title: Intensified hypnic jerks: a polysomnographic and polymyographic analysis.
abstract: OBJECTIVE
  To analyze the nature and propagation of muscle bursts in patients presenting with intensified hypnic jerks and sleep onset insomnia.
  
  
  METHODS
  We obtained polymyographic recordings from cranially and spinally innervated muscles during polysomnographic study in 10 subjects presenting with repeated jerking movements at sleep onset, anxiety and sleep onset insomnia. One subject also had daytime polymyography during relaxed wakefulness and drowsiness as well as back-averaging of the EEG preceding the muscle bursts.
  
  
  RESULTS
  We observed 4 patterns of muscle propagation: synchronous and symmetrical patterned muscle bursts between the two sides and agonist-antagonist muscles similar to those noted in audiogenic startle reflex, reticular reflex myoclonus, dystonic myoclonus, and pyramidal myoclonus with rostrocaudal propagation of muscle bursts.
  
  
  CONCLUSIONS
  Hypnic jerks are physiological phenomena which may be accentuated and repeated and may be of several physiological subtypes.
authors.affiliation: Division of Sleep Medicine, New Jersey Neuroscience Institute at JFK Medical Center and Seton Hall University. schok@att.net
authors.forename: Sudhansu
authors.initials: S
authors.lastname: Chokroverty
authors.forename: Sushanth
authors.initials: S
authors.lastname: Bhat
authors.forename: Divya
authors.initials: D
authors.lastname: Gupta
mesh_terms: D000328:Adult; D000368:Aged; D001007:Anxiety / Q000209:etiology / Q000503:physiopathology; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009207:Myoclonus / Q000150:complications / Q000503:physiopathology*; D017286:Polysomnography / Q000295:instrumentation / Q000379:methods*; D007319:Sleep Initiation and Maintenance Disorders / Q000209:etiology / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology; D013997:Time Factors; D055815:Young Adult