Biomedical subjects

C Wedekind

Publications and source records attributed to C Wedekind.

At least 19 recordsLinked to original sources

PubMed2006

F-wave amplitudes indicate evolving spinal autonomy during spontaneous recovery of hindlimb function in rat spinal cord contusion.

STUDY DESIGN: Experimental rat model of spinal cord contusion. OBJECTIVES: To reveal the extent of spinal autonomy contributing to recovery of hindlimb function. SETTING: Experimental laboratory of a neurosurgical university department. METHODS: F-wave amplitudes as a probe for spinal cord excitability were recorded from both sciatic nerves (lumbar segments L2-L5) before and after an experimental spinal cord contusion performed in the lower thoracic spinal cord. Additionally, transcranial electrically motor evoked potentials from the hindlimbs and cerebral somatosensory potentials evoked by sciatic nerve stimulation were recorded. Clinical evaluation of hindlimb function was done regularly for survival periods of 3 and 50 days, respectively. Electrophysiological testing was performed immediately prior and after lesioning of the cord and at the endpoint of survival periods. RESULTS: Hindlimb function recovered from a mean Basso-Beattie-Bresnahan score of 5.6 on day 1 to 9.2 on day 3 (3-day-survivors) and from 7.7 to 17.2 on day 50 (50-day-survivors). This was accompanied by a significant increase of F-wave amplitudes on day 50 compared to baseline values, whereas amplitudes of somatosensory and motor-evoked potentials remained significantly depressed. CONCLUSION: Recovery of hindlimb function may at least in part be attributed to evolving spinal autonomy, which can be assessed by F-wave amplitudes.

Action Potentials↗

PubMed2006

Development of chronic hydrocephalus and early cranial CT findings in spontaneous intracerebral/intraventricular hemorrhage.

INTRODUCTION: Since intracerebral hemorrhage (ICH) is frequently associated with intraventricular bleeding (IVH), we sought to detect cranial computed tomography features that would indicate early on in the patient's history the development of chronic hydrocephalus with a permanent need for cerebrospinal fluid (CSF) diversion. METHODS AND MATERIALS: A total of 25 consecutive cases presenting with ICH/IVH was studied retrospectively. Outcome was assessed using the Glasgow Outcome Scale at an average of 8 months subsequently. Diagnosis of ICH/IVH and (acute) hydrocephalus was made by early cranial CT scanning employing a selection of radiological criteria according to the literature including the Evans ratio. All patients then received external ventricular drainage. Chronic hydrocephalus was diagnosed by intraventricular pressure monitoring or by cranial CT follow-up after removal of the external drainage. RESULTS: None of the radiological criteria nor the scores obtained differed between the two groups. However, the ratio of scores for IVH/ICH was higher among the patients who developed a chronic hydrocephalus. All other parameters including volume of ICH and IVH were equally distributed. Overall outcome was poor with a median GOS score of 3. CONCLUSIONS: The ICH/IVH ratio presented here can be interpreted as an individual measure of propensity to impairment of CSF circulation. Further studies on larger populations will be needed to show whether this can be employed as an early diagnostic criterion with respect to chronic hydrocephalus.

Aged↗

PubMed2006

Early maternal investment in mice: no evidence for compatible-genes sexual selection despite hybrid vigor.

Confronting a recently mated female with a strange male can induce a pregnancy block ('Bruce effect'). The physiology of this effect is well studied, but its functional significance is still not fully understood. The 'anticipated infanticide hypothesis' suggests that the pregnancy block serves to avoid the cost of embryogenesis and giving birth to offspring that are likely to be killed by a new territory holder. Some 'compatible-genes sexual selection hypotheses' suggest that the likelihood of a pregnancy block is also dependent on the female's perception of the stud's and the stimulus male's genetic quality. We used two inbred strains of mice (C57BL/6 and BALB/c) to test all possible combinations of female strain, stud strain, and stimulus strain under experimental conditions (N(total) = 241 mated females). As predicted from previous studies, we found increased rates of pregnancy blocks if stud and stimulus strains differed, and we found evidence for hybrid vigour in offspring of between-strain mating. Despite the observed heterosis, pregnancies of within-strain matings were not more likely to be blocked than pregnancies of between-strain matings. A power analysis revealed that if we missed an existing effect (type-II error), the effect must be very small. If a female gave birth, the number and weight of newborns were not significantly influenced by the stimulus males. In conclusion, we found no support for the 'compatible-genes sexual selection hypotheses'.

