Obstructive sleep apnea in Arnold-Chiari malformation treated with acetazolamide

Vocal Cord Paralysis in Pediatric Chiari Malformation: A Systematic Review and Meta-analysis

OBJECTIVE

Arnold-Chiari Malformation is one possible cause of congenital vocal cord paralysis (VCP). The natural history of VCP in children with Chiari malformation has previously been limited to small case studies. This systematic review seeks to better characterize the prognostic factors that may predict symptom severity and resolution of congenital VCP in children with Arnold-Chiari malformation. We hypothesized that the onset of stridor or VCP at a younger age would be associated with a poorer prognosis and earlier intervention with posterior fossa decompression would be associated with better outcomes.

DATA SOURCES

PubMed, Web of Science, Cochrane Library, and bibliographic review.

REVIEW METHODS

A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Database search yielded 866 articles. Study abstracts were reviewed by 2 independent examiners. One hundred and seventy-six studies underwent full-text review. The following were extracted: age at onset of stridor or VCP, Chiari malformation type, laryngoscopy findings, type and timing of neurosurgical intervention, and tracheostomy history. Statistical analyses utilized χ2 tests.

RESULTS

Younger age at symptom onset showed statistically significant associations with decreased likelihood for symptom resolution and tracheostomy decannulation. The shorter time interval from symptom onset to neurosurgical intervention was not significantly associated with better outcomes.

CONCLUSION

This meta-analysis suggests poorer prognosis in those with earlier-onset symptoms, reinforcing prior case series findings. Additional prospective studies are needed to elucidate the natural history and utility of early intervention in children with vocal cord paralysis secondary to Chiari malformation.

Cheyne-Stokes respiration, periodic circulation, and pulsus alternans in spinal cord injury patients

STUDY DESIGN

Case reports.

OBJECTIVES

To describe Cheyne-Stokes respiration (CSR) and associated circulatory abnormalities in three patients with spinal cord lesions.

SETTING

Veterans Administration Hospital, USA.

SUBJECTS

One paraplegic patient with coronary artery disease in congestive heart failure, one tetraplegic patient with alcoholic cardiomyopathy and postural hypotension, and one tetraplegic complete patient with cardiomegaly, severe aortic atherosclerosis, and postural hypotension.

METHODS

Breathing activity was measured with a nasal thermistor or abdominal stretch transducer. Cardiac activity was estimated with a photoelectric sensor for cutaneous blood flow placed on the forehead or a piezoelectric transducer for pressure positioned over an artery or the cardiac apex. Tracings were drawn on a strip chart recorder. The subjects were at rest in semireclining positions.

RESULTS

Survey times were 17-21 min, and cycling periods were 41-72 s. Periodic changes in the depth of breathing were accompanied by periodic changes in amplitude of forehead cutaneous pulse, blood pressure, or apical cardiac impulse in all patients. Peak circulation occurred at or following peak respiration. In addition, cyclical pulsus alternans occurred in two patients.

CONCLUSION

Three spinal cord injury patients sustained CSR and circulatory periodicity associated with cardiac disease and postural hypotension.

Treatment of obstructive sleep apnea in children: do we really know how?

Obstructive sleep apnea syndrome (OSAS) is a frequent, albeit underdiagnosed problem in children. If left untreated, OSAS may lead to substantial morbidities affecting multiple target organs and systems. The immediate consequences of OSAS in children include behavioral disturbance and learning deficits, pulmonary hypertension, as well as compromised somatic growth. However, if not treated promptly and early in the course of the disease, OSAS may also impose long-term adverse effects on neurocognitive and cardiovascular function, thereby providing a strong rationale for effective treatment of this condition. This review provides a detailed description of the current treatment modalities for pediatric OSAS, and uncovers the potential limitations of the available data on these issues. Furthermore, we postulate that OSAS will persist relatively often after tonsillectomy and adenoidectomy, and that critical studies need to be conducted to identify such patients and refine the clinical management algorithm for pediatric OSAS.

