Impact of childhood cerebellar tumor surgery on cognition revealed by precuneus hyperconnectivity

Background

Childhood cerebellar pilocytic astrocytomas harbor excellent overall survival rates after surgical resection, but the patients may exhibit specific cognitive and behavioral problems. Functional MRI has catalyzed insights into brain functional systems and has already been linked with the neuropsychological performance. We aimed to exploit the question of whether resting-state functional MRI can be used as a biomarker for the cognitive outcome assessment of these patients.

Methods

We investigated 13 patients (median age 22.0 years; range 14.9-31.3) after a median interval between surgery and examination of 15.0 years (range 4.2-20.5) and 16 matched controls. All subjects underwent functional 3-Tesla MRI scans in a resting-state condition and battery neuropsychological tests.

Results

Patients showed a significantly increased functional connectivity in the precuneus compared with controls (P < .05) and at the same time impairments in various domains of neuropsychological functioning such as a lower mean Wechsler Intelligenztest für Erwachsene (WIE) IQ percentile (mean [M] = 48.62, SD = 29.14), lower scores in the Trail Making Test (TMT) letter sequencing (M = 49.54, SD = 30.66), worse performance on the WIE subtest Digit Symbol Coding (M = 38.92, SD = 35.29), subtest Symbol Search (M = 40.75, SD = 35.28), and test battery for attentional performance (TAP) divided attention task (M = 783.92, SD = 73.20).

Conclusion

Childhood cerebellar tumor treated by resection only strongly impacts the development of precuneus/posterior cingulate cortex functional connectivity. Functional MRI has the potential to help deciphering the pathophysiology of cerebellar-related cognitive impairments in these patients and could be an additional tool in their individual assessment and follow-up.

Neuronal correlates of cognitive function in patients with childhood cerebellar tumor lesions

While it has been shown that cerebellar tumor lesions have an impact on cognitive functions, the extent to which they shape distant neuronal pathways is still largely undescribed. Thus, the present neuroimaging study was designed to investigate different aspects of cognitive function and their neuronal correlates in patients after childhood cerebellar tumor surgery. An alertness task, a working memory task and an incompatibility task were performed by 11 patients after childhood cerebellar tumor surgery and 17 healthy controls. Neuronal correlates as reflected by alterations in functional networks during tasks were assessed using group independent component analysis. We were able to identify eight networks involved during task performance: default mode network, precuneus, anterior salience network, executive control network, visual network, auditory and sensorimotor network and a cerebellar network. For the most ‘basic’ cognitive tasks, a weaker task-modulation of default mode network, left executive control network and the cerebellar network was observed in patients compared to controls. Results for higher-order tasks are in line with a partial restoration of networks responsible for higher-order task execution. Our results provide tentative evidence that the synchronicity of brain activity in patients was at least partially restored in the course of neuroplastic reorganization, particularly for networks related to higher-order cognitive processes. The complex activation patterns underline the importance of testing several cognitive functions to assess the specificity of cognitive deficits and neuronal reorganization processes after brain lesions.

The inability to self-evaluate smell performance. How the vividness of mental images outweighs awareness of olfactory performance

To rate one’s individual olfactory performance is difficult and in many cases differs clearly from validated objective olfactory performance measures. This study aimed to investigate the basis for this measurement drift between objective and subjective olfactory performance evaluation. In absence of an actual odor, one may imagine an olfactory stimulus to evaluate his subjective olfactory performance. Therefore, the impact of the vividness of mental images on self-evaluation of smell performance in patients with mild to severe olfactory dysfunction and healthy controls was investigated. Fifty-nine patients with peripheral olfactory dysfunction ranging from reduced olfactory function (hyposmia) to complete loss of olfactory perception (anosmia) and 16 healthy controls were included. Olfactory performance was assessed using the Sniffin’ Sticks battery, the vividness of olfactory mental images was evaluated using the vividness of olfactory imagery questionnaire (VOIQ). Decreased vividness of odor images was obtained for anosmic patients, and a trend of poorer odor imagery was determined in hyposmic patients. Multiple regression analyses revealed the VOIQ score as significant predictor for olfactory self-evaluation for hyposmic patients and healthy controls. In contrast, for anosmic patients, the only significant predictor for self-rating of olfactory performance was the threshold-detection-identification (TDI) score, measuring overall olfactory performance. The results of this study indicate that sensory perception and mental images are closely related to each other. Furthermore, subjects who were able to perceive odors, even to a smaller extent, rely on the vividness of their mental odor images to evaluate their olfactory performance. In contrast, anosmic patients rather trust in their knowledge that they are not able to perceive odors. We are therefore able to subjectively rate our olfactory performance levels, if we are not able to perceive odors, but not if we are able to perceive olfactory input.

