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Biomedical subjects

A Schnider

Publications and source records attributed to A Schnider.

At least 19 recordsLinked to original sources
PubMed2006

The prognosis of agenesis of the corpus callosum might mostly be favourable.

The post-natal development of 6 patients with complete agenesis of the corpus callosum was assessed. The diagnosis of agenesis of the corpus callosum had been suspected prenatally in 3 cases. In the remaining 3 cases diagnostic neuro-imaging was performed because of partial seizures (n = 2) and pendular nystagmus (n = 1). The neurological examination was normal in all patients with the exception of nystagmus in one. The neuro-developmental outcome was found to be normal in all 6 patients. In conclusion, these data suggest that good outcome is predominant in agenesis of the corpus callosum.

Adolescent↗
PubMed2006

[Ischemic, an uncommon complication of Biermer disease (pernicious anemia)].

INTRODUCTION: Stroke in a young adult justifies an extensive etiologic workup. OBSERVATION: We present a 44-year-old women victim of a frontal ischemic stroke. Extensive evaluation was normal, except for high plasma level of homocysteine in the context of pernicious anemia, otherwise asymptomatic. DISCUSSION: Hyperhomocysteinemia is a known marker, and probably risk factor for stroke, fostering atherosclerosis and thrombosis. It can be found among individuals suffering from homocystinuria, in individuals homozygous for the MHTFR T allele but also when there is deficiency of vitamin B12 or folic acid. Although it is very seldom ascribed, pernicious anemia would be a cause of stroke, possibly though hyperhomocysteinemia.

Adult↗
PubMed2005

[17 year old patient with acute abdominal pain, hematochezia and exanthema].

A 17-year old adolescent presented with abdominal pain, petechial lesions, arthralgia, and hematochezia. Abdominal ultrasound showed a suspicious ileocecal region and a lower endoscopy revealed the picture of an ileitis terminalis. The diagnosis of Purpura Henoch Schoenlein was made and confirmed by skin-biopsy showing a leucocytoclastic vasculitis. This case report demonstrates the various clinical symptoms of Purpura Henoch Schoenlein and its clinical course.

Abdominal Pain↗
PubMed2004

Neurological improvement and rehabilitation potential following toxic myelopathy due to intrathecal injection of doxorubicin.

STUDY DESIGN: Case report of a 31-year-old woman who presented with toxic myelopathy due to intrathecal administration of doxorubicin. OBJECTIVE: To describe the pathology and the rehabilitation of an uncommon complication of intrathecal drug administration during the oncologic treatment of acute lymphoma. SETTING: Spinal cord rehabilitation center, University Hospital. METHOD: Clinical and radiological observations during a rehabilitation program. RESULTS: Evidence of neurological improvement and rehabilitation potential after severe myelopathy due to intrathecal injection of doxorubicin. CONCLUSION: This is, to our knowledge, the first report of severe myelopathy following accidental intrathecal administration of doxorubicin. Despite early complete paraplegia, some neurological and functional recovery was observed.

Adult↗
PubMed2003

Perioperative detection of disseminated tumour cells is an independent prognostic factor in patients with colorectal cancer.

BACKGROUND: The objective of the present investigation was to assess the prognostic significance of disseminated tumour cells in peritoneal lavage, and peripheral and mesenteric venous blood in patients undergoing curative resection of colorectal cancer. METHODS: The prognostic impact of perioperative cytological and immunocytochemical detection of disseminated colorectal cancer cells was evaluated prospectively. Peritoneal lavage fluid, and peripheral and mesenteric venous blood from 53 consecutive patients undergoing curative surgery for colorectal cancer were analysed. The dichotomous results (positive versus negative) from the cytological and immunocytochemical analysis were used as a predictor along with other co-variates in proportional hazard regression models of disease-free and overall survival. RESULTS: Disseminated colorectal cancer cells were found in 13 of 53 patients (25 per cent) using cytology (CYT) and/or immunocytochemistry (ICC). The median follow-up at the time of the analysis was 37 months. In multivariate proportional hazard regression models CYT/ICC status was a significant predictor for disease-free (P = 0.002) and overall (P = 0.006) survival. CONCLUSION: Disseminated tumour cells detected by CYT and ICC represent an independent prognostic factor in patients undergoing surgery for colorectal cancer and may identify patients at high risk of recurrence.

