[Show abstract][Hide abstract] ABSTRACT: Dirofilaria repens, a filarial nematode of dogs and other carnivores, can accidentally infect humans. Clinical symptoms are usually restricted to a subcutaneous nodule containing a single infertile parasite. Here, we report a case of D. repens infection with a subcutaneous gravid worm and the patient's concomitant meningoencephalitis and aphasia.
Full-text · Article · Nov 2009 · Emerging Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: Der Einsatz bildgebender Verfahren und neurophysiologischer Techniken erlaubt in zunehmendem Maße die Exploration neuroplastischer
Veränderungen, wie sie möglicherweise infolge einer Intervention im zentralen Nervensystem (ZNS) auftreten können. Dies wird
anhand von Laufbanduntersuchungen zur Pathophysiologie des Ganges, zur robotergestützten Laufbandtherapie (Lokomat®) und für
die obere Extremität exemplarisch für die „constraint induced movement therapy“ (CIMT) – Behandlungen, die sich durch Aufgabenspezifität
und Zielorientierung auszeichnen – dargestellt. Sowohl auf spinaler als auch auf kortikaler Ebene lassen sich durch die Interventionen
hervorgerufene Veränderungen nachweisen und Unterschiede im Ansprechen auf die Therapie in Abhängigkeit des Läsions- und Reorganisationstyps
darstellen. Dies belegt, dass eine aufgabenspezifische Plastizität des ZNS bei Patienten mit Zerebralparese vorhanden ist
und dass in klinischen Studien systemphysiologische Untersuchungen und Erkenntnisse als Stratifizierung- oder Evaluationsinstrument
Berücksichtigung finden sollten.
Functional magnetic resonance imaging and neurophysiological techniques allow the investigation of plastic changes that might
take place, through therapeutic interventions, within the nervous systems of patients with cerebral palsy. This is outlined
using studies dealing with treadmill training/spinal reflex modulation, robotic medicine (Lokomat®), and constraint induced
movement therapy. These examples show that plastic changes do occur and that the type of lesion and the reorganisation of
the nervous system might have an impact on treatment outcome. These findings underpin the idea that movement science should
be an integral consideration when planning clinical studies for patients with cerebral palsy.
No preview · Article · Nov 2009 · Monatsschrift Kinderheilkunde
[Show abstract][Hide abstract] ABSTRACT: In healthy children, short latency leg muscle reflexes are profoundly modulated throughout the step cycle in a functionally meaningful way and contribute to the electromyographic (EMG) pattern observed during gait. With maturation of the corticospinal tract, the reflex amplitudes are depressed via supraspinal inhibitory mechanisms. In the soleus muscle the rhythmic part of the modulation pattern is present in children with cerebral palsy (CP), but the development of tonic depression with increasing age, as seen in healthy children, is disturbed. Treadmill training clinically improves the walking pattern in children with CP. Presuming that short latency reflexes contribute significantly to the walking pattern, a change in the modulation may occur after training. The aim of this study was to assess whether treadmill training also improves the soleus reflex modulation during gait in children with CP. Seven children with CP underwent brief treadmill training for 10 min a day over 10 consecutive days; all of them were functional walkers. Soleus Hoffmann (H-) reflexes were investigated during walking on a treadmill before the first, and one day after the last, training session. Treadmill training led to a considerable clinical improvement in gait velocity. After 10 days of training, soleus H-reflexes during gait were almost completely depressed during the swing phase. The complete suppression of the soleus H-reflex during the swing phase, which is also exhibited by healthy subjects, could reflect an improvement towards a functionally more useful pattern. In conclusion, treadmill training can induce changes in the modulation of short latency reflexes during gait.
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to investigate the effect of WBV on stretch reflexes involved in knee joint control. We evoked stretch reflexes of the hamstring muscles by inducing an anterior tibial translation during standing in 23 healthy subjects which were divided into a control and an intervention group. WBV with a frequency of 30 Hz and a vertical amplitude of 4 mm was induced by an uniformly oscillating platform. The WBV session lasted 60 seconds and was repeated twice. Short (SLR) and medium latency responses (MLR) of the hamstring muscles and maximum tibia translation were assessed using surface EMG and linear potentiometers. While there were no significant changes in latency, the size of the lateral and medial hamstring SLR was significantly increased after WBV (p = 0.039 and p = 0.043, respectively). No significant differences were found for the hamstring MLR size after WBV. Maximum tibial translation was significantly decreased after WBV (p = 0.031). Our results suggest that single WBV exposure has a positive effect on knee joint stability as a short-term adaptation on neuromuscular level. This appears to be directly associated with an increase of hamstring SLR size in response to the anterior tibial movement which may cause the decrease in anterior tibial translation.