Same same but different. Different trigeminal chemoreceptors share the same central pathway

Intranasal trigeminal sensations are important in everyday life of human beings, as they play a governing role in protecting the airways from harm. Trigeminal sensations arise from the binding of a ligand to various sub-types of transient receptor potential (TRP) channels located on mucosal branches of the trigeminal nerve. Which underlying neural networks are involved in the processing of various trigeminal inputs is still unknown. To target this unresolved question fourteen healthy human subjects were investigated by completing three functional magnetic resonance imaging (fMRI) scanning sessions during which three trigeminal substances, activating varying sub-types of chemoreceptors and evoking different sensations in the nose were presented: CO2, menthol and cinnamaldehyde. We identified similar functional networks responding to all stimuli: an olfactory network, a somatosensory network and an integrative network. The processing pathway of all three stimulants was represented by the same functional networks, although CO2 evokes painful but virtually odorless sensations, and the two other stimulants, menthol and cinnamaldehyde are perceived as mostly non painful with a clear olfactory percept. Therefore, our results suggest a common central processing pathway for trigeminal information regardless of the trigeminal chemoreceptor and sensation type.

Stress matters! Psychophysiological and emotional loadings of pregnant women undergoing fetal magnetic resonance imaging

Background

While the application of fetal MRI in high-risk pregnant women is steadily rising, little is known about the psychological consequences of this procedure. The aim of the present study was to investigate emotional and psychophysiological reactions of females undergoing fetal MRI.

Methods

Sixty women (17–44 ys), assigned for fetal MRI, were included. Affective state was assessed by standardized measures of anxiety, emotional states and depressive symptoms. Stress coping strategies were assessed using a self-report questionnaire. Stress responses were determined using skin conductance levels (SCL) during fetal MRI as well as measurement of salivary cortisol levels immediately before and after fetal MRI.

Results

Analysis of fast and slow physiological stress measures revealed significant differences between women with and without a supporting person accompanying them to the examination. For SCLs, lower levels of stress during MRI emerged in accompanied women. Women with well-marked stress-coping-strategies experienced lower levels of stress during the examination. Although fast and slow stress measures before and after MRI did not show significant correlations, a significant difference of SCLs pre and post examination was clearly detectable, as well as a trend of decreased cortisol levels for both time points.

Conclusions

The results imply that the elevation of SCLs is an accurate instrument to assess fast stress alterations in patients during fetal MRI. Stress coping strategies and whether women are accompanied or not play an important role in the experience of anxiety and depressive symptoms. These factors should be considered especially in patients with high-risk-pregnancies to improve patient care.

The impact of olfactory dysfunction on interoceptive awareness

This study aimed to investigate how the impairment of the olfactory system influences interoception. Interoception is known as the awareness of one's body or the sense of the condition of the body; more precisely, this construct is defined as the processing, representation, and perception of the internal physical state. Interoceptive sensitivity and chemosensory performance were assessed in 77 subjects, including 43 functional anosmics, 18 hyposmics, and 16 healthy controls. Interoceptive awareness was predicted by odor detection threshold, as well as the duration of olfactory loss in patients who suffered from reduced olfactory function-the longer the olfactory impairment, the worse the perception of bodily signals. The results of this study will significantly contribute to the basic understanding of the multifaceted effects of olfactory alterations.

Gender effects and sexual-orientation impact on androstadienone-evoked behavior and neural processing

In humans, the most established and investigated substance acting as a chemosignal, i.e., a substance that is excreted from the body, is 4,16-androstadien-3-one (AND). AND, which is found in sweat and saliva, is known to be responsible for influencing several variables, such as psychophysiological status, behavior, as well as cortical processing. The aim of the present review is to give insight into the variety of AND effects, with special regard to specific cross-sexual characteristics of this putative human chemosignal, emphasizing the neural activation patterns and factors such as contextual conditions. This review highlights the importance of including those contributing factors into the analysis of behavioral as well as brain-related studies.

