Is there a correlation between sleep disordered breathing and foramen magnum stenosis in children with achondroplasia?

Children with achondroplasia have midface hypoplasia, frontal bossing, spinal stenosis, rhizomelia, and a small foramen magnum. Central sleep apnea, with potential resultant sudden death, is thought to be related to compression of the spinal cord at the cervicomedullary junction in these patients. Screening polysomnography and/or cervical spine MRI are often performed for infants with achondroplasia. Decompressive suboccipital craniectomy has been performed in selected cases. We aim to better delineate the relationship between polysomnography, cervical spine MRI, and indications for surgical decompression in achondroplasia.We retrospectively review electronic medical records of all children with achondroplasia in our IRB-approved skeletal dysplasia registry who had received screening polysomnography and cervical spine MRI examination was performed. We explored correlations of polysomnography, MRI parameters, and need for decompressive surgery. Seventeen patients with both polysomnography and MRI of the cervical spine met inclusion criteria. The average age at time of the sleep study was 2.4 ± 3.6 years. An abnormal apnea-hypopnea index was found in all patients, with central sleep apnea found in 6/17. Five patients (29%) required foramen magnum decompression. We found no statistically significant correlation between central sleep apnea and abnormal MRI findings suggestive of foramen magnum stenosis. Screening polysomnography is an important tool but does not appear to correlate with MRI findings of foramen magnum stenosis. Cord compression, with either associated T2 cord signal abnormality or clinical findings of clonus, was most predictive of subsequent surgical decompression.

Sleep-related breathing disorder in children with vagal nerve stimulators.

The effects of vagal nerve stimulation on sleep-related breathing have not been well-described in children. Vagal nerve stimulation was reported to cause decreases in airflow during sleep, although most studies reported this condition to be clinically insignificant. We present a retrospective case series of nine children who underwent polysomnography after vagal nerve-stimulator placement. All children, except for one, had sleep-disordered breathing after stimulator implantation. We describe in further detail a child who manifested severe, obstructive sleep apnea postimplantation, with apneas occurring regularly and consistently with stimulator activity, resulting in an elevated apnea-hypopnea index of 37 per hour. Polysomnography was repeated with the stimulator turned off, and revealed complete resolution of the stimulator-related sleep apnea. With the vagal nerve stimulator back on, continuous positive airway pressure treatment was effective in normalizing the apnea-hypopnea index. This study demonstrates that severe and clinically significant disturbances in sleep-related breathing may occur with vagal nerve stimulators. Obstructive apneas of this severity, related to vagal nerve stimulators, were not previously described in pediatric patients. This effect on sleep-related breathing warrants further investigation and care in managing pediatric patients.

Quantitative computed tomographic scan and polysomnographic analysis of patients with syndromic midface hypoplasia before and after Le Fort III distraction advancement.

BACKGROUND: Distraction advancement has been advocated for treatment of obstructive sleep apnea associated with congenital midface hypoplasia. The purpose of this study was to relate changes in maxillary position to changes in obstructive sleep apnea measures on polysomnography in a consecutive series of patients. METHODS: Among 26 syndromic pediatric patients undergoing Le Fort III distraction over a 5-year period, 15 had documented obstructive sleep apnea with an apnea hypopnea index greater than 5. Linear and angular displacement of key bone landmarks were measured using quantitative computed tomographic scan analysis before and after distraction. Differences of linear and angular movements of maxillary landmarks were tested between those patients with improvement of obstructive sleep apnea (apnea hypopnea index <5) after treatment, and those with no improvement. RESULTS: Mean postoperative apnea hypopnea index was 9.5 (range, 2.1 to 22.7). Eight patients had a decrease in apnea hypopnea index following distraction (improved group) and three additional patients had resolution of symptoms but declined postoperation polysomnography. Four had no improvement or worsening of apnea hypopnea index (no improvement group). Comparison of changes in maxillary position between the improved group and the no improvement group revealed no significant difference in magnitude or direction of linear displacement of key landmarks. Postdistraction change in sella-nasion-point A angle was the only measure significantly (p = 0.02) greater in the improved group. CONCLUSIONS: Based on the authors' comparison of quantitative bone measurements and associated polysomnography changes, an angular increase in sella-nasion-point A angle on presurgical planning of maxillary movement for the treatment of sleep apnea may be more important than absolute linear changes in maxillary position alone.

Sleep-disordered breathing in children with thoracic insufficiency syndrome.

