Congenital central hypoventilation syndrome associated with multiple ganglioneuromas

Elevated transaminases in congenital central hypoventilation syndrome

Patients with CCHS who also have Hirschsprung disease, elevated or low BMI, or pulmonary hypertension may be predisposed to elevated transaminases and may need periodic follow-up of their hepatic function https://bit.ly/3uW7AUG.

The genetics of congenital central hypoventilation syndrome: clinical implications

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder of the autonomic nervous system (ANS) and respiratory control. This disorder, formerly referred to as Ondine’s curse, is due to a mutation in the PHOX2B gene that affects the development of the neural crest cells. CCHS has an autosomal dominant pattern of inheritance. Majority of the patients have a polyalanine repeat mutation (PARM) of the PHOX2B, while a small group has non-PARM (NPARM). Knowledge of the patient’s PHOX2B gene mutation helps predict a patient’s clinical presentation and outcome and aids in anticipatory management of the respiratory and ANS dysfunction.

Rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation in Saudi Arabia

Rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) is a rare disease, but could be fatal if not diagnosed early. It mimics many other diseases and it may take few years after the onset of rapid obesity to have the other clinical features. Therefore, any patient with rapid-onset obesity after the age of 2 years should have high index of suspicion and long term follow up. We report a case of ROHHAD in Saudi Arabia and we highlight the clinical features and the importance of early diagnosis and management.

Sleep Disturbances and Behavioral Disturbances in Children and Adolescents

Sleep deprivation and sleep disorders are commonly seen in children and adolescents. They are often undiagnosed and undertreated. A balance of circadian rhythm and homeostatic drive determine sleep quality, quantity, and timing, which changes across the developmental years. Environmental and lifestyle factors can affect sleep quality and quantity and lead to sleep deprivation. A comprehensive assessment of sleep disorders includes parental report, children's self-report, and school functioning. Diagnostic tools are used in diagnosing and treating sleep disorders.

Outcomes in multifocal neuroblastoma as part of the neurocristopathy syndrome

The neurocristopathy syndrome occurs because of a germline mutation of the paired-like homeobox 2b (PHOX2B) gene at 4p12, a neurogenesis regulator gene. The result is abnormal neural crest cell development resulting in congenital central hypoventilation syndrome, Hirschsprung disease, and neuroblastoma (NB), which is often multifocal and disseminated in its presentation. Previously, such widespread disease was regarded as highly aggressive and treated either with palliative intent or, conversely, with very intense, high-dose chemotherapy. We now present a patient who had neurocristopathy syndrome who had multifocal NB associated with an underlying germline PHOX2B mutation. He was treated conservatively with surgery and low-dose chemotherapy. After treatment he had extensive residual disease that has continued to mature despite no further treatment. A literature review identified 26 similar patients presenting with multifocal NB as part of the neurocristopathy syndrome. In all cases the NB behaved in an indolent manner with no deaths from tumor reported when patients received appropriate treatment. These provocative findings suggest for the first time that children who have neurocristopathy-associated NB should be treated conservatively, despite the aggressive appearance of their disease.

Treatment of dyssomnias and parasomnias in childhood

OPINION STATEMENT

Dyssomnias are sleep disorders associated with complaints of insomnia or hypersomnia. The daytime sleepiness of narcolepsy is treated by a combination of planned daytime naps, regular exercise medications such as modafinil, or salts of methylphenidate, or amphetamine. Cataplexy that accompanies narcolepsy is treated with anticholinergic agents, selective serotonin reuptake inhibitors, or sodium oxybate. Children with neurodevelopmental disabilities such as autism have sleep initiation and maintenance difficulties on a multifactorial basis, with favorable response to melatonin in some patients. Childhood onset restless legs syndrome is often familial, associated with systemic iron deficiency, and responsive to iron supplementation and gabapentin. Parasomnias are episodic phenomena events which occur at the sleep -- wake transition or by intrusion on to sleep. Arousal parasomnias such as confusional arousals and sleep walking can sometimes be confused with seizures. A scheme for differentiating arousal parasomnias from nocturnal seizures is provided. Since arousal parasomnias are often triggered by sleep apnea, restless legs syndrome, or acid reflux, treatment measures directed specifically at these disorders often helps in resolution. Clonazepam provided in a low dose at bedtime can also alleviate sleep walking and confusional arousals. Obstructive sleep apnea affects about 2 percent of children. Adeno-tonsillar hypertrophy, cranio-facial anomalies, and obesity are common predisposing factors. Mild obstructive sleep apnea can be treated using a combination of nasal corticosteroids and a leukotriene antagonist. Moderate to severe obstructive sleep apnea are treated with adeno-tonsillectomy, positive airway pressure breathing devices, or weight reduction as indicated. This paper provides an overview of the topic, with an emphasis on management steps. Where possible, the level of evidence for treatment recommendations is indicated.

