iarjmsIARJMSIARJMS2708-3594https://doi.org/10.47310/iarjms.2021.v02i01.010Exacerbation of Sero-Negative Myasthenia may be Attributable to Anti-SARS-CoV-2 MedicationJosefFinstererFulvioA. ScorzaKlinik Landstrasse, Messerli Institute, Vienna, AustriaDisciplina de Neurociência. Universidade Federal de São Paulo/Escola Paulista de Medicina (UNIFESP/EPM). São Paulo, BrasilWith interest we read the article by Scopelliti et al. about a 46yo male with upper respiratory tract infection followed by three episodes of dyspnoea and exercise intolerance being attributed to an infection with SARS-CoV-2 despite repeatedly negative PCR-tests [1]. The patient was lastly diagnosed with sero-negative myasthenia gravis (MG) and responded favourably to appropriate treatments [1]. We have the following comments and concerns. Why was the patient diagnosed with COVID-19 pneumonia despite a negative swab PCR test for SARS-CoV-2? Interstitial pneumonia may not only occur in the context of a SARS-CoV-2 infection but due to a number of other causes [2].  If the patient was diagnosed with COVID-19 at his first admission, why was he discharged already after three days? It is unclear why the diagnosis of COVID-19 was confirmed despite a second negative PCR test for the virus. We admit that the naso-pharyngeal swab test can be negative but nonetheless a patient may be infected with SARS-CoV-2 [3]. However, in this case, SARS-CoV-2 should have been documented in a compartment other than the naso-pharynx or by determination of antibodies. Since there are cases with negative swab test but positive PCR in the bronchi, it would have been an option to initiate a bronchoscopy. Why was no treatment initiated for bilateral basal infiltrates during the second hospitalisation?  The index patient was diagnosed with MG upon the clinical presentation, the results of the repetitive nerve stimulation (RNS) and the beneficial response to pyridostigmine and steroids. Missing for the diagnosis of MG is a single fiber electromyographic (SF-EMG) examination, which should show an increased jitter and an increase in blockings. We should also be told about the results of high-frequency repetitive nerve stimulation. The patient was initially treated with azithromycin from which it is known that it may trigger myopathy or rhabdomyolysis [4]. Since azithromycin may trigger the development of myopathy [5] it is conceivable that the “myasthenic” symptoms rather reflect myopathy than myasthenia. Patients with COVID-19 frequently receive drugs which are potentially myotoxic, such as chloroquine, azithromycin, remdesivir/lopinavir or tacilizumab. We should be told if any of these compounds were administered to the index patient and if relapses of dyspnoea were attributable to myotoxic side effects of these drugs. An O2 saturation of 91-97% is normal. This is no indication for oxygen supplementation. More meaningful would have been lung function tests to see if there was truly muscular respiratory dysfunction.  The results of RNS are not convincing. The decrement was mild and may be also recorded in other neuromuscular disorders, why a false positive result of RNS cannot be excluded. Missing in this respect is the family history. We should be informed if the family history was positive for neuromuscular disorders or for multisystem disease additionally affecting the muscles.  Overall, the report about and the management of the index patient has a number of shortcomings, which should be addressed before attributing the clinical presentation truly to MG. Thorough work-up is particularly required for patients with sero-negative MG.