title: Myasthenia Gravis: Unusual Presentations and Diagnostic Pitfalls.
abstract: Myasthenia gravis (MG) is an autoimmune disorder presenting with fluctuating, fatigable muscle weakness. Initial symptoms classically involve ocular and proximal limb muscles. Rarely, MG may onset with unusual features, so it can be misdiagnosed with other neuromuscular diseases.
  
  
  
  To describe unusual and atypical presentations of MG in a large cohort of patients, considering and discussing diagnostic difficulties and pitfalls.
  
  
  
  We report on 21 out of 508 MG patients, coming to our department in the last 27 years and presenting with atypical or unusual features. The diagnosis was achieved performing a careful clinical examination, a proper neurophysiological assessment, the neostigmine test, the AChR and MuSK antibodies assay and chest CT-scan.
  
  
  
  Patients with atypical/unusual MG onset were the 4.4% of all MG patients population. We describe seven different clinical categories: asymmetric distal upper limbs weakness, foot drop, isolated triceps brachii weakness and foot drop, post exertional axial weakness with dropped head, acute facial dyplegia, limb-girdle MG and MG with sudden lower limbs weakness and recurrent falls.
  
  
  
  Atypical and unusual presentations may increase the risk to misdiagnose or delay MG diagnosis. Isolated limb-girdle presentation is the most frequent atypical form in our series.
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Rodolico
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Parisi
authors.affiliation: IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Portaro
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Fiammetta
authors.initials: F
authors.lastname: Biasini
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Sinicropi
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Ciranni
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Toscano
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Messina
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Olimpia
authors.initials: O
authors.lastname: Musumeci
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vita
authors.affiliation: Department of Clinical and Experimental Medicine - University of Messina, Messina, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Girlanda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000276:immunology; D004576:Electromyography; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology; D009157:Myasthenia Gravis / Q000150:complications / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology / Q000503:physiopathology; D020294:Myasthenic Syndromes, Congenital / Q000209:etiology / Q000503:physiopathology; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology; D011950:Receptors, Cholinergic / Q000276:immunology; D013945:Thymoma / Q000000981:diagnostic imaging; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases
keywords: Myasthenia gravis; distal myasthenia; foot 
  drop; limb girdle myasthenia