Christelle Haddad1, Matthew Varon2, Jeffrey Statland2, Omar Jawdat2, Constantine Farmakidis2, Mamatha Pasnoor2, Swathy Chandrashekhar2, Mazen Dimachkie2
1Division of Neuromuscular Medicine, Neurology Department, 2University of Kansas Medical Center
Objective:
To describe clinical phenotypes of patients with IBM, assess sensitivity of cN1A antibody and correlate antibody positivity with clinical patterns and disease progression.
Background:
Characteristic clinical patterns in inclusion body myositis (IBM) include knee extensors and finger flexors but dysphagia is variable. Sensitivity of cN1A antibody ranges from 33-76%. Correlation between antibody positivity, disease phenotype and clinical course remains unclear.
Design/Methods:
Retrospective chart review of IBM patients evaluated at the Neuromuscular Clinics of an academic medical center.
Results:
We identified over 100 patients and abstracted data on 30 patients fulfilling ENMC 2011 criteria for IBM. Median onset age was 59 years, 19 males and 90% white. For the first symptom, 15 had proximal leg weakness, 8 dysphagia, 3 hand weakness, 3 foot weakness and 1 myalgias. For the second symptom, 10 had hand weakness, 8 proximal leg weakness, 5 dysphagia, 4 proximal arm weakness and 3 foot weakness. For the third symptom, 9 had hand weakness, 7 dysphagia, 5 proximal arm weakness, 5 proximal leg weakness, 3 foot weakness and 1 eyelid closure weakness. The median age at first, second, and third symptoms were 59, 62, and 65 years. Dysphagia occurred in 80% at median 1.5 years after onset. 3 of 8 tested were positive for cN1A antibody. Disease progression to requiring cane or walker occurred in 70% and 67 %, respectively, at median 7 and 10 years from first symptom onset.
Conclusions:
While it is premature to draw conclusions about sensitivity of cN1A testing or correlation with clinical phenotype and disease progression, more subject data is being abstracted and will be presented.