Congenital central hypoventilation syndrome in children

Congenital central hypoventilation syndrome (CCHS) is a rare, lifelong condition wherein control of breathing is abnormal and patients present with symptoms of alveolar hypoventilation. The severity of hypoventilation varies and although most patients present in the neonatal period, late onset cases have been reported. In 2003, it was discovered that mutations in the PHOX2B gene were responsible for CCHS. This gene also plays a role in neural crest cell migration, and many patients present with symptoms of autonomic dysfunction in addition to hypoventilation. The pathophysiology responsible for hypoventilation remains unclear although a unifying hypothesis is that the abnormality is located in areas of the brain involved in integration of chemoreceptor afferent pathways for ventilation. The goal of treatment for CCHS is to ensure adequate ventilation during wakefulness and sleep. A variety of ventilation modalities are available including positive pressure ventilation via tracheostomy, non-invasive ventilation via nasal mask, and diaphragmatic pacing. With close monitoring and support, children with CCHS can be expected to function well in society and have a good quality of life.

Congenital central alveolar hypoventilation syndrome (Ondine's curse) with survival into adulthood

Ondine's curse or central alveolar hypoventilation (CCAH) syndrome is a disorder of the autonomic nervous system resulting in respiratory dysregulation. The clinical outcome is typically poor, with few individuals living into adulthood and even fewer surviving to adulthood with normal neurological function. Our patient initially presented following an uncomplicated delivery with hypotonia, poor respiratory effort, and hypoxemia that required ventilatory support. Laboratory workup, radiographic evaluation, and ancillary testing ruled out brain stem lesions, neuromuscular diseases, cardiovascular and pulmonary disease, and metabolic disorders, resulting in a diagnosis of CCAH syndrome. The patient underwent tracheotomy and chronic ventilatory support. Close long-term management and appropriate treatment modifications have provided for an excellent outcome and good quality of life. The patient is currently 22 years old and is earning her teaching degree for K-12 art education. A combination of early recognition and a multidisciplinary approach may lead to a successful outcome in patients with CCAH syndrome.

Brainstem Anomalies in Two Patients Affected by Congenital Central Hypoventilation Syndrome

Congenital central hypoventilation syndrome (CCHS) is a rare neurocristopathy characterized by absence of automatic control of respiration; decreased sensibility to hypoxia and hypercapnia, mainly during sleep; and autosomal dominant inheritance due to heterozygous polyalanine expansions and frameshift mutations in the PHOX2B gene. Because the CCHS phenotype could hide other neurologic diseases, the American Thoracic Society established that the initial evaluation of suspected CCHS should exclude neuroanatomic impairments as the structural basis of the reduced autonomic system function. In this work, we describe the clinical history of two unrelated patients with hypoventilation during sleep and harboring hypoplasia of the pons and a Chiari I malformation, respectively. In both patients, CCHS was diagnosed by detection of PHOX2B polyalanine expansion, suggesting that the American Thoracic Society diagnostic criteria may be too restrictive. Moreover, to exclude a putative role of PHOX2B in non-CCHS neurologic diseases, we have performed PHOX2B mutation screening in a group of individuals with Chiari I malformation, confirming the exclusive role of PHOX2B in the pathogenesis of CCHS.

[Ondine's Curse and rare oculomotor abnormalities: a case report]

Ondine's Curse or congenital central hypoventilation syndrome (CCHS) is a neurocristopathy (failure of migration or differentiation of neural crest-derived precursor cells) and is characterized by hypoventilation or apnea, which is most pronounced during sleep, with no other abnormalities of the neuro-respiratory system. Because of respiratory distress soon after birth, patients must be intubated and ventilated for a long time. This disorder may be associated with other symptoms of neurocristopathy (Hirschsprung disease, neuroblastoma, neuroganglioma) and other abnormalities of the autonomic nervous system (vasomotor dysfunctions or ophthalmic abnormalities: abnormal pupils, insufficient convergence, strabismus, or ptosis). We report the original case of a CCHS patient who presented with alternative ptosis of both the right and left eyes and esotropia. The ocular findings should lead to earlier diagnosis and speedier adequate treatment.

