A prospective controlled study of sleep respiratory events in patients with craniovertebral junction malformation

The Role of Neurophysiology in Managing Patients with Chiari Malformations

Chiari malformation type 1 (CM1) includes various congenital anomalies that share ectopia of the cerebellar tonsils lower than the foramen magnum, in some cases associated with syringomyelia or hydrocephalus. CM1 can cause dysfunction of the brainstem, spinal cord, and cranial nerves. This functional alteration of the nervous system can be detected by various modalities of neurophysiological tests, such as brainstem auditory evoked potentials, somatosensory evoked potentials, motor evoked potentials, electromyography and nerve conduction studies of the cranial nerves and spinal roots, as well as brainstem reflexes. The main goal of this study is to review the findings of multimodal neurophysiological examinations in published studies of patients with CM1 and their indication in the diagnosis, treatment, and follow-up of these patients, as well as their utility in intraoperative monitoring.

Adult Saethre-Chotzen Syndrome: A Unique Abnormal Breathing Pattern

ABSTRACT

A 35-year-old male with Saethre-Chotzen syndrome presented with severe complaints. Neuroimaging showed a Chiari-I malformation, mild ventriculomegaly, a syrinx of the wide central canal, and various cerebral vascular anomalies including a large occipital emissary vein on the right. Ultrasound of this vein confirmed blocking of the outflow-track when turning his head to the right, which also provoked the headaches and bruit. Polysomnography revealed severe positional sleep apnea with a mixed breathing pattern, the central components consisted of periodic breathing with, at times, crescendo-decrescendo reminiscent of a Cheyne-Stokes versus Biot breathing pattern, pointing to possible brain stem/pontine problems. Continuous positive airway pressure was initiated, and the patient was instructed to avoid sleeping in the right lateral position. One year later, nearly all his complaints have resolved. A questionnaire was sent to all adult Saethre-Chotzen patients in our craniofacial unit, none reported any of the severe symptoms as described by our index case.

Central sleep apnea and Chiari 1 malformation in a pediatric patient with Klippel-Feil syndrome

None

Klippel-Feil sequence (KFS) is a rare congenital condition that presents with congenital cervical spine fusion, reduced cervical spine flexion, and low posterior hairline. Chiari malformation type 1 and sleep-disordered breathing (SDB) are frequent comorbidities of KFS. The pathologic basis of the connection between Chiari malformation type 1 and SDB in the setting of KFS is not clearly understood. Here we report a pediatric patient with KFS, SDB, and drooling who also had Chiari malformation type 1. Posterior fossa decompression of this patient significantly improved most symptoms including sleep disturbances. Repeat polysomnogram 8 weeks after posterior fossa decompression revealed worsening central sleep apnea despite the patient being clinically asymptomatic. Taken together, this case highlights the point that, although it is critical to recognize the association of SDB in the setting of KFS, decompression alone may not be sufficient to completely alleviate SDB and certain neurologic symptoms.

Role of sleep study in children with Chiari malformation and sleep disordered breathing

PURPOSE

Chiari malformation incorporate numerous forms of congenital or acquired cerebellar herniation through the foramen magnum. This may lead to brain stem, high spinal cord and cranial nerve compression resulting in obstructive and central apneas. This review highlights he high prevalence of sleep-disordered breathing in this population and the importance of refering these patients for sleep studies as part of their workup.

METHODS

A review of the literature was performed through a PubMed and EMBASE search of original articles and reviews using the key words "chiari" "chiari malformation" "hindbrain herniation" "sleep disordered breathing" "obstructive sleep apnea" "central sleep apnea" "sleep study" and "foramen magnum decompression".

DISCUSSION

We highlight the pathophysiology of sleep disordered breathing in patients with Chiari malformation, how it can be diagnosed and what the treatment options are.

CONCLUSIONS

Sleep-disordered breathing is highly prevalent in patients with CM1. Clinicians caring for these patients should be aware of this and prioritise sleep diagnostic testing to allow for early diagnosis and management particularly in the presence of neurological symptoms and specific brain MRI pointers.

