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G A Zäch

Publications and source records attributed to G A Zäch.

At least 19 recordsLinked to original sources
PubMed2003

The short-term effect of hippotherapy on spasticity in patients with spinal cord injury.

STUDY DESIGN: Assessment of spasticity before and after hippotherapy treatment. OBJECTIVE: To evaluate the short-term effect of hippotherapy on spasticity of spinal cord injured patients (SCIs). SETTING: Swiss Paraplegic Centre, Nottwil. METHODS: 32 patients with spinal cord injury with various degrees of spasticity had repeated sessions (mean 11) of Hippotherapy-K. Spasticity of the lower extremities was scored according to the Ashworth Scale. RESULTS: In primary rehabilitation patients Ashworth values after hippotherapy were significantly lower than before (Wilcoxon's signed-rank test: P<0.001). Highest improvements were observed in SCIs with very high spasticity. No significant difference between short-term effect in paraplegic and short-term effect in tetraplegic subjects was found. CONCLUSIONS: Hippotherapy significantly reduces spasticity of lower extremities in SCIs.

Adult↗
PubMed2002

Characteristics of sleep apnea syndrome in tetraplegic patients.

OBJECTIVE: To include a larger number of tetraplegics than in previous studies, in order to more reliably characterize the pathogenesis and predisposing factors of sleep apnea in tetraplegia. METHODS: Sleep breathing data and oxymetric values were investigated in 50 randomly selected tetraplegic patients and discussed in context with age, gender, BMI, neck circumference, type and height of lesion, time after injury, spirometric values and medication. A non-validated short questionnaire on daytime complaints was added. RESULTS: Thirty-one patients out of 50 had an RDI > or =15, defined as sleep disordered breathing (SDB); 24 of them combined with an apnea index of 5 or more, these cases were diagnosed as sleep apnea syndrome (SAS). SAS was apparent in 55% and 20% of the studied men and women, respectively. Regression analyses showed no significant correlation between RDI and lesion level, ASIA impairment scale or spirometric values. In contrast, a significant correlation between RDI and age, BMI, neck circumference and time after injury could be shown. Kruskal-Wallis test for dichotomous non-parametric factors, such as gender, cardiac medication and daytime complaints, showed significant differences with regard to RDI. In contrast to able-bodied people with SAS, daytime complaints were only present in tetraplegic patients with severe pathology (RDI>40). CONCLUSION: Incidence of SAS is high in tetraplegia, particularly in older male patients with large neck circumference, long standing spinal cord injury and under cardiac medication. As tetraplegics with RDI between 15 and 40 reported no daytime complaints and often have normal BMI, these tetraplegics are not clinically suspicious for SAS. The increased use of cardiac medication in tetraplegics with SAS may implicate a link between SAS and cardiovascular morbidity, one of the leading causes of death in tetraplegia.

Adult↗
PubMed2001

[MRI in spinal injuries].

The improvement of preclinical emergency medicine has increased the long-term survival of patients which sustained severe injuries of the spinal cord. However, the incidence of late complications has been increased due to the long-term survival. With the increasing use of magnetic resonance imaging (MRI) in this patient group the diagnosis of typical late complications of the spinal cord has improved. In this article we suggest the following terms to describe late complications of the spinal cord: syrinx, atrophy, cyst, malacia, disruption, and thethering.

Atrophy↗
PubMed2000

Reorganization of the human central nervous system.