Neurotrophic factor expression in three infants with Ondine's curse

This study investigates the expression of some neurotrophic factors (brain-derived neurotrophic factor, glial-derived neurotrophic factor, and nerve growth factor) in the cerebrospinal fluid of infants suffering from idiopathic congenital central hypoventilation syndrome and determines their correlations with this syndrome. Cerebrospinal fluid samples were collected from three infants suffering from idiopathic congenital central hypoventilation syndrome and 15 control subjects with obstructive hydrocephalus to measure the expression of brain-derived neurotrophic factor, glial-derived neurotrophic factor, and nerve growth factor using an immunoenzymatic assay. In the cerebrospinal fluid of patients, analysis of neurotrophic factors expression indicated a reduction, not statistically significant, of brain-derived neurotrophic factor compared with the mean level of the control group (1554 pg/mL, 1509 pg/mL, and 1582 pg/mL respectively, in comparison to 1954 +/- 103 pg/mL), whereas nerve growth factor and glial-derived neurotrophic factor did not undergo significant variations in either group. Neurotrophic factors, namely brain-derived neurotrophic factor, regulate the maturation and differentiation of respiratory neurons. The reduced expression of brain-derived neurotrophic factor in the cerebrospinal fluid samples of infants with Ondine's curse, although not statistically significant, is suggestive of a dysregulation in the brain-derived neurotrophic factor synthesis that could play an important role in the breathing disorders observed in patients with idiopathic congenital central hypoventilation syndrome.

In pursuit (and discovery) of a genetic basis for congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome (CCHS) typically presents in the newborn period with a phenotype including alveolar hypoventilation, symptoms of autonomic nervous system dysregulation, and in a subset of cases Hirschsprung disease and later tumors of neural crest origin. Study of genes related to the autonomic dysregulation and the embryologic origin of the neural crest has led to identification of the genetic basis for CCHS, the mode of inheritance, and the presence of mosaicism in a subset of parents. Polyalanine expansion mutations in PHOX2B have been identified to be the disease-defining mutation in CCHS, with a small subset of patients having other mutations in PHOX2B. Further, the size of the polyalanine repeat mutation in PHOX2B is correlated with the severity of the phenotype in CCHS, and non-polyalanine repeat mutations appear to, in general, result in CCHS phenotypes at the severe end of the spectrum. These studies highlight the utility of PHOX2B genetic testing for confirmation of the CCHS diagnosis, for prenatal diagnosis, and for identification of previously undiagnosed adults with unexplained hypercarbia or control of breathing deficits. This diagnostic approach may be a consideration for other complex, seemingly undecipherable diseases that affect infants and children. The purpose of this article is to provide a comprehensive review of current research into the genetic basis for CCHS, an explanation for how these studies evolved, recent studies that begin to explain the mechanisms through which mutations in PHOX2B exert their effects, and clinical application of the genetic testing.

Sleep and breathing disturbances in infancy and early childhood

The nature of sleep-related breathing problems varies with age. Ventilatory function may be compromised at the level of the brainstem, the autonomic nerves, or the upper airway musculature. These disorders are state-dependent, being impacted by both rapid eye movement and non-rapid eye movement sleep, and also by the degree of maturation of the nervous system. Many are treatable. An understanding of the molecular basis of these disorders is just now becoming apparent.

Idiopathic congenital central hypoventilation syndrome: Analysis of genes pertinent to early autonomic nervous system embryologic development and identification of mutations in PHOX2b

Idiopathic congenital central hypoventilation syndrome (CCHS) has been linked to autonomic nervous system dysregulation and/or dysfunction (ANSD) since it was first described in 1970. A genetic basis of CCHS has been proposed because of the reports of four families with two affected children, because of mother-child transmission, and because of a recent report of a polyalanine expansion mutation in PHOX2b in a subset of CCHS subjects. We, therefore, studied genes pertinent to early embryologic development of the ANS including mammalian achaete-scute homolog-1 (MASH1), bone morphogenic protein-2 (BMP2), engrailed-1 (EN1), TLX3, endothelin converting enzyme-1 (ECE1), endothelin-1 (EDN1), PHOX2a, and PHOX2b in 67 probands with CCHS, and gender- and ethnicity-matched controls. No disease-defining mutations were identified in MASH1, BMP2, EN1, TLX3, ECE1, EDN1, or PHOX2a. The 65/67 CCHS probands (97%) were found to be heterozygous for the exon 3 polyalanine expansion mutation identified previously in PHOX2b. Further, there was an association between repeat mutation length and severity of the CCHS/ANSD phenotype. Of the two probands who did not carry the expansion mutation, one had a nonsense mutation in exon 3 which truncated the protein and the other had no mutation in PHOX2b but had a previously reported EDN3 frameshift point mutation. The polyalanine expansion mutation was not found in any of 67 matched controls. Of 54 available families (including 97 unaffected parents), whose child carried the PHOX2b mutation, 4 parents demonstrated mosaicism for an expansion mutation identical to that seen in the CCHS cases, suggesting that not all mutations in affected probands with unaffected parents are de novo. We also studied four women with CCHS who were heterozygous for the PHOX2b mutation, each with one child. Three of the four children were also affected and had the same mutation, demonstrating autosomal dominant inheritance of the mutation. Assay of the PHOX2b polyalanine repeat mutation represents a highly sensitive and specific technique for confirming the diagnosis of CCHS. Identification of the CCHS mutation will lead to clarification of the phenotype, allow for prenatal diagnosis for parents of CCHS probands and adults with CCHS in future pregnancies, and potentially direct intervention strategies for the treatment of CCHS.

