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Biomedical subjects

G Hertel

Publications and source records attributed to G Hertel.

At least 37 records · Page 2Linked to original sources
PubMed1979

[Treatment of myasthenia gravis with plasmapheresis (author's transl)].

Nine out of eleven severely ill patients with myasthenia gravis could be markedly improved by a combination of immunosuppressive drug therapy and plasmapheresis, two patients however suffered grave complications. The effectiveness of plasma exchange underlines the importance of plasma factors in the pathomechanism of myasthenic functional disturbance. Treatment with plasmapheresis may be regarded as a supportive measure of immunosuppressive drug therapy. However, the considerable risk and high technical requirements limit the indication to severe forms of the disease.

Adolescent↗
PubMed1979

Influence of temperature on isometric contraction and passive muscular tension in paramyotonia congenita (Eulenburg).

Four patients without symptoms of episodic hyperkalemic weakness from two families with paramyotonia congenita (Eulenburg) are described. 1. Maximum voluntary muscle contraction of the upper and lower arm was studied under isometric conditions at different temperatures. If the temperature was lowered stepwise, distinct paresis occured at 32--31 degrees C which increased with the amount of muscular effort. The upper arm muscles, however, developed weakness gradually after cooling. 2. During cooling of the resting muscle, the EMG showed dense spontaneous activity of the fibrillary type, which decreased again at about 30 degrees C. It can be assumed that in paramyotonia congenita cooling produces muscle cell membrane depolarization which at a critical level causes the firing of action potentials and finally muscular paresis. 3. Increasing muscular stiffness can be interpreted as abnormally slow muscular relaxation after isometric contraction. In the forearm muscles the time to 3/4 relaxation after cooling was about six times normal, in the upper arm muscles only two times normal. As an additional parameter the mechanical resistance to passive stretching of a muscle has been studied. This passive muscular tension increased simultaneously with the onset of weakness. 4. The close relation between weakness and stiffness suggest that both symptoms are caused by the same basic defect which is probably located in the sarcolemma. It is suggested that a defect of the sodium channel causes a cooling-dependent increase in sodium conductance. Raised intracellular sodium causes in the first place membrane depolarization, and in the second place depression of calcium reuptake through competition by sodium for calcium binding sites. This would explain muscle stiffness and delayed relaxation as well.

Arm↗
PubMed1978

Transient muscular weakness in severe recessive myotonia congenita. Improvement of isometric muscle force by drugs relieving myotomic stiffness.

The maximum force of voluntary muscle contraction was registered under isometric conditions in nine patients with recessive myotonia congenita. The recordings were made on the upper arm. Five patients with severe myotonia had a transient weakness after muscle rest. Electromyographic registrations with wire electrodes showed that the myotonic muscle fiber discharges disappeared during the transient weakness. Medication improving myotonic stiffness also improved the weakness. The cause of transient weakness seems to be similar to that of myotonic stiffness. It is known that an increasing depolarization of the myotonic muscle fiber membrane leads to the myotonic discharges and myotonic stiffness. In severe myotonia the progressing depolarization could cause a loss of excitability of the muscle fiber membrane and thereby a transient paresis of a more or less large number of muscle fibers.

Adult↗
PubMed1977

The influence of local cooling on neuromuscular transmission in the myasthenic syndrome of Eaton and Lambert.

The effect of local cooling was studied in two patients with the Eaton-Lambert syndrome. We stimulated the ulnar nerve and registered the compound muscle action potential, the twitch force, and the maximum tetanic force. A distinct improvement of neuromuscular transmission occurred after cooling. The amplitude of the muscle action potential and the twitch force were larger and the time of the postactivation facilitation was longer. This effect of cooling is similar to the effect of guanidine on neuromuscular transmission. The release of acetylcholine at the nerve terminal is probably enhanced by cooling.

Aged↗
PubMed1977

Influence of temperature on neuromuscular transmission in myasthenia gravis.