Full-text · Article · May 2008 · International Journal of Sports Medicine
[Show abstract][Hide abstract] ABSTRACT: Periventricular leukomalacia (PVL) is the most frequent cause of spastic diplegia. The movement disorder is attributed to damage to the corticospinal tract, but there is increasing evidence of additional cortical dysfunction associated with PVL. Aim of the present study was to evaluate the integrity of the corticospinal tract and cortical inhibitory function using transcranial magnetic stimulation. Fifteen children with bilateral PVL and spastic diplegia and twenty-two healthy children underwent single-pulse stimulations to the right tibial anterior muscle. We compared central motor conduction time and amplitudes of motor evoked potentials as markers for corticospinal integrity and the postexcitatory silent period (SP), representing cortical inhibitory interneurons. The patients' parameters of corticospinal tract function did not differ significantly from those in the control children. In contrast, the SP was significantly shortened in children with PVL (mean 25.6 +/- 6.9 ms; controls: mean 47.6 +/- 23.2 ms, P = 0.018). This suggests cortical involvement with reduced cortical inhibitory function in PVL. This could be due to impaired functioning of the cortical interneurons themselves, or to decreased input from activating fibres, e.g. thalamocortical or cortico-cortical connections.
No preview · Article · May 2008 · Experimental Brain Research
[Show abstract][Hide abstract] ABSTRACT: The stretch-shortening cycle (SSC) is characterized by stretching of the target muscle (eccentric phase) prior to a subsequent shortening in the concentric phase. Stretch reflexes in the eccentric phase were argued to influence the performance of short lasting SSCs. In drop-jumps, the short latency component of the stretch reflex (SLR) was shown to increase with falling height. However, in jumps from excessive heights, the SLR was diminished. So far, it is unclear whether the modulation of the SLR relies on spinal mechanisms or on an altered fusimotor drive. The present study aimed to assess the spinal excitability of the soleus Ia afferent pathway at SLR during jumps from low height (LH - 31 cm) and excessive height (EH - 76 cm).
In 20 healthy subjects (age 25 +/- 3 years), H-reflexes were timed to occur at the peak of the SLR during drop-jumps from LH and EH.
H-reflexes were significantly smaller at EH than at LH (P < 0.05). Neither soleus and tibialis anterior background EMG nor the size of the maximum M-wave changed with falling height.
Differences in the H-reflex between EH and LH indicate that spinal mechanisms are involved in the modulation of the SLR. A decreased excitability of the H-reflex pathway at EH compared with LH is argued to serve as a 'prevention strategy' to protect the tendomuscular system from potential injuries caused by the high load. It is argued that pre-synaptic inhibition of Ia afferents is most likely responsible for the change in H-reflex excitability between the two jump conditions.
No preview · Article · Apr 2008 · Acta Physiologica
[Show abstract][Hide abstract] ABSTRACT: In healthy adults, soleus H-reflexes are rhythmically modulated and generally depressed during gait compared with rest. From ages 6 to 13 yr, there is a progressive increase in the tonic inhibition of H-reflexes during walking, especially during the stance phase of the step cycle. In adults, rhythmic modulation and tonic depression are severely disturbed after bilateral spinal lesions but remain partly preserved after unilateral cerebral lesions. Children with diplegic cerebral palsy (CP) suffer from a bilateral supraspinal lesion of the corticospinal tract that occurs before the maturation of the CNS is complete. If supraspinal structures are involved in the tonic, but not rhythmic, age-dependent reflex depression, it could be hypothesized that the tonic reflex depression with age is disturbed in CP, whereas the rhythmic part of the modulation remains unaffected. To test this hypothesis, soleus H-reflexes were assessed during gait in 16 CP children aged 5-11 and 15-16 and compared with 25 age-matched healthy children walking at similar velocities. Although the rhythmic part of the modulation pattern was present in CP, there was no significant tonic reflex depression with age, thus reflecting a lack of maturation of the corticospinal tract. It is argued the rhythmic part of the modulation may be generated on a spinal or brain stem level and is therefore not affected by the bilateral supraspinal lesion, whereas the tonic depression that occurs with maturation of the CNS is under supraspinal control. In conclusion, the supraspinal structures affected in CP are therefore likely involved in this age-dependent tonic depression.
