title: Proton magnetic resonance spectroscopy of the intrinsic tongue muscles in patients with myasthenia gravis with different autoantibodies.
abstract: OBJECTIVE
  To assess lipid composition of the intrinsic tongue muscles in patients with myasthenia gravis (MG).
  
  
  METHODS
  This study included 15 MG patients with antibodies against muscle-specific kinase (MuSK), 15 matched MG patients with antibodies against acetylcholine receptor (AChR) and 15 matched healthy subjects. Middle posterior region of the tongue was analyzed by single voxel point-resolved proton magnetic resonance spectroscopy (MRS) using 1.5T MRI scanner.
  
  
  RESULTS
  MRS obtained from subject with AChR MG showed a broad resonance arising from methylene groups of lipids (PMN) with no observable shoulder attributed to methyl groups (PML). Full-width at half maximum (FWHM) of PMN+PML peak showed higher value in patients with AChR MG in comparison to healthy subjects and MuSK MG patients (p<0.05). In patients with MuSK MG, the shape and FWHM of PMN+PML peak was similar as in healthy subjects (p>0.05), with tendency toward increased ratio between PMN and resonance from vinyl protons of lipids (PV). In both AChR and MuSK MG, total creatine resonance (creatine+phosphocreatine, CP) was almost absent with significant increase of PMN/CP ratio in comparison to healthy subjects (p<0.05).
  
  
  CONCLUSIONS
  MRS is useful in revealing muscle lipid composition in MG. In patients with AChR MG, MRS showed increased lipid content in the tongue muscles due to the lipid migration from intra- to extramyocellular space. Finding in patients with MuSK MG might reflect intramyocellular lipid deposition in the tongue. CP decrease in tongue muscles indicated impairment of oxidative metabolism in both AChR MG and MuSK MG.
authors.affiliation: Institute of Neurology, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia. dragana.lav@sbb.rs
authors.forename: Dragana
authors.initials: D
authors.lastname: Lavrnic
authors.forename: Marko
authors.initials: M
authors.lastname: Dakovic
authors.forename: Stojan
authors.initials: S
authors.lastname: Peric
authors.forename: Vidosava
authors.initials: V
authors.lastname: Rakocevic-Stojanovic
authors.forename: Ivana
authors.initials: I
authors.lastname: Basta
authors.forename: Ivan
authors.initials: I
authors.lastname: Marjanovic
authors.forename: Tatjana
authors.initials: T
authors.lastname: Stosic-Opincal
authors.forename: Slobodan
authors.initials: S
authors.lastname: Lavrnic
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000032:analysis*; D015992:Body Mass Index; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology*; D009157:Myasthenia Gravis / Q000201:enzymology / Q000276:immunology* / Q000473:pathology*; D010725:Phosphocreatine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism; D014059:Tongue / Q000473:pathology*
chemical_list: D001323:Autoantibodies; D008055:Lipids; D011950:Receptors, Cholinergic; D010725:Phosphocreatine; D011505:Protein-Tyrosine Kinases; D003401:Creatine