The effect of local cooling was studied in 28 patients with myastenia gravis. We stimulated the ulnar nerve with single stimuli and trains at 3/s for 2s and at 50/s for 1.5 s. The compound muscle action potential (MAP), the muscle twitch and the isometric tetanic force of the adductor pollicis were registered. 1. At 3/s stimulation the pathological decrement of the MAP decreased after slight cooling. 2. The amplitude of the single MAP was higher at lower temperature when compared to normal temperature. The same increase is however to be found in healthy subjects. 3. After slight cooling, the maximum tetanic force was higher. However, the decrement of the force was higher also, therefore ruling out a practicable application of cooling for the patient. 4. After severe cooling (18-22 degrees C) the tetanic force was much lower and in many cases a complete failure of the neuromuscular transmission occured.

Action Potentials↗
PubMed1977

Myotonia not aggravated by cooling. Force and relaxation of the adductor pollicis in normal subjects and in myotonia as compared to paramyotonia.

The effect of local cooling has been studied in 27 normal subjects, 8 cases of myotonia congenita, 5 of myotonic dystrophy and one of paramyotonia. Using the adductor pollicis we registered the compound muscle action potential, the isometric twitch force and the time to half relaxation, the maximum tetanic force and to time 3/4 relaxation. 1. In normal subjects the twitch force and maximum tetanic force decreased after cooling (Fig. 2). The amplitude of the action potential increased. 2. Myotonia congenita and myotonic dystrophy were not aggravated by cooling. Muscle force was reduced only in the same proportion as in normal subjects (Fig. 2). The myotonic after-contraction was made normal by cooling (Figs. 5 and 6). 3. In paramyotonia initial tonic stiffness with a pronouncedly prolonged twitch relaxation occured directly after cooling (Fig. 1 B). Paradoxical myotonia occured only after exercise and was accompained by increasing paresis (Figs. 3 and 8). The results indicate that exposure to cold has a specific effect on muscle function only in paramyotonia.

Adolescent↗
PubMed1977

Increased voltage of the muscle action potential of normal subjects after local cooling.

The compound muscle action potential (MAP) and the isometric twitch force of the adductor pollicis of 25 normal subjects were registered after local cooling. Intramuscular temperature ranged from 36.6 to 18.0 degrees C. The amplitude of the MAP increased while the twitch force decreased at lower temperatures. The increase of the MAP could be caused by the effect of cooling directly at the muscle cell membrane. The decreased twitch force probably is due to an affect on the contractile apparatus.

Action Potentials↗
PubMed1977

The regional curare test in myasthenia gravis.

30 subjects without disturbance of neuromuscular transmission and 18 patients with myasthenia gravis were used in conducting the regional curare test. The adductor pollicis and the hypothenar muscles were studied with the 3/sec stimulation test. With three different dosages of curare one could find no reliable border between "normal" and "pathological". In the patients with myasthenia no definite relation could be found between the findings with the regional curare test and the clinical picture. The curare concentration reaching the muscle is probably quite variable from case to case as regards diffusion and volume in the tissue. The 3/sec stimulation test with registration from the deltoid muscle, and in certain cases the systemic curare test, appear more suitable than the regional curare test for routine diagnosis as well as indication for thymectomy. But for cases of ocular myasthenia showing no further weakness by the systemic curare test, the regional curare test can be put to use. The advantage lies in the higher concentration of curare which can thereby be brought to the muscle. The precautionary measures should be similar to those taken with the systemic curare test.

Adolescent↗
PubMed1976

Electrophysiological findings in the syndrome of acute ocular muscle palsy with ataxia (Fisher syndrome).

4 patients are described with ophthalmoplegia (Figs. 1 and 2) and ataxia with acute onset. Three of them showed only very slight symptoms of generalized polyneuritis. Measurement of sensory nerve conduction velocity (Fig. 4, Table 2) and determination of vibration sense by an electrical vibrator (Fig. 3) proved to be helpful for diagnosis. The ocular EMG revealed signs of peripheral denervation in 3 cases. Pathological changes of the somatosensory evoked potential (Fig. 5) which has been registered in one case, might give some speculation as to whether or not central nervous pathways are affected.

Adult↗