title: Mechanomyography as an access pathway: corporeal contraindications.
abstract: OBJECTIVE
  The purpose of this study is to delineate the impairments of body functions and structures which specifically inhibit mechanomyography (MMG)-based switch control as an alternative access pathway.
  
  
  METHODS
  Seven individuals with severe physical disabilities and varied diagnoses of neuromuscular or neurological conditions tested a MMG switch. A semi-structured protocol was used to gather quantitative and qualitative indications of the switch's performance, and descriptive perceptions of the participants and their care givers.
  
  
  RESULTS
  The participants controlled the switch by contracting muscles of their forehead, forearm or shoulder. Body functions and structures that negatively affect the signal-to-noise ratio (SNR) of the recorded MMG signal included involuntary dystonic movement, impaired muscle control, atrophied muscles, muscle spasticity and involuntary activity of neighbouring muscles.
  
  
  CONCLUSIONS
  The MMG switch is strongly recommended where the muscle site and its control are intact and signal artefact is minimal. Its viability when muscle activity at the access site may be confounded by signal artefact is dependent on the strength of the voluntary muscle contraction relative to that of artefacts such as spastic contractions, involuntary dystonic movements, muscle spasms and physiological vibrations. Neurological conditions, such as spasticity, that compromise the user's ability to voluntarily contract or suppress muscle contractions may be considered contraindications to MMG-based access.
authors.affiliation: Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, Toronto, ON, Canada.
authors.forename: Natasha
authors.initials: N
authors.lastname: Alves
authors.forename: Tom
authors.initials: T
authors.lastname: Chau
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D000690:Amyotrophic Lateral Sclerosis / Q000534:rehabilitation*; D002547:Cerebral Palsy / Q000534:rehabilitation*; D002648:Child; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D009213:Myography / Q000295:instrumentation / Q000379:methods; D011782:Quadriplegia / Q000534:rehabilitation; D012656:Self-Help Devices; D013119:Spinal Cord Injuries / Q000534:rehabilitation*; D055815:Young Adult