Sleep apnoea in syndromic craniosynostosis occurs independent of hindbrain herniation

What We Know About Intracranial Hypertension in Children With Syndromic Craniosynostosis

OBJECTIVE

A scoping review of literature about mechanisms leading to intracranial hypertension (ICH) in syndromic craniosynostosis (sCS) patients, followed by a narrative synopsis of whether cognitive and behavioral outcome in sCS is more related to genetic origins, rather than the result of ICH.

METHODS

The scoping review comprised of a search of keywords in EMBASE, MEDLINE, Web of science, Cochrane Central Register of Trials, and Google scholar databases. Abstracts were read and clinical articles were selected for full-text review and data were extracted using a structured template. A priori, the authors planned to analyze mechanistic questions about ICH in sCS by focusing on 2 key aspects, including (1) the criteria for determining ICH and (2) the role of component factors in the Monro-Kellie hypothesis/doctrine leading to ICH, that is, cerebral blood volume, cerebrospinal fluid (CSF), and the intracranial volume.

RESULTS

Of 1893 search results, 90 full-text articles met criteria for further analysis. (1) Invasive intracranial pressure measurements are the gold standard for determining ICH. Of noninvasive alternatives to determine ICH, ophthalmologic ones like fundoscopy and retinal thickness scans are the most researched. (2) The narrative review shows how the findings relate to ICH using the Monro-Kellie doctrine.

CONCLUSIONS

Development of ICH is influenced by different aspects of sCS: deflection of skull growth, obstructive sleep apnea, venous hypertension, obstruction of CSF flow, and possibly reduced CSF absorption. Problems in cognition and behavior are more likely because of genetic origin. Cortical thinning and problems in visual function are likely the result of ICH.

Syndromic Craniosynostosis: Objective and Parent-Reported Outcome Measurements after Cranio-Facial Remodelling Surgeries

INTRODUCTION

Syndromic craniosynostosis (SC) is a rare entity compared to the non-syndromic variant. Treatment involves a multidisciplinary approach towards a multitude of problems. Early intervention is known to be better for optimum results. We reviewed outcomes of children with SC who underwent reconstructive cranio-facial surgery.

MATERIALS AND METHODS

A retrospective study was conducted using data from hospital case files and the picture archival communication system. Objective data like the cephalic index (CI), both preoperatively and post-operatively, were compared. Subjective data for the cosmesis outcome - "Sloan and Whitaker outcome class" - following surgery were assessed. Also, parent-reported outcome measurement (PROM) was performed with various parameters to assess quality of life (QOL).

RESULTS

We had 21 operated cases of SC, with 19 needing cranio-facial remodelling. The male to female ratio was 11:10. Crouzon's syndrome was the most common syndromic association followed by Apert's syndrome. Nineteen patients underwent cranio-facial remodelling surgeries and 2 underwent the ventriculo-peritoneal shunt only - for raised intracranial pressure (ICP). Nine patients underwent cranial remodelling with fronto-orbital advancements, and 3 of these patients also received le-fort's type 3 osteotomy and advancement later. Ten patients underwent fronto-orbital advancement with parieto-occipital barrel-stave osteotomies.

OUTCOMES

Improvement in the CI was maximum at the 6-month follow-up. Six (37.5%) cases had Sloan class 1 outcome, 9 (56.25%) had class 2 outcomes, and 1 patient had a class 6 outcome. Whitaker cosmesis outcomes - 14 out of 16 cases (87.5%) had Category 1 outcomes. PROM was assessed. All parents reported at least a moderate improvement in cosmesis following surgery. Out of 15 cases, 10 (66%) reported significant improvement, while 4 (26.6%) cases reported moderate improvement with respect to eye and visual problems. Four parents reported snoring as a significant problem even after surgery. Most parents felt that the children were doing well, attending regular school, and social well-being was normal and had an overall good QOL.

CONCLUSIONS

SC cases may have a multitude of other problems like raised ICP, ophthalmological problems, poor intelligence, and cognition apart from cosmetic concerns. PROMs revealed good outcomes in terms of cosmesis, cognition, and ophthalmological and oral cavity-related problems. Significant improvement in overall QOL was seen in most patients following cranio-facial remodelling surgery.

Cervical Spinal Cord Compression and Sleep-Disordered Breathing in Syndromic Craniosynostosis

BACKGROUND AND PURPOSE

Cerebellar tonsillar herniation arises frequently in syndromic craniosynostosis and causes central and obstructive apneas in other diseases through spinal cord compression. The purposes of this study were the following: 1) to determine the prevalence of cervical spinal cord compression in syndromic craniosynostosis, and 2) to evaluate its connection with sleep-disordered breathing.

