Roman Schniepp - Academia.edu (original) (raw)
Papers by Roman Schniepp
Frontiers in Human Neuroscience
Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehensi... more Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehension of losing balance or falling. We investigated contributions of visual feedback and attention on gait performance of subjects with vHI. Materials and Methods: Sixteen subjects with vHI walked over a gait mat (GAITRite®) on a 15-m-high balcony and at ground-level. Subjects walked at different speeds (slow, preferred, fast), during changes of the visual input (gaze straight/up/down; eyes open/closed), and while doing a cognitive task. An rmANOVA with the factors “height situation” and “gait condition” was performed. Subjects were also asked to estimate the height of the balcony over ground level. The individual estimates were used for correlations with the gait parameters. Results: Study participants walked slower at heights, with reduced cadence and stride length. The double support phases were increased (all p < 0.01), which correlated with the estimated height of the balcony (R2 = ...
Klinische Neurophysiologie, 2010
Klinische Neurophysiologie, 2014
Acta Neurochirurgica, 2015
In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is th... more In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005. The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups. Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group). Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment and urinary incontinency without the risk of overdrainage complications requiring surgical intervention when compared with patients who received differential pressure valves in previous years.
Annals of the New York Academy of Sciences, 2015
This review shows that persons with visual height intolerance or acrophobia exhibit typical restr... more This review shows that persons with visual height intolerance or acrophobia exhibit typical restrictions of visual exploration and imbalance during stance and locomotion when exposed to heights. Eye and head movements are reduced, and gaze freezes to the horizon. Eye movements tend to be horizontal saccades during stance and vertical saccades during locomotion. Body posture is characterized by a stiffening of the musculoskeletal system with increased open-loop diffusion activity of body sway, a lowered sensory feedback threshold for closed-loop balance control, and increased co-contraction of antigravity leg and neck muscles. Walking is slow and cautious, broad-based, consisting of small, flat-footed steps with less dynamic vertical oscillation of the body and head. Anxiety appears to be the critical symptom that causes the typical but not specific eye and body motor behavior, which can be described as tonic immobility. Guidelines for preventing acrophobia, which could be an add-on to behavioral therapy, are provided.
Physiological Reports, 2014
Fear of heights occurs when a visual stimulus causes the apprehension of losing balance and falli... more Fear of heights occurs when a visual stimulus causes the apprehension of losing balance and falling. A moderate form of visual height intolerance (vHI) affects about one third of the general population and has relevant consequences for the quality of life. A quantitative evaluation of balance mechanisms in persons susceptible to vHI during height exposure is missing. VHI-related changes in postural control were assessed by center-of-pressure displacements and electromyographic recordings of selected leg, arm, and neck muscles in 16 subjects with vHI while standing at heights on an emergency balcony versus standing in the laboratory at ground level. Characteristics of open-and closed-loop postural control were analyzed. Body sway and muscle activity parameters were correlated with the subjective estimates of fear at heights. During height exposure, (1) open-loop control was disturbed by a higher diffusion activity (P < 0.001) and (2) the sensory feedback threshold for closed-loop control was lowered (P < 0.010). Altered postural control was predominantly associated with increased co-contraction of leg muscles. Body sway and leg and neck muscle co-contraction correlated with the severity of subjective anxiety (P < 0.050). Alterations in postural control diminished if there were nearby stationary contrasts in the visual surrounding or if subjects stood with eyes closed. The performance of a cognitive dual task also improved impaired balance. Visual heights have two behavioral effects in vHI subjects: A change occurs in (1) open-and closed-loop postural control strategy and (2) co-contraction of anti-gravity leg and neck muscles, both of which depend on the severity of evoked fear at heights.
Frontiers in Human Neuroscience, 2014
Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehensi... more Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehension of losing balance or falling. We investigated contributions of visual feedback and attention on gait performance of subjects with vHI.
