What is (are) congenital central hypoventilation syndrome ?
Congenital central hypoventilation syndrome (CCHS) is a disorder that affects breathing. People with this disorder take shallow breaths (hypoventilate), especially during sleep, resulting in a shortage of oxygen and a buildup of carbon dioxide in the blood. Ordinarily, the part of the nervous system that controls involuntary body processes (autonomic nervous system) would react to such an imbalance by stimulating the individual to breathe more deeply or wake up. This reaction is impaired in people with CCHS, and they must be supported with a machine to help them breathe (mechanical ventilation) or a device that stimulates a normal breathing pattern (diaphragm pacemaker). Some affected individuals need this support 24 hours a day, while others need it only at night.  Symptoms of CCHS usually become apparent shortly after birth. Affected infants hypoventilate upon falling asleep and exhibit a bluish appearance of the skin or lips (cyanosis). Cyanosis is caused by lack of oxygen in the blood. In some milder cases, CCHS may be diagnosed later in life. In addition to the breathing problem, people with this disorder may have difficulty regulating their heart rate and blood pressure, for example in response to exercise or changes in body position. They may have abnormalities in the nerves that control the digestive tract (Hirschsprung disease), resulting in severe constipation, intestinal blockage, and enlargement of the colon. They are also at increased risk of developing certain tumors of the nervous system called neuroblastomas, ganglioneuromas, and ganglioneuroblastomas. Some affected individuals develop learning difficulties or other neurological problems, which may be worsened by oxygen deprivation if treatment to support their breathing is not completely effective.  Individuals with CCHS usually have eye abnormalities, including a decreased response of the pupils to light. They also have decreased perception of pain, low body temperature, and occasional episodes of profuse sweating.  People with CCHS, especially children, may have a characteristic appearance with a short, wide, somewhat flattened face often described as "box-shaped." Life expectancy and the extent of any cognitive disabilities depend on the severity of the disorder, timing of the diagnosis, and the success of treatment.