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Biomedical subjects

Bernhard Schaller

Publications and source records attributed to Bernhard Schaller.

At least 19 recordsLinked to original sources
PubMed2006

Intradural, extramedullary spinal sarcoidosis: report of a rare case and review of the literature.

BACKGROUND: Spinal sarcoidosis represents a rare subgroup of neurosarcoidosis. Most spinal sarcoid lesions are intramedullary, and only eight cases of intradural, extramedullary sarcoid lesions have been reported hitherto. We describe the complete entity of intradural, extramedullary spinal sarcoidosis. METHODS: A 39-year-old woman presented with a 2-year history of slowly progressive numbness and paresthesia of the right medial upper arm followed by brachialgia and cephalgia. Magnetic resonance imaging revealed an intradural extramedullary T1 isointense and T2 hyperintense mass lesion near the right C3 nerve root exit C3, extending into the right neuroforamen. The cervical cord was not severely compressed. The mass lesion showed a high T2 signal. After intravenous administration of gadolinium-diethylenetriaminepentaacetic acid, there was marked enhancement of the process. RESULTS: The patient underwent a C2 to C3 laminoplasty and total resection of the intradural extramedullary tumor. The lesion encroached along the right neuroforamen, involving the C3 nerve root, and was grossly adherent to some of the rootlets. Histopathological examination of the specimen showed a noncaseating granulomatosis consistent with sarcoidosis. Postoperative testing did not reveal systemic involvement of sarcoidosis but bilateral hilar and mediastinal lymphadenopathy with normal lung parenchyma. The patient was therefore treated with corticosteroids. During the follow-up period of 16 months, the patient made a satisfactory recovery, though with persistent, distally pronounced sensory disturbance in the C3 or C4 root areas, and returned to work full-time. CONCLUSION: An extramedullary sarcoid lesion is rare. Unlike intramedullary sarcoid lesions, it can be totally removed. Even if systemic sarcoidosis is present, the patient can have an excellent recovery. From a review of the literature, we can hypothesize that intradural extramedullary spinal sarcoidosis may represent a very early stage of spinal sarcoidosis progressing to intramedullary intradural spinal sarcoidosis. The intradural extramedullary spinal sarcoidosis can be subdivided into a peripheral and a central subtype. Positive histological examination is required to establish the diagnosis since other diagnostic tests are unspecific.

Adult↗
PubMed2005

Prospects for the future: the role of free radicals in the treatment of stroke.

Studies using animal models of stroke have demonstrated that free radicals are highly reactive molecules generated predominantly during cellular respiration and normal metabolism. Imbalance between cellular production of free radicals and the ability of cells to defend against them is referred to as oxidative stress. After ischemic brain damage introduced by ischemic stroke or reperfusion, production of reactive oxygen species may increase, sometimes drastically, leading to tissue damage via several different cellular molecular pathways. The damage can become more widespread due to weakened cellular antioxidant defense systems after ischemic stroke. These experimental findings have important implications for the treatment of human cerebral ischemia. Agents directed at eliminating oxygen radicals must be administered before, or in the early stages of, reperfusion after ischemia. The therapeutic window seems to be narrow and limited to, at most, a few hours. Future research may clarify the current hypothesis that the accuracy of gene expression could account for the recovery of cellular function after ischemic stroke. This may open the window to the future use of drug combinations that may be rationally administered sequentially. If the phenomenon of ischemic tolerance plays a role in this concept is still a matter of debate.

Animals↗
PubMed2005

Ischemic preconditioning as induction of ischemic tolerance after transient ischemic attacks in human brain: its clinical relevance.

