Résumé :
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Central Hypoventilation Syndrome (CHS) is a rare syndrome of ventilatory dysregulation where patients underventilate (hypopnea) or fail to ventilate (apnea) in sleep, and more rarely, also when awake. The incidence is unknown, but is thought to be more common than previously suspected, with more than 500 cases worldwide with a confirmed genetic diagnosis. Since the opening of the British Columbia's Children's Hospital in 1982, the Home Ventilation Program has cared for four patients with CHS, and is aware of a fifth patient who died as a neonate. L.E is a 40 year old woman with seizures and developmental delay as a child, who was not diagnosed nor treated until age 10 years when she underwent tracheotomy and began nighttime ventilation. Because there were no resources for pediatric home ventilation available in 1978, she "checked in" each night into the adult ICU in her home city until she was 20 years old and she began home ventilation. She has married and has two healthy children, neither with CHS. L.G. was found "dead in bed" at three years of age. She had been diagnosed with CHS as a baby, underwent tracheotomy, and was receiving night only ventilation. It was suspected that her parents, who had a history of psychosis, had been trying to wean her from mechanical ventilation. E.W. is an 11 year old girl who underwent tracheotomy for upper airway obstruction, later was diagnosed with CHS, and then was discharged home on night only mechanical ventilation. She has failed three attempts to change to NIPPV and is being evaluated for diaphragmatic pacing. R.C. died at 23 days of age with no respiratory drive awake or asleep. At autopsy he was found to have a ganglionosis extending fromthe ligament of Treitz to the rectum (Hirshsprung's disease), a small ganglioneuroblastoma, and genetic analysis confirmed the PHOX2B mutation. C.P is an 18 month old girl with "classic" CHS who has been noninvasively ventilated at home since hospital discharge at 3 months of age. CHS was first described in 1970. The degree of ventilatory dysfunction ranges from hypoventilation in sleep to 24 hour apnea, with the "classical" form being that of apnea occurring with the onset of sleep. Prior to the discovery of the polyalanine expansion mutation of the PHOX2B gene in 2003, the diagnosis was one of exclusion. More than 95% of clinical CHS cases may be positive for the mutation. The PHOX2B gene is expressed in both the central and peripheral autonomic nervous system during embryological development, and is thought to play an essential role in the normal patterning of autonomous ventilatory drive, and more generally of the autonomic nervous system. CHS may be associated with Hirshsprung's disease and tumors of neural crest origin (neuroblastoma, ganglioneuroblastoma, ganglioneuroma). Patients with CHS also may exhibit symptoms of diffuse autonomic nervous system dysregulation/ dysfunction (ANSD) including decreased heart rate variability, an attenuated heart rate response to exercise, arrythmias, decreased basal body temperature, esophageal dysmotility or dysphagia, constipation, decreased perception of discomfort, decreased perception of anxiety, sporatic profuse sweating, and pupillary abnormalities. Modalities of treatment include tracheostomy and sleep mechanical ventilation, noninvasive sleep ventilation, and nighttime phrenic or diaphragmatic pacing. Some children who underwent tracheotomy as a baby, have been successfully decannulated and supported with NIPPV. Patients with CHS whose ventilation is supported may have a full and satisfactory life, and possibly, a normal life expectancy.
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