The key strategies on which the discovery of the functional organization of the central nervous system (CNS) under physiologic and pathophysiologic conditions have been based included (1) our measurements of phase and frequency coordination between the firings of alpha- and gamma-motoneurons and secondary muscle spindle afferents in the human spinal cord, (2) knowledge on CNS reorganization derived upon the improvement of the functions of the lesioned CNS in our patients in the short-term memory and the long-term memory (reorganization), and (3) the dynamic pattern approach for re-learning rhythmic coordinated behavior. The theory of self-organization and pattern formation in nonequilibrium systems is explicitly related to our measurements of the natural firing patterns of sets of identified single neurons in the human spinal premotor network and re-learned coordinated movements following spinal cord and brain lesions. Therapy induced cell proliferation, and maybe, neurogenesis seem to contribute to the host of structural changes during the process of re-learning of the lesioned CNS. So far, coordinated functions like movements could substantially be improved in every of the more than 100 patients with a CNS lesion by applying coordination dynamic therapy. As suggested by the data of our patients on re-learning, the human CNS seems to have a second integrative strategy for learning, re-learning, storing and recalling, which makes an essential contribution of the functional plasticity following a CNS lesion. A method has been developed by us for the simultaneous recording with wire electrodes of extracellular action potentials from single human afferent and efferent nerve fibres of undamaged sacral nerve roots. A classification scheme of the nerve fibres in the human peripheral nervous system (PNS) could be set up in which the individual classes of nerve fibres are characterized by group conduction velocities and group nerve fibre diameters. Natural impulse patterns of several identified single afferent and efferent nerve fibres (motoneuron axons) were extracted from multi-unit impulse patterns, and human CNS functions could be analyzed under physiologic and pathophysiologic conditions. With our discovery of premotor spinal oscillators it became possible to judge upon CNS neuronal network organization based on the firing patterns of these spinal oscillators and their driving afferents. Since motoneurons fire occasionally for low activation and oscillatory for high activation, the coherent organization of subnetworks to generate macroscopic function is very complex and for the time being, may be best described by the theory of coordination dynamics. Since oscillatory firing has also been observed by us in single motor unit firing patterns measured electromyographically, it seems possible to follow up therapeutic intervention in patients with spinal cord and brain lesions not only based on the activity levels and phases of motor programs during locomotion but also based on the physiologic and pathophysiologic firing patterns and recruitment of spinal oscillators. The improvement of the coordination dynamics of the CNS can be partly measured directly by rhythmicity upon the patient performing rhythmic movements coordinated up to milliseconds. Since rhythmic dynamic, coordinated, stereotyped movements are mainly located in the spinal cord and only little supraspinal drive is necessary to initiate, maintain, and terminate them, rhythmic, dynamic, coordinated movements were used in therapy to enforce reorganization of the lesioned CNS by improving the self-organization and relative coordination of spinal oscillators (and their interactions with occasionally firing motoneurons) which became pathologic in their firing following CNS lesion. Paraparetic, tetraparetic spinal cord and brain-lesioned patients re-learned running and other movements by an oscillator formation and coordination dynamic therapy. Our development in neurorehabilitation is in accordance with those of theoretical and computational neurosciences which deal with the self-organization of neuronal networks. In particular, jumping on a springboard 'in-phase' and in 'anti-phase' to re-learn phase relations of oscillator coupling can be understood in the framework of the Haken-Kelso-Bunz coordination dynamic model. By introducing broken symmetry, intention, learning and spasticity in the landscape of the potential function of the integrated CNS activity, the change in self-organization becomes understandable. Movement patterns re-learned by oscillator formation and coordination dynamic therapy evolve from reorganization and regeneration of the lesioned CNS by cooperative and competitive interplay between intrinsic coordination dynamics, extrinsic therapy related inputs with physiologic re-afferent input, including intention, motivation, supervised learning, interpersonal coordination, and genetic constraints including neurogenesis. (ABSTRACT TRUNCATED)

Animals↗
PubMed1998

Neuronal reorganization through oscillator formation training in patients with CNS lesions.

A method has been developed for the simultaneous recording with wire electrodes of extracellular action potentials from single human afferent and efferent nerve fibres of undamaged sacral nerve roots. A classification scheme of the human peripheral nervous system (PNS) could be set up in which the individual classes of nerve fibres are characterized by group conduction velocities and group nerve fibre diameters. Natural impulse patterns of several identified single afferent and efferent nerve fibres can be extracted from the multi-unit impulse patterns, and human central nervous system (CNS) functions can be analyzed under physiologic and pathophysiologic conditions. With the discovery of premotor spinal oscillators it became possible to judge upon CNS neuronal network functions based on the firing patterns of these spinal oscillators. Since oscillatory firing has also been observed in electromyographic (EMG) single motor unit firing patterns, it seems possible to follow up therapeutic intervention in patients with spinal cord lesion not only based on the activity levels and phases of motor programs during locomotion but also based on the physiologic and pathophysiologic firing patterns and recruitment of spinal oscillators. Since rhythmic, dynamic, stereotyped, symmetric movements are mainly located in the spinal cord and only little supraspinal drive is necessary to initiate, maintain (especially), and terminate them, rhythm training methods were used to enforce reorganization of the CNS following spinal cord and CNS lesions to improve the self-organization and relative coordination of spinal oscillators which became pathologic in their firing following CNS lesion. Paraparetic, tetraparetic and brain-lesioned patients relearned running and other movements by an oscillator formation training. This development in neurorehabilitation is in accordance with those of theoretical and computational neurosciences which consider self-organization of neuronal networks. In particular, jumping on a springboard 'in phase' and 'in antiphase' to relearn phase relations of oscillator coupling can be understood in the Haken-Kelso-Bunz model. By introducing broken symmetry, intention, learning and spasticity in the landscape of the potential function of the integrated CNS activity, the change in self-organization becomes understandable. In conclusion, movement patterns relearned by oscillator formation training evolve from reorganization, and perhaps regeneration, of the lesioned CNS by cooperative and competitive interplay between intrinsic coordination dynamics, extrinsic training-related inputs with physiologic re-afferent input, including intention and supervised learning, and genetic constraints including neurogenesis.

