis and dissociated sensory disturbances caudal to segment T8. In his history, he had received an aortoiliac Y-prothesis for a ruptured retroperitoneal intrarenal aortic aneurysm 39 months previously. Diagnostically, magnetic resonance imaging of the spine revealed advanced degenerative changes with osseous stenoses in segments C5-6 and less pronounced on C6-7. There were no signs of myelopathy. The results of the computerized tomogram of the neurocranium were consistent with the patient's age. The computerized tomogram of the chest and abdomen revealed a left outward bulge in the descending branch of the thoracic artery that was almost 20 mm in length. Based on the differential diagnosis, this was interpreted as an aneurysmatic sacculation with wall thrombosis or a locally circumscribed intramural hematoma upon dissection. Electrophysiologic testing by conduction of magnet-evoked potentials showed no lesions of the pyramidal tract to the extremities above the lumbosacral level. Lumbosacral stimulation evoked potentials on both sides whereas cortical stimulation did not. Based on the patient's history, the clinical findings and additional tests, the diagnosis of anterior spinal artery syndrome was rendered although its cause could not be determined with certainty. The previous transitory ischemic attack and the varying course of the disease is very exceptional in the presented case.

Aged↗
PubMed2001

Do we really need routine computed tomographic scanning in the primary evaluation of blunt chest trauma in patients with "normal" chest radiograph?

BACKGROUND: A major cause of morbidity and mortality after blunt chest trauma remains undetected injuries. This study evaluates the role of routine computed tomographic (CT) scan. METHODS: We studied 93 consecutive patients from January 1999 to July 2000: 73 (76.3%) after motor vehicle crash with crash speed > 10 mph, and 22 (23.7%) after fall from height > 5 ft. Simultaneous with initial clinical evaluation, anteroposterior chest radiograph and helical chest CT scan were obtained for all patients. RESULTS: Sixty-eight patients (73.1%) showed at least one pathologic sign on chest radiograph, and 25 patients (26.9%) had normal chest radiograph. In 13 (52.0%) of these 25 patients, the CT scan showed multiple injuries; among these were two aortic lacerations, three pleural effusions, and one pericardial effusion. CONCLUSION: Over 50% of patients with normal initial chest radiograph showed multiple injuries on the CT scan, among which were also two (8%) potentially fatal aortic lesions. We therefore recommend primary routine chest CT scan in all patients with major chest trauma.

Adolescent↗
PubMed2000

Glial cell line-derived neurotrophic factor stimulates the morphological differentiation of cultured ventral mesencephalic calbindin- and calretinin-expressing neurons.

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for mesencephalic dopaminergic neurons. Subpopulations of these neurons express the calcium-binding proteins calbindin (CB) and calretinin (CR). Understanding the specific effects of GDNF on these neurons is important for the development of an optimal cell replacement therapy for Parkinson's disease. To investigate the effects of GDNF on the morphological complexity of mesencephalic tyrosine hydroxylase (TH)-immunoreactive (-ir), CB-ir, and CR-ir neurons, dissociated cultures of embryonic (E14) rat ventral mesencephalon were prepared. Chronic administration of GDNF (10 ng/ml) for 7 days promoted the survival of TH-ir and CB-ir neurons but did not alter the density of CR-ir neurons. Total fiber length/neuron and number of branching points/neuron of CB-ir and CR-ir cells were significantly increased after GDNF treatment (2x for CB-ir cells and 1.4x and 1.7x, respectively, for CR-ir cells), which resulted in a significantly larger size of neurite field/neuron (2.9x and 1.5x for CB-ir and CR-ir neurons, respectively). The number of primary neurites/neuron of CB-ir neurons was found to be 1.5x larger, while no difference could be detected for CR-ir cells. Assessment of the effects of GDNF on TH-ir neurons unveiled a similar outcome with an increased total fiber length/neuron (1.5x), an increased number of primary neurites/neuron (1.6x), and a twofold larger size of neurite field/neuron. In conclusion, our findings recognize GDNF as a neurotrophic factor that stimulates the morphological differentiation of ventral mesencephalic CB-ir and CR-ir neurons.