Animals↗

PubMed2005

Long-term outcome in severe traumatic brain injury is significantly influenced by brainstem involvement.

PRIMARY OBJECTIVE: To study the 1-year-outcome of 32 survivors of severe traumatic brain injury with respect to the impact of brainstem injury. RESEARCH DESIGN: Retrospective clinical study performed in a university hospital. METHODS AND PROCEDURES: Thirty-two 1-year-survivors (15 with brainstem injury present) of severe traumatic brain injury were investigated for neurological function, activities of daily living, need for care and professional ability. MAIN OUTCOMES AND RESULTS: Visual impairment, spasticity, co-ordination deficits and organic psychosis were more frequent in the group harbouring brainstem lesions. Professional ability was worse among these patients. CONCLUSION: Brainstem involvement in survivors of severe traumatic brain injury conveys a negative impact on long-term outcome.

Activities of Daily Living↗

PubMed2005

Foreign accent syndrome following traumatic brain injury.

Foreign accent syndrome (FAS) is a very rare disorder, caused by lesions of the dominant brain hemisphere and defined as a loss of normal phonetic contrast when using the mother language. The pronunciation is perceived by native speakers as compromised by a foreign accent. This study reports about a 35-years old woman, with a FAS following a brain injury with a traumatic left temporal haemorrhage, who experienced excellent remission after 2 years.

Adult↗

PubMed2004

MHC-linked susceptibility to a bacterial infection, but no MHC-linked cryptic female choice in whitefish.

Non-random gamete fusion is one of several potential cryptic female choice mechanisms that have been postulated and that may enhance the survival probability of the offspring. Previous studies have found that gamete fusion in mice is influenced by genes of the major histocompatibility complex (MHC) region. Here we test (i) whether there is MHC-dependent gamete fusion in whitefish (Coregonus sp.) and (ii) whether there is a link between the MHC and embryo susceptibility to an infection by the bacterium Pseudomonas fuorescens. We experimentally bred whitefish and reared sibships in several batches that either experienced or did not experience strong selection by P. fluorescens. We then determined the MHC class II B1 genotype of 1016 surviving larvae of several full sibships. We found no evidence for MHC-linked gamete fusion. However, in one of seven sibships we found a strong connection between the MHC class II genotype and embryo susceptibility to P. fluorescens. This connection was still significant after correcting for multiple testing. Hence, the MHC class II genotype can considerably influence embryo survival in whitefish, but gamete fusion seems to be random with respect to the MHC.

Animals↗

PubMed2003

[Severe ethanol-intoxication mimics symptoms of intracranial hypertension].

We report on a patient intoxicated with ethanol, who was found unconscious with fixed dilated pupils, deviation of eyes, absent cough and corneal reflexes, with her arms in decerebrate posture. Because of an orbital haematoma a traumatic intracranial hemorrhage with elevated intracranial pressure and compression or concussion of the brain stem was suspected. A CT-scan of the head did not reveal an intracranial mass or any radiographic signs of intracranial hypertension. Drug screening, blood gas analysis and other laboratory tests as well anamnestic data were not indicative of other intoxications or a metabolic decompensation. These unusual neurological findings were caused by a life-threatening ethanol intoxication with a blood-alcohol concentration of 700 mg/dl (151.8 mmol/l). The patient was extubated after several hours of mechanical ventilation in the intensive care unit and was discharged to a regular ward on the following day.

Adult↗

PubMed2002

Early rehabilitative concepts in therapy of the comatose brain injured patients.