Biological Clocks↗
PubMed1997

Antiseptic efficacy of disinfecting solutions in suspension test in vitro against methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in pressure sore wounds after spinal cord injury.

In pressure sore wounds after spinal cord injury, methicillin-resistant Staphylococcus aureus can be detected in 2% of the cases. The elimination of the germ is the aim of the treatment. Pressure sore wounds are an often found complication after spinal cord injury. For local treatment five commercially available antiseptics for the skin and mucous membrane were tested in vitro. The method used is a modified qualitative and quantitative suspension test. The antiseptics were tested without and with addition of 5% albumin in order to simulate the conditions of the wound in vivo. The results show a superior efficacy of the povidone-iodine preparations. Betadine, probably due to the higher concentration, is more efficacious than Braunol; chlorhexidine is sufficiently efficacious without the addition of albumin. These results still have to be confirmed by in vivo studies.

Anti-Infective Agents, Local↗
PubMed1996

Classification, oscillatory and alternating oscillatory firing of alpha 1 (FF) and alpha 2-motoneurons (FR) in patients with spinal cord lesion.

Single-nerve fibre action potentials (APs) were recorded extracellularly from sacral nerve roots of people with spinal cord lesion (patients with paraplegia). Single-fibre APs of certain fibres were identified by the conduction velocity and the AP waveform, and simultaneous impulse patterns were extracted from the summed impulse traffic and analysed with respect to spacio-temporal relationships. The velocity values of components of compound APs, induced by electrical nerve root stimulation or electrical intravesical stimulation, were similar to the group conduction velocity values obtained from single-nerve fibre APs of natural impulse traffic. When changing the root temperature in one case from 32 degrees C to 35.5 degrees C, the group conduction velocities changed in the following way: secondary muscle spindle afferents (SP2): 40 m/s (32 degrees C) to 50 m/s (35.5 degrees C); bladder stretch afferents (S1): 31.3 to 40 m/s; bladder tension afferents (ST): 25 to 33.8 m/s; mucosal afferents (M): 12.5 to 13.8 m/s; alpha 1:-; alpha 2-motoneurons: 40 to 50 m/s; alpha 3: 33 to 40 m/s. The group conduction velocities showed different temperature dependence apart from SP2 fibres and alpha 2-motoneurons, which were therefore used for calibration. The distance between two Pacinian corpuscle (PC) receptors in a sacral dermatome of one paraplegic patient was calculated to be approximately 20 mm. A similar distance between PC receptors was found in a brain-dead individual. Receptor densities seem therefore to remain unchanged following spinal cord lesion. Motoneurons fired irregularly repeatedly with impulse trains. In paraplegics the oscillation periods and the interspike intervals of the impulse trains varied much more than observed for brain-dead and normal individuals. Motoneurons could therefore not always be identified by their pattern of oscillatory firing. Alternating long and short oscillation periods (T) could be measured in an oscillatory firing alpha 1 (T = 125 ms) and alpha 2-motoneuron (T = 150 ms). In both cases the average difference between the alternating oscillation periods was 5 ms. Tremor, alternating long and short oscillation periods, cellular oscillator properties, and recurrent excitation and inhibition are discussed with respect to the oscillator theory of the functioning of the human central nervous system. Mathematical predictions from populations of interacting biological oscillators are compared to measurements on neuronal network data.