Sleep disorders in childhood

Childhood sleep-wake disorders are common and associated with significant impairment of quality of life. The recent discovery of hypocretin deficiency as the pathophysiologic basis for narcolepsy-cataplexy is likely to spur the development of hypocretin analogs for definitive treatment [82,83]. The link between disrupted sleep and daytime learning and childhood inattention is a challenging area of mind-brain interaction in which further progress is likely, once methodologic issues have been sorted out. The recent recognition of genetic influences in the control of circadian rhythms also may spur the development of specific therapies for circadian rhythm disorders. In many ways, sleep medicine is benefiting from recent progress in the basic neurosciences, genetics, and technology.

Treatment of neuroblastoma in patients with neurocristopathy syndromes

Neuroblastoma, a neoplasm of neural crest cell origin, occasionally presents in association with other neural crest abnormalities such as Hirschsprung disease, congenital central hypoventilation, autonomic disturbances, and other tumors. These associations have been termed "neurocristopathy syndromes." In the past, chemotherapy has not been considered for patients with neurocristopathy-associated neuroblastoma because of their complicated medical problems. The authors describe two patients with neurocristopathy syndromes from our institution who underwent surgery and standard chemotherapy treatment of their intermediate-risk neuroblastoma. They represent two of only three long-term disease-free survivors of neurocristopathy-associated neuroblastoma reported in the literature.

Idiopathic congenital central hypoventilation syndrome: the next generation

Idiopathic congenital central hypoventilation syndrome (CCHS) is a rare disorder in which affected children have a decreased sensitivity of their respiratory centers to hypercarbia and hypoxia, as well as evidence for generalized autonomic nervous system dysfunction. A genetic origin has long been hypothesized for CCHS. Previous reports of the syndrome among twins, siblings, and half siblings, as well as an established association with Hirschsprung disease and neural crest tumors support this genetic hypothesis. Here, we present the first reported offspring born to four women diagnosed with idiopathic CCHS. Their children display a spectrum of abnormalities with one child being diagnosed with CCHS, one child with recurrent apparent life threatening events, one infant born prematurely with severe chronic lung disease and diminished ventilatory responses to carbon dioxide, and one infant who is apparently healthy with no clinical manifestations suggestive of disordered respiratory control to date. Two and potentially three of these patients illustrate transmission of altered respiratory control by CCHS patients into the next generation, furthering the evidence that CCHS is part of a broadly based inherited syndrome of autonomic nervous system dysfunction.

Congenital central hypoventilation syndrome: a novel mutation of the RET gene in an isolated case

Recently, a few genetic abnormalities were identified in congenital central hypoventilation syndrome (CCHS or Ondine's curse). CCHS is often associated with other neurocristopathies, especially with Hirschsprung's disease (HSCR). Mutations of the genes involved in the receptor tyrosine kinase RET (REarranged during Transfection) (RET)-glial cell line-derived neurotrophic factor (GDNF) and/or endothelin 3 (EDN3)-endothelin receptor-B (EDNRB) signaling pathway have been found in some of HSCR patients. In this study, we analyzed candidates for HSCR, namely the RET, GDNF, EDN3 and EDNRB genes in three isolated CCHS patients to confirm the hypothesis that some CCHS patients have a common genetic abnormality with patients having HSCR or other neurocristopathies. We found a novel R114H mutation of the RET gene in one patient. The R114H mutation is unlikely to be a polymorphism and appears to be associated with CCHS. In addition, we also examined the HOX11L2 (RNX) gene, for which knock-out mice showed CCHS-like syndrome in these isolated CCHS patients and did not detected any mutation. Further cases should be analyzed for more candidates to clarify the pathophysiology of CCHS.

