Utility of Repetitive Nerve Stimulation in the Diagnosis of Myasthenia Gravis in the Inpatient Setting

Objectives

Sensitivity and specificity of Repetitive Nerve Stimulation (RNS) is typically reported from outpatient centers, and we hypothesized that these values might not apply to hospitalized patients with higher grades of weakness. RNS may be helpful in rapidly confirming diagnosis of myasthenia gravis (MG) in the inpatient setting, as results from confirmatory antibody testing are often delayed. We sought to characterize the sensitivity and specificity of RNS in the inpatient setting to assist in the early diagnosis of MG.

Methods

We performed a retrospective analysis of all adult patients who had inpatient RNS at our center from 2016 to 2021. Inclusion criteria included RNS performed at least at one site and a neurological evaluation which prompted an electrodiagnostic study to evaluate for neuromuscular junction (NMJ) pathology. Descriptive statistics and Fisher exact analysis were performed.

Results

Of the 32 identified hospitalized patients, 6 had greater than 10% decrement on slow RNS, confirming NMJ dysfunction. Five were diagnosed with MG, and 1 with Lambert-Eaton myasthenic syndrome. Of the 26 patients with normal RNS, 25 ultimately had alternative causes of weakness. One was later diagnosed as seronegative MG based on clinical improvement with acetylcholinesterase inhibitors. In our inpatient population, the overall sensitivity and specificity of RNS were 83.3% and 96.2% respectively. There was a statistically significant association between a positive RNS and diagnosis of MG (P = .0002).

Conclusions

RNS is a highly sensitive and specific test for the diagnosis of MG in an inpatient setting, and these results are likely more rapidly available compared to antibody testing.

Characterization of autonomic symptom burden in long COVID: A global survey of 2,314 adults

BACKGROUND

Autonomic dysfunction is a known complication of post-acute sequelae of SARS-CoV-2 (PASC)/long COVID, however prevalence and severity are unknown.

OBJECTIVE

To assess the frequency, severity, and risk factors of autonomic dysfunction in PASC, and to determine whether severity of acute SARS-CoV-2 infection is associated with severity of autonomic dysfunction.

DESIGN

Cross-sectional online survey of adults with PASC recruited through long COVID support groups between October 2020 and August 2021.

PARTICIPANTS

2,413 adults ages 18-64 years with PASC including patients who had a confirmed positive test for COVID-19 (test-confirmed) and participants who were diagnosed with COVID-19 based on clinical symptoms alone.

MAIN MEASURES

The main outcome measure was the Composite Autonomic Symptom 31 (COMPASS-31) total score, used to assess global autonomic dysfunction. Test-confirmed hospitalized vs. test-confirmed non-hospitalized participants were compared to determine if the severity of acute SARS-CoV-2 infection was associated with the severity autonomic dysfunction.

KEY RESULTS

Sixty-six percent of PASC patients had a COMPASS-31 score >20, suggestive of moderate to severe autonomic dysfunction. COMPASS-31 scores did not differ between test-confirmed hospitalized and test-confirmed non-hospitalized participants [28.95 (15.62, 46.60) vs. 26.4 (13.75, 42.10); p = 0.06].

CONCLUSIONS

Evidence of moderate to severe autonomic dysfunction was seen in 66% of PASC patients in our study, independent of hospitalization status, suggesting that autonomic dysfunction is highly prevalent in the PASC population and independent of the severity of acute COVID-19 illness.

Ocular health status of chemical industrial workers

BACKGROUND

Approximately 1.2 million workers are employed within chemical industries throughout South Africa. Very little basic data exists regarding the ocular health status and prevalence of occupationally related eye disorders of these workers.

METHOD

A questionnaire was administered and an ocular health examination was carried out on 78 workers in a chemical factory. Workers and the ocular disorders found were then classified according to those exposed and those not exposed to chemicals.

RESULTS

Ocular disorders were more prevalent in exposed workers (73.1%) than in nonexposed workers (43.6%). Statistically significant differences between exposed and nonexposed workers were found with respect to the prevalence of certain anterior segment disorders, viz., tear disorders, dry eye conditions, allergic conjunctivitis, and conjunctival melanosis. In respect to the prevalence of ocular disorders found, 40.8% were attributed to occupational exposure to chemicals.

CONCLUSION

This pilot study shows that further research is required to explore the cause-effect relation between chemical exposure and development of certain anterior segment disorders. Occupational exposure to chemicals should be reduced and exposure protocols at work need to be revised in order to reduce the prevalence of occupationally related eye disorders.

Oral rehydration therapy in a rehydration centre at a teaching hospital in southern Africa

A study was carried out to delineate the use of oral rehydration therapy (ORT) for gastro-enteritis in a unit that had previously used intravenous therapy (IVT) almost exclusively. Most children with dehydrating gastro-enteritis who were 5% or less dehydrated received ORT initially, while those who were more severely affected were given IVT. The success rate using ORT alone was 73%, which was much lower than that achieved in other studies. Possible factors associated with this poor outcome are discussed. It was concluded that with the exceptions of lactose intolerance and coexisting infection, lack of commitment to ORT and the easy access to IVT must have contributed significantly to the suboptimal outcome.