Action Potentials↗
PubMed1996

Mono- and polysynaptic drive of oscillatory firing alpha 1 (FF) and alpha 2-motoneurons (FR) in a patient with spinal cord lesion.

Single-nerve fibre action potentials (APs) were recorded extracellularly from lower sacral nerve roots of patients with spinal cord lesions (paraplegics), and simultaneous single-fibre impulse patterns of alpha 1 (FF) and alpha 2-motoneurons (FR) and primary and secondary muscle spindle afferents were analyzed. An alpha 1-motoneuron was activated in a time-locked manner by a primary spindle afferent fibre to fire oscillatory with an oscillation period of 110 to 140 ms. The distribution width for the time-locking (phase) was approx. 3 ms, which is interpreted as monosynaptic activation. A phase-correlated firing of a secondary muscle spindle afferent fibre gave rise to an additional oscillation period of the oscillatory firing alpha 1-motoneuron, when the primary fibre ceased firing. The phase distribution width was approx. 80 ms, and therefore indicates polysynaptic drive. The drive of the oscillatory firing alpha 1-motoneuron thus included a monosynaptic from a primary and a polysynaptic activation from a secondary muscle spindle afferent fibre. An alpha 2-motoneuron was simultaneously activated to fire oscillatory by a different secondary spindle afferent fibre. The phase distribution width between them was approx. 120 ms, which indicates polysynaptic drive. The alpha 1 and alpha 2-motoneurons fired in the occasional firing mode and in the transient and continuous oscillatory firing mode. Upon touch, pin-prick and bladder and anal catheter pulling, the alpha 1-motoneuron changed its firing rate more quickly than did the alpha 2-motoneuron. Thus, the alpha 1-motoneuron fired more dynamically than did the alpha 2-motoneuron. Synchronous oscillatory firing of the alpha 1 and alpha 2-motoneurons occurred transiently during pin-pricking. It is discussed that transient synchronization of oscillatory firing motoneurons points to relative coordination of self-organized oscillatory firing motoneuronal networks to generate locomotion and other integrative functions. It is further discussed that loss of specific properties of spinal oscillators following spinal cord lesion may give rise to pathologic synchronization, and in this way to disorders in movement.

Action Potentials↗
PubMed1996

Reflex stimulation of continuously oscillatory firing alpha and gamma-motoneurons in patients with spinal cord lesion.

Single nerve-fibre action potentials (APs) were recorded extracellularly from lower human sacral nerve roots, and simultaneous single-fibre impulse patterns of alpha and gamma-motoneurons and secondary muscle spindle afferents were analysed. Identified alpha and gamma-motoneurons fired oscillatory, due to the sustained stretch reflex of the external sphincters induced by an anal catheter (and, possibly, the bladder catheter). The motoneurons and the secondary muscle spindle afferents transiently synchronized their firing upon repetitive touch, pin-prick and dimpling stimulation of the perianal skin inside the anal reflex area, by reducing the duration of their oscillation period until resetting of the oscillation cycle. In one case, the anal reflex area extended approximately 6 cm laterally from the anus. The responses to pin-prick stimulation were different from those to touch stimulation in three aspects. Firstly, the response time till the shortening of the oscillation period was longer than the oscillation period (approximately 100 ms) for pin-prick, and it was shorter for touch. Second, the response to pain stimulus was longer (shortening of several oscillation periods) and stronger than for touch stimulation. Pin-prick stimulation reduced the oscillation period to between 5 and 40 ms (mean = 18 ms), and touch stimulation to between 8 and 28 ms (mean = 15 ms). Third, transient synchronization of afferents and efferents was most pronounced for pin-prick stimulation. The shortest latency following touch was approx. 10 ms when measuring from the afferent volley running in the direction of the spinal cord, and 30 ms when measuring from the beginning of the skin touch. It is discussed that repetitive touch stimulation reinforced the sustained stretch reflex of the anal sphincter which is possible with no network reorganization (variation of the same network state) and therefore fast, whereas repetitive pin-prick stimulation replaced the sustained stretch reflex by the protection reaction of the anal sphincter (change from one network state to a different one) which made time consuming network reorganization necessary. Different sacral reflexes were analysed by studying time-related activation changes of group conduction velocities in velocity distributions. During the reflex response to stretch of the external anal sphincter, the alpha 2-motoneurons (FR) (and the secondary muscle spindle afferents) were strongly activated whereas upon eliciting the bulbocavernosus reflex (squeezing of the glans penis) the alpha 3-motoneurons (S) were mainly activated. Sacral reflexes are discussed with respect to the organization and reorganization of preformated neuronal networks, and the synchronization of oscillatory firing networks is discussed with respect to the overlapping of synfire chains.