A Conditional Inference Tree Model for Predicting Sleep-Related Breathing Disorders in Patients With Chiari Malformation Type 1: Description and External Validation

STUDY OBJECTIVES

The aim of this study is to generate and validate supervised machine learning algorithms to detect patients with Chiari malformation (CM) 1 or 1.5 at high risk of the development of sleep-related breathing disorders (SRBD) using clinical and neuroradiological parameters.

METHODS

We prospectively included two independent datasets. A training dataset (n = 90) was used to obtain the best model, whereas a second dataset was used to validate it (n = 74). In both cohorts, the same clinical, neuroradiological, and sleep studies were carried out. We used two supervised machine learning approaches, multiple logistic regression (MLR) and the unbiased recursive partitioning technique conditional inference tree (URP-CTREE), to detect patients at high risk of SRBD. We then compared the accuracy, sensitivity, and specificity of the two prediction models.

RESULTS

Age (odds ratio [OR] 1.1 95% confidence interval [CI] 1.05-1.17), sex (OR 0.19 95% CI 0.05-0.67), CM type (OR 4.36 95% CI 1.14-18.5), and clivus length (OR 1.14 95% CI 1.01-1.31) were the significant predictor variables for a respiratory disturbance index (RDI) cutoff that was ≥ 10 events/h using MLR. The URP-CTREE model predicted that patients with CM-1 who were age 52 years or older and males with CM-1 who were older than 29 years had a high risk of SRBD. The accuracy of predicting patients with an RDI ≥ 10 events/h was similar in the two cohorts but in the URP-CTREE model, specificity was significantly greater when compared to MLR in both study groups.

CONCLUSIONS

Both MLR and URP-CTREE predictive models are useful for the diagnosis of SRBD in patients with CM. However, URP-CTREE is easier to apply and interpret in clinical practice.

Diagnosis, follow-up and management of sleep-disordered breathing in children with osteogenesis imperfecta

OBJECTIVES

Osteogenesis imperfecta (OI) is the most common genetic skeletal disorder. Extraskeletal findings are common but an association with sleep-disordered breathing (SDB) has never been described. The aim of this study was to investigate clinical features of children with OI and suspected SDB.

METHODS

A retrospective study of clinical records, signs of SDB and polysomnographic recordings of children with OI was performed. We paid particular attention to symptoms that could be associated with SDB in this population - scoliosis, kyphosis, vertebral arthrodesis, chest wall deformities, basilar impression, autonomy - as well as data already known to be associated with obstructive sleep apnea such as body mass index and upper-airway impairment.

RESULTS

We reviewed the clinical charts of 188 patients referred to our genetic skeletal disorders reference center for OI. Among the 15 patients (8%) with polysomnographic recordings, 12 (6.4%) had sleep-disordered breathing. We found a negative correlation between the Brief Assessment of Motor Function score and Apnea Hypopnea Index (r=-0.68; p=0.01) and Desaturation Index (r=-0.62; p=0.02). The Apnea Hypopnea Index was higher for non-walkers than walkers (mean [SD]: 6.5 [3.6] vs. 2.4 [1.5]; p=0.02) and with type III versus IV OI. Two patients were started on continuous positive airway pressure ventilation, with clinical improvement.

CONCLUSION

For OI children, symptoms suggesting obstructive sleep disorders should be searched for systematically, especially in children with compromised autonomy, high body mass index, trunk deformations, and severe OI type.

Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

There is growing recognition of the kyphotic clivo-axial angle (CXA) as an index of risk of brainstem deformity and craniocervical instability. This review of literature and prospective pilot study is the first to address the potential correlation between correction of the pathological CXA and postoperative clinical outcome. The CXA is a useful sentinel to alert the radiologist and surgeon to the possibility of brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographically manifest as a kyphotic CXA, underwent correction of deformity (normalization of the CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessed preoperatively and at one, three, six, and twelve months after surgery, using established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, and Karnofsky Index. Parametric and non-parametric statistical tests were performed to correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screws adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinical metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinical improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Are evoked potentials clinically useful in the study of patients with Chiari malformation Type 1?

