title: Respiratory pattern changes in sleep in children on vagal nerve stimulation for refractory epilepsy.
abstract: BACKGROUND
  An altered breathing pattern in sleep, over two to three weeks, reported by the parents of a child on Vagal Nerve Stimulation (VNS) therapy for refractory epilepsy, prompted a sleep study in him. His polysomnography (PSG) revealed respiratory irregularity concordant with VNS activation. Dyspnoea is a well recognised and reported side effect of the VNS. However there are only a few studies looking at respiration in sleep with VNS. We therefore undertook PSGs in seven other children on VNS.
  
  
  METHODS
  Sleep studies were undertaken, in accordance with standard clinical practice. Sleep and apnoeas and hypopneas were scored in accordance with conventional criteria. Respiratory pattern changes in sleep (RPCS) with VNS were looked for.
  
  
  RESULTS
  Respiratory pattern changes in sleep were seen during PSG in seven of eight children on VNS for refractory epilepsy. Decreased effort and tidal volume occurred in seven children, concordant with VNS activation. In one child, this was associated with a fall in respiratory rate, i the other six children with an increase. No study showed an apnoea/hypopnoea index in the abnormal range. The RPCS were not associated with significant hypoxia or hypercapnoea.
  
  
  CONCLUSIONS
  Our results suggest that RPCS occur in most children with VNS. This is not surprising in view of the significant influence vagal afferents have on respiratory control centres. The RPCS did not appear to have a clinical impact in our group. However further investigations are suggested to explore this phenomenon, especially in patients with sleep apnoea syndromes or compromised respiratory function.
authors.affiliation: Department of Neurology, Princess Margaret Hospital for Children, PO Box D184, Perth,WA 6840, Australia.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Nagarajan
authors.forename: Peter
authors.initials: P
authors.lastname: Walsh
authors.forename: Pauline
authors.initials: P
authors.lastname: Gregory
authors.forename: Stephen
authors.initials: S
authors.lastname: Stick
authors.forename: Jennifer
authors.initials: J
authors.lastname: Maul
authors.forename: Soumya
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004599:Electric Stimulation Therapy; D004827:Epilepsy / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D015656:Respiratory Mechanics; D012890:Sleep; D013990:Tidal Volume; D014630:Vagus Nerve / Q000503:physiopathology*; D014939:Work of Breathing