title: Kinematic and diffusion tensor imaging definition of familial Marcus Gunn jaw-winking synkinesis.
abstract: BACKGROUND
  Marcus Gunn jaw-winking synkinesis (MGJWS) is characterized by eyelid ptosis, which disappears during jaw movement. Familial MGJWS is an extremely rare condition. Some authors suggested that MGJWS is due to neural misdirection in the brainstem whereas others suggested that aberrant reinnervation or ephapse may be responsible for synkinetic activity. Pathogenesis of this condition is therefore still unclear.
  
  
  RESULTS
  To investigate pathogenetic mechanism in familial MGJWS we performed neurophysiological (EMG, Blink Reflex, Recovery cycle of the R2 component of the blink reflex, Masseter inhibitory reflex, BAEPS and kinematic analysis) and neuroradiological (MRI, Diffusion Tensor Imaging) investigations in a member of a multigenerational family with autosomal dominant Marcus Gunn jaw-winking synkinesis (MGJWS). Kinematic analysis of eyelid and jaw movements disclosed a similar onset and offset of the eyelid and jaw in both the opening and closing phases. The excitability of brainstem circuits, as assessed by the blink reflex recovery cycle and recovery index, was normal. Diffusion Tensor Imaging revealed reduced fractional anisotropy within the midbrain tegmentum.
  
  
  CONCLUSIONS
  Kinematic and MRI findings point to a brainstem structural abnormality in our familial MGJWS patient thus supporting the hypothesis of a neural misdirection of trigeminal motor axons to the elevator palpebralis muscle.
authors.affiliation: IRCCS Neuromed, Pozzilli, Isernia, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Conte
authors.forename: Francesco
authors.initials: F
authors.lastname: Brancati
authors.forename: Francesco
authors.initials: F
authors.lastname: Garaci
authors.forename: Nicola
authors.initials: N
authors.lastname: Toschi
authors.forename: Matteo
authors.initials: M
authors.lastname: Bologna
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fabbrini
authors.forename: Marika
authors.initials: M
authors.lastname: Falla
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallapiccola
authors.forename: Patrizio
authors.initials: P
authors.lastname: Bollero
authors.forename: Roberto
authors.initials: R
authors.lastname: Floris
authors.forename: Alfredo
authors.initials: A
authors.lastname: Berardelli
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001763:Blepharoptosis / Q000175:diagnosis*; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006330:Heart Defects, Congenital / Q000175:diagnosis*; D006801:Humans; D007569:Jaw Abnormalities / Q000175:diagnosis*; D008297:Male; D009422:Nervous System Diseases / Q000175:diagnosis*; D059906:Neuroimaging; D009482:Neurophysiology; D015835:Ocular Motility Disorders / Q000175:diagnosis*; D012021:Reflex, Abnormal; D013577:Syndrome; D046608:Synkinesis / Q000175:diagnosis*; D000093922:Congenital Cranial Dysinnervation Disorders