Ischemic preconditioning has been well-established in different animal models of cerebral ischemia. Suggesting that transient ischemic attack (TIAs) may represent a clinical model of ischemic tolerance, patients with ipsilateral TIA before ischemic stroke may have a better neurological outcome compared to patients without TIA before ischemic stroke. A retrospective case-control study. Analysis of clinical and neuroradiological findings of 130 patients treated with local intra-arterial thrombolysis using urokinase after ischemic stroke between January 2000 and May 2002. Eleven patients (8%) demonstrated prestroke ipsilateral TIA in the same vascular territory. Despite no significant differences in baseline characteristics, independence (modified Ranking Scale score) and neurological outcome (NIHS score) were significantly associated with prior TIA in multivariante models. Patients with prestroke TIA, showing a similar clinical picture (NIHS score) on admission, demonstrated a more favorable outcome (NIHS score (p<0.001) and modified Ranking score (p<0.0001)) compared to patients with unheralded ischemic stroke. The interval between TIA and ischemic stroke (1-7 days), duration of TIAs (0-20 min) and number of TIAs (2-3) influenced the better outcome in this patients' subgroup. In addition, we could show an induction of ischemic tolerance by prestroke ASA treatment in patients without previous new-onset TIA. Two to three ipsilateral TIA of the same vascular territory and of up to 20 min duration within 1-7 days may lead to ischemic tolerance to a subsequent ischemic stroke as demonstrated by significantly diminished infarct extention throughout all cortical imagines in neuroradiological studies. The role of ASA has to been further elucidated.

Case-Control Studies↗
PubMed2005

Spinal meningioma: relationship between histological subtypes and surgical outcome?

Intraspinal meningiomas are slow growing benign tumors that produce indolent neurological deficits, which are often reversible following operation. It is unclear, if there is a correlation between postoperative neurological restoration and histopathological parameters. The aim of the present work was to seek for existence of such parameters. Retrospectively, we reviewed the charts of 33 patients with spinal meningiomas who were operated on from January 1980 through December 1995. Histological classification was performed according to WHO criteria. Laminoplasty or hemilaminoplasty was performed in 29 patients (88%) and suboccipital craniotomy with cervical laminoplasty in 4 patients (12%). Mean age of the 30 women (91%) and the 3 men (9%) was 63+/-20 years (range 22-88). Spinal meningiomas were of high-cervical location in 9 (27%) and of low-cervico-thoracic location in 24 (73%) patients. Tumor position was laterally in 19 (58%), posteriorly in 8 (24%) and anteriorly in 6 (18%) patients. Histological classification was psammomatous in 22 (66%), fibroblastic in 7 (22%) and meningothelial in 4 (11%) patients. Following tumor resection, neurological deficits resolved in 26 of 33 patients (79%) and worsened in 7 of 33 patients (21%) all of the latter had meningiomas of the psammomatous type. Resection of psammomatous meningiomas of the spine is associated with a less favorable neurological outcome postoperatively than resection of spinal meningiomas of other pathological subtypes. Posterior or lateral tumor position in the spinal canal, location below C4, age less than 60 years, and duration of preoperative symptoms seem to be correlated with a good outcome.

Adult↗
PubMed2005

Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas.

BACKGROUND: The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility. It occurs during ocular surgery or other manipulations around the orbit and can also be elicited by stimulation of the central part of the trigeminal nerve during surgery for processes of the cerebellopontine angle. The present retrospective study was conducted to determine if TCR occurs during transsphenoidal surgery in the same way. METHODS: TCR was defined as a drop in mean arterial blood pressure (MABP) and the heart rate (HR) of more than 20% to the baseline values before the stimulus and coinciding with manipulation of the trigeminal nerve. Pre-, intra-, and postoperative HR and MABP were retrospectively reviewed in 117 patients who underwent resection of pituitary adenomas near the trigeminal nerve at the cavernous sinus in the supine position. Tumor invasiveness was classified according to the modified Hardy criteria. RESULTS: Of the 117 patients with immunohistochemically and/or electromicroscopically proven pituitary adenoma, 12 (10%) patients demonstrated intraoperative evidence of TCR according to the strict inclusion criteria. In these 12 patients, the HR and MABP decreased by a mean of 43 and 54%, respectively, from the preoperative mean levels during microsurgical manipulation near the cavernous sinus and returned to physiological levels within 10 min after cessation of this surgical maneuver. The percentage of invasive adenomas (grade III-IV) was significantly higher in the TCR subgroup than in the non-TCR subgroup (83% versus 22%). CONCLUSION: The present results give evidence for the first time that TCR may occur during transsphenoidal surgery in the supine position for resection of pituitary adenomas near the cavernous sinus, leading to a significant decrease in HR and MABP under a standardized anesthetic protocol.