OBJECTIVE

In this study, the authors describe the brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) alterations found in a large cohort of patients with Chiari malformation Type 1 (CM-1), the relationship between the BAEPs/SSEPs and the clinical findings, the abnormalities in patients with associated syringomyelia, and the clinical and neuroradiological risk factors that are associated with abnormal evoked potentials (EPs).

METHODS

A prospectively collected database containing 545 patients with CM-1 was queried to search for patients satisfying the following criteria: 1) an age of at least 14 years, 2) neuroradiological criteria of CM-1, 3) no prior Chiari-related surgeries, and 4) preoperative EP studies conducted at the authors' institution. The 200 patients included in this cohort were classified into CM-0, CM-1, and CM-1.5 subtypes. Linear, planimetric, and angular measurements of the posterior fossa were conducted, as well as syringomyelia measurements. Two separate multiple logistic regression models were used, one to predict the covariates associated with abnormal BAEPs, and a second model to explore the variables associated with an abnormal SSEP. In these models, the BAEPs and SSEPs were dichotomized as being normal or abnormal.

RESULTS

Headaches were the main symptom in 70.5% of the patients, and Valsalva-induced headaches were most frequent in patients with CM-1 and CM-1.5 compared with patients with CM-0 (p = 0.031). BAEPs were abnormal in 38.5% of patients, and abnormal SSEPs were found in 43.5% of the entire cohort. Syringomyelia was most frequent in patients with CM-0 (64.3%) and CM-1 (51.1%) compared with those with CM-1.5 (34.7%; p = 0.03). Age (OR 1.03, 95% CI 1.00–1.06), the degree of tonsillar herniation (OR 1.08, 95% CI 1.01–1.16), and lower cranial nerve dysfunction (OR 3.99, 95% CI 1.29–14.01) had a statistically significant correlation with abnormal BAEPs. Only age (OR 1.07, 95% CI 1.04–1.10) and the degree of tonsillar herniation (OR 1.11, 95% CI 1.04–1.19) had a statistically significant correlation with abnormal SSEPs.

CONCLUSIONS

A high percentage of patients with CM-1 exhibited EP alterations regardless of their clinical or radiological findings. These findings suggest that EPs do not add any clinically relevant information nor are they helpful in establishing which symptomatic patients with CM should undergo surgical treatment. However, BAEP and SSEP studies clearly play an important role in incidentally detected patients with CM and may help to establish objective evidence of subclinical dysfunctions. In addition, neurophysiological studies may help to define subgroups of patients who require further testing and follow-up to personalize strategies for the management of incidental and oligosymptomatic patients.

Heart failure and sleep disorders

Awareness of the importance of sleep-related disorders in patients with cardiovascular diseases is growing. In particular, sleep-disordered breathing, short sleep time, and low sleep quality are frequently reported by patients with heart failure (HF). Sleep-disordered breathing, which includes obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), is common in patients with HF and has been suggested to increase the morbidity and mortality in these patients. Both OSA and CSA are associated with increased sympathetic activation, vagal withdrawal, altered haemodynamic loading conditions, and hypoxaemia. Moreover, OSA is strongly associated with arterial hypertension, the most common risk factor for cardiac hypertrophy and failure. Intrathoracic pressure changes are also associated with OSA, contributing to haemodynamic alterations and potentially affecting overexpression of genes involved in ventricular remodelling. HF treatment can decrease the severity of both OSA and CSA. Indeed, furosemide and spironolactone administration, exercise training, cardiac resynchronization therapy, and eventually heart transplantation have shown a positive effect on OSA and CSA in patients with HF. At present, whether CSA should be treated and, if so, which is the optimal therapy is still debated. By contrast, more evidence is available on the beneficial effects of OSA treatment in patients with HF.