OBJECTIVES: To evaluate the changes of vegetative parameters and behavioural assessment in comatose patients after severe brain injury during the Multimodal-Early-Onset-Stimulation (MEOS) in early rehabilitation. MATERIAL AND METHODS: We studied 16 predominantly male (3:1) patients, age mean 43.6 (16-77) years. Mean coma duration was 22.2 (8-41) days, therapy duration (MEOS) 9.8 (1-30) days. The initial GCS was 6.6 (3-9), KRS 5.3 (0-15). Including criteria for therapy: Severe head trauma, coma for at least 48 hours (GCS < 8), vegetative stability, normal intracranial pressure, abandon of mechanical ventilation, sedation and severe infections. MEOS was finished in achieving GCS > 9, follow-up investigations were made after 2 years. RESULTS: We identified significant changes in two vegetative parameters (heart/respiratory frequencies), even in deep coma (GCS 3-4). Most significant changes were caused by tactile and acoustic stimulation. Standardized behavioural assessment turned out to be particularly advisable in cases of medium coma (GCS 5-7). Stimulation of tactile and acoustic senses resulted mainly in mimical, head and eye movements. Follow-up was possible in 14 patients: One remained in a vegetative state (GOS 2), two exhibited severe neurologic/neuropsychologic deficits, depending on care (GOS 3), six substained major functional deficits (GOS 4), at though they were able to perform the tasks of daily life on their own, three patients reached GOS 5. Two returned to their former jobs. DISCUSSION AND CONCLUSION: The present results indicate that stimulation therapy should be based on a close observation of patterns of behaviour, and, at least in deep coma stages, involve the registration of vegetative parameters. It may be sensitive to identify parameters predicting a favourable or unfavourable outcome. Preliminary data seem to support the hypothesis that the absence of any response to external stimuli is indicative of an unfavourable outcome.

Acoustic Stimulation↗

PubMed2002

Intermediate and long-term outcome in traumatic brain injury is not influenced by additional multiple organ injury.

BACKGROUND: This investigation aims at evaluating the influence of additional multiple organ injury in traumatic brain injury on the outcome in terms of the ability to perform the activities of daily life, of the need of care, and of job ability. METHODS: 62 victims (male to female ratio 4 : 1; age range 15-68 years) of traumatic brain injury were studied. Group 1 (n = 24) consisted of patients who suffered from traumatic brain injury with additional multiple organ injury, group 2 (n = 38) comprised patients with isolated brain injury. Outcome was assessed at 6 and 12 months after trauma by means of different rehabilitation scores. RESULTS: After 6 as well as after 12 months, the majority of both groups were independent in the activities of daily living. Furthermore, no differences were observed concerning the need of care. Job ability was almost equal for both groups. CONCLUSION: Additional multiple organ injury does not pertain to prognosis of traumatic brain injury.

Activities of Daily Living↗

PubMed2002

Trauma to the pontomesencephalic brainstem-a major clue to the prognosis of severe traumatic brain injury.

The objective of this study was to assess the significance of an injury to the pontomesencephalic brainstem in severe traumatic brain injury [Glasgow coma score (GCS) below 8]. Forty victims of severe traumatic brain injury with and with out compounding pathologies almost equally distributed among both groups were studied. The outcome (mean follow-up, 11.3 months) was assessed by means of the Glasgow outcome score (GOS) and of the Disability rating scale (DRS). Injury of the brainstem was detected by electrophysiological investigation (evoked potentials, brainstem reflexes) and magnetic resonance imaging (MRI) carried out early after trauma. Statistical analysis (Wilcoxon signed rank test for matched pairs) revealed a significantly worse initial GCS (median 5 versus 6), GOS (median 3 versus 4), and DRS score (median 6 versus 2) for the group with brainstem lesions than for the group without such lesions. Moreover, there was a significant accumulation of lesions of the corpus callosum, the basal ganglia, and the (para-)hippocampal area detected by MRI in the brainstem lesion group. In addition, the finding of an abnormal cortical component of the median nerve evoked somatosensory potential was significantly more frequent in the patients with brainstem injury. Traumatic brainstem lesions diagnosed by MRI a nd/or electrophysiological investigation are associated with injury to other 'deeply' situated parts ofthe brain. The finding of a brainstem lesion influences to the outcome of patients after severe traumatic brain injury.

Adolescent↗

PubMed2001

Age related signal decrease in functional magnetic resonance imaging during motor stimulation in humans.