Journal of Neurochemistry, 2003
Surface expression of the glial glutamate transporter EAAT1 is stimulated by insulin-like growth ... more Surface expression of the glial glutamate transporter EAAT1 is stimulated by insulin-like growth factor 1 through activation of phosphatidylinositol-3-kinase. Downstream targets include serum and glucocorticoid-sensitive kinase isoforms SGK1, SGK2 and SGK3, and protein kinase B. SGK1 regulates Nedd4-2, a ubiquitin ligase that prepares cell membrane proteins for degradation. To test whether Nedd4-2, SGK1, SGK3 and protein kinase B regulate EAAT1, cRNA encoding EAAT1 was injected into Xenopus oocytes with or without additional injection of wild-type Nedd4-2, constitutively active S422D SGK1, inactive K127N SGK1, wild-type SGK3 and/or constitutively active T308D,S473D PKB. Glutamate induces a current in Xenopus oocytes expressing EAAT1, but not in water-injected oocytes, which is decreased by co-expression of Nedd4-2, an effect reversed by additional co-expression of S422D SGK1, SGK3 and T308D,S473D PKB, but not K127N SGK1. Site-directed mutagenesis of the SGK1 phosphorylation sites in the Nedd4-2 protein ( S382A,S468A Nedd4-2) and in the EAAT1 protein ( T482A EAAT1, T482D EAAT1) significantly blunts the effect of S422D SGK1. Moreover, the current is significantly larger in T482D EAAT1-than in T482A EAAT1-expressing oocytes, indicating that a negative charge mimicking phosphorylation at T482 increases transport. The experiments reveal a powerful novel mechanism that regulates the activity of EAAT1. This mechanism might participate in the regulation of neuronal excitability and glutamate transport in other tissues. Abbreviations used: EAAT, excitatory amino acid transporter; ENaC, epithelial Na + channel; IGF, insulin-like growth factor; I GLU , glutamateinduced inward current; Nedd4-2, neuronal developmentally downregulated gene 4, isoform 2; PKB, protein kinase B; SGK, serum and glucocorticoid-inducible kinase.
Journal of Electromyography and Kinesiology, 2015
Automated pattern recognition systems have been used for accurate identification of neurological ... more Automated pattern recognition systems have been used for accurate identification of neurological conditions as well as the evaluation of the treatment outcomes. This study aims to determine the accuracy of diagnoses of (oto-)neurological gait disorders using different types of automated pattern recognition techniques. Clinically confirmed cases of phobic postural vertigo (N=30), cerebellar ataxia (N=30), progressive supranuclear palsy (N=30), bilateral vestibulopathy (N=30), as well as healthy subjects (N=30) were recruited for the study. 8 measurements with 136 variables using a GAITRite® sensor carpet were obtained from each subject. Subjects were randomly divided into two groups (training cases and validation cases). Sensitivity and specificity of k-nearest neighbor (KNN), naive-bayes classifier (NB), artificial neural network (ANN), and support vector machine (SVM) in classifying the validation cases were calculated. ANN and SVM had the highest overall sensitivity with 90.6% and 92.0% respectively, followed by NB (76.0%) and KNN (73.3%). SVM and ANN showed high false negative rates for bilateral vestibulopathy cases (20.0% and 26.0%); while KNN and NB had high false negative rates for progressive supranuclear palsy cases (76.7% and 40.0%). Automated pattern recognition systems are able to identify pathological gait patterns and establish clinical diagnosis with good accuracy. SVM and ANN in particular differentiate gait patterns of several distinct oto-neurological disorders of gait with high sensitivity and specificity compared to KNN and NB. Both SVM and ANN appear to be a reliable diagnostic and management tool for disorders of gait.
