Periodic breathing is clusters of breaths separated by intervals of apnea or near-apnea. As opposed to normal breathing which is usually regular, periodic breathing is defined as three or more episodes of central apnea lasting at least 4 seconds, separated by no more than 30 seconds of normal breathing.Periodic breathing was originally thought to arise from serious neurologic or cardiovascular disease and therefore to carry a poor outlook. It is now known that periodic breathing also tends to occur during sleep, it can occur in healthy persons, and the apnea in periodic breathing is usually central sleep apnea rather than obstructive sleep apnea. Periodic breathing during sleep occurs typically in adult patients with congestive heart failure. Periodic breathing is also a normal variation of breathing found in premature and full term infants. It occurs when the infant has pauses in breathing for no more than 10 seconds at a time followed by a series of rapid, shallow breaths. Then the breathing returns to normal without any stimulation or intervention. These pauses in breathing may be accompanied by minor oxygen desaturation and bradycardia. It usually occurs when the infant is sleeping deeply, but may occur with light sleep or even when awake. Studies have shown that 78% of healthy full-term infants experience episodes of periodic breathing in the first two weeks of life, which typically resolves in the first six months of life. == References ==
This leads to impaired regulation of cellular proliferation, survival, homeostasis, migration and other critical functions. The most typically affected organs include the brain, skin, kidney, heart and lung. The incidence of TSC is approximately 1 in 6,000 live births. Similar to other neurocutaneous disorders there is variable penetrance and expressivity. TSC1 mutations tend to have a less severe phenotype and are more likely to be familial. A major development in the treatment of this condition occurred in 2010s when the FDA approved mTOR inhibitors for the treatment of several manifestations of TSC. Epilepsy is among the most common manifestations of TSC and it occurs 80-90% of patients. It usually presents during the first few years of life and is medically refractory in two-thirds of patients. Approximately, one-third of patients have infantile spasms. There are several types of brain lesions that can be found in TSC including subependymal nodules (SENs), cortical tubers and subependymal giant cell astrocytomas (SEGAs). SENs and cortical tubers occur in approximately 80% and 90% of patients, respectively. SEGAs occur in 10-15% of patients and are a major potential cause of morbidity and potentially mortality. They tend to present during the first 20 years of life. TSC-Associated Neuropsychiatric Disorder (TAND) refers to the behavioral, intellectual and psychiatric manifestations of TSC including autism spectrum disorder, attention deficit hyperactivity disorder, intellectual disability, depression and anxiety. Approximately 90% of patients will have at least 1 symptom of TAND.Lymphangioleiomyomatosis (LAM) occurs in the lung and may result in pneumothorax, cystic lung destruction and pleural effusions.