Action Potentials↗
PubMed1996

External loops of human premotor spinal oscillators identified by simultaneous measurements of interspike intervals and phase relations.

Single nerve-fibre action potentials (APs) were recorded extracellularly from alpha and gamma-motoneurons and secondary muscle spindle afferents from a ventral S4 nerve root (some afferents are contained in lower sacral motor roots) in an individual with traumatic spinal cord lesion sub TH1. Simultaneous interspike intervals (IIs) of, and phases between, the APs of 5 nerve fibres were measured, and distributions were constructed. The II distributions were of a broad peak type. Phase distributions showed 1 to 3 peaks interpreted as phase relations between the firings of the nerve fibres. Under certain phase relations, the rhythmic firing of alpha and gamma-motoneurons is further interpreted as an interaction of oscillatory firing neuronal subnetworks driving alpha and gamma-motoneurons. Following repetitive touch and pin-prick stimulation in- and outside the anal reflex area, the II distributions of alpha and gamma-motoneurons and of secondary spindle afferents assimilated partly or fully, while preserving their phase relations. This coordinated firing is interpreted as the oscillatory firing of alpha neuronal networks building up an external loop to the periphery via the gamma-loop. Upon touch, pin-prick, and anal reflex stimulation, and anal and bladder catheter pulling, the values and the number of the phase relations changed. Mostly two phase relations per oscillation cycle were observed. Two phase relations probably represent the physiologic case for the somatic nervous system. Only one phase relation was found when full synchronization of all units occurred. Three phase relations were found when the parasympathetic nervous system division interacted with the somatic one. Based on data obtained from brain-dead individuals it is discussed that the increased synchronization and instability in the number and the values of phase relations suggested pathologic functioning of the caudal functionally disconnected spinal cord in patients with spinal cord lesions: Oscillatory firing neuronal networks, which lost their specific properties, interacted more easily and unspecifically with other oscillatory firing networks. Further, it is discussed that physiologic tremor is caused by chance synchronization of oscillatory firing neuronal networks and therefore originates in the central nervous system (CNS). Since spinal oscillators build up external loops to the periphery, it is suggested that in patients with incomplete spinal cord lesions it should be possible to re-preformate oscillatory firing neuronal networks by a rhythm training, to reduce spasticity and to re-train useful movements, especially locomotion.

Afferent Pathways↗
PubMed1996

Electromyographic identification of spinal oscillator patterns and recouplings in a patient with incomplete spinal cord lesion: oscillator formation training as a method to improve motor activities.

