Myasthenia gravis with muscle specific kinase antibodies mimicking amyotrophic lateral sclerosis
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Publication date
2016-06
Authors
Huijbers, Maartje G
Niks, Erik H
Klooster, Rinse
de Visser, Marianne
Kuks, Jan B
Veldink, Jan
Klarenbeek, Pim
Van Damme, Philip
de Baets, Marc H
van der Maarel, Silvère M
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Article
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taverne
Abstract
Muscle-specific kinase (MuSK) myasthenia gravis (MG) is hallmarked by the predominant involvement of bulbar muscles and muscle atrophy. This might mimic amyotrophic lateral sclerosis (ALS) presenting with bulbar weakness. We encountered four cases of MuSK MG patients with an initial misdiagnosis of ALS. We analyzed the clinical data of the four misdiagnosed MuSK MG patients, and investigated the presence of MuSK autoantibodies in a group of 256 Dutch bulbar-onset ALS patients using a recombinant MuSK ELISA and a standard MuSK radioimmunorecipitation assay. Clues for changing the diagnosis were slow progression, clinical improvement, development of diplopia and absence of signs of upper motor neuron involvement. No cases of MuSK MG were identified among a group of 256 bulbar ALS patients diagnosed according to the revised El Escorial criteria. A misdiagnosis of ALS in patients with MuSK MG is rare. We recommend to carefully consider the diagnosis of MuSK MG in patients presenting with bulbar weakness without clear signs of upper motor neuron dysfunction.
Keywords
Amyotrophic lateral sclerosis, Myasthenia gravis, MuSK, Neuromuscular junction, IgG4, Taverne, Journal Article
Citation
Huijbers, M G, Niks, E H, Klooster, R, de Visser, M, Kuks, J B, Veldink, J H, Klarenbeek, P, Van Damme, P, de Baets, M H, van der Maarel, S M, van den Berg, L H & Verschuuren, J J 2016, 'Myasthenia gravis with muscle specific kinase antibodies mimicking amyotrophic lateral sclerosis', Neuromuscular Disorders, vol. 26, no. 6, pp. 350-353. https://doi.org/10.1016/j.nmd.2016.04.004