title: Hypnic jerks are an underestimated sleep motor phenomenon in patients with parkinsonism. A video-polysomnographic and neurophysiological study.
abstract: Hypnic jerks (HJs) are sudden contractions of one or more body segments occurring mostly at sleep onset. They are highly sporadic and affect all ages and both sexes with prevalence between 60% and 70% in the general population.
  
  
  
  This study describes the frequency and the neurophysiological characteristics of HJs in a population of patients with parkinsonism by means of nocturnal video-polysomnographic recordings.
  
  
  
  This is a prospective cohort study and is reported following the STROBE guidelines. We analyzed the clinical and video-polysomnographic data of the first 66 consecutive patients recruited in the ongoing prospective study "Bologna motor and non-motor Prospective study on Parkinsonism at onset" (BoProPark). Each patient underwent a full neurological workup including a whole-night video- polysomnography. Neurophysiological characteristics including the propagation patterns of the HJs were studied with an extended muscle montage polysomnography.
  
  
  
  We recorded a total of 62 HJs in 16 patients out of 66 (24%). Sleep parameters were not statistically different between patients with and without HJs. All HJs were spontaneous and occurred randomly throughout the night. Electromyographic analysis showed that muscle activity arose from different muscles with no prevalence of one over the other and without any ordered propagation. No recurring motor pattern of the jerks was detected.
  
  
  
  Our findings demonstrated that HJs are a frequent, underestimated, sleep-related motor phenomenon in patients with parkinsonism. As they may represent a further cause of sleep disruption and insomnia, HJs should be actively examined. Neurophysiological analysis suggests a subcortical origin of HJs as shown previously for a healthy subject.
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Chiaro
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; IRCCS, Institute of Neurological Sciences of Bologna, Bologna, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Calandra-Buonaura
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; IRCCS, Institute of Neurological Sciences of Bologna, Bologna, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Sambati
authors.affiliation: IRCCS, Institute of Neurological Sciences of Bologna, Bologna, Italy.
authors.forename: Annagrazia
authors.initials: A
authors.lastname: Cecere
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Ferri
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors.forename: Maria Turchese
authors.initials: MT
authors.lastname: Caletti
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; IRCCS, Institute of Neurological Sciences of Bologna, Bologna, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Cortelli
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; IRCCS, Institute of Neurological Sciences of Bologna, Bologna, Italy. Electronic address: federica.provini@unibo.it.
authors.forename: Federica
authors.initials: F
authors.lastname: Provini
mesh_terms: D000368:Aged; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009207:Myoclonus / Q000150:complications / Q000503:physiopathology*; D020189:Nocturnal Myoclonus Syndrome / Q000150:complications / Q000503:physiopathology*; D020734:Parkinsonian Disorders / Q000150:complications / Q000503:physiopathology*; D017286:Polysomnography; D011446:Prospective Studies; D012890:Sleep; D012894:Sleep Stages; D014741:Video Recording
keywords: Hypnic jerks; Myoclonus; Parkinsonism; Sleep fragmentation; Sleep starts; Video-polysomnography