Surgical History of Sleep Apnea in Pediatric Patients with Chiari Type 1 Malformation

Sleep apnea represents a relative indication for posterior fossa decompression in pediatric patients with Chiari malformation type 1. Duraplasty was associated with improvement of sleep apnea in 100% of patients and dural splitting with improvement in 50% of patients. Duraplasty and dural splitting were associated with a similar reduction in tonsillar herniation on radiographic imaging of 58% (37% excluding tonsillectomy) and 35%, respectively. Longitudinal follow-up studies of patients with either neurologic deficits or severe symptoms will further elucidate the natural history of Chiari malformation type 1 and more appropriately gauge the risk-benefit tradeoff of surgical intervention.

Upper airway dimensions in patients with craniocervical junction malformations with and without sleep apnea. A pilot case-control study

OBJECTIVE

Patients with craniocervical junction malformations (CCJM) tend to suffer more frequently from sleep respiratory disturbances, which are more frequent and severe in patients with basilar invagination. Here we evaluate if patients with CCJM and sleep respiratory disorders (SRD) present smaller airway dimensions than patients without SRD.

METHOD

Patients with CCCM with and without sleep respiratory disturbances were evaluated clinically by Bindal's score, modified Mallampati classification, full-night polysomnography and upper airway cone beam tomography.

RESULTS

Eleven patients had sleep respiratory disorders (SRD), and nine patients performed control group without SRD. CCJM patients with SRD were predominantly female, older, had higher BMI, were more likely to have Mallampati grades 3 and 4 and had statistically significant smaller anteroposterior diameter of the upper airway than patients without SRD.

CONCLUSION

Patients with CCJM and sleep respiratory disturbances have higher BMI, higher Mallampati score and smaller anterior posterior diameter of the upper airway.

Chiari malformation and central sleep apnea syndrome: efficacy of treatment with adaptive servo-ventilation

The Chiari malformation type I (CM-I) has been associated with sleep-disordered breathing, especially central sleep apnea syndrome. We report the case of a 44-year-old female with CM-I who was referred to our sleep laboratory for suspected sleep apnea. The patient had undergone decompressive surgery 3 years prior. An arterial blood gas analysis showed hypercapnia. Polysomnography showed a respiratory disturbance index of 108 events/h, and all were central apnea events. Treatment with adaptive servo-ventilation was initiated, and central apnea was resolved. This report demonstrates the efficacy of servo-ventilation in the treatment of central sleep apnea syndrome associated with alveolar hypoventilation in a CM-I patient with a history of decompressive surgery.

The association between sleep-disordered breathing and magnetic resonance imaging findings in a pediatric cohort with Chiari 1 malformation

BACKGROUND

The prevalence of sleep-disordered breathing (SDB) reported in the literature for Chiari malformation type 1 (CM1) is uniformly high (24% to 70%). In Canada, there is limited access to pediatric polysomnography (PSG). Therefore, the identification of clinical features would be invaluable for triaging these children.

OBJECTIVE

To identify demographic features, clinical symptoms/signs and radiological findings associated with SDB in a large pediatric cohort with CM1.

METHODS

A retrospective review was conducted on children with CM1 who underwent baseline PSG. Data were collected on patient demographics (age, sex, weight, height, body mass index), clinical symptoms (chart review and clinical questionnaires), diagnostic imaging of the brain and cervicothoracic spine, and medical history at the time of referral.

RESULTS

A total of 68 children were included in the review. The mean (± SD) age of the children at the time of PSG was 7.33 ± 4.01 years; 56% (n=38) were male. There was a 49% prevalence of SDB in this cohort based on the overall apnea-hypopnea index. Obstructive sleep apnea was the predominant type of SDB. Tonsillar herniation was significantly correlated with obstructive apnea-hypopnea index (r=0.24; P=0.036).

CONCLUSIONS

A direct relationship between the degree of cerebellar tonsillar herniation and obstructive sleep apnea was demonstrated. However, further prospective studies that include neurophysiological assessment are needed to further translate the central nervous system imaging findings to predict the presence of SDB.

Chiari 1 Malformation Presenting as Central Sleep Apnea during Pregnancy: A Case Report, Treatment Considerations, and Review of the Literature

Purpose: Chiari malformation (CM) type-1 frequently causes obstructive or central sleep-disordered breathing (SDB) in both adults and children, although SDB is relatively rare as a presenting manifestation in the absence of other neurological symptoms. The definitive treatment of symptomatic CM is surgical decompression. We report a case that is, to our knowledge, a novel manifestation of central sleep apnea (CSA) due to CM type-1 with severe exacerbation and initial clinical presentation during pregnancy.