Adult↗
PubMed2003

Subdural catheter migration may lead to baclofen pump dysfunction.

OBJECTIVES: To report an unusual cause of intrathecal drug delivery failure in baclofen pump device. STUDY DESIGN: A case report of an SCI patient treated with intrathecal baclofen, presenting a drug withdrawal. SETTING: Regional spinal cord injuries centre in Geneva (Switzerland). METHODS: We present a case of a 38-year-old male with complete T9 spastic paraplegia for 15 years, treated with intrathecal baclofen for 11 years. He recently presented to our centre with a spastic hypertonic episode, associated with rhabdomyolysis. RESULTS: Standard investigations were unrevealing. However, a CT scan performed after injecting a radio-opaque solution by the side port of the pump, showed an unexpected catheter migration into the subdural space. Surgical revision reversed withdrawal symptoms. CONCLUSIONS: Subdural catheter migration must be considered in the differential diagnosis of intrathecal drug delivery system failures. We recommend the use of the CT scan after contrast injection, to detect the localization of the distal catheter tip and confirm the normal diffusion into the subarachnoid space.

Accidental Falls↗
PubMed2001

Hypothalamic amnesia with spontaneous confabulations: a clinicopathologic study.

Previous studies demonstrated that patients producing spontaneous confabulations fail to suppress currently irrelevant memory traces and have anterior limbic lesions, particularly involving the orbitofrontal cortex or the basal forebrain. Here, a woman is described who had sarcoidosis damaging the medial hypothalamus and endocrine dysfunction, and a severe memory failure characterized by spontaneous confabulation, disorientation, and severely impaired free recall with preserved recognition. Isolated hypothalamic damage may produce the same type of memory disorder as orbitofrontal damage.

Aged↗
PubMed2001

[Minimal invasive surgery. Aspects of surgical oncology of the gastrointestinal tract].

The general potential and current position of minimally invasive surgery for the surgical treatment of malignant tumours of the gastrointestinal tract are discussed. A reliable validation of these procedures for tumour surgery is still impossible due to the lack of long-term results, the selective experience, and the ongoing process of learning and development. However, it seems clear that minimally invasive procedures will have an important position within surgical oncology. This is especially true with respect to improved staging of gastrointestinal tumours by laparoscopy and various palliative procedures that may be performed laparoscopically. Minimally invasive procedures may suffice for the treatment of certain, highly selected cases of preneoplastic and early cancerous lesions. The definitive acceptance of minimally invasive procedures in the future will require further clinical, preferably randomised trials, comparing the advantages of the minimally invasive access route to possible long-term disadvantages with regard to recurrence-free and overall survival.

Gastrointestinal Neoplasms↗
PubMed2001

Time estimation in Parkinson's disease: normal long duration estimation despite impaired short duration discrimination.

It has been claimed that patients with Parkinson's disease (PD) are deficient in estimating and reproducing time intervals in the range of seconds. This deficit is more severe when subjects are requested to count internally during the demanded intervals, and when the rate of internal counting is fast. The observed deficit might therefore reflect slow internal counting, i. e. motor slowness, rather than a specific deficit of temporal processing. However, PD patients also have a higher temporal discrimination threshold for sensory stimuli, a finding purportedly indicating a slow 'internal clock'. In this study we examined PD patients' processing of short durations (approx. 1s,'psychological present') and long durations (up to 48 s,'extended present'). In the first experiment the ability to discriminate between temporally overlapping presentations of two visual stimuli (darkened rectangles on the computer screen) in the range of one second was tested. In the second experiment PD patients' ability to estimate time intervals between 12 and 48 s was investigated. During these intervals, subjects were required to tap and read a random number on the computer screen at a rate of 1 Hz. We found that the patients were impaired at discriminating between short intervals. This deficit was independent of task difficulty and appeared to be based on an impairment of divided attention. Despite this deficit, the PD patients estimated time intervals up to 48 s as accurately as the controls. We suggest that time estimation, i. e. the feeling for the flow of time, is normal in PD patients despite impaired discrimination of brief intervals in the range of seconds.

Aged↗
PubMed2001

Spontaneous confabulation, reality monitoring, and the limbic system--a review.