Treatment of sleep-disordered breathing in children with myelomeningocele

The prevalence of moderate to severe sleep-disordered breathing (SDB) in patients with myelomeningocele may be as high as 20%, but little information is available regarding treatment of these patients. To assess the efficacy and complications of treatments for these children, we collected data on 73 patients from seven pediatric sleep laboratories. Obstructive sleep apnea (OSA, n = 30) and central apnea (n = 25) occurred more frequently than central hypoventilation (n = 12). We also describe a sleep-exacerbated restrictive lung disease type of SDB in 6 patients who had hypoxemia during sleep without apnea or central hypoventilation. For each type of SDB, effective treatments were identified in a stepwise process, moving towards more complex and invasive therapies. For OSA, adenotonsillectomy was often ineffective (10/14), whereas nasal continuous positive airway pressure (CPAP) was usually successful (18/21). For central apnea, methylxanthines and/or supplemental oxygen proved sufficient in 2 of 9 and 3 of 6, respectively, but noninvasive positive pressure ventilation was required in 7 children. For central hypoventilation, supplemental oxygen (alone or with methylxanthines), noninvasive positive pressure ventilation, and tracheostomy with positive pressure ventilation were effective in 3, 2, and 2 patients, respectively. Sleep-exacerbated restrictive lung disease always required supplemental oxygen treatment, but in 2 cases also required noninvasive positive pressure ventilation; nutritional and orthopedic procedures also were helpful. Posterior fossa decompression was used for the first three types of SDB, but data were insufficient to delineate specific recommendations for or against its use. In summary, evaluation by an experienced, multidisciplinary team can establish an effective treatment regime for a child with myelomeningocele and SDB.

Effects of intralaryngeal carbon dioxide and acetazolamide on the laryngeal chemoreflex

Sudden infant death syndrome is the leading cause of death in infants in the United States. The laryngeal chemoreflex (LCR) is thought to contribute to its pathogenesis. In adult animals, increasing levels of intralaryngeal CO2 result in a decrease in ventilatory activity. Intravenous acetazolamide (AZ) abolishes this response. The purpose of this study was to determine the effects of intralaryngeal CO2 and AZ on the LCR and respiratory physiology of piglets under normoxic and hypoxic conditions. We applied 0% or 10% CO2 in a randomized order to the larynx of 26 piglets. Intubation via tracheotomy prevented inhalation of the gas mixtures. Laryngeal stimulation was performed under normoxic conditions (PaO2 of >70 mm Hg) in 15 animals and under hypoxic conditions (PaO2 of 50 to 65 mm Hg) in 11 animals both with and without intravenous AZ (5 mg/kg). Respiratory and cardiovascular response data were recorded. Ten percent intralaryngeal CO2 has no significant effect on mean baseline respiratory rate, systemic PaCO2 or PaO2 levels, or apnea duration (p > .05). The use of AZ (versus no AZ) resulted in significantly higher baseline respiratory rates (64 versus 51 breaths per minute; p = .016), a decreased baseline systemic PaCO2 level (38.8 versus 45.9 mm Hg; p < .001), a higher baseline PaO2 level (97.9 versus 82.8 mm Hg; p < .001), shorter mean apnea durations (15.5 versus 24.8 seconds; p = .001), a higher lowest O2 saturation level after the stimulus (78.0% versus 68.4%; p = .003), and fewer profound apneas (10 of 90 versus 41 of 90 trials; p < .001). We conclude that 10% intralaryngeal CO2 does not decrease ventilatory activity in piglets and has no significant effect on the LCR. Acetazolamide, however, appears to have a protective effect against the LCR, resulting in shorter and less severe apneas. The protective effect of AZ against the LCR appears to be related to its ability to stimulate the respiratory drive and increase oxygenation at baseline.

Airway abnormalities in patients with Arnold-Chiari malformation

OBJECTIVES

The goal was to determine the incidence and types of airway abnormalities in patients with Arnold-Chiari malformation (ACM).

METHODS

The study was a retrospective chart review of 24 patients with ACM who were evaluated and treated between November 1991 and August 1997.

RESULTS

Eighteen (75%) and 6 (25%) of the 24 patients had types I and II ACM, respectively. Three (12.5% of 24 patients) of the type II ACM patients had vocal cord impairment: 1 bilateral paralysis, 1 bilateral paresis, and 1 unilateral paralysis. None of the type I ACM patients had vocal cord impairment. Tracheotomy was necessary in 3 of the 24 patients and all in patients with type II ACM. Central sleep apnea was found in 5 of 6 type II ACM patients, but not in any of the type I ACM patients.