Animals↗
PubMed2000

[Pylorus preserving or classical Whipple operation in tumors. Initial clinical results of a prospective randomized study].

UNLABELLED: During the last decades, the classical Whipple resection (cWhipple) and pylorus-preserving Whipple (ppWhipple) operation have been evolved for the resection of cancer of the pancreatic head. However no definitive answer exists whether the more conservative ppWhipple indeed equalizes the short and long term results of the cWhipple procedure. METHODS: Therefore we conducted a randomized prospective trial in a non-selected, consecutive patient series. All relevant data concerning patient's demographics, intraoperative and histological findings as well as postoperative mortality morbidity and follow-up after discharge were analyzed. RESULTS: From 6/96 to 10/99 139 patients with suspicion of pancreatic or periampullary tumor were prospectively randomized to undergo either a cWhipple or a ppWhipple (intention to treat). Based on the inclusion and exclusion criteria, 93 of these patients were finally analyzed in the study. There were 51 cWhipple and 42 ppWhipple resections. There were no differences concerning age, sex, ASA classification, tumor type and stage, length of ICU- and in-hospital stay. However, the ppWhipple group had a significant shorter operation time. There was no difference in mortality and morbidity. The incidence of delayed gastric emptying was identical in both groups. For long-term follow-up, a total of 76 patients with histological proven pancreatic or periampullary carcinoma were analyzed. There was no difference in tumor recurrence and in long-term survival after a median follow-up of 1.5 years (0.1-3.5). CONCLUSION: Our intermediate results demonstrate that cWhipple and ppWhipple are equally radical. However, ppWhipple may be the procedure of choice for the treatment of pancreatic and periampullary cancer.

Adenocarcinoma↗
PubMed1999

[Cerebellar syndrome after varicella infection without virus identification in cerebrospinal fluid--an important differential ataxia diagnosis].

We report on a 35 year old female with a 26 day history of an intermittent cerebellar syndrome (dysarthria, ataxia of extremities, gait and trunk, nystagmus), mild meningism, cephalgia, recurrent emesis and nausea. Symptoms developed after typically chickenpox exanthema. Examination of the liquor showed mild pleocytosis, elevated protein and increased albumin quotient. Virus was not found by EIA or PCR. There were elevated levels of IgM- and IgG-antibodies to VZV. The EEG showed mild general changes, compatible with an encephalitis. Neuroradiological examinations were unremarkful. The neurological deficits partly regressed in the follow-up of two months. To the best of our knowledge we are the first that describe the paradox of an intermittent cerebellar syndrome after infection with chickenpox without detection of the virus in the liquor. This phenomenon can be related to the unusual combination of cerebellar ataxia and the later occurrence of mild encephalitis.

Adult↗
PubMed1999

[Intermittent paraparesis as manifestation of a bilateral chronic subdural hematoma].

Chronic subdural haematomas are mainly related to slight or moderate head trauma with consecutive lesion of bridge or cortical veins and bleeding in the subdural space. Further predisposing factors are known impairment of coagulation (coagulopathies, treatment with anticoagulants, alcohol abuse), risk factors for degenerative disease of the arteries (diabetes mellitus, arterial hypertension), and development of pressure gradients (hydrocephalus, epileptic seizures, lumbar puncture, CSF drainage and cerebral atrophy). Chronic subdural haematomas appear bilaterally in 20 to 25% of cases. We report on a 69-year-old male with a 4-day history of intermittent, proximal, painless paraparesis (BMA grade M2-5) without a trigger event. Sensibility was normal in all qualities and vigilance was not disturbed. Computed tomography of the neurocranium revealed a bitemporally located chronic subdural haematoma with extension to parietal on both sides. Trepanation was performed over the tuber parietale and temporoparietally on both sides, with release of 150 ml fluid. The neurologic deficits regressed totally within 12 hours postoperatively. To the best of our knowledge, we are the first to describe the clinical paradox of intermittent, painless paraparesis with preserved sensibility and without disturbances of vigilance, as manifestation of a chronic subdural haematoma possibly leading to impairment of cerebral blood flow in the area of the middle cerebral artery. Small changes in systemic blood pressure lead to changes in cerebral perfusion pressure due to vessel compression by the haematoma, thus explaining the intermittent character of the clinical presentation.