Thoracic insufficiency syndrome (TIS) is a collection of chest and spine malformations that results in progressively restrictive pulmonary mechanics and an inability of the thorax to adequately support lung growth. Many children with TIS are too young to perform standard pulmonary function tests, yet need functional assessments of their restrictive thoracic disease. We report on the sleep architecture and frequency of sleep-related breathing abnormalities in 11 children with TIS who underwent overnight polysomnography from retrospective chart review. Ten of 11 (92%) had sleep disordered breathing as defined by currently accepted criteria of apnea-hypopnea index (AHI) >2 events/hr. The median AHI was 4.3 events/hr, with obstructive hypopneas (median 3.7 events/hr) accounting for 75% of abnormalities. Respiratory events occurred most frequently during REM sleep (median REM-AHI 17.3 events/hr), and were associated with oxyhemoglobin desaturation, and rarely carbon dioxide retention. Sleep disordered breathing with hypoxemia appears to be a common but under recognized problem among children with TIS. Polysomnogram may have a role as a non-invasive screening tool used in conjunction with other functional respiratory assessments in children with TIS, and warrants further study in a prospective manner.

Sleep outcomes in children with hemifacial microsomia and controls: a follow-up study.

OBJECTIVE: Children with craniofacial anomalies are at high risk for sleep-disordered breathing (SDB), yet its prevalence among children with craniofacial conditions is not known. Children with hemifacial microsomia (HFM) are likely particularly vulnerable to SDB as a result of underdevelopment of the mandible and oropharynx. Nevertheless, most children with HFM are not referred for sleep studies. We hypothesized that sleep outcomes would be worse in children with HFM versus control subjects. METHODS: We conducted a follow-up study among 124 case participants and 349 control subjects who previously participated in a study of HFM risk factors. Parents completed the Pediatric Sleep Questionnaire (PSQ) regarding symptoms of SDB and sleep habits. Regression models were adjusted for region, age, sex, race/ethnicity, and maternal education. RESULTS: Snoring was more commonly reported for children with HFM (29%) than for control subjects (17%). Compared with control subjects, children with HFM more often had symptoms consistent with SDB. On average, case participants' parents reported 1.9 times as many symptoms on the PSQ breathing scale and 1.3 times more symptoms on the PSQ sleepiness scale than did control subjects' parents, with little difference on the PSQ behavior scale. Parents of children with HFM reported 1.4 times more night awakenings than did control subjects' parents. CONCLUSIONS: Children with HFM experienced more snoring and other symptoms of SDB than did control subjects. Pediatricians should be aware of the increased vulnerability for SDB among children with mandibular or external ear underdevelopment or asymmetry and should refer to a sleep specialist as needed.

Sleep disturbances in 22q11.2 deletion syndrome: a case with obstructive and central sleep apnea.

The 22q11.2 deletion syndrome is characterized by wide phenotypic variability, frequently involving characteristic craniofacial features, cardiac malformations, and learning difficulties. Skeletal anomalies are also common and include an obtuse angle of the cranial base, retrognathia, and cervical spine abnormalities. Despite these anomalies, sleep-disturbed breathing is not reported frequently in patients with 22q11.2 deletion syndrome. We describe a patient with an obstructive sleep disturbance that was successfully treated with a tonsillectomy followed by mandibular distraction osteogenesis. She also had central sleep apnea, initially attributed to spinal cord impingement from cervical instability. Posterior cervical fusion was associated with a decrease in the number of central apneic events.

Response to nonprescription epinephrine inhaler during nocturnal asthma.

BACKGROUND: Many health care professionals believe that a nonprescription epinephrine metered-dose inhaler is less effective and shorter acting and has more cardiovascular adverse effects than prescription beta2-agonists. OBJECTIVE: To determine if increasing the epinephrine dose improves efficacy safely. METHODS: Eight patients with nocturnal asthma (age range, 20-46 years) were treated in a randomized, crossover manner on 2 different nights while sleeping in a clinical research center. On awakening from asthma symptoms, 2, 4, and 8 actuations of epinephrine or albuterol were administered at 17-minute intervals (14 cumulative actuations). Forced expiratory volume in 1 second (FEV1), asthma symptoms, and systemic effects were measured before the first dose, during the 9- to 17-minute period after each dose, and 30 minutes after the last dose. RESULTS: The mean +/- SD FEV1 at the onset of symptoms was 45% +/- 11% and 44% +/- 12% predicted before epinephrine and albuterol, respectively, and increased to a maximum of 86% +/- 11% and 93% +/- 10%, respectively (P = .04). Symptoms decreased as FEV1 improved and did not return after either treatment; 6 patients were symptom free after 14 cumulative actuations of epinephrine compared with 6 cumulative actuations of albuterol. Heart rate decreased to 71 +/- 10/min after epinephrine but increased to 92 +/- 14/min after albuterol (P = .001). After the last dose, serum potassium concentration was 3.6 +/- 0.3 micromol/L after epinephrine and 3.2 +/- 0.4 micromol/L after albuterol (P = .01). CONCLUSION: Epinephrine was nearly as effective as albuterol in terminating an acute episode of airway obstruction but without cardiovascular effects in these otherwise healthy young adults.