Patients with anterior limbic damage may present a distinct syndrome, spontaneous confabulation: they fail in common memory tests, act on the basis of previous habits rather than currently relevant memories, produce confabulations composed of elements of past true events, are disorientated, and are absolutely convinced about the veracity of their perceived reality. Spontaneous confabulation is independent of other false memories, such as, provoked confabulations or illusory recognition. Studies showed that spontaneous confabulators fail to suppress (inactivate) evoked memories that do not pertain to ongoing reality. Rehabilitation differs from other memory failures. Prognosis depends on the lesion site, but recovery is always associated with recovery of this suppression capacity. Lesions typically involve the posterior medial orbitofrontal cortex or its connections in the basal forebrain. Imaging and evoked potential studies in healthy subjects support the idea that the anterior limbic system provides a reality monitoring mechanism which selects memories of current relevance by suppressing (inactivating) currently irrelevant memories. This mechanism appears to adjust the cortical representation of activated memories before their content is recognised and consolidated. Comparison with animal studies suggests that human reality monitoring is a property of the brain's reward system.

Delusions↗
PubMed2001

Prophylactic surgery in families with familial adenomatous polyposis (FAP) and in colitis.

Colorectal cancer is the second most common cause of death from malignant tumors in western countries with approximately 3800 new cases/year in Switzerland. For individuals known to be at high risk for the development of colorectal cancer, screening, chemoprevention and/or prophylactic surgery are the only tools to avoid unnecessary premature death from this disease. With modern molecular and/or genetic testing the risk of developing colorectal cancer can be more precisely estimated on an individualized basis. These individuals need to be enrolled in strong surveillance programs and are clear candidates for prophylactic surgery. The risk of prophylactic surgery (morbidity, mortality, quality of life following surgery) must be clearly weighted against the increasing risk of cancer. These patients should be treated in experienced centers for colorectal surgery in close connection with a genetic testing and counseling team, a molecular laboratory and a psychological support group.

Adenomatous Polyposis Coli↗
PubMed2001

Probabilistic contingency learning with limbic or prefrontal damage.

A fundamental capacity of the human brain is to learn relations (contingencies) between environmental stimuli and the consequences of their occurrence. Some contingencies are probabilistic; that is, they predict an event in some situations but not in all. Animal studies suggest that damage to limbic structures or the prefrontal cortex may disturb probabilistic learning. The authors studied the learning of probabilistic contingencies in amnesic patients with limbic lesions, patients with prefrontal cortex damage, and healthy controls. Across 120 trials, participants learned contingent relations between spatial sequences and a button press. Amnesic patients had learning comparable to that of control subjects but failed to indicate what they had learned. Across the last 60 trials, amnesic patients and control subjects learned to avoid a noncontingent choice better than frontal patients. These results indicate that probabilistic learning does not depend on the brain structures supporting declarative memory.

Adult↗
PubMed2001

Dissociated active and passive tactile shape recognition: a case study of pure tactile apraxia.

Disorders of tactile object recognition (TOR) may result from primary motor or sensory deficits or higher cognitive impairment of tactile shape representations or semantic memory. Studies with healthy participants suggest the existence of exploratory motor procedures directly linked to the extraction of specific properties of objects. A pure deficit of these procedures without concomitant gnostic disorders has never been described in a brain-damaged patient. Here, we present a patient with a right hemispheric infarction who, in spite of intact sensorimotor functions, had impaired TOR with the left hand. Recognition of 2D shapes and objects was severely deficient under the condition of spontaneous exploration. Tactile exploration of shapes was disorganized and exploratory procedures, such as the contour-following strategy, which is necessary to identify the precise shape of an object, were severely disturbed. However, recognition of 2D shapes under manually or verbally guided exploration and the recognition of shapes traced on the skin were intact, indicating a dissociation in shape recognition between active and passive touch. Functional MRI during sensory stimulation of the left hand showed preserved activation of the spared primary sensory cortex in the right hemisphere. We interpret the deficit of our patient as a pure tactile apraxia without tactile agnosia, i.e. a specific inability to use tactile feedback to generate the exploratory procedures necessary for tactile shape recognition.

Adult↗
PubMed2000

Selection of currently relevant memories by the human posterior medial orbitofrontal cortex.