A patient with a strongly lesioned spinal cord, sub C5, relearned running, besides improving other movements, by an oscillator formation training (rhythmic, dynamic, stereotyped exercise). After 45 days of jumping on a springboard and other rhythm trainings, the patient was able to run 90 m in 41 s (7.9 km/h) (even 9.3 km/h 3 years after the lesion) besides marching (5.7 km/h), cycling, playing tennis and skiing. FF-type (alpha 1) (f = 8.3-11.4 Hz) and FR-type (alpha 2) (f = 6.7 Hz) motor unit firings were identified by electromyography (EMG) with surface electrodes by their oscillatory firing patterns in this patient. In EMG literature, the alpha 2-oscillatory firing is called "myokymic discharging". Alternating long and short oscillation periods were measured in FF-type motor units, with changing focus (change from long/short to short/long oscillation periods). The alternating mean period durations differed by approximately 10 ms. Transient synchronization of oscillatory firing FF-type motor units was observed with up to two phase relations per oscillation cycle. In recumbent position, the phase change in synchronization of two oscillatory firing motor units in the soleus muscle of one leg correlated with the change from alternating to symmetrical oscillatory firing of a third motor unit in the soleus muscle of the other leg. This measurement indicates that the alternating oscillatory firing of premotor neuronal networks is correlated with synchronization of oscillatory firing neuronal subnetworks, i.e., with coupling changes of oscillators, and is not due to reciprocal inhibition of half-centre oscillators as suggested by the change from alternating to symmetrical oscillatory firing. Coupling changes of oscillatory firing subnetworks to generate macroscopic (integrative) network functions are therefore a general organization form of the central nervous system (CNS), and are not related to rhythmic movements like walking or running only. It is proposed that synchronization of spinal oscillators, phase changes in synchronization, changes from alternating to symmetrical firing and backwards, and changes in the focus of alternating oscillatory firing are, among others, physiologic coupling rules of the human CNS to generate, by ongoing coupling changes of oscillatory firing subnetworks, integrative functions such as rhythmic and non-rhythmic movements. One phase relation between two oscillatory firing alpha 1-motor units was preserved from one volitional leg muscle activation (isometric contraction) to the subsequent one. Since running times improved upon successive runs for 90 m, the spinal cord seems to be able to store pattern organization for seconds up to minutes. Controlled and uncontrolled oscillatory firing of alpha 1-motor units in volitionally activated leg muscles were observed in this patient, which indicated that there still were pathologic recruitments of subnetworks after re-learning running and other movements. During walking, running, and jumping on a springboard, the activation patterns of the vastus lateralis, hamstrings, tibialis anterior, peronaeus longus, peronaeus brevis and soleus muscles were recorded (surface electromyography) to be still pathologic in accordance with partly still pathologic joint rotation angles measured kinematically. Especially upon running, the left knee joint flexion was reduced in swing by a rather permanent activity of the rectus femoris combined with an extra burst of the vastus lateralis in mid-swing. The recorded abnormalities are due to modification of the motor program rather than to muscle weakness per se. A further improvement of the movements of the patient seems possible by improving the motor program, i.e., by improving the functioning of the spinal pattern generators.(ABSTRACT TRUNCATED)

Accidents, Traffic↗
PubMed1995

Classification of human peripheral nerve fibre groups by conduction velocity and nerve fibre diameter is preserved following spinal cord lesion.

(1) Single nerve fibre action potentials (APs) of lower sacral nerve roots were recorded extracellularly with two pairs of wire electrodes during an operation in which an anterior root stimulator for bladder control was implanted in 9 humans with a spinal cord lesion and dyssynergia of the urinary bladder. Roots that were not saved and that were used to record from were later used for morphometry. (2) Nerve fibre groups were identified by conduction velocity distribution histograms of single afferent and efferent fibres and partly by nerve fibre diameter distribution histograms, and correlation analysis was performed. Group conduction velocity values were obtained additionally from compound action potentials (CAPs) evoked by electrical stimulation of nerve roots and the urinary bladder. (3) The group conduction velocities and group nerve fibre diameters had the following pair-values at 35.5 degrees C: Spindle afferents: SP1 (65 m/s/13.1 microns), SP2 (51/12.1); touch afferents: T1 (47/11.1), T2 (39/10.1), T3 (27/9.1), T4 (19/8.1); urinary bladder afferents: S1 (41 m/s/-), ST (35/-); alpha-motoneurons: alpha 13 (-/14.4), alpha 12 (65m/s/13.1 microns), alpha 11 (60?/12.1)(FF), alpha 2 (51/10.3)(FR), alpha 3 (41/8.2)(S); gamma-motoneurons: gamma beta (27/7.1), gamma 1 (21/6.6), gamma 21 (16/5.8), gamma 22 (14/5.1); preganglionic parasympathetic motoneurons: (10 m/s/3.7 microns). (4) The values of group conduction velocity and group nerve fibre diameter measured in the paraplegics were very similar to those obtained earlier from brain-dead humans and patients with no spinal cord lesions. Also, the number and the density of myelinated fibres were preserved in the roots. Thus, the classification and identification of nerve fibre groups remained preserved following spinal cord lesion. A direct comparison can thus be made of natural impulse patterns of afferent and efferent nerve fibres between paraplegics (pathologic) and brain-dead humans (supraspinal destroyed CNS, in many respects physiologic). (5) When changing the root temperature from 32 degrees C to 35.5 degrees C, the group conduction velocities changed in the following way in one case: SP2: 40 m/s (32 degrees C) to 50 m/s (35.5 degrees C), S1: 31.3 to 40, ST: 25 to 33.8, M: 12.5 to 13.8; alpha 2: 40 to 50, alpha 3: 33 to 40. The group conduction velocities showed different temperature dependence apart from SP2 fibres and alpha 2-motoneurons. (6) Upon retrograde bladder filling the urinary bladder stretch (S1) and tension receptor afferent (ST) activity levels were undulating and increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1995

Detrusor-sphincteric dyssynergia in paraplegics compared with the synergia in a brain-dead human by using the single-fibre action potential recording method.

