Type I Chiari malformation presenting central sleep apnea

The relationship between Chiari 1.5 malformation and sleep-related breathing disorders on polysomnography

OBJECTIVE

Chiari 1.5 malformation is a subgroup of the Chiari malformation in which tonsillar descent into the foramen magnum is accompanied by brainstem descent. No data exist on whether operative decompression in patients with Chiari 1.5 improves sleep-related breathing disorders (SRBDs) and whether there are radiological parameters predicting improvement.

METHODS

The authors performed a retrospective cohort study of consecutive pediatric patients with Chiari 1.5 malformation and SRBDs at the Alberta Children's Hospital. An SRBD was characterized using nocturnal polysomnography (PSG), specifically with the apnea-hypopnea index (AHI), the obstructive apnea index, and the central apnea index. Preoperative values for each of these indices were compared to those following surgical decompression. The authors also compared preoperative radiographic factors as predictors to both preoperative AHI and the change in AHI with surgery. Radiological factors included tonsillar and obex descent beneath the basion-opisthion line, the presence of syringomyelia, the frontooccipital horn ratio, the pB-C2 line, and the clivoaxial angle.

RESULTS

Seven patients (5 males, 2 females) met inclusion criteria. One patient had two surgical decompressions, each with pre- and postoperative PSG studies (n = 8). The median age was 9 years. Before surgical decompression, 75% underwent tonsillectomy/adenoidectomy. The majority (87.5%) experienced snoring/witnessed apnea preoperatively. The median tonsillar and obex descent values were 21.3 mm and 11.2 mm, respectively. The median values for the pB-C2 line and clivoaxial angle were 5.4 mm (interquartile range [IQR] 4.5 mm, 6.8 mm) and 144° (IQR 139°, 167°), respectively. There was a statistically significant change from preoperative to postoperative AHI (19.7 vs 5.1, p = 0.015) and obstructive apnea index (4.5 vs 1.0, p = 0.01). There was no significant change in the central apnea index with surgery (0.9 vs 0.3, p = 0.12). No radiological factors were statistically significant in predicting preoperative AHI and change in AHI.

CONCLUSIONS

This is the first series of pediatric patients with Chiari 1.5 with SRBDs who demonstrated a marked improvement in their PSG results postdecompression. Sleep apnea has a significant impact on learning and development in children, highlighting the urgency to recognize Chiari 1.5 as a more severe form of the Chiari I malformation.

Treatment emergent obstructive sleep apnea after Chiari surgery: A case report

Patients with Chiari type I malformation may also present with sleep disordered breathing mainly central sleep apnea. Here, we report a patient with Chiari I malformation referred to our clinic because of snoring and sleep disordered breathing. He was a 28-year-old man referred to us for evaluation of snoring. An overnight polysomnography revealed central sleep apnea. On further evaluation of central sleep apnea, the patient found to have Chiari malformation type I on brain MRI. The patient developed obstructive sleep apnea after surgery for Chiari malformation. Accordingly, pap titration was performed for the patient's obstructive sleep apnea. In patients with central sleep apnea comprehensive evaluation of predisposing causes is required. Lesions of central nervous system including Chiari malformation should not be overlooked. Furthermore, after treatment of central sleep apnea follow up PSG is warranted to confirm newly emerged sleep breathing disorder such as obstructive sleep apnea.

3D structural complexity analysis of cerebellum in Chiari malformation type I

Chiari malformation type I (CM-I), described by a descent of the cerebellar tonsils, is assumed to be a neurological developmental disorder. The aim of the present study was to investigate morphological variance in cerebellar sub-structures, including gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF), using magnetic resonance (MR) images with three-dimensional (3D) fractal dimension (FD) analysis in patients with CM-I. MRI data of 16 patients and 15 control subjects were obtained, and structural complexity analyses were performed using a box-counting FD algorithm. Results showed that patients with CM-I had significantly reduced FD values for WM and CSF in comparison with controls, and statistically significant differences in cerebellar GM and CSF volumes between patients and controls were found. Moreover, a significant difference was not found between the WM volumes. This may suggest that there are changes in structural complexity in WM even when its volume is unaffected. We conclude that the findings of this preliminary study indicate the possibility of using FD analysis to understand the pathophysiology of CM-I in patients.

Bilateral vocal cord palsy causing stridor as the only symptom of syringomyelia and Chiari I malformation, a case report

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We present the case of a three year old female who had a long standing stridor, previously being incorrectly managed as asthma by family practitioner.

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She was found to have a bilateral vocal cord palsy causing her stridor, as a result of a large syrinx formation and Arnold Chiari malformation.

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We highlight the importance of MRI as a diagnostic tool in the evaluation of vocal cord palsy and stridor.

Introduction

Bilateral vocal cord palsy is a condition which has many causes (Gupta et al., 2012) [1]. Syringomyelia is an uncommon condition which describes the formation of fluid filled cavity, occupying the spinal cord (Chang, 2003) [2]. It rarely manifests itself as subacute onset of stridor.

Presentation of case

We present the case of a three year old female who presented for evaluation of her speech and language delay, when incidentally it was made note of her loud breathing which had previously been managed as bronchiolitis by her general practitioner. In hospital she was found to have a bilateral vocal cord palsy. Further investigation revealed a large syrinx as well as an associated Arnold Chiari 1 malformation, for which she required neurosurgical decompression.

Conclusion

Although uncommon, formation of a syrinx should be considered for patients who present with stridor and reiterates the importance of MRI as an important investigative tool of bilateral vocal cord palsy.