Preview · Article · Jan 2008 · Journal of Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: During locomotion spinal short latency reflexes are rhythmically modulated and depressed compared to rest. In adults this modulation is severely disturbed after bilateral spinal lesions indicating a role for supra-spinal control. Soleus reflex amplitudes are large in the stance phase and suppressed in the swing phase contributing to the reciprocal muscle activation pattern required for walking. In early childhood the EMG pattern during gait underlies an age-dependent process changing from co-contraction of agonists and antagonists to a reciprocal pattern at the age of 5-7 years. It is unknown whether at this stage apart from the EMG also reflexes are modulated, and if so, whether the reflex modulation is fully mature or still underlies an age-dependent development. This may give important information about the maturation of CNS structures involved in gait control. Soleus Hoffmann H-reflexes were investigated in 36 healthy children aged 7-16 years during treadmill walking at 1.2 km/h and 3.0 km/h. At 7 years old a rhythmic modulation similar to adults was observed. The H-reflex size during the stance phase decreased significantly with age while the maximum H-reflex (H (max)) at rest remained unchanged. At 3.0 km/h H-reflexes were significantly larger during the stance phase and smaller during the swing phase as compared to 1.2 km/h but the age-dependent suppression was observed at both walking velocities. In conclusion H-reflex modulation during gait is already present in young children but still underlies an age-dependent process independent of the walking velocity. The finding that the rhythmic part of the modulation is already present at the age of 7 years may indicate that the supra-spinal structures involved mature earlier than those involved in the tonic reflex depression. This may reflect an increasing supra-spinal control of spinal reflexes under functional conditions with maturation.
No preview · Article · May 2007 · Experimental Brain Research
[Show abstract][Hide abstract] ABSTRACT: Changes in gravity conditions result in various adaptations of the whole body. Especially under microgravity the nervous system is affected to a great extent. Until now, only the adaptation of M. soleus (SOL) H-reflex was measured under microgravity during parabolic flight experiments (1, 2). For that reason there are two notable restrictions, considering the functional interpretation of the existing results. First, the H-reflex is evoked by electrical stimulation of Ia afferents providing an estimate of alpha motoneuron excitability in the target motoneuron (MN) pool, bypassing the muscle spindle. Therefore, only the stretch reflex reflects changes in fusimotor activation, muscle or tendon properties, which are of functional importance for movement and neuromuscular control (3, 4). Second, the SOL is a postural muscle, acting to a much larger extent against gravitational forces than its antagonist the M. tibialis anterior (TA). Eliciting the TA H-reflex is much more difficult than eliciting the SOL H-reflex. Therefore, only few studies investigated short latency reflexes in TA and SOL to describe adaptations for both an antigravity muscle and its antagonist (5). Therefore, the aim of the present study was to determine the gravity dependent modulation of mechanically (stretch reflex) induced stimuli of a lower leg antigravity muscle (SOL) and its antagonist (TA). Eight healthy subjects (6 men and 2 women) participated in a parabolic flight procedure. Several gravity levels were imposed perpendicular to the floor of the aircraft, The subjects were asked to maintain an erect posture. They were fixed to an ergometer, which induced fast dorsi- and plantarflexion of the ankle joint. Thus, stretch reflexes of either SOL or TA were elicited mechanically. Electromyographic activity (EMG) of SOL and IA was recorded in both legs using a pair of surface electrodes. Position signal of ergometer pedals and EMG traces were summed up for each subject in three gravity conditions (normal gravity NG: 0,95-1,05g; hyper gravity HG: ¿1,7g and micro-gravity MG: -0,05-0,05g Stretch reflexes were larger during MG compared to NG in SOL muscle indicating the excitability of the SOL motoneuron pool is dependent on some gravity-related factors. This was suggested by previous studies that demonstrated reduced H-reflexes during sitting and lying compared to standing. Interestingly, this was not the case for TA stretch reflexes. In TA short latency reflexes were considerably decreased during MG. The results indicate differences in the gravity dependent modulation of short latency reflexes between an antigravity muscle and its antagonist.
[Show abstract][Hide abstract] ABSTRACT: The role of force feedback during gait is still a matter of debate. From work on cats, it is known that input from Golgi tendon organs from triceps surae does produce Ib facilitation during locomotion instead of autogenic inhibition. In humans, Stephens and Yang (Stephens, M.J., Yang, J.F., 1996. Short latency, non-reciprocal group I inhibition is reduced during the stance phase of walking in humans. Brain Res. 743, 24-31) found that voluntary contraction results in a reduction of Ib inhibition. During gait, they even observed Ib facilitation in a subset of subjects. This raises the question whether the crucial elements involved in these changes are either loading of the leg or locomotion. To examine this question, Ib reflexes were investigated during sitting, lying supine, lying supine with 300 N pressure applied to the foot sole, standing, and a rhythmic loading and unloading task called "reduced" gait. Ib inhibition was obtained during sitting and lying supine. This inhibition was significantly reduced or disappeared during standing and when lying supine but loaded. During the stance phase of "reduced" gait, the inhibition disappeared in eight subjects, and even a facilitation was observed in six subjects. It is concluded that the decrease in Ib inhibition from gastrocnemius to soleus occurs during a load-bearing condition and does not require locomotion. In contrast, Ib facilitation requires locomotion at least in a rudimentary form.