(1) Humans with spinal cord lesions often show detrusor-sphincteric dyssynergia of the urinary bladder which is reflected urodynamically in the detrusor pressure and a simultaneous increase in electromyographic pelvic floor activity. (2) The time-course of the increase in the secondary muscle spindle afferent activity, induced by the parasympathetic nervous system in muscle spindles contributing to continence, is very similar to that of detrusor pressure. The detrusor-sphincteric dyssynergia is therefore analysed by comparing the natural impulse patterns of secondary muscle spindle afferents (SP2) and sphincteric motoneurons in a brain-dead human with those in patients with spinal cord lesion. The parasympathetic nervous system was activated by painful bladder catheter pulling. (3) In a brain-dead human the sphincteric motoneurons subserving continence were inhibited at a time, when preganglionic parasympathetic efferents increased their activity for 10 s and an SP2 fibre increased its activity for several minutes. In a paraplegic with a strong bladder dysfunction, the SP2 fibre activity increased, due to parasympathetic activation, lasted for approx. 1 min, showed undulations and its amplitude was smaller than that measured in a brain-dead human. The sphincteric motoneurons were not inhibited. (4) In the brain-dead human, an SP2 fibre showed doublet firing with interspike intervals (IIs) of a duration between 10 and 14 ms for low level parasympathetic activation. For high level parasympathetic activation this single parent spindle afferent fibre showed multi-ending regular firing of up to 6 endings with IIs of a duration of predominantly 15 to 25 ms. In one paraplegic with a strong bladder dysfunction the doublet firing was less regular, even though two II peaks at 10.2 and 11.2 ms occurred in a II distribution similar to the brain-dead human. The multi-ending regular firing was replaced by a repeated burst firing. In a second paraplegic with strong detrusor-sphincteric dyssynergia the burst firing consisted of up to 6 impulses with increasing IIs and a first II of approx. 0.2 ms (transmission frequency 5000 Hz). In a third paraplegic with a lesser dysfunction of the bladder a highly activated SP2 fibre showed an activity pattern intermediate to those of multi-ending regular firing and burst firing. (5) The time constant for the activity decrease of a spindle afferent fibre following parasympathetic activation was to 31 s in a paraplegic and approx. 40 s in a brain-dead human. It is concluded that the muscle spindles are unchanged following spinal cord lesion.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1994

Nerve compound action potentials analysed with the simultaneously measured single fibre action potentials in humans.

1. Compound action potentials (APs) and single fibre APs were recorded with two pairs of wire electrodes from an S5 root from a paraplegic patient during surgery. 2. Frequency distribution histograms of single nerve fibre conduction velocities were constructed and nerve fibre group conduction velocities compared with the conduction velocities of the peaks of the compound APs. By increasing the strength of the stimulation, the peaks in the compound AP could be identified, and the threshold order of efferent nerve fibre groups determined. Using additional literature data, it is likely that the primary spindle afferents have the lowest threshold due to electrical nerve root stimulation followed by the alpha 1-motoneurons (FF), the secondary muscle spindle afferents, the alpha 2-motoneurons (FR), the alpha 3-motoneurons (S), the gamma beta, gamma 1 (dynamic), gamma 21 (static), gamma 22 (static), and the parasympathetic motoneurons. 3. In first approximations, the Ap duration increases in the same way as the AP amplitude decreases with decreasing conduction velocity, and the area between the average single fibre AP curve and the base-line is the same for all single fibre APs with an average same distance to the recording electrodes in the root cross-section. By comparing the mean area of a single fibre AP with the areas of the peaks of the compound APs, it was found that 230 single fibre APs contributed to the compound AP. In the secondary spindle afferent fibre and alpha 2-motoneurons groups 53 fibres were stimulated (23%). The alpha 3-motoneuron peak and the afferents in the same velocity range contained 101 fibres (44%), the gamma beta peak contained 9 fibres (4%), the gamma 1 32 (14%), the gamma 21 23 (10%) and the gamma 22 12 (5%) fibres. Additionally two primary spindle afferents and two alpha 1-motoneurons most likely contributed to the compound AP. Since the large peaks in the compound APs did not change their area with increasing stimulation, most likely all muscle spindle afferents and alpha-motoneurons were activated to contribute to the compound AP. 4. Transfer functions of nerves and the stimulation with natural impulse patterns of the adequate afferents to spinal oscillators with respect to continence in paraplegia are discussed.

