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Biomedical subjects

H H Schiller

Publications and source records attributed to H H Schiller.

18 recordsLinked to original sources
PubMed1978

Human botulism studied with single-fiber electromyography.

In two cases of mild human botulism, conventional electromyography (EMG) was normal. In one case, the investigation with reptitive nerve stimulation showed slightly abnormal results, but in the other case the findings were within normal limits. Single-fiber EMG showed abnormal neuromuscular function and at later investigations as well, when the patient no longer showed any muscular fatigability. The jitter was frequency dependent and decreased with higher innervation frequency. The single-fiber EMG findings normalized after three months. The results are in agreement with the known disturbance of acetylcholine release.

Adult↗
PubMed1978

F responses studied with single fibre EMG in normal subjects and spastic patients.

Recurrent responses of single human motor neurones after antidromic activation, the so-called F response, have been studied in the abductor digiti minimi muscle in normal subjects and in spastic patients with the single fibre EMG technique. The F response occurs rarely and in groups. Half of all motor neurones did not produce any F response within an arbitrarily chosen time interval of 200 successive stimuli at 1 and 2 Hz. Spastic patients had as many silent neurones as the normal subjects but the responding neurones more frequently produced F responses (P less than 0.001). When a neurone has few responses at rest the frequency increases under activation of the contralateral or ipsilateral muscle (P less than 0.05). When there are many responses in the relaxed state there is a decrease (P less than 0.001) under activation. The behaviour of an individual neurone is consistent in different activation periods.

Action Potentials↗
PubMed1977

Clinical, neurophysiological and morphological findings in Eaton Lambert syndrome.

Two patients with maysthenic syndrome apparently not associated with carcinoma were studied in detail with repetitive stimulation of motor nerves, single fibre electromyography and histology. One patient showed signs of widespread autonomic dysfunction and the other patient had multifocal CNS symptoms of unclear etiology. Both cases showed a marked improvement with guanidine treatment which could be documented by the electrophysiological investigations. Due to severe adverse effects of the guanidine treatment on kidney, pancreatic and bone marrow functions the drug had to be withdrawn. Edrophonium given intravenously caused a marked and longlasting improvement of the muscle weakness and of the neurophysiological parameters. The mechanism of action is suggested to be different from that seen in myasthenia gravis. Single fibre electromyography showed a marked increase of neuromuscular jitter and blockings which decreased with increasing innervation frequency. The morphological study showed a selective affection of type II (fast twitch) fibres, a finding which is suggested to be secondary to an impaired neuromuscular transmission in the type II motor units.

Action Potentials↗
PubMed1977

Correlation between single fibre EMG jitter and endplate potentials studied in mild experimental botulinum poisoning.

To study the correlation between single fibre EMG jitter and endplate potential amplitude we examined neuromuscular transmission in rats paralysed with botulinum toxin type A with single fibre EMG (SFEMG) in vivo and with intracellular microelectrode techniques in vitro. In muscles that were not completely paralysed SFEMG showed an increased neuromuscular jitter on nerve stimulation and in these muscles endplate potentials were of reduced amplitude. When the nerve stimulation frequency increased the jitter decreased. Intravenous injection of drugs that increase the acetylcholine release and endplate potential amplitude markedly reduced the jitter and the frequency dependence disappeared.

Action Potentials↗
PubMed1977

Distubed neuromuscular transmission in viral infections.

14 subjects with influenza or echovirus infection, all suffering myalgia, and 9 subjects with mumps, in whom this symptom was lacking, were investigated with single fibre electromyography (EMG) in the acute phase and during convalescence to reveal a possible disturbance in neuromuscular transmission. In both groups about the same percentage of the potential pairs studied showed abnormal transmission characteristics in the acute phase. Two weeks after the acute infection, this percentage had decreased significantly in the group with myalgia, whilst in the non-myalgia group it was still at the same level. However, on both occasions of investigation and in both groups the percentages were substantially greater than those recorded in healthy individuals. This study demonstrates that acute febrile infections may adversely affect neuromuscular transmission in previously healthy human subjects. The effects observed might offer an explanation to the accentuated muscular weakness in association with infections in patients with an already low safety margion of neuromuscular transmission, e.g. in myasthenia gravis.

Adolescent↗
PubMed1976

The normal motor unit in man. A single fibre EMG multielectrode investigation.

The motor unit in the normal EDC and biceps brachii muscle was studied with a multielectrode technique permitting recording from 44 sites 300 mum apart. It was found that the muscle fibres in man are scattered with no evidence of grouping, similar to the findings in glycogen depletion experiments in animals.

Adult↗
PubMed1976

The reinnervated motor unit in man. A single fibre EMG multielectrode investigation.

Motor units in patients with motor neurone disease and polyneuropathy were studied with a new multielectrode technique allowing fibre mapping. In these disorders which are characterised by reinnervation the motor unit fibre distribution is changed from a normal scattered pattern to grouping often in clinically uninvolved muscles without definite EMG abnormalities. The changes found with this multielectrode technique in man are in accordance with those found in reinnervated motor units studied histochemically in the experimental animal.

Adult↗
PubMed1976

Discharge pattern of single motor units in the tonic vibration reflex of human triceps surae.

Using a single fibre EMG electrode the firing pattern of 46 motor units in the triceps surae has been studied during vibration of the Achilles tendon at frequencies of 25--200 Hz. Potentials activated in the tonic vibration reflex (TVR) were phase-locked to the vibration cycle but tended to become somewhat less so with continued vibration. The firing pattern of voluntarily activated motor units became locked to the waveform by the application of the vibrator. The discharges of 21 motor units were studied during low threshold (sub-M wave) tetanic stimulation of the tibial nerve at 25--100 Hz. No evidence was found of synchronization of potentials activated in the resulting tonic contraction. During weak voluntary contractions, stimulation also failed to regularize voluntarily activated motor units. The findings can be reconciled by postulating that, in normal man, vibration activates monosynaptic and polysynaptic pathways, the latter circuit being adequate to generate reflex contraction, while the former merely affects the temporal patterning of the motor outflow.

Action Potentials↗
PubMed1975

Safety factor in single human motor end-plates studied in vivo with single fibre electromyography.

In a single fibre EMG investigation on healthy subjects the relationship between the neuromuscular jitter and the safety factor of the motor end-plate relative to curare was studied. A positive correlation was found between the jitter increase after a standard dose of D-tubocurarine and the initial jitter. The conclusion was drawn that the neuromuscular jitter can be used as an indicator of the safety factor. There are a number of nerve-muscle disorders in which the jitter is increased, probably indicating a reduced safety factor which may be of clinical importance when these patients are subjected to diseases or drugs which would otherwise not produce neuromuscular symptomatology.

Adult↗
PubMed1975

Regional curare for the reduction of the safety factor in human motor end-plates studied with single fibre electromyography.

A method employing six minutes of regional curarization with 0.5 mg D-tubocurarine and single fibre electromyographic measurements (SFEMG) was used in order to study the effect of an additional small dose of D-tubocurarine. The effect of the additional dose was most pronounced in terms of increased jitter, on motor end-plates with the initially highest jitter. The combination of regional curarization and SFEMG jitter recordings offers a sensitive technique for detecting mild effects of various drugs on neuromuscular transmission not detectable with decrement investigations.

Action Potentials↗