Idiopathic congenital central hypoventilation syndrome: evaluation of brain-derived neurotrophic factor genomic DNA sequence variation

Idiopathic congenital central hypoventilation syndrome (CCHS) is an unique disorder of respiratory control, occurring in association with Hirschsprung disease (HSCR), tumors of neural crest origin, and symptoms of autonomic nervous system dysfunction (ANSD). CCHS is thought to be genetic in origin based upon 1) affected sib pairs, 2) genetic analysis, and 3) identification of genetic mutations in both HSCR and CCHS patients. Because these mutations have been found in but a few cases of CCHS, exploration of other candidate genes has continued. Brain-derived neurotrophic factor (BDNF) represents a potential candidate gene to consider because of altered respiratory control in the BDNF knock-out mouse model and localization to the enteric nervous system in human tissue. The objective of this study was to determine the frequency of BDNF mutations among 19 children with CCHS (five with HSCR) compared to 40 unaffected unrelated controls. Using the known genomic DNA sequence for BDNF, polymerase chain reaction (PCR)-amplified genomic DNA was analyzed by standard sequencing methods. A discrete mutation was identified in one of 19 children with isolated CCHS and the unaffected father. Specifically, an isoleucine was substituted for a threonine or serine in the amino acid sequence. Absence of this mutation in 40 controls confirmed that this mutation was likely not a common polymorphism. These data further support a genetic basis for CCHS, though mutations of BDNF are not consistent in this disorder.

Congenital central hypoventilation syndrome associated with Hirschsprung's disease and neuroblastoma: case of multiple neurocristopathies

We report on a male infant with the rare combined occurrence of congenital central hypoventilation syndrome (CCHS or Ondine's curse), Hirschsprung's disease (HD), and neuroblastoma. Current therapeutical options leave no doubt that children with isolated forms of CCHS, HD, or neuroblastoma must be treated, but management decisions and the ethical dilemma become more difficult with the presence of multiple neurocristopathies. Our patient was dependent on mechanical ventilation and total parenteral nutrition, when a neuroblastoma was diagnosed at age 5 months. We initiated an attempt at curative chemotherapy. The tumor failed to respond to recommended chemotherapeutic regimens, and the patient died at 11 months of age. We emphasize the importance of screening CCHS patients for associated illnesses such as neuroblastoma and ganglioneuroblastoma at time of diagnosis.

Case/control family study of autonomic nervous system dysfunction in idiopathic congenital central hypoventilation syndrome

Children with idiopathic congenital central hypoventilation syndrome (CCHS) have a complex phenotype consistent with an imbalance of the autonomic nervous system (ANS). Since CCHS may be genetic in origin, we hypothesized that relatives of individuals with CCHS may exhibit symptoms of ANS dysfunction (ANSD), albeit in a milder form. We tested this hypothesis by assessing aspects of ANS function in relatives of CCHS cases vs. relatives of matched controls with a scripted questionnaire. Only those 35 symptoms of ANSD exhibited by > or =5% of the CCHS cases were included in the analysis as the basis for determining ANSD affection status. Two different arbitrary ANSD affection status definitions are presented in detail: any case, control, or relative with positive findings (1) in two or more symptoms, or (2) in two or more systems. The subjects included in the analysis totaled 2,353, including 56 CCHS cases, 56 age-, gender-, and race-matched controls, and their families. Under each of the two arbitrary ANSD affection statuses, CCHS cases and parents of cases were more likely to be affected than controls and parents of controls (P < 0.001 for both comparisons), 16% of the CCHS siblings had the ANSD phenotype with two or more symptoms, compared to 4% of control siblings (P = 0.03). Aunts and uncles of the CCHS cases were also significantly more likely to have two or more ANSD symptoms than were aunts and uncles of the controls (P= 0.009). These results support our hypothesis and also indicate that relatives of the CCHS cases tended to manifest a milder spectrum of ANSD, with fewer systems and/or fewer symptoms than the cases.