CONCLUSIONS

Vocal cord impairment and sleep apnea were found in 12. 5% and 21%, respectively, of this ACM population. When type II ACM patients were considered separately, the incidences of vocal cord impairment and sleep apnea were 50% and 83%, respectively. Type II ACM patients tend to have a higher incidence of airway abnormalities and other neurologic dysfunctions. Flexible fiberoptic laryngoscopy is recommended in the airway evaluation of ACM patients. Early recognition, diagnosis, and management of these abnormalities may be lifesaving.

Sleep-disordered breathing in children with myelomeningocele

BACKGROUND

Although patients with myelomeningocele and the Chiari II malformation are known to have sleep apnea and respiratory control deficits, the prevalence, types, severities, and associations of sleep-disordered breathing (SDB) have not been adequately defined.

METHODS

A cross-sectional study of our myelomeningocele clinic population was undertaken to correlate polysomnographic results with historical data and findings from magnetic resonance imaging of the Chiari malformation, pulmonary function results, and nocturnal pulse oximetry.

RESULTS

A questionnaire survey of symptoms was available for 107 of 109 children (98% of the clinic population), and 83 patients agreed to undergo overnight polysomnography. Breathing during sleep was classified as normal in 31 cases (37%), mildly abnormal in 35 cases (42%), and moderately/severely abnormal in 17 cases (20%). Among the 17 patients with moderately/severely abnormal SDB, 12 patients had predominantly central apneas and 5 had predominantly obstructive apnea. Patients with a thoracic or thoracolumbar myelomeningocele, those who had previously had a posterior fossa decompression operation, those with more severe brain-stem malformations, and those with pulmonary function abnormalities were more likely to have moderately/severely abnormal SDB, relative risks (95% confidence intervals) 9.2 (2.9 to 29.3), 3.5 (1.3 to 8.9), 3.0 (0.9 to 10.5), and 11.6 (1.6 to 81.3), respectively. Failure of obstructive SDB to resolve after adenotonsillectomy in four patients suggested abnormal control of pharyngeal airway patency during sleep. Nocturnal pulse oximetry accurately predicted moderately/severely abnormal SDB with a sensitivity of 100% and a specificity of 67%.

CONCLUSIONS

The pathogenesis of SDB in patients with myelomeningocele involves the functional level of the spinal lesions, congenital and acquired brainstem abnormalities, pulmonary function abnormalities, disorders of upper airway maintenance, and sleep state. Polysomnography and nocturnal pulse oximetry should be performed in high-risk patients to detect and classify SDB.

[Symptomatic Chiari type II malformation]

The Chiari type II malformation is the leading cause of death in infants with myelomeningocele. The authors report 17 cases of symptomatic Chiari type II malformation occurring in two distinct age dependent population. In Group I, 13 neonates and infants in the first year of life presented with cranial nerve and brain stem dysfunction characterized by vocal cord paralysis, apnea, dysphagia and laryngeal stridor. In Group II, 4 patients developed signs and symptoms after the first year of life. In this group, the presentation was more insidious and included neck pain and cerebellar manifestations. The surgical treatment consisted initially in shunt implantation or revision and when there was no improvement, posterior fossa decompression was performed. The response to the surgical treatment differed considerably between the two groups: older patients improved promptly after surgery and there was no casualties; in newborn and infants, especially those under 6 months of age, the mortality rate was 46.1%. The authors stress that prompt diagnosis and surgical intervention should be performed in order to produce a favorable outcome.

Multifactorial obstructive sleep apnea in a patient with Chiari malformation

We report a patient with severe obstructive sleep apnea (OSA) associated with a unique combination of syringobulbia-myelia, Chiari malformation type I (CM), absent hypoxic ventilatory drive, vocal cord paralysis, post-menopausal status, obesity, and acute respiratory failure necessitating mechanical ventilation. The remote onset of OSA five years after surgery underscores the need for long-term follow-up of patients with syringobulbia-myelia and CM and the importance of addressing multiple interacting neurologic, metabolic, and mechanical predispositions to sleep-disordered breathing.