Adolescent↗
PubMed2005

Trigemino-cardiac reflex during microvascular trigeminal decompression in cases of trigeminal neuralgia.

The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility during ocular surgery or other manipulations in and around the orbit. Thus far, it could bee shown that central stimulation of the trigeminal nerve during transsphenoidal surgery and surgery for tumors in the cerebellopontine angle can lead to TCR. In cases of microvascular trigeminal decompression for trigeminal neuralgia, no data of the possible occurrence of TCR are available. TCR was defined as a drop in mean arterial blood pressure (MABP) and the heart rate (HR) of more than 20% to the baseline values before the stimulus and coinciding with the manipulation of the trigeminal nerve. Electronic anesthetic recorded perioperative HR and MABP values were reviewed retrospectively in 28 patients who received microvascular trigeminal decompression in cases of trigeminal neuralgia and were divided into two subgroups on the basis of occurrence of TCR during surgery. Of the 28 patients, 5 (18%) showed evidence of TCR during manipulation at the trigeminal radix by separation from microvascular structures. Their HR fell 46% and their MABP 57% during operative procedures near the trigeminal nerve as compared with levels immediately before the stimulus. After cessation of manipulation, HR and MABP returned (spontaneously) to levels before the stimulus. Risk factors of TCR were compared with results from the literature. In conclusion, the present results give evidence of TCR during manipulation of the central part of the trigeminal nerve during microvascular trigeminal decompression in cases of trigeminal neuralgia under a standardized anesthetic protocol.

Adult↗
PubMed2005

Gender-related differences in prolactinomas. A clinicopathological study.

BACKGROUND/AIMS: Prolactinomas are the most common tumors of the pituitary gland. Only few studies have documented gender-related differences in the growth and presentation of these tumors, but nothing is known about their effects on their subsequent surgical outcome and prognosis. PATIENTS & METHODS: Twenty-six patients with prolactinomas, that met strict immunohistochemical and electron microscopic criteria and were surgically treated between January 1990 and June 1997, were retrospectively reviewed. The patient charts, as well as histological (mitotic index) immunohistological (MIB-1 labeling-index) and electronic microscopical staining were analyzed. RESULTS: Nineteen patients were women, and seven were men; the female-to-male-ratio was 2.7:1. Men were significantly older, both at diagnosis and surgery. Menstrual abnormalities were the most common presenting symptom in women, whereas impotence predominated in men. Psychological symptoms were significantly more common in men than in women. Men had a significantly shorter preoperative duration of symptoms and higher preoperative serum prolactin levels than women. The preoperative prolactin levels and proliferative activities (mitotic index, MIB-1 labeling index) were lower in women compared to men and showed a direct correlation to postoperative outcome. The overall outcome was significantly better in women than in men. In women, age less than 35 years was a beneficial prognostic factor, and preoperative bromocriptine treatment was associated with a significantly worse long-term-outcome. CONCLUSION: The biology and the clinical course of prolactinomas seem to differ in women and men. In men, the preoperative durations of symptoms is shorter, the tumors are larger and more invasive at surgery, and the outcome is worse than in women. Based on proliferative activities (mitotic index, MIB-1 labeling index), the predominance of marcoadenomas in men is due to a high frequency of rapidly growing tumors, which are often invasive and frequently correlated with a worse outcome. Our findings may justify a more aggressive therapeutic approach to prolactinomas in men than in women.

Adolescent↗
PubMed2004

Cerebral ischemia and reperfusion: the pathophysiologic concept as a basis for clinical therapy.