Methods: Case report from tertiary care comprehensive sleep medicine center with literature review of SDB manifestations associated with CM type-1. PubMed search was conducted between January 1982 and October 2013.

Results: We report a 25-year-old woman with severe CSA initially presenting during her first pregnancy that eventually proved to be caused by CM type-1. The patient was successfully treated preoperatively by adaptive servoventilation (ASV), with effective resolution of SDB following surgical decompression, and without recurrence in a subsequent pregnancy. Our literature review found that 58% of CM patients with SDB had OSA alone, 28% had CSA alone, 8 (10%) had mixed OSA/CSA, and 6 (8%) had hypoventilation. Of CM patients presenting with SDB, 50% had OSA, 42% had CSA, 8% had mixed OSA/CSA, and 10.4% had hypoventilation. We speculate that CSA may develop in CM patients in whom brainstem compression results in excessive central chemoreflex sensitivity with consequent hypocapnic CSA.

Conclusion: Chiari malformation type-1 may present with a diversity of SDB manifestations, and timely recognition and surgical referral are necessary to prevent further neurological deficits. ASV therapy can effectively manage CSA caused by CM type-1, which may initially present during pregnancy.

Chiari I malformation associated with atlanto-occipital assimilation presenting as orthopnea and cough syncope: a case report and review of literature

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who harbored both a Chiari I malformation and atlanto-occipital assimilation who complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and cervical level 2 laminectomy. However, due to a possible initial underappreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient may have had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and requiring a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2-year follow-up, he has remained asymptomatic.

MRI findings and sleep apnea in children with Chiari I malformation

Chiari I malformation is characterized by downward herniation of the cerebellar tonsils through the foramen magnum. Scant data are available on the clinical course, relationship to the extent of herniation on magnetic resonance imaging in Chiari I malformation and the presence of sleep-disordered breathing on polysomnography. Retrospective analysis was performed looking at polysomnographic findings of children diagnosed with Chiari I malformation. Details on how Chiari I malformation was diagnosed, brainstem magnetic resonance imaging findings, and indications for obtaining the polysomnogram in these patients were reviewed. We also reviewed available data on children who had decompression surgery followed by postoperative polysomnography findings. Twenty-two children were identified in our study (11 males, median age 10 years, range 1 to 18). Three had central sleep apnea, five had obstructive sleep apnea, and one had both obstructive and central sleep apnea. Children with sleep-disordered breathing had excessive crowding of the brainstem structures at the foramen magnum and were more likely to have a greater length of herniation compared with those children without sleep-disordered breathing (P = 0.046). Patients with central sleep apneas received surgical decompression, and their conditions were significantly improved on follow-up polysomnography. These data suggest that imaging parameters may correlate with the presence of sleep-disordered breathing in children with Chiari I malformation.

Sleep apnoea in syndromic craniosynostosis occurs independent of hindbrain herniation

PURPOSE

Hindbrain herniation (HH) is frequently found in syndromic craniosynostosis. It may cause impairment of the respiratory centres and manifest as sleep-disordered breathing. Our aim was to quantify sleep apnoea caused by HH in children with syndromic craniosynostosis.

METHODS

Seventy-one children with syndromic and complex craniosynostosis (aged 0-18 years) underwent prospective magnetic resonance imaging and a sleep study. The position of the cerebellar tonsils and respiratory parameters were evaluated and analysed. None of the included patients had undergone previous foramen magnum decompression.

RESULTS

HH was present in 35% of the patients and was more frequent in children with Crouzon syndrome (63%) than in other types of craniosynostosis (p = .018). There was a positive association between the position of the cerebellar tonsils and papilledema (p = .002). Sleep studies of children with craniosynostosis and HH were not different from those without HH. Obstructive sleep apnoea syndrome was not more prevalent in children with HH compared to those without HH (p = .12). A cluster analysis using indices of apnoea revealed that three new clusters between which age was significantly different (p = .025).