We have demonstrated previously that patients producing spontaneous confabulations fail to suppress currently irrelevant memory traces, so that they act and think on the basis of a false, temporally displaced (past) reality. All spontaneous confabulators had anterior limbic damage, in particular of the orbitofrontal cortex and basal forebrain. These findings indicated that these structures are essential for distinguishing between mental representations of ongoing reality and currently irrelevant memories. In the present study, we used a similar experimental paradigm as in our clinical studies and H(2)(15)O positron emission tomography to explore the selection of currently relevant memories by the healthy human brain. Subjects were repeatedly presented with the same set of pictures, arranged in different order each time, and were requested to indicate picture recurrences within the runs. Thus, performance in the first run depended on new learning, whereas subsequent runs required the distinction between picture repetitions within the current run ("now") and previous picture presentations in earlier runs. Whereas initial learning activated medial temporal structures, subsequent runs provoked circumscribed posterior medial orbitofrontal activation. We suggest that this area is essential for sorting out mental associations that pertain to ongoing reality.

Adult↗
PubMed2000

Recovery from spontaneous confabulations parallels recovery of temporal confusion in memory.

BACKGROUND: In previous studies, the authors found that patients with spontaneous confabulation differ from those with nonconfabulating amnesia by 1) temporal context confusion (TCC) in memory based on an inability to suppress intrusions of currently irrelevant memory traces into ongoing thinking; and 2) lesions involving the orbitofrontal cortex, basal forebrain, or amygdala and perirhinal cortex. OBJECTIVES: To study the long-term clinical course of spontaneous confabulations, determine whether TCC in memory also parallels the clinical course of spontaneous confabulations, and study the impact of lesion site on clinical course. METHODS: Eight patients with spontaneous confabulation were re-examined 18 months after onset. Tests of memory and executive functioning and measurement of TCC in memory were again applied. MRI according to a standard protocol was performed to determine areas of permanent damage. RESULTS: Seven patients eventually stopped confabulating. TCC, but not common memory or executive tests, precisely paralleled the course of spontaneous confabulations. Patients with isolated, less extensive, orbitofrontal lesions stopped confabulating first and had the best neuropsychological outcome. Patients with basal forebrain lesions continued to confabulate for several months and remained amnesic. One patient with extensive orbitofrontal damage and perirhinal cortex damage continues to confabulate after more than 3 years, continuing to confuse memory traces. CONCLUSIONS: Temporal context confusion in memory is not only the sole feature reliably separating patients with spontaneous confabulation from those with nonconfabulating amnesia in the acute stage, it is also the only feature that precisely parallels the clinical course of spontaneous confabulations. Most patients eventually stop confabulating but duration of confabulations depends on the lesion site.

Adult↗
PubMed2000

Spontaneous confabulations, disorientation, and the processing of 'now'.

We have previously demonstrated that spontaneous confabulations and disorientation in amnesia emanate from temporal context confusion in memory characterised by intrusion of previously acquired information into ongoing thinking. This failure appears to be due to an inability to suppress previously activated memory traces of events dating back hours, weeks or even years. In the present study, the possibility was explored that spontaneous confabulators also have a problem in processing information in the very short-term range of the psychological present (the 'now'), which has been defined as the duration of an experiential process. Tasks assessing the processing of time within the psychological present were devised to test this possibility. In experiment 1, spontaneous confabulators, in comparison with other amnestic patients, failed to discriminate brief, visually presented intervals in the now. In experiment 2, they failed to make motion-associated time estimations within the now. These deficits also correlated with disorientation. Although these results do not prove a causal relationship, they indicate that spontaneously confabulating and disorientated patients typically do fail to process information within the 'now'.

Adolescent↗
PubMed1999

Spontaneous confabulators fail to suppress currently irrelevant memory traces.

Human actions require integration of past experiences, ongoing percepts and future concepts. To adapt behavior to reality, the brain must identify mental representations of current relevance. Occasional amnesic subjects act according to invented stories ('spontaneous confabulations'), disregarding present reality. We used repeated runs of a continuous recognition task to measure the ability to distinguish currently relevant from previously encountered but currently irrelevant information. Spontaneous confabulators detected target items as accurately as nonconfabulating amnesics, but increasingly failed to suppress false-positive responses, confusing presentation in previous runs with presentation in the current run. Lesions involved the anterior limbic system: medial orbitofrontal cortex, basal forebrain, amygdala and perirhinal cortex or medial hypothalamus. We suggest that the anterior limbic system represents 'now' in human thinking by suppressing currently irrelevant mental associations.

Amnesia↗