Abstract Details

Title Evidence of Higher Incidence of Myasthenia Gravis During Summer

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P12 - Poster Session 12 (11:45 AM-12:45 PM)

Poster/Presentation
Number 11-034

Objective To investigate the association between seasonality and onset of myasthenia gravis (MG) symptoms.

Background Environmental factors may contribute to MG development, sometimes with seasonal patterns of exposure. However, whether seasonality has an impact on MG incidence remains unclear.

Design/Methods We retrospectively reviewed data of MG patients with acetylcholine receptor (AChR)-IgG and disease onset between January 2010-December 2019, from two Italian cohorts: 1) An hospital-based cohort of patients consecutively seen at the Neurology Unit of the IRCCS Fondazione Policlinico Gemelli, in Rome; and 2) a previously described population-based cohort of incident cases resident in the Sanitary District of Sassari, in the region of Sardinia. MG cases were assigned to four season-trimesters (e.g., summer trimester = June-August) based on month of MG symptoms onset, seasonal variability was explored comparing the median number of incident MG cases per trimester over the study period (Kruskal Wallis). Generalized additive model (GAM) was also applied to evaluate the relationship between temperature and new MG cases.

Results A total of 316 patients were included: hospital-based cohort, 214; population-based cohort, 102. Median age at onset was 66 years (range, 8-92); 41% were female. The seasonal MG incidence was significantly higher in summer with 11 cases (range, 7-15), compared to 6 (3-11) cases in autumn, 8.5 (3-11) cases in winter, and 7 (2-10) cases in spring; p=0.009. We also found a significant, non-linear association between average temperature and MG cases; p=0.005.

Conclusions

Our study suggests that onset of AChR-MG may follow a clear seasonal distribution, with a peak during the summer months. Seasonal variability at MG onset was comparable in patients from two geographically and genetically distinct Italian regions, making unlikely a random association and suggesting a major role of environmental factors in unmasking MG symptoms.

Authors/Disclosures
Silvia Falso, MD PRESENTER	Dr. Falso has nothing to disclose.
Pietro Zara, MD (University of Sassari)	Dr. Zara has nothing to disclose.
Sofia Marini, MD	Dr. Marini has nothing to disclose.
Mariangela Puci, PhD	Dr. Puci has nothing to disclose.
Eleonora Sabatelli	Eleonora Sabatelli has nothing to disclose.
Giovanni Sotgiu, MD, PhD	Prof. Sotgiu has nothing to disclose.
Martina Marini, MD	Mrs. Marini has nothing to disclose.
Gregorio Spagni	Gregorio Spagni has nothing to disclose.
Amelia Evoli, MD	Prof. Evoli has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Dianthus. Prof. Evoli has received personal compensation in the range of $500-$4,999 for serving as a jury member for research grant with Grifols. Prof. Evoli has received personal compensation in the range of $500-$4,999 for serving as a speaker with UCB.
Paolo Solla, MD (Ospedale Binaghi)	Dr. Solla has nothing to disclose.
Raffaele Iorio, MD (Catholic University)	Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Dianthus Therapeutics. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Johnson & Johnson. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Argenx. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Johnson&Johnson.
Elia Sechi, MD (University of Sassari)	Dr. Sechi has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion. Dr. Sechi has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Argenx.

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