Genetic segregation analysis of autonomic nervous system dysfunction in families of probands with idiopathic congenital central hypoventilation syndrome

Idiopathic congenital central hypoventilation syndrome (CCHS) is a very rare syndrome with major respiratory complications. Hypothesizing that CCHS is the most severe manifestation of general autonomic nervous system dysfunction (ANSD), we applied a case-control family study design to investigate the genetics of ANSD. Fifty-two probands with CCHS were identified, as well as 52 age-, race-, and gender-matched controls. ANSD phenotypic features were characterized in the cases, controls, and their family members. Our earlier studies found that most ANSD symptoms were more likely in CCHS cases and their relatives than in controls and their relatives (P < 0.05). The goal of the current study was to determine if the familiality of ANSD was consistent with a genetic pattern. We performed major locus segregation analysis of ANSD utilizing regressive models. CCHS probands were assumed to be affected; controls and relatives were designated as affected if they had two or more relevant symptoms. The hypothesis of "no transmission and no familial effects" was rejected in both case and control families. Case families were consistent with transmission of a major effect; control families were not (the difference in the pattern of results was significant, P < 0.0001). In the total data set, the best-fitting model was codominant Mendelian inheritance of a major gene for ANSD. These case-control family studies support our hypothesis that CCHS is the most severe manifestation of a general ANSD, with a family pattern consistent with Mendelian transmission, and demonstrate the potential utility of the approach to studies of other, similarly intractable disorders.

Cardiac rhythm disturbances among children with idiopathic congenital central hypoventilation syndrome

The objective of this study was to determine whether subjects with congenital central hypoventilation syndrome (CCHS) had an increased frequency of cardiac arrhythmias and decreased heart rate variability when compared to subjects without a known deficit in control of breathing, and that these abnormalities would be exaggerated by anesthesia. Continuous ambulatory Holter recordings were obtained in patients with CCHS and compared to two otherwise healthy control groups without a deficit in control of breathing: one with an intact airway (n = 11) and a second group with a tracheostomy (n = 6). Holter recordings were obtained before, during (under general anesthesia), and after bronchoscopy. Fourteen children with CCHS (age: 9.3 +/- 4.4 years mean +/- S.D.) were studied, and 7 underwent bronchoscopy. Seventeen control children were studied (age 6.6 +/- 3.6 years): 11 without a tracheostomy, and 6 with a tracheostomy who also underwent bronchoscopy. Maximum heart rate during baseline recording was significantly lower in the CCHS subjects as compared to controls (P = 0.0001). At baseline the difference in the number of arrhythmias/24 hr/subject in all CCHS vs. all control subjects was significant (P = 0.0002); for the subjects who had bronchoscopy, CCHS vs. control, the difference was also significant (P = 0.03). In addition, there was a significant decrease in the number of events/24 hr/subject among the CCHS subjects between baseline and post-bronchoscopy (P = 0.0288). The predominant arrhythmias were sinus bradycardia and transient asystole. The longest asystole in a CCHS subject was 6.50 sec, and in a control subject, 1.42 sec (at baseline the means of the longest asystole were 2.69 +/- 1.4 vs. 1.24 +/- 0.13; P = 0.003 in the CCHS vs. control groups). Other indices of heart rate variability were significantly reduced in the CCHS subjects (P < 0.05). These results substantiate our hypothesis that subjects with CCHS have more arrhythmias than controls, an increased frequency of bradyarrhythmias, and decreased cyclical sinus arrhythmia.

Late-onset central hypoventilation with hypothalamic dysfunction: a distinct clinical syndrome

Idiopathic central hypoventilation has occasionally been reported in previously well children after infancy. The relationship between this late-onset central hypoventilation syndrome (LO-CHS) and congenital central hypoventilation syndrome (CCHS) has not been established. Both CCHS and LO-CHS have been associated with neural crest tumors, such as ganglioneuroblastoma and ganglioneuroma, and they generally occur in the presence of a histologically normal central nervous system. At least 10 case reports of idiopathic LO-CHS featured evidence of hypothalamic dysfunction (HD), including hyperphagia, hypersomnolence, thermal dysregulation, emotional lability, and endocrinopathies. We report on a case of LO-CHS/HD successfully treated by nasal intermittent positive pressure ventilation (NIPPV). Despite the commonalties with CCHS, we propose that LO-CHS/HD is a distinct clinical syndrome. In addition to the markedly different age at presentation, features of hypothalamic dysfunction are not seen in CCHS. Review of the literature was undertaken to further clarify the full spectrum of the disease.

Anesthetic care for the child with congenital central alveolar hypoventilation syndrome (Ondine's curse)

Idiopathic congenital central alveolar hypoventilation syndrome, otherwise known as Ondine's curse, is a rare neuropathologic syndrome characterized by an inadequate respiratory drive with hypoventilation and periods of prolonged apnea resulting in hypercarbia and hypoxemia. Although no definite pathologic abnormality has been identified to account for the disorder, it is thought to represent a primary defect related to altered function of central chemoreceptors resulting in defective control of minute ventilation. Associated problems related to neural crest cell migration, including neuroblastoma formation and Hirschsprung's disease, suggest that the primary defect is defective neural crest cell migration and function. Problems that may impact on perioperative care include the defective central control of ventilation and defective control of upper respiratory musculature, which may lead to upper airway obstruction. Although many patients will have previously undergone tracheostomy and chronic mechanical ventilation, problems in other organ systems can impact on perioperative care. Cardiovascular issues include the possible presence of cor pulmonale and autonomic nervous system dysfunction. Central nervous system issues include the frequent occurrence of seizures and mental retardation. The preoperative work-up, premedication, and the intraoperative/postoperative care and monitoring of these patients is reviewed.