CONCLUSION

Sleep apnoea in syndromic craniosynostosis is not caused by HH. Rather, our evidence suggests that sleep-disordered breathing in craniosynostosis may be caused by brain stem immaturity in young children or upper airway obstruction. Therefore, as long as the child remains asymptomatic, our preferred management of HH is to be conservative and provide regular neurosurgical follow-up.

Improvement of obstructive sleep apneas caused by hydrocephalus associated with Chiari malformation Type II following surgery

Chiari malformation (CM) is the downward herniation of the caudal part of the cerebellum and/or medulla oblongata into the spinal canal. It can alter several neurological functions, including respiratory control and upper airway motility, and can be the cause of sleep-disordered breathing (SDB). The authors describe a 6-year-old boy affected by CM Type II associated with myelomeningocele who showed symptoms indicative of severe airway obstruction during sleep. Polysomnography revealed severe obstructive sleep apnea syndrome (OSAS). Magnetic resonance imaging demonstrated herniation of the cerebellar tonsils and diffuse ventricular dilation with a large pseudocystic formation in the third ventricle. Surgical marsupialization of the cystic wall was performed, associated with ventriculocystostomy and endoscopic replacement of the ventricular catheter. Polysomnography repeated 2 months after surgery revealed a striking improvement in the sleep-related respiratory pattern. The pathogenesis of OSAS was probably referable to a combination of CM and elevated intracranial pressure. However, the striking improvement of symptoms after ventriculoatrial shunt placement suggested that hydrocephalus plays a major role in this condition. Assessment and effective treatment of SDB is crucial in the care of patients with CM.

The effects of posterior fossa decompressive surgery in adult patients with Chiari malformation and sleep apnea

Object

One of the feared consequences of craniovertebral junction diseases is apnea. Although several cases of patients with central apnea have been described, obstructive sleep apnea has been identified as the most frequent manifestation of sleep respiratory disorder. Neuronal involvement may be responsible for both central and obstructive apneas. The objective of this work was to study the effect of posterior fossa decompressive surgery on respiratory parameters during sleep in patients with craniovertebral junction malformations and breathing-related sleep disorders.

Methods

In this study, prospectively enrolled consecutive symptomatic adult patients were monitored with full-night polysomnography before and after surgical decompression of the cranial posterior fossa.

Results

Of the 25 patients who were evaluated, 68% received a diagnosis of sleep apnea. After surgery, the mean number of respiratory events decreased from 180.70 to 69.29 (p = 0.005); the mean number of obstructive events decreased from 107.37 to 60.58 (p = 0.01); and the mean number of central events decreased from 38.45 to 8.05 (p = 0.01). The mean preoperative apnea/hypopnea index decreased from 26.68 to 12.98 (p = 0.06), and the mean central apnea index decreased from 13.81 to 1.68 (p = 0.01).

Conclusions

Decompressive surgery in patients with craniovertebral junction malformations resulted in decreased respiratory events during sleep, lowered sleep fragmentation, and enhanced the sleep apnea index in a significant number of patients. The effect was more pronounced in patients with central apnea.

Sleep apnea and REM sleep behavior disorder in patients with Chiari malformations

BACKGROUND: Chiari malformations (CM) may result in the appearance of REM sleep behavior disorder (RBD) and sleep apnea syndrome (SAS) that can be considered markers of brain stem dysfunction. PURPOSE: To evaluate the frequency of RBD and SAS in patients with CM type I and II. METHOD: Were evaluated 103 patients with CM by means of full night polysomnography. Were scoring different sleep stages, frequency of abnormal movements (through video monitoring) and abnormal respiratory events. RESULTS: Of the 103 patients, 36 showed CM type I and 67 CM type II. Episodes of RBD were observed in 23 patients. Abnormal apnea-hypopnea index (AHI) was observed in 65 patients. CONCLUSION: The high rate of RBD suggests that this parassomnia and the increased frequency of central sleep apnea episodes, may be considered as a marker of progressive brain stem dysfunction.

