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Biomedical subjects

A Struppler

Publications and source records attributed to A Struppler.

At least 73 records · Page 4Linked to original sources
PubMed1982

Recruitment of single motor units in the human blink reflex.

The recruitment of single motor units (MU) in the early (R1) and late (R2) components of the electrically evoked human blink reflex (BR) was studied using bipolar needle electrodes with a limited take-off area. It could be shown that the same MUs can discharge in R1 and R2 of a BR as well as during voluntary eyelid contraction. At repetitive stimulation (1 Hz), facilitation of MU discharges in R1 and habituation in R2 became apparent. The visible reflex eyelid contraction may mainly be due to repetitive MU discharges in R2. The discharges of the same MUs in R1, however, contribute to it and shorten the latency between stimulus and reflex response.

Adult↗
PubMed1982

Estimation of generator potentials in primary spindle endings evoked by brief tendon taps in man.

The ligamentum patellae in human subjects was tapped by a random triangular waveform, while single primary spindle afferent spikes were recorded from the femoral nerve. Cross-correlation between the primary spindle afferent spikes and the taps revealed a prominent peaked distribution of the discharge probability. The cross-correlograms showed that response time from the onsets of taps to the afferent spike was 7.5 +/- 0.6 msec in 6 units and that the width between the feet of the peaked distribution was 3.3 +/- 0.2 msec in 6 units. The width of the peak implies jitter of the response time of the primary spindle spikes which appear to correspond with the time-to-peak of generator potentials elicited by the taps in primary endings of muscle spindles. Integration of the peaked distribution showed a slow slope at the beginning and near the summit and a steep slope on the way. This curve is assumed to represent the rising phase of the generator potentials in primary spindle endings.

Afferent Pathways↗
PubMed1982

Quantitative analysis of blink reflexes in patients with hemiplegic disorders.

Electrically evoked blink reflexes were investigated in 18 patients with hemiplegia and in 15 control subjects, using common electromyographic techniques. The EMG activities of the early and late components were quantitatively and integration. In addition, the latencies of the single components were determined. Regarding the EMG activity of the late components two major types of BR alteration could be distinguished. In type I stimulation of the clinically affected side evoked significantly decreased late components on both the affected and the unaffected sides. This pattern points to a lowered excitability of the brain stem trigeminal systems and may be associated with predominantly sensory disorders. In type II the decrease of the late components was confined to the affected side independent of the side of stimulation. This pattern may indicate a lowered excitability of the brain stem facial systems and/or of the lateral bulbar reticular formation and may be correlated with predominantly motor deficits. Both types are presumably due to a loss of facilitatory influences associated with the hemispheral lesion. Although the early component was frequently decreased on the affected side there was no consistent pattern and no relation to the alterations of the late components. The latencies of both responses, predominantly of the late ones were frequently prolonged, in particular following stimulation of the affected side. Comparison of the seemingly normal components in the patients with the corresponding control values pointed to a generally lowered blink reflex excitability in hemiplegic patients.

Adult↗
PubMed1982

Unilateral reduction of the early and late blink reflex component in hemiparkinson syndrome.

Electrically evoked blink reflexes were recorded in 10 patients with unilateral tremor and/or rigor, mostly diagnosed as hemiparkinson syndrome. Five of the patients could be investigated before and after stereotaxic thalamo-subthalamotomy. The EMG activity of the early and late components was quantified by means of averaging and integrations techniques. In addition, the latencies of the reflex components were determined. The major finding was a unilateral decrease of the EMG activity of both the early and late components confined to the clinically affected side. This pattern points to a lowered state of excitability of neurons in or close to the facial nucleus, probably due to a dysfunction of contralateral EPMS structures. A loss of facilitatory influences from EPMS centers, e.g. the nigro-striatal system, on brain stem neurons in the area of the facial nucleus appears most probable. The latencies of the early and late components were mostly normal. After stereotaxic surgery, the BR activity was decreased bilaterally. The difference between the affected and unaffected sides, however, was nearly unchanged. At present an unspecific postoperative effect cannot be excluded.

Adult↗
PubMed1981

Ultrastructure of a cerebral white matter lesion in a 41-year-old man with Leigh's encephalomyelopathy (LEM).

A brain biopsy taken from a 41-year-old man with Leigh's encephalomyelopathy (LEM) was studied under the electron microscope. The sample of cerebral white matter revealed degenerated oligodendrocytes, reactive astrocytes and scavenger cells filled with miscellaneous debris. Myelin underwent splitting and vacuole formation as well as lamellar and vesicular dissolution. Degenerative and reactive changes were prominent in the axons, many of which were calcified. There was marked fibrous gliosis of the tissue and the extracellular space was enlarged. The small vessels were notably involved; evidence of capillary growth was also found. In sum, the overall picture was one of loss of tissue continuity, loss of axons and loss of myelin, opposite to which stood expansion of the extracellular space, accumulation of filament-filled astroglial process, hypertrophy and hyperplasia of the capillaries and increase of the tissue cellularity. The study has confirmed and defined at the ultrastructural level the well-known histological features of LEM. However, the formal, let alone the causal pathogenesis of the disease remains as obscure as ever.