Congenital central hypoventilation syndrome: an update

Awareness of the existence of CCHS has led to increasingly frequent reports of such patients from all over the world. However, the exact pathophysiologic mechanisms underlying the clinical manifestations of this congenital disease entity remain unknown. For the respiratory physiologist, CCHS can be viewed as an experiment of nature that provides an important and unique window into central cardiorespiratory regulation. For the pediatrician, CCHS children represent an unique clinical challenge in coordinating the diagnostic and therapeutic procedures required to enhance the patients' quality of life.

Congenital central hypoventilation syndrome: mutation analysis of the receptor tyrosine kinase RET

Congenital central hypoventilation syndrome (CCHS) usually occurs as an isolated phenotype. However, 16% of the index cases are also affected with Hirschsprung disease (HSCR). Complex segregation analysis suggests that CCHS is familial and has the same inheritance pattern with or without HSCR. We postulate that alteration of normal function of the receptor tyrosine kinase, RET, may contribute to CCHS based on RET's expression pattern and the identification of RET mutations in HSCR patients. To further explore the nature of the inheritance of CCHS, we have undertaken two main routes of investigation: cytogenetic analysis and mutation detection. Cytogenetic analysis of metaphase chromosomes showed normal karyotypes in 13 of the 14 evaluated index cases; one index case carried a familial pericentric inversion on chromosome 2. Mutation analysis showed no sequence changes unique to index cases, as compared to control individuals, and as studied by single strand conformational polymorphism (SSCP) analysis of the coding region of RET. We conclude that point mutations in the RET coding region cannot account for a substantial fraction of CCHS in this patient population, and that other candidate genes involved in neural crest cell differentiation and development must be considered.

Congenital central hypoventilation syndrome: inheritance and relation to sudden infant death syndrome

We evaluated the families of 50 children with idiopathic congenital central hypoventilation syndrome (CCHS) to 1) test genetic hypotheses, 2) explore the relationship to Hirschsprung disease (HD), and 3) examine other clinical findings including sudden infant death syndrome (SIDS) in relatives of CCHS patients. A questionnaire was administered to parents of each proband to determine a detailed pedigree and medical history for 3 generations including 1,482 relatives. The data were analyzed under the unified mixed model method (assumes individual genotype composed of multifactorial [MF] and major locus [ML] components). Analysis was made of the Total dataset and on subdivided data sets: HIR1 = families of probands with HD (n = 8) vs. HIR2 = families of probands without HD; then under a premise that severe, chronic constipation may be a milder form of HD (i.e., ganglion cells present but dysfunctional), CON1 = families of probands with HD or constipation (n = 13) vs. CON2 = families of probands without HD or constipation. By statistical genetic analysis of the Total, HIR1, and CON1 datasets, the MF and ML hypotheses were about equally likely, with the MF model slightly more parsimonious. Although HIR2 and CON2 datasets indicated no familiality, statistical evidence of heterogeneity between the results of HIR1 and HIR2, or between CON1 and CON2 was lacking. A SIDS incidence of 11.2/1,000 was documented among the relatives of CON1 vs. 1.8/1,000 among relatives of CON2. Our results are consistent with familiality by either MF or ML models. Recurrence risk is likely < 5%. The relationship of CCHS to the high familial incidence of SIDS is intriguing and demands further investigation.

Cardio-respiratory control in an infant with Ondine's curse: a multivariate autoregressive modelling approach

We applied spectral analysis through multivariant autoregressive model fitting [1] to RR interval (RRI) and respiratory (RES) oscillation obtained during quiet sleep in an infant with congenital central hypoventilation syndrome (Ondine's curse), a child with obstructive sleep apnea, and two healthy children. Power spectra, impulse response and noise contribution ratio between RRI and RES oscillation were calculated by using a minicomputer PFU-1200 (FACOM) to determine the structure of the feedback system between RRI and RES within the central nervous system. We found that the respiratory noise contribution ratio to RRI was significantly smaller in Ondine's curse (37 +/- 7.7%, at 0.23 Hz) than in obstructive sleep apnea (90 +/- 6.7%, at 0.39 Hz) and healthy subjects. We postulate that the result shows disturbance of the central autonomic control of breathing and heart rate in Ondine's curse.