Altered likelihood of brain activation in attention and working memory networks in patients with multiple sclerosis: an ALE meta-analysis

Multiple sclerosis (MS) is a chronic neurological disease, frequently affecting attention and working memory functions. Functional imaging studies investigating those functions in MS patients are hard to compare, as they include heterogeneous patient groups and use different paradigms for cognitive testing. The aim of this study was to investigate alterations in neuronal activation between MS patients and healthy controls performing attention and working memory tasks. Two meta-analyses of previously published fMRI studies investigating attention and working memory were conducted for MS patients and healthy controls, respectively. Resulting maps were contrasted to compare brain activation in patients and healthy controls. Significantly increased brain activation in the inferior parietal lobule and the dorsolateral prefrontal cortex was detected for healthy controls. In contrast, higher neuronal activation in MS patients was obtained in the left ventrolateral prefrontal cortex and the right premotor area. With this meta-analytic approach previous results of investigations examining cognitive function using fMRI are summarized and compared. Therefore a more general view on cognitive dysfunction in this heterogeneous disease is enabled.

Attention shifts the language network reflecting paradigm presentation

OBJECTIVES

Functional magnetic resonance imaging (fMRI) is a reliable and non-invasive method with which to localize language function in pre-surgical planning. In clinical practice, visual stimulus presentation is often difficult or impossible, due to the patient's restricted language or attention abilities. Therefore, our aim was to investigate modality-specific differences in visual and auditory stimulus presentation.

METHODS

Ten healthy subjects participated in an fMRI study comprising two experiments with visual and auditory stimulus presentation. In both experiments, two language paradigms (one for language comprehension and one for language production) used in clinical practice were investigated. In addition to standard data analysis by the means of the general linear model (GLM), independent component analysis (ICA) was performed to achieve more detailed information on language processing networks.

RESULTS

GLM analysis revealed modality-specific brain activation for both language paradigms for the contrast visual > auditory in the area of the intraparietal sulcus and the hippocampus, two areas related to attention and working memory. Using group ICA, a language network was detected for both paradigms independent of stimulus presentation modality. The investigation of language lateralization revealed no significant variations. Visually presented stimuli further activated an attention-shift network, which could not be identified for the auditory presented language.

CONCLUSION

The results of this study indicate that the visually presented language stimuli additionally activate an attention-shift network. These findings will provide important information for pre-surgical planning in order to preserve reading abilities after brain surgery, significantly improving surgical outcomes. Our findings suggest that the presentation modality for language paradigms should be adapted on behalf of individual indication.

Knee muscle activity during ambulation of trans-tibial amputees

Gait analysis of trans-tibial amputees brings to light asymmetries of different gait parameters between the amputated and sound legs. The present study investigated the activity of the vastus medialis and biceps femoris muscles during ambulation of trans-tibial amputees. Peak activities of the vastus medialis were reached similarly in both legs (6.06+/-4.9% and 8.84+/-3.6% of gait cycle, in the sound and amputated leg, respectively). Biceps femoris peak activities were reached at 92.43+/-6.6% of gait cycle in the sound leg, and significantly later (at 9.81+/-4.8% of gait cycle) in the amputated leg (p < 0.05). Integrated EMG activity ratios, between swing and stance periods, were similar for the vastus medialis (0.33 in the sound and 0.35 in the amputated leg). However, these ratios differed significantly for the biceps femoris since the amputated leg presented a substantial (p < 0.05) smaller ratio (0.22) compared with the sound leg (0.83). The use of prosthesis in trans-tibial amputees requires further activity of the biceps femoris during stance period to improve support of the amputated leg knee joint.

Double-limb support and step-length asymmetry in below-knee amputees

The sequence of gait events and symmetry of kinematic parameters between both lower limbs are compromised in below-knee amputees. In the present study the periods of double-limb support and the step length in below-knee amputees were investigated. The symmetry of the two periods of double-limb support occurring in each stride was obviously abnormal (ratio: 0.74) among temporal and distance parameters. The time of double-limb support (0.211 +/- 0.05 seconds) measured from heel-strike of the amputated leg until toe-off of the normal leg was significantly longer (p = 0.011) when compared with the contralateral leg (0.173 +/- 0.04 seconds). The step length of the normal leg (0.709 +/- 0.07 m) was significantly (p = 0.045) shorter than that of the amputated leg (0.752 +/- 0.08 m). Most of these differences between measured kinematic parameters can be explained by the limited ability of the prosthesis ankle-foot component to reproduce the normal functions of both foot and ankle.

