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Published on: September 13, 2015
Sensitivity of Repetitive Nerve Stimulation Performed in Early and Later Stages of Myasthenia Gravis
Morgan E Heber1, Jeremy Hill1, Janice M Massey2
1Department of Neurology, Neurological Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Introduction/Aims:
Repetitive nerve stimulation (RNS) is a valuable tool in the diagnostic evaluation of myasthenia gravis (MG). However, there are conflicting reports of its sensitivity when performed ≤ 30 days from symptom onset. We aim to compare the sensitivity of RNS performed in the early versus later stages of MG.
Methods:
Data from patients with MG who underwent RNS testing from 2017 to 2021 at Cleveland Clinic and from 1975 to 2001 at Duke University Medical Center were reviewed.
Results:
A total of 525 patients with MG underwent RNS testing. RNS was performed ≤ 30 days after symptom onset in 32 patients (Early RNS) and in 493 patients > 30 days after onset (Late RNS). RNS was abnormal in 56.3% of patients in the Early RNS group and 59.4% of those in the Late RNS group (p = 0.72). There was no difference in RNS positivity rates for either group between the institutions.
Discussion:
We found no significant difference in the sensitivity of RNS performed within or after 30 days from the onset of MG. Our findings support the use and value of RNS in the diagnostic evaluation of MG in patients presenting both early and late.
Insights
Repetitive nerve stimulation (RNS) is equally sensitive for diagnosing myasthenia gravis (MG) whether performed within or after 30 days of symptom onset. This finding supports RNS utility in early and late-stage MG diagnosis.
Area of Science:
- Neurology
- Clinical Neurophysiology
Background:
- Repetitive nerve stimulation (RNS) is crucial for diagnosing myasthenia gravis (MG).
- Conflicting data exists regarding RNS sensitivity in the early phase of MG (within 30 days of symptom onset).
Purpose of the Study:
- To compare the diagnostic sensitivity of RNS in early versus late stages of myasthenia gravis.
Main Methods:
- Retrospective review of RNS testing data from 525 myasthenia gravis patients across two institutions (Cleveland Clinic and Duke University Medical Center).
- Patients were categorized into 'Early RNS' (≤30 days from symptom onset) and 'Late RNS' (>30 days from symptom onset) groups.
Main Results:
- RNS was performed in 32 patients early and 493 patients late after symptom onset.
- Abnormal RNS results were observed in 56.3% of the Early RNS group and 59.4% of the Late RNS group.
- No statistically significant difference in RNS sensitivity was found between the early and late groups (p=0.72).
Conclusions:
- RNS sensitivity is not significantly different when performed within or after 30 days from myasthenia gravis symptom onset.
- These findings validate the use of RNS for diagnosing MG in patients presenting at various stages of the disease.
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