Autoimmune myasthenia gravis : the impact of heterogeneous patterns of muscle weakness on outcome measures and diagnosis

Meel, R.H.P. de (2020)

Doctoral Thesis

The distribution of muscle weakness in MG is highly heterogeneous and frequently shifts in patients. In 5% of patients MG was restricted to ocular weakness, whereas 7% of patients never had any form of ocular weakness throughout their disease course. In 83% of MG patients at least one other extra-ocular muscle was involved at the second visit.
Patients with late-onset MG and the presence of additional autoimmune diseases had more exacerbations (OR = 47) and emergency treatments (OR = 26) than early-onset MG patients without other autoimmune diseases.
MG-ADL (patient questionnaire on ADL) was found to be relatively insensitive to changes in generalized weakness. This led to the absence of a significant treatment response on MG-ADL in the presence of a significant response on QMG (an objective measure of muscle weakness) in the eculizumab study. A new ADL outcome measure, MGII, was shown to have a higher sensitivity for generalized weakness than MG-ADL.
RoVEMP, a novel neurophysiological test, was shown to be a specific measure for myasthenic extra-ocular muscle weakness. In addition, we found a significant correlation between magnitude of decrement and the time since the last intake of pyridostigmine, supporting that RoVEMP decrement reflects reversible neuromuscular transmission failure.

• Myasthenia gravis
• Autoimmune disease
• Muscle weakness
• Phenotype
• Outcome measure
• Diagnosis
• Repetitive ocular vestibular evoked myogenic potentials
• Ocular muscle weakness
• MG-ADL
• MGII

• All authors: Meel, R.H.P. de
• Supervisor: Verschuuren, J.J.G.M.
• Co-supervisor: Tannemaat, M.R.
• Committee: Maartel, S.M. van der; De Baets, M.H.; Evoli, A.
• Qualification: Doctor (dr.)
• Awarding Institution: Faculty of Medicine, Leiden University Medical Center (LUMC), Leiden University
• Date: 2020-01-30
• ISBN (print): 9789463613835