PLoS ONE, 2014
Downbeat nystagmus (DBN) is a common form of acquired fixation nystagmus with key symptoms of osc... more Downbeat nystagmus (DBN) is a common form of acquired fixation nystagmus with key symptoms of oscillopsia and gait disturbance. Gait disturbance could be a result of impaired visual feedback due to the involuntary ocular oscillations. Alternatively, a malfunction of cerebellar locomotor control might be involved, since DBN is considered a vestibulocerebellar disorder. Investigation of walking in 50 DBN patients (age 72 ± 11 years, 23 females) and 50 healthy controls (HS) (age 70 ± 11 years, 23 females) using a pressure sensitive carpet (GAITRite). The patient cohort comprised subjects with only ocular motor signs (DBN) and subjects with an additional limb ataxia (DBNCA). Gait investigation comprised different walking speeds and walking with eyes closed. In DBN, gait velocity was reduced (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) with a reduced stride length (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001), increased base of support (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.050), and increased double support (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Walking with eyes closed led to significant gait changes in both HS and DBN. These changes were more pronounced in DBN patients (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Speed-dependency of gait variability revealed significant differences between the subgroups of DBN and DBNCA (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.050). (I) Impaired visual control caused by involuntary ocular oscillations cannot sufficiently explain the gait disorder. (II) The gait of patients with DBN is impaired in a speed dependent manner. (III) Analysis of gait variability allows distinguishing DBN from DBNCA: Patients with pure DBN show a speed dependency of gait variability similar to that of patients with afferent vestibular deficits. In DBNCA, gait variability resembles the pattern found in cerebellar ataxia.
![Research paper thumbnail of Sequential [(18)F]FDG µPET whole-brain imaging of central vestibular compensation: a model of deafferentation-induced brain plasticity](https://attachments.academia-assets.com/43899875/thumbnails/1.jpg)
](Brain structure & function, 2014
Unilateral inner ear damage is followed by a rapid behavioural recovery due to central vestibular... more Unilateral inner ear damage is followed by a rapid behavioural recovery due to central vestibular compensation. In this study, we utilized serial [(18)F]Fluoro-deoxyglucose ([(18)F]FDG)-µPET imaging in the rat to visualize changes in brain glucose metabolism during behavioural recovery after surgical and chemical unilateral labyrinthectomy, to determine the extent and time-course of the involvement of different brain regions in vestibular compensation and test previously described hypotheses of underlying mechanisms. Systematic patterns of relative changes of glucose metabolism (rCGM) were observed during vestibular compensation. A significant asymmetry of rCGM appeared in the vestibular nuclei, vestibulocerebellum, thalamus, multisensory vestibular cortex, hippocampus and amygdala in the acute phase of vestibular imbalance (4 h). This was followed by early vestibular compensation over 1-2 days where rCGM re-balanced between the vestibular nuclei, thalami and temporoparietal cortice...
Klinische Neurophysiologie, 2012
Movement Disorders, 2011
Temporal gait variability is a critical parameter in patients with balance problems. Increased ma... more Temporal gait variability is a critical parameter in patients with balance problems. Increased magnitude of temporal gait variability corresponds to a higher risk of falls. The purpose of this study was to investigate the influence of walking speed on temporal stride-to-stride variability in patients with cerebellar and vestibular deficits. A GAITRite system was used to analyze the gait of 40 patients with cerebellar ataxia, 22 patients with bilateral vestibular failure, and 51 healthy subjects over the entire range of the individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s speed capacity. The coefficient of variability of stride time was calculated for each walk. Temporal gait variability was increased in cerebellar patients and vestibular patients. The magnitude of this variability depended on walking speed in a disease-specific manner. In patients with cerebellar ataxia, variability was increased during slow (8.4 ± 5.3%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01) and fast (7.9 ± 6.4%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01) walking speed but was normal during preferred walking speed. This resulted in a speed-related U-shaped function of stride-time variability. Patients with vestibular failure had increased variability during slow walking (9.9 ± 4.3%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01). During walking with medium and fast walking speed, stride time variability was normal. Minimal temporal gait variability appears to be attractive for the locomotor system in cerebellar patients because these patients preferred to walk at a velocity associated with minimal stride-time variability. In contrast to previous studies, vestibular patients accelerate rather than decelerate gait to achieve dynamic stability. This may be explained by reduced sensory integration during fast locomotion.
Klinische Neurophysiologie, 2011
Klinische Neurophysiologie, 2010
Parkinsonism & Related Disorders, 2010
Parkinsonism & Related Disorders, 2010
Parkinsonism & Related Disorders, 2010
Multiple Sclerosis Journal, 2013
The reversible potassium channel blocker 4-aminopyridine is effective in the treatment of numerou... more The reversible potassium channel blocker 4-aminopyridine is effective in the treatment of numerous cerebellar dysfunctions, such as episodic ataxia type 2 and downbeat nystagmus syndrome. In 2011, its sustained release form, dalfampridine, was admitted in Europe for the treatment of walking difficulties in patients with multiple sclerosis (MS).