Chiari malformation and sleep related breathing disorders

OBJECTIVE

To estimate the frequency, mechanisms and predictive factors of sleep apnoea syndrome (SAS) in a large group of children and adults with type I (CMI) and II (CMII) Chiari malformation (CM).

BACKGROUND

The anatomical and functional integrity of both respiratory circuits and lower cranial nerves controlling the upper airway is necessary for breathing control during sleep. These latter structures may be altered in CM, and a few investigations have reported CM related sleep disordered breathing.

METHODS

Forty-six consecutive unrelated patients with CM (40 CMI, six CMII), of which 20 were children (eight males) and 26 were adults (12 males), underwent physical, neurological and oto-rhino-laryngoscopic examination, MRI and polysomnography.

RESULTS

SAS was present in 31 (67.4%) of the patients with CM (70% of CMI, 50% of CMII, including mainly children). Sixty per cent of children with CM exhibited SAS, including 35% with obstructive (OSAS) and 25% with central (CSAS) sleep apnoea syndrome. SAS was observed in 73% of CM adults (57.7% OSAS, 15.4% CSAS). Severe SAS was found in 23% of CM adults. Multiple regression analysis revealed that age, type II Chiari and vocal cord paralysis predicted the central apnoea index.

CONCLUSION

SAS is highly prevalent in all age groups of patients suffering from CM. CSAS, a rare condition in the general population, was common among the patients with CM in our study. Sleep disordered breathing associated with CM may explain the high frequency of respiratory failures observed during curative surgery of CM. Our results suggest that SAS should be systematically screened for in patients with CM, especially before surgery.

Basilar impression and osteogenesis imperfecta: a 21-year retrospective review of outcomes in 20 patients

Object

Basilar impression (BI) secondary to osteogenesis imperfecta (OI) is a rare but debilitating condition that is often progressive unless it is halted. More recently, ventral decompression surgery has been advocated for this condition. This study is a retrospective review of the 21-year experience of ventral decompression surgery and dorsal occipitocervical fixation in patients with BI secondary to OI and is the largest patient series reported to date.

Methods

Twenty patients treated between 1982 and 2003 by the senior author at the authors' institution were included in this study. All patients underwent ventral decompression surgery followed by dorsal craniocervical stabilization. Patients were followed up for a median of 10 years.

Results

There were no intraoperative or perioperative deaths. Postoperatively, 16 of 20 (80%) patients showed objective improvement or maintained their good preoperative level of function. After surgery, of the 15 patients admitted with Karnofsky Performance Scale (KPS) scores of 70% or less, 11 improved, two remained unchanged, one patient's condition deteriorated, and one patient died of an unrelated cause. Of five patients admitted with a KPS score of 80% or greater, no patient's condition deteriorated in the short- and midterm period, but one patient had recurrence 15 years after surgery. At the end of follow-up, 25% of the patients had recurrence of brainstem compression symptoms or had died, and 15% showed no improvement after surgery. All of the remaining patients (60%) had sustained a long-term benefit from surgery.

Conclusions

Aggressive ventral decompression surgery and dorsal stabilization for patients with BI secondary to OI can not only halt disease progression but can also produce a good and sustainable long-term functional outcome, even in those patients who present as severely symptomatic. Patients who presented early with minor symptoms had good long-term outcomes.

Adult Chiari malformation and sleep apnoea

Chiari malformation (CM) is primarily characterised by herniation of the cerebellar tonsils through the foramen magnum. Clinically, two main types of CM represent the vast majority of cases: type I (in adults) and type II (in infants). CM may result in neuronal impairment of the brainstem, upper spinal cord and cranial nerves. Part of the afferent and efferet systems and the central respiratory controlling system are located in the cranium-cervical transition and may be damaged in these pathologies, leading to respiratory disorders, such as respiratory failure and death. The ventilatory responses to exogenous and endogenous stimuli, such as responses to hypoxia and hypercapnia, are usually diminished, and apnea may be manifested and detected during sleep, allowing for the diagnosis. This study is a review of the relationship between sleep apnoea and adult CM.