Right handed healthy volunteers underwent functional magnetic resonance imaging (fMRI) examinations on a 1.5 Tesla MRI-scanner (Gyroscan ACS NT; Philips, Best, NL). Blood oxygen level dependent (BOLD) images were obtained using a three dimensional multi-shot echo planar imaging sequence employing a shifted echo technique (Principles of echo shifting with a train of observations). Finger tapping of the right hand was used as a task for motor stimulation. A total of 86 subjects was included into statistical analysis. Absolute and relative signal differences and cluster sizes of activation for the left motor cortex were obtained. In addition, Z-score, pooled Z-score and cross correlation activation maps were calculated and matched with high resolution anatomic images. A significant decrease with age could be detected for absolute and relative signal intensity differences for the whole group and for the male subgroup. Correlation analysis for the female subgroup also bore negative albeit non-significant correlation coefficients. An age-related decline of BOLD-contrast can be assumed to explain signal decrease. This age-related effect should be considered in clinical fMRI applications.

Adult↗

PubMed2001

A normative study on human facial F waves.

F waves from the nasalis muscle were obtained bilaterally after transcutaneous constant-current stimulation of the facial nerve in 37 of 42 (88%) healthy volunteers examined. F waves were of varying shape and latency. Standard parameters (latencies, amplitudes, ratios, chronodispersion) of F-wave analysis were assessed. Of these, minimum and mean F-wave latencies, the F ratio, and F-wave and peripheral conduction times (PCT) were approximately normally distributed, with a low standard deviation. Latencies and conduction times exhibited a significantly positive correlation with body height, as has been demonstrated for the F-wave latencies in limb muscles. Side and sex differences were present but without statistical significance. Chronodispersion and chronodispersion range, F-wave amplitudes, and F-wave frequencies were broadly scattered. It is concluded that F-wave latencies and conduction times are best suited to define a range of reference values. Moreover, facial F waves bear characteristics similar to those described for F waves recorded from limb muscles.

Adult↗

PubMed2001

Functional magnetic resonance imaging of human pontine auditory pathway.

The purpose of this study is to visualize brainstem auditory pathways by functional magnetic resonance imaging (fMRI). Eighteen healthy volunteers (age 28 to 42 years) with normal hearing function underwent fMRI examination on a 1.5 Tesla imaging system (Philips, Best, The Netherlands) with periodic click stimulation. Blood oxygen level dependent images were obtained using a three-dimensional EPI sequence with shifted echo technique (principles of echo shifting with a train of observations). Control scans without click stimulation were obtained in the identical setting. Cross correlation activation maps were calculated using a postprocessing tool (Philips). They were matched with anatomic slices of identical orientation and thickness. Five of 18 subjects were excluded because of motion artifacts. In 4/13 significant activation was observed at the root entry zone of the ipsilateral acoustic nerve corresponding to the cochlear nuclei. In 11/13 subjects, significant activation was found in the same slice contralaterally close to the floor of the 4th ventricle, corresponding to the expected region of the superior olivary nucleus. Activation of the rostral parts of the auditory pathway (inferior colliculus, medial geniculate body) was not found. In the absence of the stimulus no activation occurred in these structures. It was concluded that activation of the brainstem auditory pathways by click stimuli can be visualized by fMRI.

Acoustic Stimulation↗

PubMed2001

Does wave VI of BAEP pertain to the prognosis of coma?

OBJECTIVES: The significance of brainstem auditory evoked potential (BAEP) wave VI for the outcome of comatose patients was assessed and compared to the prognostic impact of median nerve evoked somatosensory potential (MSEP) recording. PATIENTS AND METHODS: One hundred sixteen patients in a comatose state due to traumatic brain injury (n = 57) and to intracerebral hemorrhage or tumours (n = 59) were investigated prospectively. Outcome was assessed 3 months after the onset of coma using Glasgow Outcome Score (GOS). Standard BAEP and MSEP recordings were obtained within 24 h after coma onset. The frequency of findings was correlated with outcome by means of non-parametric statistical analysis. Additionally, 27 healthy volunteers were studied to confirm the constant presence of wave VI in normal BAEP. RESULTS: In healthy controls, wave VI was present in 53/54 ears stimulated. Outcome correlation analysis revealed a significantly (p < 0.01) higher frequency of abnormal wave VI in patients with unfavourable outcome (GOS 1-3) irrespective of the underlying pathology. Similarly, abnormal MSEP findings were significantly more frequent in this outcome group. Diagnostic sensitivity for an unfavourable outcome was low for both parameters, whereas specificity and positive predictive value of abnormal wave VI as well as of abnormal MSEP were equally high. CONCLUSION: Abnormal BAEP wave VI bears prognostic information in comatose patients.