Influence of speed on gait parameters and on symmetry in trans-tibial amputees

Normal gait is characterised by a high level of inter-leg symmetry of gait parameters. Therefore, efforts in rehabilitation of amputees are directed at the construction of a prosthesis which provides normal leg function and allows a more symmetrical gait. Analysis of the gait of trans-tibial amputees was performed when they were ambulating at their own freely selected speed and at a faster speed. The effect of speed on selected gait parameters in each leg was evaluated and the influence on symmetry established by comparing the inter-leg changes for each of the selected parameters. The faster gait trail affected significantly all temporal and distance parameters in both legs but not the level of symmetry between legs. At the faster speed, the hip angles at heel-strike and during swing and the knee angle during load response, in the normal leg, and the knee angle during swing in the amputated leg, all increased significantly. Speed of gait significantly affected symmetry between knee angles as reflected by the increased differences measured during load response (from 2.62 +/- 5.2 to 7.06 +/- 4.2 degrees) and during toe-off (from 1.80 +/- 7.4 to 9.50 +/- 9.1 degrees). Timing and sequence of selected gait events, as related to stride time, were not significantly affected by speed of gait. These results might contribute to a better understanding of gait characteristics in trans-tibial amputees and provide design guidance for prosthetic components.

Ankle muscle activity before and after botulinum toxin therapy for lower limb extensor spasticity in chronic hemiparetic patients

BACKGROUND AND PURPOSE

Recent studies have been made of the novel treatment of lower limb spasticity after stroke with botulinum toxin A, and the results were based mostly on the clinical assessment made before and after treatment. This study investigated the effects of toxin on ankle muscle activity during gait in patients with severe extensor spasticity. The questions posed were whether the toxin particularly diminishes the so-called premature muscle activity as a major cause of equinovarus deformity and whether different types of altered motor control allow a prediction of the outcome of the treatment.

METHODS

In 12 chronic hemiparetic outpatients with pronounced lower limb spasticity, we injected 400 U botulinum toxin A into the soleus and tibialis posterior muscles and both heads of the gastrocnemius muscles. Ankle spasticity and complex gait analysis including kinematic electromyography (EMG) of the soleus and tibialis muscles were assessed before treatment and 4 weeks after the injection.

RESULTS

Nine patients profited with a reduction of spasticity, improved gait ability, and a more normal temporal pattern of muscle activity with a prominent reduction of the premature activity of the plantar flexors. Eight patients exhibited a qualitative pattern (type I) corresponding to an increased stretch-reflex excitability. Three patients did not profit; their muscle tone, gait ability, and muscle activation remained stable or even deteriorated.

CONCLUSIONS

This study further supports the beneficial effects of botulinum toxin in the treatment of lower limb extensor spasticity. A correlation was observed between the clinical reduction of muscle tone, functional gait parameters, and a more normal EMG pattern with a predominant reduction of the premature activity of the plantar flexors. The qualitative type of EMG pattern corresponding to an increased stretch-reflex excitability (type I) was a positive predictor for the outcome.

Therapeutic effects of multisite electric stimulation of gait in motor-disabled patients

Therapeutic effects in ten hemiplegic patients and one paraparetic patient treated by multisite electric stimulation of gait were compared with effects in ten hemiplegic patients treated by standard rehabilitation methods after 2.6 months of extensive therapy. Average step length and gait velocity, ground reaction forces and their distribution under both feet, and crutch loading were measured; goniograms of joint angles, kinesiologic gait analysis, and EMG recordings from the main muscles used in ambulation and in standing, were made while patients in both groups walked without stimulation. Quantitative measurements before, during, at the end, and 8.4 months posttherapy were taken based on at least 40 strides per patient. The results for the stimulated group in midtherapy indicated faster recovery rates (3.15 times in step length and 2.25 times in gait velocity) than in the control group, and at the end of therapy the stimulated group had higher improvement levels (2.14 times in step length, 1.42 times in gait velocity, and 1.63 times in kinesiologic gait analysis). The differences between the two groups faded after 8.4 months without treatment, and some kinesiologic deficits reappeared, mostly those in the more distal muscle groups. These findings indicate a need for a simpler orthotic electric stimulation after multisite therapy in several cases. Immediate effects of the six-site stimulation were also considered for orthotic possibilities after the therapy.