MATERIALS AND METHODS

This was a cross-sectional study including patients with syndromic craniosynostosis who underwent MR imaging and polysomnography. Measures encompassed the compression ratio at the level of the odontoid process and foramen magnum and the cervicomedullary angle. MR imaging studies of controls were included. Linear mixed models were developed to compare patients with syndromic craniosynostosis with controls and to evaluate the association between obstructive and central sleep apneas and MR imaging parameters.

RESULTS

One hundred twenty-two MR imaging scans and polysomnographies in 89 patients were paired; 131 MR imaging scans in controls were included. The mean age at polysomnography was 5.7 years (range, 0.02-18.9 years). The compression ratio at the level of the odontoid process was comparable with that in controls; the compression ratio at the level of the foramen magnum was significantly higher in patients with Crouzon syndrome (+27.1, P < .001). The cervicomedullary angle was significantly smaller in Apert, Crouzon, and Saethre-Chotzen syndromes (-4.4°, P = .01; -10.2°, P < .001; -5.2°, P = .049). The compression ratios at the level of the odontoid process and the foramen magnum, the cervicomedullary angle, and age were not associated with obstructive apneas (P > .05). Only age was associated with central apneas (P = .02).

CONCLUSIONS

The prevalence of cervical spinal cord compression in syndromic craniosynostosis is low and is not correlated to sleep disturbances. However, considering the high prevalence of obstructive sleep apnea in syndromic craniosynostosis and the low prevalence of compression and central sleep apnea in our study, we would, nevertheless, recommend a polysomnography in case of compression on MR imaging studies.

Intracranial Venous Hypertension in Craniosynostosis: Mechanistic Underpinnings and Therapeutic Implications

Patients with complex, multisutural, and syndromic craniosynostosis (CSO) frequently exhibit intracranial hypertension. The intracranial hypertension cannot be entirely attributed to the craniocephalic disproportion with calvarial restriction because cranial vault expansion has not consistently alleviated elevated intracranial pressure. Evidence has most strongly supported a multifactorial interaction, including venous hypertension along with other pathogenic processes. Patients with CSO exhibit marked venous anomalies, including stenosis of the jugular-sigmoid complex, transverse sinuses, and extensive transosseous venous collaterals. These abnormal intracranial-extracranial occipital venous collaterals might represent anomalous development, with persistence and subsequent enlargement of channels normally present in the fetus, either as a primary defect or as nonregression in response to failure of the development of the jugular-sigmoid complexes. It has been suggested by some investigators that venous hypertension in patients with CSO could be treated directly via jugular foraminoplasty, venous stenting, or jugular venous bypass, although these options are not in common clinical practice. Obstructive sleep apnea, occurring as a consequence of midface hypoplasia, can also contribute to intracranial hypertension in patients with syndromic CSO. Thus, correction of facial deformities, as well as posterior fossa decompression, could also play important roles in the treatment of intracranial hypertension. Determining the precise mechanistic underpinnings underlying intracranial hypertension in any given patient with CSO requires individualized evaluation and management.

Sleep Architecture Linked to Airway Obstruction and Intracranial Hypertension in Children with Syndromic Craniosynostosis

BACKGROUND

Children with syndromic craniosynostosis often have obstructive sleep apnea and intracranial hypertension. The authors aimed to evaluate (1) sleep architecture, and determine whether this is influenced by the presence of obstructive sleep apnea and/or intracranial hypertension; and (2) the effect of treatment on sleep architecture.

METHODS

This study included patients with syndromic craniosynostosis treated at a national referral center, undergoing screening for obstructive sleep apnea and intracranial hypertension. Obstructive sleep apnea was identified by polysomnography, and categorized into no, mild, moderate, or severe. Intracranial hypertension was identified by the presence of papilledema on funduscopy, supplemented by optical coherence tomography and/or intracranial pressure monitoring. Regarding sleep architecture, sleep was divided into rapid eye movement or non-rapid eye movement sleep; respiratory effort-related arousals and sleep efficiency were scored.

RESULTS

The authors included 39 patients (median age, 5.9 years): 19 with neither obstructive sleep apnea nor intracranial hypertension, 11 with obstructive sleep apnea (four moderate/severe), six with intracranial hypertension, and three with obstructive sleep apnea and intracranial hypertension. Patients with syndromic craniosynostosis, independent of the presence of mild obstructive sleep apnea and/or intracranial hypertension, have normal sleep architecture compared with age-matched controls. Patients with moderate/severe obstructive sleep apnea have a higher respiratory effort-related arousal index (p < 0.01), lower sleep efficiency (p = 0.01), and less rapid eye movement sleep (p = 0.04). An improvement in sleep architecture was observed following monobloc surgery (n = 5; rapid eye movement sleep, 5.3 percent; p = 0.04).