Adolescent↗

PubMed2001

Recording nasal muscle F waves and electromyographic activity of the facial muscles: a comparison of two methods used for intraoperative monitoring of facial nerve function.

OBJECT: A comparison of two electrophysiological methods used to assess facial nerve function intraoperatively was conducted in 33 patients with tumors of the cerebellopontine angle. METHODS: All 33 patients had presented with normal facial nerve function preoperatively. After general anesthesia had been induced by a mixture of midazolam and fentanyl, continual online EMG recordings from the orbicularis oculi and oris muscles were alternated with nasal muscle F-wave recordings. Facial nerve outcomes, assessed using a modified House-Brackmann scale, varied among good (48%), moderate (18%), and poor (33%). Analysis of electromyographic (EMG) data resulted in a significant correlation between the finding of only transient manipulation-evoked activity and a good outcome, whereas in cases in which there was poor outcome, an increase in the amplitude or duration of ongoing activity was detected. A permanent loss of nasal muscle F waves specifically appeared to indicate a severe dysfunction of the facial nerve that was linked to a poor outcome. All patients with latency and/or amplitude changes or even a transient loss of the F wave achieved good or moderate facial nerve outcomes. A transient loss of the F wave, however, was detected significantly more frequently in patients with moderate outcomes. None of these patients exhibited normal facial function (House-Brackmann Grade I) postoperatively. CONCLUSIONS: Online EMG monitoring can provide some information on imminent or even present damage to the facial nerve intraoperatively. The diagnostic sensitivity, specificity, and positive predictive values of a permanent F-wave loss, however, are much higher than those of EMG monitoring. Additionally, this loss of the F wave is supposed to be transient if the surgical procedure is stopped until the F wave recovers. Therefore, F-wave monitoring serves to alert the surgeon that the facial nerve is about to receive a lesion.

Electromyography↗

PubMed2000

Cooperation through image scoring in humans.

The "tragedy of the commons," that is, the selfish exploitation of resources in the public domain, is a reason for many of our everyday social conflicts. However, humans are often more helpful to others than evolutionary theory would predict, unless indirect reciprocity takes place and is based on image scoring (which reflects the way an individual is viewed by a group), as recently shown by game theorists. We tested this idea under conditions that control for confounding factors. Donations were more frequent to receivers who had been generous to others in earlier interactions. This shows that image scoring promotes cooperative behavior in situations where direct reciprocity is unlikely.

Altruism↗

PubMed2000

Assessment of facial nerve function in acoustic tumor disease by nasal muscle F waves and transcranial magnetic stimulation.

Standard transcranial magnetic stimulation and nasal muscle F-wave recordings were used to assess proximal facial nerve function in 27 patients with unilateral acoustic tumors (mean diameter, 29 mm) and clinically intact facial nerve function. Latency measurements for F waves and cortical magnetic stimulation were abnormal. Moreover, F ratios, central motor conduction time, and the ratio of response latency to cortical and cisternal magnetic stimulation were significantly increased. Amplitudes were unchanged. Correlation analysis with tumor diameter as dependent variable yielded maximum r values for F-wave latencies (0.57) and F ratios (0.41), whereas for magnetic stimulation, a significant correlation could be found (0.4) only for cortical stimulation. Nasal muscle F-wave recording can reveal clinically inapparent facial nerve dysfunction. Its efficacy in predicting tumor diameter seems to be superior to that of standard magnetic stimulation.

Adult↗

PubMed2000

Prognostic significance of preoperative electrophysiologic investigation for facial nerve outcome in acoustic neuroma surgery.

The prognostic significance of transcranial magnetic stimulation and nasal muscle F-wave recording to predict postoperative facial nerve function was assessed in 24 patients with unilateral acoustic neuromas (mean diameter, 31 mm) and clinically intact facial nerve function. Latency of F waves and response to cortical magnetic stimulation, as well as F ratios, central motor conduction time, and the ratio of response latency to cortical and cisternal magnetic stimulation were significantly increased. Outcome analysis revealed no significant correlation between preoperative electrophysiologic changes and postoperative facial nerve function. However, a significant correlation with tumor diameter was detected. Thus, acoustic neuroma size seems to be the best predictor of facial nerve function after surgery.

Adult↗