title: An Objective Functional Characterisation of Head Movement Impairment in Individuals with Neck Muscle Weakness Due to Amyotrophic Lateral Sclerosis.
abstract: BACKGROUND
  Neck muscle weakness and head drop are well recognised in patients with Amyotrophic lateral sclerosis (ALS), but an objective characterisation of the consequent head movement impairment is lacking. The aim of this study was to quantitatively characterise head movements in ALS compared to aged matched controls.
  
  
  METHODS
  We evaluated two groups, one of thirteen patients with ALS and one of thirteen age-matched controls, during the execution of a series of controlled head movements, performed while wearing two inertial sensors attached on the forehead and sternum, respectively. We quantified the differences between the two groups from the sensor data using indices of velocity, smoothness and movement coupling (intended as a measure of undesired out of plane movements).
  
  
  RESULTS
  Results confirmed a general limitation in the ability of the ALS patients to perform and control head movements. High inter-patient variability was observed due to a wide range of observed functional impairment levels. The ability to extend the head backward and flex it laterally were the most compromised, with significantly lower angular velocity (P < 0.05, Cohen's d > 0.8), reduced smoothness and greater presence of coupled movements with respect to the controls. A significant reduction of angular velocity (P < 0.05, Cohen's d > 0.8) in extension, axial rotation and lateral flexion was observed when patients were asked to perform the movements as fast as possible.
  
  
  CONCLUSIONS
  This pilot study is the first study providing a functional objective quantification of head movements in ALS. Further work involving different body areas and correlation with existing methods of evaluating neuromuscular function, such as dynamometry and EMG, is needed to explore the use of this approach as a marker of disease progression in ALS.
authors.affiliation: Department of Mechanical Engineering, University of Sheffield, Sheffield, United Kingdom.|INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pancani
authors.affiliation: INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, United Kingdom.|NIHR Devices for Dignity Healthcare Technology Co-operative, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield, United Kingdom.|Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom.
authors.forename: Wendy
authors.initials: W
authors.lastname: Tindale
authors.affiliation: Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Shaw
authors.affiliation: NIHR Devices for Dignity Healthcare Technology Co-operative, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield, United Kingdom.|Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: McDermott
authors.affiliation: Department of Mechanical Engineering, University of Sheffield, Sheffield, United Kingdom.|INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Claudia
authors.initials: C
authors.lastname: Mazzà
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications* / Q000503:physiopathology*; D016022:Case-Control Studies; D055724:Electrophysiological Phenomena; D005260:Female; D019416:Head Movements; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D009334:Neck Muscles / Q000503:physiopathology*; D010865:Pilot Projects