facioscapulohumeral muscular dystrophy ( fshd ) is a common inherited muscular dystrophy presented clinically with slowly progressive weakness and wasting of facial and limb muscles and rare bulbar muscle involvement .
we present herein a known case of fshd presented with recent onset of severe bulbar symptoms and was found to have myasthenia gravis ( mg ) based on electrodiagnostic study , elevated level of acetylcholine receptor antibody and dramatic improvement with choline esterase inhibitor agents .
clinical presentation , electrodiagnostic and pathologic findings of this patient are described . a 70-year - old man presented to our department with complaint of 15-day history of progressive difficulty in chewing and dysartheria .
he had a 50-year history of slowly progressive asymmetrical weakness of proximal upper limb muscles .
examinations revealed reduction in forces of bilateral orbicularis oculi muscles , weakness and wasting of bilateral triceps muscles especially on right side and bilateral winging of scapula more prominent on right side . the legs and pelvic girdle muscles had normal forces .
edrophonium test was performed and dysartheria and chewing difficulty showed dramatic improvement but had no effect on limb weakness .
muscle biopsy showed myopathic changes with invariability in muscle fiber size , intramuscular infiltration of chronic inflammatory cells , mostly lymphocytes , few hyaline fibers and prominent fat infiltration .
our patient 's bulbar symptoms showed dramatic improvement following administration of choline - esterase inhibitor agents .
a 70-year - old man presented to our department with complaint of 15-day history of progressive difficulty in chewing and dysartheria .
he had a 50-year history of slowly progressive asymmetrical weakness of proximal upper limb muscles .
examinations revealed reduction in forces of bilateral orbicularis oculi muscles , weakness and wasting of bilateral triceps muscles especially on right side and bilateral winging of scapula more prominent on right side . the legs and pelvic girdle muscles had normal forces .
edrophonium test was performed and dysartheria and chewing difficulty showed dramatic improvement but had no effect on limb weakness .
muscle biopsy showed myopathic changes with invariability in muscle fiber size , intramuscular infiltration of chronic inflammatory cells , mostly lymphocytes , few hyaline fibers and prominent fat infiltration .
our patient 's bulbar symptoms showed dramatic improvement following administration of choline - esterase inhibitor agents .
it presents clinically with slowly progressive weakness and wasting of facial and shoulder girdle muscles and sometimes involvement of lower extremities .
the clinical severity is wide ranging from asymptomatic individuals to wheel - chair dependent patients .
any unusual changes in course of disease or development of unusual symptoms should raise the possibility of concomitant disease .
sansone et al . reported a 69-year - old known case of fshd who presented with sudden deterioration of limb weakness and development of bulbar symptoms and was found to have mg based on repetitive nerve stimulation , elevated level of acetylcholine receptor - binding antibody and dramatic improvement following immunomodulator administration .
reported a 50-year - old man with a 35 year history of fshd who presented with acute progressive weakness of lower extremities three weeks prior to admission .
the patient was found to have mg based on decrement response on repetitive nerve stimulation , elevated level of acetylcholine receptor - binding antibody and improvement after thymectomy and administration of corticosteroid . in another report , mcgonigal et al . presented a 56-year old newly diagnosed myasthenic patient who found to have 40-year history of progressive foot drop and
although our case is a rare coexistence of fshd and mg , low prevalence of both diseases , may raise the possibility of the presence of other etiologies . theoretically , it is related to breaking of immune tolerance to achrs as a result of muscle fiber degeneration .
patients with genetic myopathies may occasionally develop antibodies to achr . while these antibodies may not have pathogenic effects ,
their production is likely to be a consequence of sensitization to achr secondary to muscle fiber damage , rather than through an immune process in thymus .
muscle histopathological examination in some cases of fshd shows inflammatory changes , disproportionate to muscle fiber necrosis but the presence of mononuclear infiltration does not affect disease progression and the patients do not benefit from prednisone treatment . 

to the best of our knowledge , there are limited reports of concomitant occurrence of mg and fshd in literatures .
although the association of mg with fshd in our patient could be an incidental finding , it may raise the possibility of innate immune response , i.e. autoinflammation in development of achr antibodies in genetic myopathies or
it may suggest immune mechanisms in pathogenesis of fshd . moreover , our experience may warrant concomitant neuromuscular disorder in patients with unusual symptoms of fshd .
 facioscapulohumeral muscular dystrophy ( fshd ) is a common inherited muscular dystrophy presented clinically with slowly progressive weakness and wasting of facial and limb muscles and rare bulbar muscle involvement . 
 we present herein a 70-year - old man who was a known case of fshd with complaint of 15-day history of progressive difficulty in chewing and dysarthria and was found to have myasthenia gravis . 
 related literatures have been also reviewed . 