CONCLUSIONS

Children with syndromic craniosynostosis have in principle normal sleep architecture. However, moderate/severe obstructive sleep apnea does lead to disturbed sleep architecture, which fits within a framework of a unifying theory for obstructive sleep apnea, intracranial hypertension, and sleep.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Craniofacial syndromes and sleep-related breathing disorders

Children with craniofacial syndromes are at risk of sleep disordered breathing, the most common being obstructive sleep apnea. Midface hypoplasia in children with craniosynostosis and glossoptosis in children with Pierre Robin syndrome are well recognized risk factors, but the etiology is often multifactorial and many children have multilevel airway obstruction. We examine the published evidence and explore the current management strategies in these complex patients. Some treatment modalities are similar to those used in otherwise healthy children such as adenotonsillectomy, positive pressure ventilation and in the refractory cases, tracheostomy. However, there are some distinct approaches such as nasopharyngeal airways, tongue lip adhesion, mandibular distraction osteogenesis in children with Pierre Robin sequence, and midface advancement in children with craniosynostoses. Clinicians should have a low threshold for referral for evaluation of sleep-disordered-breathing in these patients.

Obstructive sleep apnea pretreatment and posttreatment in symptomatic children with congenital craniofacial malformations

STUDY OBJECTIVES

Obstructive sleep symptoms are common in children with craniofacial malformations (CFM). However objective data about obstructive sleep apnea (OSA) is still limited. The aims of this study were to investigate the frequency of OSA in symptomatic children with CFM and to determine improvement in severity of OSA after treatment.

METHODS

Symptomatic children with CFM referred for a diagnostic polysomnogram (PSG) were identified. Obstructive sleep apnea was defined as an apnea/hypopnea index (AHI) ≥ 1, with moderate/severe OSA as an AHI ≥ 5.

RESULTS

Overall, 151 symptomatic children were identified; 87% were diagnosed with OSA, of whom 24% had moderate-to-severe OSA. Children with syndromic CFM, compared to non-syndromic CFM, were more likely to have an AHI ≥ 5 (syndromic 33% vs. non-syndromic 15%, p = 0.02). Of the 131 children with OSA, 64 were treated and 32 returned for a posttreatment PSG, with 22 treated with either positive airway pressure (PAP) or adenotonsillectomy (AT). Children treated with PAP demonstrated a decrease in AHI from 6.2 to 3.5 (p = 0.057) and an increase in SpO2 from 89.1% to 91.1% (p = 0.091). There were no significant improvements for those in the AT group for either AHI (2.5 to 1.8, p = 0.19) or SpO2 (90.4% to 91.3%, p = 0.46). Normalization of the AHI (AHI < 1) occurred in only one child in each group (7% and 14% of the PAP and AT groups, respectively).

CONCLUSIONS

The vast majority of children with CFM referred for OSA evaluation are found to have objective evidence of OSA and a quarter of children have moderate-to-severe OSA. It is likely that many children with underlying OSA are not identified and referred for evaluation. Residual OSA after treatment is common in children with CFM.

Venous hypertension in syndromic and complex craniosynostosis: the abnormal anatomy of the jugular foramen and collaterals

Why craniosynostosis patients develop elevated intracranial pressure (ICP) is still a mystery. Our aim was to investigate jugular foramen size and its relation to venous hypertension and elevated ICP. Secondly, we evaluated whether occipital collateral veins develop as a compensatory mechanism for elevated ICP. We conducted a prospective study in 41 children with craniosynostosis who underwent a 3D-CT-angiography. We evaluated the anatomical course of the jugular vein, the diameter of the jugular foramen and the relation to the presence of papilledema. Additionally, we studied the anatomical variations of the cerebral venous drainage system. The diameter of the jugular foramen was significantly smaller in our patients. Abnormal venous collaterals were most often observed in patients with Apert, Crouzon-Pfeiffer and Saethre-Chotzen syndrome, even in children under two years of age. There was no significant difference in the number of collateral veins in patients with or without papilledema. Collaterals appear to reflect an inborn abnormality of the venous system, rather than a compensating mechanism for elevated ICP. This study confirms the presence of jugular foraminal narrowing in craniosynostosis patients and an abnormal venous system, which may predispose to elevated ICP.

LEVEL OF EVIDENCE

Diagnostic II.