Action Potentials↗
PubMed1994

Interspike intervals of secondary muscle spindle and urinary bladder afferents in relation to the oscillation periods of sacral spinal oscillators for continence in man.

Two pairs of wire electrodes were used to record afferent and efferent single fibre extracellular action potentials (APs) from human nerve root filaments. The nerve fibres were identified according to the group to which they belong by comparing the afferent and efferent conduction velocity distribution histograms and identifying peaks and ranges of nerve fibre groups. Secondary muscle spindle afferents and alpha 2-motoneurones (FR) were identified by having the same peak group conduction velocity (calibration relation), which is 50 m/s at 36 degrees C. On the basis of AP wave form comparisons, the natural impulse patterns of five secondary muscle spindle afferents, two fusimotor motoneurones and two oscillatory firing alpha 2-motoneurones could be identified in the dorsal S4 root. The patterns of single endings of secondary spindle afferent fibres could be identified. The shortest interspike intervals of single endings of all secondary muscle spindle afferents had the same duration as the shortest interspike intervals of the two fusimotor fibres (80 ms) and equalled a half of the oscillation period of one repetitively firing alpha 2-motoneurone (6 Hz) probably innervating the external anal sphincter (three AP impulse train firing). In another more rostral dorsal root filament (probably S3 or S2) of the same human, the interspike intervals of six secondary spindle afferents were more variable. The values of peaks in the interspike interval distributions ranged from 60 to 102 ms. In the coccygeal root, the interspike interval duration ranged from 160 to 185 ms, directly contributing to the drive of the oscillatory firing alpha 2-motoneurone. The different agreement between the oscillation period and the interspike intervals of the spindle afferents in different segments indicate that the oscillatory firing CNS circuitry was localized within S3 to S5 segments of the conus medullaris for the drive of the anal sphincter. An alpha 2-motoneurone firing repeatedly with 1 to 2 AP impulse trains, innervating most likely the external urethral sphincter, fired at a frequency of 9.1 to 6.7 Hz, a similar frequency of the oscillation as the interspike intervals from two activated stretch receptors of the urinary bladder wall. The measurements of this brain-dead human indicates that in this case the neuronal circuitry driving the external anal sphincter was mainly confined to the sacral micturition and defecation centre, mainly located in the S3 to S5 segments.

Action Potentials↗
PubMed1992

Oxygen uptake and static lung compliance during automatic ventilation.

Oxygen uptake is an important parameter to control proper tissue oxygen delivery. Oxygen uptake is dependent on adequate lung function and easily disturbed by changes in lung compliance and related parameters such as the tidal volume controlling pressure support. Simultaneous on-line registration of oxygen uptake and lung compliance together with ventilatory pressures applied to achieve preset tidal volumes has been made possible using the computer feedback controlled closed circuit ventilatory system Physio-Flex (Physio Co, Hoofdorp, The Netherlands). The system guarantees for leakage free functioning (maximal leakage 7 mL gas loss/minute) and, therefore, patient oxygen consumption measurements with an accuracy of more than 95%. A specially developed membrane ventilation mode registers on-line flow and displaced volume automatically corrected for temperature, pressure and compressible volume. The current investigation has shown: Decrease oxygen consumption versus oxygen delivery supply dependency may be induced by reflectory decreases of heart rate and cardiac output; in this case a reactive pulmonary parameter change is preceding the event in form of a drop in compliance and corresponding changes in ventilatory pressures necessary to maintain the preset tidal volume. In contrast, decrease of oxygen uptake following changes in cardiac output due to acute hypovolemia has no effect on pulmonary function parameters. This can be diagnostically used as moderate changes of tidal volume also have no significant influence on pulmonary parameters. However, changes due to reduction in depth of anesthesia and relaxation have some influence and need to be excluded.

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