The ischemic penumbra has been documented in the laboratory animal as severely hypoperfused, nonfunctional, but still viable brain tissue surrounding the irreversibly damaged ischemic core. Saving the penumbra is the main target of acute stroke therapy, and is the theoretical basis behind the reperfusion concept. In experimental focal ischemia, early reperfusion has been reported to both prevent infarct growth and aggravate edema formation and hemorrhage, depending on the severity and duration of prior ischemia and the efficiency of reperfusion, whereas neuronal damage with or without enlarged infarction also may result from reperfusion (so-called reperfusion injury). Activated neutrophils contribute to vascular reperfusion damage, yet posthypoxic cellular injury occurs in the absence of inflammatory species. Protein synthesis inhibition occurs in neurons during reperfusion after ischemia, underlying the role that these pathways play in prosurvival and proapoptotic processes that may be differentially expressed in vulnerable and resistant regions of the reperfused brain tissue. Ischemia-induced decreases in the mitochondrial capacity for respiratory activity probably contribute to the ongoing impairment of energy metabolism during reperfusion and possibly also the magnitude of changes seen during ischemia. From these experimental data, the concept of single-drug intervention cannot be effective. Further experimental research is needed, especially of the study of biochemical markers of the injury process to establish the role of several drugs.

Animals↗
PubMed2003

Hemodynamic and metabolic effects of decompressive hemicraniectomy in normal brain. An experimental PET-study in cats.

Hemicraniectomy is increasingly used as treatment option in stroke and in head trauma, but little is known on the (patho)physiological regional effects of hemicraniectomy in the normal brain. A standard left-sided craniectomy was performed in three cats. Regional cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO(2)) and cerebral metabolic rate of glucose (CMR(glc)) were measured from the brain tissue underneath the craniectomy at 2, 20 and 28 h after hemicraniectomy. CBF significantly decreased (P<0.01) and oxygen extraction fraction (OEF) (P<0.05) significantly increased. CMRO(2) and CMR(glc) decreased only in regions with most severe CBF reduction. These effects remained for at least a day irrespective of corrective sustaining cranioplasty. The authors demonstrated for the first time that decompressive hemicraniectomy in the cat decreases CBF, and to a lesser extent CMR02 and CMR(glc) 2 h after hemicraniectomy in normal brain tissue that last for at least 1 day. Even though the underlying basis of these phenomena are not fully understood, this finding implies that persisting pathophysiological processes are induced by hemicraniectomy and should be taken into consideration for surgical indications.

Animals↗
PubMed2003

Brain tumor and seizures: pathophysiology and its implications for treatment revisited.

Seizures affect approximately 50% of patients with primary and metastatic brain tumors. Partial seizures have the highest incidence, followed by secondarily generalized, depending on histologic subtype, location, and tumor extent. The underlying pathophysiologic mechanisms of tumor-associated seizures are poorly understood and include theories of altered peritumoral amino acids, regional metabolism, pH, neuronal or glial enzyme and protein expression, as well as immunologic activity. An involvement of changed distribution and function of N-methyl-d-aspartate subclass of glutamate receptors also has been suggested. The often unpredictable responses to seizures after surgical tumor removal add substantial evidence that multiple factors are involved. The therapy of tumor-related seizures is far from perfect. Several factors contribute to these treatment difficulties, such as tumor growth and drug interactions; however, one of the main reasons for poor seizure control may result from the insufficient or even absent influence of the currently available antiepileptic drugs (AEDs) on most of the pathophysiologic mechanisms of tumor-related seizures. Studies are needed to elucidate more clearly the pathophysiologic mechanisms of tumor-related seizures and to identify and develop the optimal AEDs.

Animals↗
PubMed2003

Headache after removal of vestibular schwannoma via the retrosigmoid approach: a long-term follow-up-study.

OBJECTIVE: Our goal was to study the occurrence and source of origin of postcraniotomy headache syndrome after removal of vestibular schwannoma via the retrosigmoid approach. METHODS: A retrospective chart analysis was conducted of all patients with headache at 3 months after removal of vestibular schwannoma from January 1981 through March 1997 and with a minimum of 24 months of follow-up. Diagnosis was made according to the headache classification and was graded using the HARNER scale. Recovery outcome was compared in selected groups of patients with and without headache. A descriptive statistical analysis was used to analyze differences between groups. RESULTS: Of the patients who underwent retrosigmoid craniotomy for removal of vestibular schwannomas, 52 of 155 patients (34%) reported having severe headache of requiring medication every day and/or feeling incapacitated 3 months after surgery. Headache was more prevalent in those who had the bone flap replaced (94% versus 27%), if there was duraplastic or direct dura closure (0% versus 100%). Laboratory-proven aseptic meningitis, most likely due to the use of fibrin glue and drilling of posterior aspect of the internal auditory canal, was mainly associated with postoperative headache (81% versus 2%). In 75% of these cases, calcifications along the brainstem had been noted. CONCLUSION: The origin of postoperative headaches after retrosigmoid vestibular schwannoma resections is not yet fully understood. Different factors may play a role in preventing or reducing headache: dural adhesions to nuchal muscles or to subcutaneous tissues and dural tension in the case of direct dural closure may explain postoperative headache from dural tension. Intradural drilling and the use of fibrin glue may be the source of aseptic meningitis as the etiology of persistent postoperative headache. Prevention of postoperative headache may include the replacement of bone flap at the end of surgery, duraplastic instead of direct dural closure, and prevention of the use of fibrin glue or extensive drilling of the posterior aspect of internal auditory canal.