Journal of Neurology, 2011
Frontiers in Human Neuroscience
Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehensi... more Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehension of losing balance or falling. We investigated contributions of visual feedback and attention on gait performance of subjects with vHI. Materials and Methods: Sixteen subjects with vHI walked over a gait mat (GAITRite®) on a 15-m-high balcony and at ground-level. Subjects walked at different speeds (slow, preferred, fast), during changes of the visual input (gaze straight/up/down; eyes open/closed), and while doing a cognitive task. An rmANOVA with the factors “height situation” and “gait condition” was performed. Subjects were also asked to estimate the height of the balcony over ground level. The individual estimates were used for correlations with the gait parameters. Results: Study participants walked slower at heights, with reduced cadence and stride length. The double support phases were increased (all p < 0.01), which correlated with the estimated height of the balcony (R2 = ...
Klinische Neurophysiologie, 2010
Klinische Neurophysiologie, 2014
Acta Neurochirurgica, 2015
In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is th... more In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005. The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups. Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group). Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment and urinary incontinency without the risk of overdrainage complications requiring surgical intervention when compared with patients who received differential pressure valves in previous years.
Annals of the New York Academy of Sciences, 2015
This review shows that persons with visual height intolerance or acrophobia exhibit typical restr... more This review shows that persons with visual height intolerance or acrophobia exhibit typical restrictions of visual exploration and imbalance during stance and locomotion when exposed to heights. Eye and head movements are reduced, and gaze freezes to the horizon. Eye movements tend to be horizontal saccades during stance and vertical saccades during locomotion. Body posture is characterized by a stiffening of the musculoskeletal system with increased open-loop diffusion activity of body sway, a lowered sensory feedback threshold for closed-loop balance control, and increased co-contraction of antigravity leg and neck muscles. Walking is slow and cautious, broad-based, consisting of small, flat-footed steps with less dynamic vertical oscillation of the body and head. Anxiety appears to be the critical symptom that causes the typical but not specific eye and body motor behavior, which can be described as tonic immobility. Guidelines for preventing acrophobia, which could be an add-on to behavioral therapy, are provided.
Physiological Reports, 2014
Fear of heights occurs when a visual stimulus causes the apprehension of losing balance and falli... more Fear of heights occurs when a visual stimulus causes the apprehension of losing balance and falling. A moderate form of visual height intolerance (vHI) affects about one third of the general population and has relevant consequences for the quality of life. A quantitative evaluation of balance mechanisms in persons susceptible to vHI during height exposure is missing. VHI-related changes in postural control were assessed by center-of-pressure displacements and electromyographic recordings of selected leg, arm, and neck muscles in 16 subjects with vHI while standing at heights on an emergency balcony versus standing in the laboratory at ground level. Characteristics of open-and closed-loop postural control were analyzed. Body sway and muscle activity parameters were correlated with the subjective estimates of fear at heights. During height exposure, (1) open-loop control was disturbed by a higher diffusion activity (P < 0.001) and (2) the sensory feedback threshold for closed-loop control was lowered (P < 0.010). Altered postural control was predominantly associated with increased co-contraction of leg muscles. Body sway and leg and neck muscle co-contraction correlated with the severity of subjective anxiety (P < 0.050). Alterations in postural control diminished if there were nearby stationary contrasts in the visual surrounding or if subjects stood with eyes closed. The performance of a cognitive dual task also improved impaired balance. Visual heights have two behavioral effects in vHI subjects: A change occurs in (1) open-and closed-loop postural control strategy and (2) co-contraction of anti-gravity leg and neck muscles, both of which depend on the severity of evoked fear at heights.
Frontiers in Human Neuroscience, 2014
Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehensi... more Introduction: Visual height intolerance (vHI) manifests as instability at heights with apprehension of losing balance or falling. We investigated contributions of visual feedback and attention on gait performance of subjects with vHI.
