Regional Curare Test in Evaluation of Ocular Myasthenia

Horowitz, Steven H.; Genkins, Gabriel; Kornfeld, Peter; Papatestas, Angelos E.

doi:10.1001/archneur.1975.00490440034004

Cited by 30 publications

(7 citation statements)

References 8 publications

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“…The technique of regional curarization has been used for studying the effect of neuromuscular transmission with repetitive stimulation in normals and in patients with myasthenia gravis Horowitz et al, 1975). In normal subjects 15 mg D-tubocurarine given systemically produces no decrement but 0.5 mg regional D-tubocurarine produces decremental response within five minutes , a feature which was also seen in the present investigation.…”

supporting

confidence: 79%

“…DISCUSSION Regional injection of D-tubocurarine (Torda and Klonymus, 1966;Foldes et al, 1968;Horowitz et al, 1975) was used in the present study as the method for partial reduction of the neuromuscular safety factor. Substances injected into the forearm venous system after application of a cuff around the upper arm diffuse through the vascular bed as shown angiographically (Fleming et al, 1966) and with radio-labelled Transferrin .…”

mentioning

confidence: 89%

“…The aim of the present investigation was to study the effect of a small additional standard dose of D-tubocurarine on slightly curarized neuromuscular junctions employing a regional curare method (Torda and Klonymus, 1966;Foldes et al, 1968;Horowitz et al, 1975) in order to establish a sensitive method for determining the effects of pharmacological agents on the neuromuscular transmission. METHODS SINGLE FIBRE ELECTROMYOGRAPHY Single fibre (Accepted 15 April 1975.…”

mentioning

confidence: 99%

“…The jitter was studied after a preceding regional intravenous dose of D-tubocurarine, employing a method similar to that used in regional intravenous anaesthesia (Bier, 1908;Thorn-Alquist, 1966) and in regional curarization (Torda and Klonymus, 1966;Foldes et al, 1968;Horowitz et al, 1975). A blood-pressure cuff around the right upper arm was insufflated to 200-250 mmHg and 0.5 mg D-tubocurarine in 20 ml NaCl was injected slowly into the dorsal vein of the right hand.…”

mentioning

confidence: 99%

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

Schiller¹,

Stålberg²,

Schwartz³

1975

Journal of Neurology, Neurosurgery & Psychiatry

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SYNOPSIS 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.

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confidence: 79%

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confidence: 89%

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confidence: 99%

mentioning

confidence: 99%

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

Schiller¹,

Stålberg²,

Schwartz³

1975

Journal of Neurology, Neurosurgery & Psychiatry

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“…RCT helpful in distinguishing patients with myasthenia gravis from controls. When used in the forearm, 5-10% of patients with generalized myasthenia (Horowitz et al 1976, Horowitz & Sivak 1978 and about 50% of patients with only ocular involvement (Horowitz et al 1975(Horowitz et al , 1976) had a normal i.v. RCT.…”

Section: The Effect Of Temperature On the Neuromuscular Transmissionmentioning

confidence: 99%

Evoked responses in normal and diseased muscle with particular reference to twitch potentiation

Krarup

1983

Acta Neurologica Scandinavica

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The compound muscle action potential and isometric twitch tension evoked by single and repetitive electrical stimuli are indicators of the number of motor units activated and of the contractile properties of the muscle. The action potentials and mechanical responses were recorded in proximal and distal muscles in patients with myasthenia gravis and myopathy and compared with findings in normal subjects. In normal muscle, at low rates of stimulation (2-3 s-1) the decrement was at most 5% in the action potential and 15-24% in the twitch tension. Tetanic stimuli (50 s-1) were unsuitable for diagnostic purposes because of movement artefact. In patients with myasthenia gravis, the incidence and size of the decrement of evoked responses were greater in the platysma than in the elbow flexors and the adductor pollicis (ADP) muscles. The 2-3 times greater post-tetanic facilitation (PTF) of the action potential in the platysma than in extremity muscles also indicates a more severe functional block in facial muscle. The PTF is an indicator of recruitment of blocked fibres. The maximal decrement was grossly related to the titre of antibodies against the acetylcholine receptor. To reveal failure of neuromuscular transmission in patients with myasthenia gravis without a decrement, a small dose of d-tubocurarine (0.2 mg in 30 ml of saline) was injected i.v. in the upper arm in a regional curare test. The sensitivity was greater in patients with myasthenia gravis than in controls and in patients with myopathy. Potentiation of twitch tension reflects contractile properties. In normal muscle twitch potentiation in the staircase (1-3 s-1, 100 s in duration) and after tetanus (50 s-1, 1.5 s in duration) was 2-3 times greater in the platysma than in the elbow flexors and ADP, presumably related to the greater proportion of fast-twitch fibers in facial muscle. The amplitude of the action potential and the twitch tension varied proportionally with the number of fibers activated and the difference in the decrements of the action potential and the twitch during the staircase in some patients with myasthenia gravis showed that the staircase phenomenon was diminished suggesting abnormalities in the excitation-contraction coupling. The diminution of the staircase and post-tetanic potentiation (PTP) in myopathy also indicates impairment of the excitation-contraction coupling. In rats with severe chronic myasthenia gravis, the staircase and PTP were decreased even when the failing neuromuscular transmission was circumvented by applying direct stimuli to the extensor digitorum longus muscle (EDL).

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Ocular Myasthenia

Hochman¹

1982

JAMA

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Regional Curare Test in Evaluation of Ocular Myasthenia

Cited by 30 publications

References 8 publications

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

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

Evoked responses in normal and diseased muscle with particular reference to twitch potentiation

Ocular Myasthenia

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