The use of ground reaction measuring shoes in gait evaluation

Ground reaction force is one of the most relevant parameters in the assessment of human gait. It is, however, difficult to measure without encumbering natural locomotion. A description of a system for measuring the vertical component of the ground reaction force and its distribution under the foot is given. The calibration procedure for the measuring shoes is described. The results of measurements are compared with those obtained from a force plate. Illustrative examples of the changes in pathological gait patterns of a hemiplegic patient during therapy by functional electrical stimulation are also given.

Multichannel electrical stimulation of gait in motor disabled patients

Effects of surface multichannel electrical stimulation of the leg muscles during gait were evaluated by a clinical kinesiological analysis of gait and measurements of average step length, gait velocity, ground reaction forces, and joint angles. Direct effects in 11 stimulated motor disabled patients showed 56% improvement at the kinesiological gait analysis during the stimulation. Long term effects of the multichannel therapy were compared in a threeyear control study with a group of ten nonstimulated patients. At the kinesiological analysis, the stimulated group improved 1.75 times better after 2.5 months of the treatment. The other measurements revealed higher and faster improvement at the stimulated group with a partial decrease of the therapeutic effects after a longer period without treatment. Orthotic multichannel stimulation was indicated after the multichannel therapy in the clinical environment, where the stimulation of proximal leg muscles was favored.

Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES

Recent advances in science have aided research toward the restoration of biped gait in paraplegic patients by means of functional electrical stimulation (FES). In this paper it is shown how FES-restrengthened muscles of paraplegic patients have been used for simple FES-assisted standing. Those experiments subsequently led to biped gait-initializing experiments and to simple forms of biped gait synthesis. The purpose of this paper is to show the feasibility of using FES for standing and for restoring biped gait in many paraplegic patients--to present the past achievements, focus on problems, and highlight directions for future research. The results of gait obtained in three complete spinal cord injured patients (out of a series of 17) are shown, using four to six channels of FES. It is also shown how preserved reflex mechanisms of the transected spinal cord can be incorporated and employed for obtaining improved function while at the same time simplifying the FES hardware. Of the three patients reported on in detail here, two patients have managed to walk in parallel bars while the third patient has mastered independent unassisted walking over shorter distances with the aid of a roller walker. The biomechanical and control problems of this last patient's gait are presented in detail.

[The treatment of mandibular fractures, complicated by inflammations in the fracture area, by means of xenogenic cartilage]

The authors used a personal technique for the management of infected jaw fractures. If the fracture cleft was not wider than 1 cm, they performed a surgical revision (having made an incision through the mucoperiosteum of the oral vestibule) and replaced the excochleated gra-ulation tissue (including sequestrums) by lyophilized cartilage. The bone fragments were immoblized by bone sutures previously applied and also by additional plastic splints. The substitution of the cartilage by bone begun 6-8 weeks after the surgical intervention (as evidenced by radiographs); the process had terminated in about 6-10 months, the implanted cartilage being completely replaced by newly formed bone. The observation involved 16 cases. The method is also recommended for treatment on an out-patient basis.

[The use of cartilage and tissue adhesives for the treatment of surgical-stomatological diseases in old age]

The authors used lyophilized cartilage in plate, bar, chip or powder form in elderly patients. The transplant was also utilized in managing defects resulting from the removal of jaw cysts, bone tumours, etc. Furthermore, the authors treated bone defects of the anterior wall of the maxillary sinus and of the hard palate as well as oro-antral perforations, infected wounds of the soft tissues and inflammatory bone processes. The patients in question had been treated in the surgical service during the years 1959--1975. The authors observed in elderly patients pathological alterations of the capillaries, haemorrhagic tendency and impairment of the blood-clotting mechanism. Furthermore, they found that the granulation tissue was of poor quality. In these cases they used cartilaginous tissue in powder form which promotes the formation of granulation tissue well supplied with blood. In the patients mentioned, the authors also utilized surgical adhesive, namely after tooth extractions and in managing their complications.