Journal of Neurochemistry, 2003
Surface expression of the glial glutamate transporter EAAT1 is stimulated by insulin-like growth ... more Surface expression of the glial glutamate transporter EAAT1 is stimulated by insulin-like growth factor 1 through activation of phosphatidylinositol-3-kinase. Downstream targets include serum and glucocorticoid-sensitive kinase isoforms SGK1, SGK2 and SGK3, and protein kinase B. SGK1 regulates Nedd4-2, a ubiquitin ligase that prepares cell membrane proteins for degradation. To test whether Nedd4-2, SGK1, SGK3 and protein kinase B regulate EAAT1, cRNA encoding EAAT1 was injected into Xenopus oocytes with or without additional injection of wild-type Nedd4-2, constitutively active S422D SGK1, inactive K127N SGK1, wild-type SGK3 and/or constitutively active T308D,S473D PKB. Glutamate induces a current in Xenopus oocytes expressing EAAT1, but not in water-injected oocytes, which is decreased by co-expression of Nedd4-2, an effect reversed by additional co-expression of S422D SGK1, SGK3 and T308D,S473D PKB, but not K127N SGK1. Site-directed mutagenesis of the SGK1 phosphorylation sites in the Nedd4-2 protein ( S382A,S468A Nedd4-2) and in the EAAT1 protein ( T482A EAAT1, T482D EAAT1) significantly blunts the effect of S422D SGK1. Moreover, the current is significantly larger in T482D EAAT1-than in T482A EAAT1-expressing oocytes, indicating that a negative charge mimicking phosphorylation at T482 increases transport. The experiments reveal a powerful novel mechanism that regulates the activity of EAAT1. This mechanism might participate in the regulation of neuronal excitability and glutamate transport in other tissues. Abbreviations used: EAAT, excitatory amino acid transporter; ENaC, epithelial Na + channel; IGF, insulin-like growth factor; I GLU , glutamateinduced inward current; Nedd4-2, neuronal developmentally downregulated gene 4, isoform 2; PKB, protein kinase B; SGK, serum and glucocorticoid-inducible kinase.
Journal of Electromyography and Kinesiology, 2015
Automated pattern recognition systems have been used for accurate identification of neurological ... more Automated pattern recognition systems have been used for accurate identification of neurological conditions as well as the evaluation of the treatment outcomes. This study aims to determine the accuracy of diagnoses of (oto-)neurological gait disorders using different types of automated pattern recognition techniques. Clinically confirmed cases of phobic postural vertigo (N=30), cerebellar ataxia (N=30), progressive supranuclear palsy (N=30), bilateral vestibulopathy (N=30), as well as healthy subjects (N=30) were recruited for the study. 8 measurements with 136 variables using a GAITRite® sensor carpet were obtained from each subject. Subjects were randomly divided into two groups (training cases and validation cases). Sensitivity and specificity of k-nearest neighbor (KNN), naive-bayes classifier (NB), artificial neural network (ANN), and support vector machine (SVM) in classifying the validation cases were calculated. ANN and SVM had the highest overall sensitivity with 90.6% and 92.0% respectively, followed by NB (76.0%) and KNN (73.3%). SVM and ANN showed high false negative rates for bilateral vestibulopathy cases (20.0% and 26.0%); while KNN and NB had high false negative rates for progressive supranuclear palsy cases (76.7% and 40.0%). Automated pattern recognition systems are able to identify pathological gait patterns and establish clinical diagnosis with good accuracy. SVM and ANN in particular differentiate gait patterns of several distinct oto-neurological disorders of gait with high sensitivity and specificity compared to KNN and NB. Both SVM and ANN appear to be a reliable diagnostic and management tool for disorders of gait.