Congenital central hypoventilation syndrome: diagnosis, management, and long-term outcome in thirty-two children

The diagnosis, management, and long-term outcome of 32 patients with congenital central hypoventilation syndrome are summarized. Sleep hypoventilation was severe in all cases, resulting in an alveolar carbon dioxide pressure (mean +/- SEM) of 62 +/- 2.5 mm Hg and a hemoglobin saturation of 65% +/- 3.3% without ventilatory or arousal response. Awake hypoventilation on initial assessment was present in 12 of the 32 patients, resulting in an alveolar carbon dioxide pressure of 58 +/- 2.2 mm Hg and a hemoglobin saturation of 59% +/- 7%. Associated conditions included pulmonary hypertension or cor pulmonale or both (78%), heart block and sick sinus syndrome requiring a cardiac pacemaker (two patients), mild atrophy by cranial imaging evidence (40%), seizures (72%), normal brain-stem auditory evoked responses in all but one patient tested, ganglioneuroblastomas (one patient), Hirschsprung disease (16%), and ophthalmologic abnormalities (60%). Growth was deficient in 44% of patients; hypotonia or major motor delay or both were apparent in all. Twenty-two patients are living; 12 of them require continuous ventilatory support and 10 breathe spontaneously while awake and require ventilatory support while asleep. Ten patients have died. Autopsy performed in six cases indicated diffuse central nervous system astrocytosis, gliosis, and atrophy but no primary brain-stem abnormality. Although these data support a diffuse central nervous system process, the specific cause and the mode of inheritance remain unclear. With early diagnosis and careful ventilatory management, the sequelae of hypoxia and morbidity should be minimized and long-term outcome improved.

Neuropsychologic abnormalities in children with congenital central hypoventilation syndrome

We hypothesized that intellectual, neurodevelopmental, and visual-motor tests would be able to characterize the scope and nature of central nervous system involvement in children with congenital central hypoventilation syndrome. Age-appropriate intellectual (Brazelton Neonatal Behavioral Assessment, Bayley Scales of Infant Development, Wechsler Preschool and Primary Scale of Intelligence-Revised and Wechsler Intelligence Scale for Children--Revised), neurodevelopmental (Halsted-Reitan neuropsychologic battery), and visual-motor (Beery visual-motor integration test) tests were given to 17 children with congenital central hypoventilation syndrome (age 0.1 to 14.3 years). We found a broad range in IQ and developmental quotient, from greater than the 85th percentile to less than the 5th percentile, with discrepancies noted between verbal and performance measures. Multiple asymmetries and deficiencies of motor performance, not consistently related to handedness, were also found. Significant eye-hand coordination deficits were uncommon, but general performance was well below average. Full, verbal, and performance IQs and developmental quotients greater than or equal to 70 and less than 70 were compared by chi-square analysis with other associated conditions, including hours of ventilatory support, duration of initial hospitalization, growth, pulmonary hypertension, seizures, brain atrophy, central and peripheral hearing deficits, and ophthalmologic abnormalities; no statistically significant associations were found. These results lend support to the hypothesis that congenital central hypoventilation syndrome is a diffuse central nervous system process. However, the effects of transient hypoxia and associated conditions on neurodevelopmental test results cannot be excluded with certainty.

Medical and psychosocial outcome of children with congenital central hypoventilation syndrome

We report the long-term medical and psychosocial outcome of 13 children with congenital central hypoventilation syndrome. One child (8%) died before initial hospital discharge. Of the remaining 12 children, 11 (92%) have been successfully cared for in their natural or foster parents' homes. Home ventilatory support was provided with positive-pressure ventilation, negative-pressure ventilation, or diaphragm pacers. After an initial lengthy hospitalization, children spent little time in the hospital. Severe medical complications were uncommon but included cor pulmonale (one child), poor growth (two children), and seizure disorder (three children). Most children functioned in the slow-learner range of mental processing, with a composite score (Kaufman Assessment Battery for Children) of 78 +/- 20 (SD); two were mentally retarded, and one functioned above the normal range. The children's care givers were assessed as having low levels of psychologic distress (Symptom Checklist 90--Revised) and good coping resources (Coping Resources Inventory) but a high level of marital discord. The children were able to attend school and partake in normal childhood activities. We conclude that with modern techniques for home ventilation, children with CCHS can have a good long-term medical and psychosocial outcome. We speculate that early diagnosis and the prevention of intermittent hypoxia will improve their physical and mental outcome.