Adolescent↗
PubMed2003

Hemodynamic changes after occlusion of the posterior superior sagittal sinus: an experimental PET study in cats.

BACKGROUND AND PURPOSE: Occlusion of the anterior third of superior sagittal sinus (SSS) is generally well tolerated because of sufficient collateral venous blood flow. In contrast, the pathophysiologic effects of occlusion of the SSS posterior to the rolandic vein remain controversial. We aimed to identify the specific hemodynamic effects of this subtype of SSS occlusion. METHODS: We ligated the SSS just behind rolandic vein and in the posterior part near the confluens sinus in three anesthetized cats. Regional cerebral blood flow (rCBF) was measured before and at 2 and 24 hours after the SSS occlusion. At around 48 hours, experimental settings were terminated with perfusion fixation with 4% paraformaldehyde solution. Hematoxylin-eosin histologic evaluation was performed. RESULTS: In all three cats with SSS occlusion, rCBF was reduced over the time period of measurement; this finding was observed in areas covering 5-20% of the brain in planes affected by the occlusion. The degree of rCBF reduction and the extension and severity of histologically proved venous infarction were correlated. CONCLUSION: To our knowledge, this is the first demonstration that occlusion of the SSS posterior to the rolandic vein is associated with a significant rCBF reduction to still-viable tissue in the related vascular territory at 24 hours after occlusion. We describe subacute venous infarction in an experimental occlusion of the SSS. Analogous to clinical conditions, occlusion of SSS alone without additional occlusion of bridging veins is adequate for producing a venous circulatory disturbance.

Animals↗
PubMed2003

Gender-related differences in non-functioning pituitary adenomas.

OBJECTIVES: Clinically non-functioning pituitary adenomas are common tumors of the pituitary gland. No studies have yet documented gender-related differences in the growth and presentation of these tumors and nothing is known about their effects on their subsequent surgical outcome and prognosis. SETTING AND DESIGN: Twenty-eight patients with non-functioning pituitary adenoma, that met strict inclusion criteria, and that underwent surgical treatment between January 1990 and June 1997, were retrospectively reviewed. METHODS: The patient charts, as well as histological (incl. immunohistochemistry) and electron microscopic findings were analyzed. Tumor invasiveness was classified according to the modified Hardy criteria. MAIN FINDINGS: Eleven patients were women and seventeen were men; the female-to-male-ratio was 1:1.5. Men were significantly older, both at diagnosis and surgery. Visual field defect and visual acuity deficit were the most common presenting symptoms with similar occurrence both in women and men, whereas blindness predominated in women. Microadenomas and invasive adenomas did not differ significantly in MIB-1 index, but patients less than 35 years old had higher MIB-1 indices (n=4, 1.72+/-1.15), than did patients over 45 years (n=11, 0.63+/-0.42) (p: n.s.). MIB-1 labeling indices were higher in adenomas of female compared to male patients (1.5 +/-1.2 vs. 0.8+/-1.8; p < 0.003). The overall outcome was significantly worse in women than in men. CONCLUSION: The biology and the clinical course of clinically non-functioning pituitary adenoma seem to differ in women and men. In men, tumors are smaller and less invasive at surgery, and the outcome is better than in women. The present findings may justify a more aggressive therapeutic approach to clinically non-functioning pituitary adenomas in women than in men, especially to improve the availability of viable pituitary cells at the time of surgery.

Adenoma↗