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Chest

Volume 148, Issue 5, November 2015, Pages 1346-1352
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Sleep-Related Breathing Disorders and the Chiari 1 Malformation

https://doi.org/10.1378/chest.14-3090Get rights and content

The Chiari 1 malformation is characterized by > 5-mm herniation of the cerebellar tonsils through the foramen magnum. Consequent compression of the brain stem and nearby neuronal structures involved in respiratory control and maintenance of pharyngeal wall muscle tone may result in respiratory changes during sleep. These changes include respiratory failure and arrest, as well as sleep-related breathing disorders (ie, OSA and central sleep apnea). Although data have accrued on the significance of sleep-related breathing disorders in patients with the Chiari 1 malformation, many management questions remain unanswered. This article reviews the available literature on prevalence and management of sleep-related breathing disorders in patients with the Chiari 1 malformation.

Section snippets

Common Symptoms and Signs of the CM1

The CM1 has traditionally been thought of as the “adult type,” because patients typically become symptomatic as adults.4 In adults, the most common symptom at presentation is headache.5 Other symptoms of CM1s include syncope (especially after Valsalva maneuver), vertigo, dysphagia, neck pain, progressive ataxia, unsteady gait, and paresthesia or weakness of the limbs.6, 7, 8 Although lower cranial nerve palsies, nystagmus, ataxia, and motor and sensory deficits may be detected on neurologic

CM1 and SRBDs

SRBDs encompass a variety of abnormal respiratory patterns in sleep.19 The exact prevalence of SRBDs in CM1s is unknown10 because many of the studies have been small. However, studies that have looked at SRBDs in CM1s (typically defining SRBD as an apnea-hypopnea index (AHI) > 5/h in adults and > 1/h in children) have reported similar prevalence values (Table 1).13, 14, 20, 21, 22, 23, 24 Two larger studies (one with 46 patients and the other with 103 patients) included both children and adults

Catastrophic Events in CM1

Paul et al5 performed a retrospective review of 71 adult patients with CM1 in an effort to document the natural history of the disease and the benefit of PFD surgery. The most common postoperative complication was respiratory depression, which occurred in 14% of the study population, typically within the first 5 days after decompression surgery.5 Two of these patients were ventilated.5 One patient had an apneic episode in sleep and died 36 h after surgery.5 In both adults and children,

OSA and Central and Mixed Sleep Apnea in CM1

Although there are certainly case reports of OSA in adult patients with CM1,6 the prevalence of OSA in this population is unclear. The prevalence of OSA in children with CM1s is higher than the estimated prevalence of 1% to 4% in the general pediatric population.19 Of 1,039 pediatric polysomnograms performed in a year, Khatwa et al14 identified five of 22 patients with CM1 who had OSA on their polysomnogram. Three of these children were described as having snored since birth.14 The prospective

Theories on the Pathophysiology of OSA and CSA in CM1

The exact cause of OSA and CSA in CM1 is unclear. The prevailing theory for OSA is that compression/stretching of cranial nerves 9 and 10 or their corresponding pontomedullary nuclei may result in impairment of the pharyngeal and laryngeal muscles, allowing for the negative thoracic pressure that naturally develops with inhalation to cause upper airway collapse. 1u3ä27 There are several proposed mechanisms by which central apneas could occur in patients with CM1. It has been hypothesized that

Screening Patients With CM1 for SRBDs and Patients With SRBDs for CM1

There are no definitive guidelines on when patients with CM1 should undergo polysomnography.14 In the general pediatric population, clinical history and examination are poor predictors of SRBD.38 Both children and adults with CM1s are at higher risk of SRBDs than the general population. If physicians relied on SRBD symptoms to determine when patients with CM1 should have a polysomnogram, many patients would likely go undiagnosed. In the prospective study by Losurdo et al,13 of 53 patients with

Treatment and Outcomes of SRBDs in Patients With CM1

There are no randomized controlled clinical trials for the treatment of SRBDs in patients with a CM1. The literature on this topic consists of case reports and small retrospective reviews. An isolated case report from 1989 described the use of caffeine as an adjunct therapy for the treatment of apnea in an infant with a Chiari malformation.39 Patients with a mixture of CSA and OSA have been described who tried CPAP, with incomplete control of respiratory events.10, 11, 34 All four had

Conclusions

Although most data on SRBDs and CM1 have come from case reports and small case series, we have learned that the prevalence of SRBDs in patients with CM1 is higher than in the general population. An SRBD in CM1 can manifest as both OSA and CSA. Although the severity of an SRBD in CM1 can be mild, it can also be severe enough that patients display severe bradypnea or respiratory dysrhythmia. An SRBD can be the sole presenting sign of CM1 and is considered an indication for PFD. However, many

Acknowledgments

Conflict of interest: None declared.

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