Adult↗
PubMed1981

Quantification and documentation of changes produced by spinal cord stimulation.

In spastic patients suffering from spastic paresis on one side the degree of spasticity on the background of isometric innervation was investigated with a new self-constructed torque motor. It offers the opportunity to analyze how external forces can be compensated automatically by reflex or reaction. In spastic patients M1, M2 and M3 were compared with the responses of the nonaffected normal side as a control. The effects of diazepam and baclofen are analyzed with this new technique.

Brain↗
PubMed1981

[Assessing the localization and extension of brainstem lesions with the orbicularis oculi reflex (author's transl)].

The electrically evoked Orbicularis Oculi Reflex (OOR) consists of two separate components (R1 and R2). Within the last years the central pathways of R1 in pontine and R2 in medullary brainstem areas could be further elucitated. We have investigated the OOR in 66 patients with signs of a brainstem affection, obtaining pathological results in 67% of the cases. Five characteristic types of OOR-alterations could be differentiated. Type A with an isolated R1- and type B with an additional R2-Alteration point to pontine lesions. Type C, D, E with different R2-Alterations are indicative for medullary lesions. Disorders of the spinal trigeminal complex or the lateral bulbar reticular formation only can be distinguished from a combined lesion of these structures. Careful analysis of the alterations of the OOR-components and correlation with the known anatomical data provide a means to localize brainstem affections and to assess their extension.

Blinking↗
PubMed1981

[Neurophysiological correlates of spinal opiate analgesia (author's transl)].

The dorsal horn of the mammalian spinal cord contains interneurones which synthetize opioid peptides (endorphins) and release them on synaptic activation. Cells of origin of the spino-thalamic tract are in close functional relationship with these interneurones. The activation of the postulated endorphinergic mechanisms in the spinal cord could explain the selective reduction of painful stimuli following epidural application of opiate agonist.

Anesthesia, Spinal↗
PubMed1980

[Functional anatomy of shoulder-arm pain (author's transl)].

The treatment of pains felt in the shoulder-arm region depends on the pathogenesis of the individual case. For this reason the functional anatomical conditions which can cause pain in various diseases are first described. This is followed by a presentation of the pathophysiological mechanisms of the causation of pain. The shoulder girdle is a functional skeletal motor unit which includes joints and muscles of the arm, neck and trunk. Disturbances of one structural element of the shoulder girdle are reflected as muscular distortion of the entire shoulder girdle and possibly also of the neighboring parts of the body communicating with the shoulder girdle. Shoulder-arm pain can arise in principle from two different sources: stimulation of pain receptors (receptor pain, physiological excitation of pain) and by functional disturbance of pain conducting and pain producing neuronal structures.

Humans↗
PubMed1979

Local analgesia by percutaneous electrical stimulation of sensory nerves.

Experimental C-fiber pain caused by radiant heat was applied to the skin area supplied by the left sural nerve of 20 subjects. Percutaneous electrical stimulation (PNS) was performed on the left sural nerve, the left superficial peroneal nerve and the right superficial radial nerve. Stimulation frequencies were: 3, 50, 100, 300, 500 and 1000 Hz. The analgesia resulting at the different stimulation sites was recorded according to a preset scale of estimation. Without considering the influence of the different frequencies, the best analgesic effects were reached if noxious heating and PNS were both performed on the left sural nerve; the anatomical conditions prevented us from distinguishing between the effects of possible peripheral blockade or spinal modification of pain. PNS of the superficial peroneal nerve seems to indicate spinal, possibly polysegmental, interactions between C-fiber pain and electrical stimulation of thick myelinated fibers. However, long loop effects may also play a part in local analgesia as demonstrated by PNS of the right radial nerve.

Adult↗
PubMed1979

Soleus motoneurone excitability in man: an indirect approach for obtaining quantitative data.

Using combinations of H and T reflexes, spatial summation has been studied in the human soleus motoneurone pool. With certain assumptions, mathematical treatment of the results yielded estimates of the thresholds of motoneurones to monosynaptic activation by Ia nerve fibres. It was found that, on average, about 62 EPSPs were required to discharge a motoneurone and that a single Ia fibre supplied about 139 neurones.

Adult↗
PubMed1979

TNS-evoked long loop effects.

Local analgesia can be produced by transcutaneous electrical stimulation of peripheral nerves. This is used in the treatment of chronic pain states. Its clinical effectiveness depends on two points; namely (1) the stimulation has to be perceptible, and (2) paresthesias elicited by TNS must be localized in the area of pain. To verify this in healthy subjects we produced an experimental pain by radiant heating of the skin and tested the analgesic effect of TNS. TNS stimuli parameters (duration, amplitude and frequency) were determined so that double blind conditions were given. Stimulation with small rectangular pulses showed the best analgesic effect especially at a stimulation rate of 100 Hz. The stimulation of various nerves showed that most of the analgesic effects depend on spinal level mechanisms but probably long loop effects are involved.

Analgesia↗