WS3.7. Repetitive Nerve Stimulation Testing

Myasthenia gravis (MG) in childhood is rare comprising 10 to 20 % of all myasthenic patients. We studied 18 patients with MG whose first symptoms started from 1 to 12 years of age, followed at the Department of Neurology of the UNIFESP-EPM, from January 1983 to August 1997. There were 10 girls and 8 boys (1.2:1). Eleven patients (61%) presented moderate or severe generalized disease and 4 (22%) had at least one myasthenic crisis. EMG with supramaximal repetitive nerve stimulation was diagnostic in 8 (47%) out of 17 patients, and chest CT was normal in 14 patients. Seropositivity to acetylcholine receptor antibodies was found in 81.6% (9 out of 11 tested) and the levels had no relation to clinical severity. Nine out of 16 patients (56%) worsened with pyridostigmine alone and were treated with prednisone. Four out of those nine continued worsening despite steroids and were subjected to thymectomy (all showed thymic lymphoid follicular hyperplasia). Three patients (75%) improved markedly after thymectomy and one (25%) worsened, eventually getting better with intravenous immunoglobulin and oral azathioprine. MG treatment, using all resources available, has to be individualized for each child.

Download Full-text

P953: Repetitive nerve stimulation often shows a normal decrement in acute severe generalised myasthenia gravis: crucial to perform CNE jitter analysis for correct diagnosis

Clinical Neurophysiology ◽

10.1016/s1388-2457(14)50988-1 ◽

2014 ◽

Vol 125 ◽

pp. S301

Author(s):

D. Triantafillidou ◽

A. Punga

Keyword(s):

Myasthenia Gravis ◽

Nerve Stimulation ◽

Correct Diagnosis ◽

Repetitive Nerve Stimulation

Download Full-text

Decremental Responses to Repetitive Nerve Stimulation in X-Linked Bulbospinal Muscular Atrophy

Journal of Clinical Neurology ◽

10.3988/jcn.2013.9.1.32 ◽

2013 ◽

Vol 9 (1) ◽

pp. 32 ◽

Cited By ~ 8

Author(s):

Jee Young Kim ◽

Kee Duk Park ◽

Seung-Min Kim ◽

Il Nam Sunwoo

Keyword(s):

Nerve Stimulation ◽

Muscular Atrophy ◽

Repetitive Nerve Stimulation

Download Full-text

Changes in miniature endplate potential frequency during repetitive nerve stimulation in the presence of Ca2+, Ba2+, and Sr2+ at the frog neuromuscular junction.

The Journal of General Physiology ◽

10.1085/jgp.77.5.503 ◽

1981 ◽

Vol 77 (5) ◽

pp. 503-529 ◽

Cited By ~ 46

Author(s):

J E Zengel ◽

K L Magleby

Keyword(s):

Nerve Stimulation ◽

Transmitter Release ◽

Neuromuscular Junctions ◽

Fourth Power ◽

Bathing Solution ◽

Frog Neuromuscular Junction ◽

Repetitive Nerve Stimulation ◽

Time Constants ◽

Endplate Potential ◽

Induced Changes

Miniature endplate potentials (MEPPs) were recorded from frog sartorious neuromuscular junctions under conditions of reduced quantal contents to study the effect of repetitive nerve stimulation on asynchronous (tonic) quantal transmitter release. MEPP frequency increased during repetitive stimulation and then decayed back to the control level after the conditioning trains. The decay of the increased MEPP frequency after 100-to 200-impulse conditioning trains can be described by four components that decayed exponentially with time constants of about 50 ms, 500 ms, 7 s, and 80 s. These time constants are similar to those for the decay of stimulation-induced changes in synchronous (phasic) transmitter release, as measured by endplate potential (EPP) amplitudes, corresponding, respectively, to the first and second components of facilitation, augmentation, and potentiation. The addition of small amounts of Ca2+ or Ba2+ to the Ca2+-containing bathing solution, or the replacement of Ca2+ with Sr2+, led to a greater increase in the stimulation-induced increases in MEPP frequency. The Sr-induced increase in MEPP frequency was associated with an increase in the second component of facilitation of MEPP frequency; the Ba-induced increase with an increase in augmentation. These effects of Sr2+ and Ba2+ on stimulation-induced changes in MEPP frequency are similar to the effects of these ions on stimulation-induced changes in EPP amplitude. These ionic similarities and the similar kinetics of decay suggest that stimulation induced changes in MEPP frequency and EPP amplitude have some similar underlying mechanisms. Calculations are presented which show that a fourth power residual calcium model for stimulation-induced changes in transmitter release cannot readily account for the observation that stimulation-induced changes in MEPP frequency and EPP amplitude have similar time-courses.

Download Full-text

Repetitive Nerve Stimulation of Facial and Hypothenar Muscles: Relative Sensitivity in Different Myasthenia Gravis Subgroups

European Neurology ◽

10.1159/000324915 ◽

2011 ◽

Vol 65 (4) ◽

pp. 203-207 ◽

Cited By ~ 16

Author(s):

T. Zambelis ◽

P. Kokotis ◽

N. Karandreas

Keyword(s):

Myasthenia Gravis ◽

Nerve Stimulation ◽

Relative Sensitivity ◽

Repetitive Nerve Stimulation ◽

Stimulation Of

Download Full-text

Effect of Hypertonicity on Augmentation and Potentiation and on Corresponding Quantal Parameters of Transmitter Release

Journal of Neurophysiology ◽

10.1152/jn.1999.81.3.1428 ◽

1999 ◽

Vol 81 (3) ◽

pp. 1428-1431 ◽

Cited By ~ 2

Author(s):

Hong Cheng ◽

Michael D. Miyamoto

Keyword(s):

Nerve Stimulation ◽

Transmitter Release ◽

Ringer Solution ◽

Hypertonic Solution ◽

Repetitive Nerve Stimulation ◽

Quantal Transmitter Release ◽

Before And After ◽

Miniature Endplate Potentials ◽

Endplate Potentials ◽

Made In

Effect of hypertonicity on augmentation and potentiation and on corresponding quantal parameters of transmitter release. Augmentation and (posttetanic) potentiation are two of the four components comprising the enhanced release of transmitter following repetitive nerve stimulation. To examine the quantal basis of these components under isotonic and hypertonic conditions, we recorded miniature endplate potentials (MEPPs) from isolated frog ( Rana pipiens) cutaneous pectoris muscles, before and after repetitive nerve stimulation (40 s at 80 Hz). Continuous recordings were made in low Ca2+ high Mg2+ isotonic Ringer solution, in Ringer that was made hypertonic with 100 mM sucrose, and in wash solution. Estimates were obtained of m (no. of quanta released), n (no. of functional release sites), p (mean probability of release), and vars p (spatial variance in p), using a method that employed MEPP counts. Hypertonicity abolished augmentation without affecting potentiation. There were prolonged poststimulation increases in m, n,and p and a marked but transient increase in vars p in the hypertonic solution. All effects were completely reversed with wash. The time constants of decay for potentiation and for vars p were virtually identical. The results are consistent with the notion that augmentation is caused by Ca2+ influx through voltage-gated calcium channels and that potentiation is due to Na+-induced Ca2+ release from mitochondria. The results also demonstrate the utility of this approach for analyzing the dynamics of quantal transmitter release.

Download Full-text