Aged↗
PubMed1999

Premeatal and retromeatal cerebellopontine angle meningioma. Two distinct clinical entities.

OBJECTIVE: Meningiomas represent the second most common type of neoplasm of the cerebellopontine angle (cpa). Their relationship to critical neural or vascular structures of the cpa is variable and they present with different signs and symptoms. MATERIALS AND METHODS: A retrosigmoid craniotomy was performed in 31 cpa-meningiomas from January 1981 to February 1997. The mean age of the 25 women (81%) and the 6 men (19%) was 53 +/- 13 years. According to their location within the posterior fossa and with special reference to the internal auditory canal (IAC), they were classified in 17 cases (55%) as retromeatal (posterior to the iac) and in 14 cases (45%) as premeatal (anterior to the iac). RESULTS: The retromeatal group showed a significantly larger tumour size (21 +/- 15 vs 29 +/- 20 mm) and the diagnosis was made later (2.7 +/- 3.2 vs 1.1 +/- 0.9 years) compared to premeatally located meningiomas. Before the operation, a reduction of the facial nerve function (64% vs 0%) and hearing function (100% vs 25%) was present significantly more often in premeatal meningiomas. The clinical appearance of the retromeatal group was dominated by cerebellar symptoms (44% vs 0%). Both preoperative and postoperative impairment of facial nerve and auditory function prevailed in the premeatal group. CONCLUSION: The topological classification of CPA-meningiomas according to their location anterior or posterior to the ICA is important, because the clinical presentation, the surgical strategy to be applied, and the functional outcome of critical neural structures differ between the two subtypes. Our results provide substantial evidence for the paradoxical observation that premeatal meningiomas have a significantly worse postoperative functional outcome compared to retromeatal meningiomas although premeatal meningiomas become symptomatic earlier and at smaller sizes.

Adult↗
PubMed1999

Trigeminocardiac reflex during surgery in the cerebellopontine angle.

OBJECT: In different experimental studies authors have analyzed the autonomic responses elicited by the electrical, mechanical, or chemical stimulation of the trigeminal nerve system. The trigeminocardiac reflex (TCR) is a well-recognized phenomenon that consists of bradycardia, arterial hypotension, apnea, and gastric hypermotility. It occurs during ocular surgery and during other manipulations in and around the orbit. Thus far, it has not been shown that central stimulation of the trigeminal nerve can also cause this reflex. METHODS: The TCR was defined as clinical hypotension with a drop in mean arterial blood pressure (MABP) of more than 20% and bradycardia lower than 60 beats/minute. Pre-, intra-, and postoperative heart rate (HR) and MABP were reviewed retrospectively in 125 patients who underwent surgery for tumors of the cerebellopontine angle (CPA), and they were divided into two groups on the basis of the occurrence of the TCR during surgery. Of the 125 patients, 14 (11%) showed evidence of the TCR during dissection of the tumor near the trigeminal nerve at the brainstem. Their HRs fell 38% and their MABPs fell 48% during operative procedures as compared with preoperative levels. After cessation of manipulation, the HRs and the MABPs returned to preoperative levels. Risk factors for the occurrence of the TCR were compared with results from the literature. CONCLUSIONS: The authors' results show the possibility of occurrence of a TCR during manipulation of the central part of the trigeminal nerve when performing surgery in the CPA.

Adolescent↗