PLoS ONE, 2014
Downbeat nystagmus (DBN) is a common form of acquired fixation nystagmus with key symptoms of osc... more Downbeat nystagmus (DBN) is a common form of acquired fixation nystagmus with key symptoms of oscillopsia and gait disturbance. Gait disturbance could be a result of impaired visual feedback due to the involuntary ocular oscillations. Alternatively, a malfunction of cerebellar locomotor control might be involved, since DBN is considered a vestibulocerebellar disorder. Investigation of walking in 50 DBN patients (age 72 ± 11 years, 23 females) and 50 healthy controls (HS) (age 70 ± 11 years, 23 females) using a pressure sensitive carpet (GAITRite). The patient cohort comprised subjects with only ocular motor signs (DBN) and subjects with an additional limb ataxia (DBNCA). Gait investigation comprised different walking speeds and walking with eyes closed. In DBN, gait velocity was reduced (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) with a reduced stride length (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001), increased base of support (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.050), and increased double support (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Walking with eyes closed led to significant gait changes in both HS and DBN. These changes were more pronounced in DBN patients (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Speed-dependency of gait variability revealed significant differences between the subgroups of DBN and DBNCA (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.050). (I) Impaired visual control caused by involuntary ocular oscillations cannot sufficiently explain the gait disorder. (II) The gait of patients with DBN is impaired in a speed dependent manner. (III) Analysis of gait variability allows distinguishing DBN from DBNCA: Patients with pure DBN show a speed dependency of gait variability similar to that of patients with afferent vestibular deficits. In DBNCA, gait variability resembles the pattern found in cerebellar ataxia.
Brain structure & function, 2014
Unilateral inner ear damage is followed by a rapid behavioural recovery due to central vestibular... more Unilateral inner ear damage is followed by a rapid behavioural recovery due to central vestibular compensation. In this study, we utilized serial [(18)F]Fluoro-deoxyglucose ([(18)F]FDG)-µPET imaging in the rat to visualize changes in brain glucose metabolism during behavioural recovery after surgical and chemical unilateral labyrinthectomy, to determine the extent and time-course of the involvement of different brain regions in vestibular compensation and test previously described hypotheses of underlying mechanisms. Systematic patterns of relative changes of glucose metabolism (rCGM) were observed during vestibular compensation. A significant asymmetry of rCGM appeared in the vestibular nuclei, vestibulocerebellum, thalamus, multisensory vestibular cortex, hippocampus and amygdala in the acute phase of vestibular imbalance (4 h). This was followed by early vestibular compensation over 1-2 days where rCGM re-balanced between the vestibular nuclei, thalami and temporoparietal cortice...
Klinische Neurophysiologie, 2012
Movement Disorders, 2011
Temporal gait variability is a critical parameter in patients with balance problems. Increased ma... more Temporal gait variability is a critical parameter in patients with balance problems. Increased magnitude of temporal gait variability corresponds to a higher risk of falls. The purpose of this study was to investigate the influence of walking speed on temporal stride-to-stride variability in patients with cerebellar and vestibular deficits. A GAITRite system was used to analyze the gait of 40 patients with cerebellar ataxia, 22 patients with bilateral vestibular failure, and 51 healthy subjects over the entire range of the individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s speed capacity. The coefficient of variability of stride time was calculated for each walk. Temporal gait variability was increased in cerebellar patients and vestibular patients. The magnitude of this variability depended on walking speed in a disease-specific manner. In patients with cerebellar ataxia, variability was increased during slow (8.4 ± 5.3%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01) and fast (7.9 ± 6.4%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01) walking speed but was normal during preferred walking speed. This resulted in a speed-related U-shaped function of stride-time variability. Patients with vestibular failure had increased variability during slow walking (9.9 ± 4.3%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .01). During walking with medium and fast walking speed, stride time variability was normal. Minimal temporal gait variability appears to be attractive for the locomotor system in cerebellar patients because these patients preferred to walk at a velocity associated with minimal stride-time variability. In contrast to previous studies, vestibular patients accelerate rather than decelerate gait to achieve dynamic stability. This may be explained by reduced sensory integration during fast locomotion.
Klinische Neurophysiologie, 2011
Klinische Neurophysiologie, 2010
Parkinsonism & Related Disorders, 2010
Parkinsonism & Related Disorders, 2010
Parkinsonism & Related Disorders, 2010
Multiple Sclerosis Journal, 2013
The reversible potassium channel blocker 4-aminopyridine is effective in the treatment of numerou... more The reversible potassium channel blocker 4-aminopyridine is effective in the treatment of numerous cerebellar dysfunctions, such as episodic ataxia type 2 and downbeat nystagmus syndrome. In 2011, its sustained release form, dalfampridine, was admitted in Europe for the treatment of walking difficulties in patients with multiple sclerosis (MS).
Journal of Neurology, 2011