title: Bulbar muscle MRI changes in patients with SMA with reduced mouth opening and dysphagia.
abstract: OBJECTIVE
  We performed a study in patients with proximal spinal muscular atrophy (SMA) to determine the prevalence of reduced maximal mouth opening (MMO) and its association with dysphagia as a reflection of bulbar dysfunction and visualized the underlying mechanisms using MRI.
  
  
  METHODS
  We performed a cross-sectional study of MMO in 145 patients with SMA types 1-4 and 119 healthy controls and used MRI in 12 patients to visualize mandibular condylar shape and sliding and the anatomy of muscle groups relevant for mouth opening and closing. We analyzed associations of reduced MMO with SMA severity and complaints of dysphagia.
  
  
  RESULTS
  Reduced MMO was defined as an interincisal distance ≤ 35 mm and was found in none of the healthy controls and in 100%, 79%, 50%, and 7% of patients with SMA types 1, 2, 3a, and 3b/4, respectively. MRI showed severe fatty degeneration of the lateral pterygoid muscles that mediate mouth opening by allowing mandibular condylar sliding but relatively mild involvement of the mouth closing muscles in patients with reduced MMO. Reduced MMO was associated with SMA type, age, muscle weakness, and dysphagia (p < 0.05).
  
  
  CONCLUSIONS
  Reduced MMO is common in SMA types 1-3a and is mainly caused by fatty degeneration of specific mouth opening muscles. Reduced MMO is a sign of bulbar dysfunction in SMA.
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Renske I
authors.initials: RI
authors.lastname: Wadman
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: H Willemijn
authors.initials: HW
authors.lastname: van Bruggen
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Theo D
authors.initials: TD
authors.lastname: Witkamp
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Stanimira I
authors.initials: SI
authors.lastname: Sparreboom-Kalaykova
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Marloes
authors.initials: M
authors.lastname: Stam
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Leonard H
authors.initials: LH
authors.lastname: van den Berg
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands.
authors.forename: Michel H
authors.initials: MH
authors.lastname: Steenks
authors.affiliation: From the Department of Neurology and Neurosurgery and Spieren voor Spieren Kindercentrum and Brain Center Rudolf Magnus (R.I.W., M.S., L.H.v.d.B., W.L.v.d.P.), Department of Oromaxillofacial Surgery and Special Dental Care (H.W.v.B.), and Department of Radiology (T.D.W.), University Medical Center Utrecht, the Netherlands; Radboud University Medical Center (H.W.v.B., S.I.S.-K., M.H.S.), Nijmegen, the Netherlands; and Center for Evidence Based Practice (H.W.v.B., S.I.S.-K., M.H.S.), Department of Oral Function and Prosthetic Dentistry, College of Dental Sciences, Nijmegen, the Netherlands. W.L.vanderPol@umcutrecht.nl.
authors.forename: W Ludo
authors.initials: WL
authors.lastname: van der Pol
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001284:Atrophy; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003680:Deglutition Disorders / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008410:Masticatory Muscles / Q000473:pathology* / Q000503:physiopathology; D008875:Middle Aged; D018908:Muscle Weakness / Q000473:pathology* / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009134:Muscular Atrophy, Spinal / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D014897:Spinal Muscular Atrophies of Childhood / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D013704:Temporomandibular Joint / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult