Stridor, myelomeningocele, and hydrocephalus in a child

Stridor in children: Is airway always the cause?

Stridor in children is usually, but not always caused by airway pathology. The anesthesiologists should have a sound knowledge of the neurological associations of stridor and its management. In such cases, prompt treatment of the neurological pathology usually resolves the stridor and may prevent unnecessary airway evaluation and intervention in the child.

Role of estimation of arterial blood gases in the management of stridor

AIM

We studied the epidemiology and etiology of stridor in our patients along with the role of arterial blood gas (ABG) analysis in their management. We also reviewed their prognostic indices and the clinical outcomes.

MATERIALS AND METHODS

It was a prospective study in a tertiary referral hospital in which 72 patients presenting with stridor, were independently evaluated by 3 different clinicians and clinically classified into mild, moderate and severe. Based on ABG values (pH, PO2, PCO2), we defined 3 groups of patients viz, those in respiratory failure, impending respiratory failure and those with no evidence of failure. Treatment was directed at the cause of stridor. Clinical outcomes were assessed and results classified as resolved, improved, stable and death.

RESULTS

Out of 72 patients, kappa coefficient of agreement between the 3 observers were found to be 0.014, indicating poor interobserver reliability for the working clinical classification. However, ABG analysis indicated otherwise, with 6 patients in respiratory failure, 19 progressing to impending failure. Hence we complied by the more objective ABG analysis in planning management. Laryngomalacia in children and hypopharyngeal malignancies in adults were found to be the most common causes of stridor in our study. As compared to other conditions, laryngomalacia in children had a poorer outcome (p = 0.001).

CONCLUSION

Early detection of impending respiratory failure was instrumental in achieving better clinical outcomes in our patients presenting with stridor. Thus we inferred that ABG analysis is a valuable tool in the effective management of stridor.

The Chiari II malformation: cause and impact

INTRODUCTION

It is the Chiari II malformation and its effects that determine the quality of life of the individual born with spina bifida.

DISCUSSION

The cause of this malformation has been a source of debate for many years. Understanding the cause enables strategies for the management of problems created by this malformation to be developed. An open neural tube defect allows fluid to escape from the cranial vesicles, altering the intracranial environment and leads to all of the brain changes seen in the Chiari II malformation. Decompression of the intracranial vesicles causes overcrowding, decrease in the size of the third ventricle, and changes in the fetal skull. It also permanently links the intracranial ventricular system to the spinal cord central canal.

Outcome following hindbrain decompression of symptomatic Chiari malformations in children previously treated with myelomeningocele closure and shunts

Between 1975 and 1989, 25 children treated with myelomeningocele closure and shunting for hydrocephalus at the Children's Hospital of Pittsburgh developed progressive lower brain-stem dysfunction from their Chiari malformation. Retrospective univariate and multivariate analyses of these cases were undertaken to assess the relationship between preoperative clinical factors and postoperative outcome. Since earlier reports have suggested that neonates with symptomatic Chiari malformations show a less favorable response than older children to craniocervical decompression, particular attention was directed at examining the effect of age on preoperative symptoms and postoperative outcome. Patients were subdivided by age into two groups, namely: 13 patients who became symptomatic before 2 months of age (neonatal group) and 12 older infants and children who developed initial symptoms between 6 months and 10 years of age. Once symptoms developed, patients in both groups deteriorated progressively until brain-stem decompression was performed. The mode of presentation and the rate and extent of neurological deterioration differed substantially in the two groups. Whereas the neonates typically showed rapid neurological deterioration and often manifested profound brain-stem dysfunction within a period of several days, the older patients experienced a more insidious symptom progression and rarely demonstrated the severe degree of impairment seen in the neonates. All patients underwent suboccipital craniectomy, cervical laminectomy, and dural decompression. A shunt from the fourth ventricle and/or syrinx to the subarachnoid space was placed in those with significant syringomyelia. Following surgery, 17 patients had complete or nearly complete resolution of all signs of brain-stem compression, three had mild to moderate residual deficits, and five showed no improvement. Outcome correlated closely with the preoperative neurological status. In particular, the presence of bilateral vocal cord paralysis was associated with a poor response to surgery (p < 0.001 on both univariate and multivariate analyses). Of the six patients (all neonates) who progressed to complete bilateral vocal cord paralysis before surgery, only one improved. In contrast, all patients with less profound but nonetheless severe deficits recovered function postoperatively. Although the neonates as a group had a poorer outcome than did the older patients (p = 0.02 on univariate analysis), this in large part reflected their more severe preoperative impairments; neonates who still had some preservation of vocal cord function before surgery subsequently did as well as the older patients. Accordingly, age did not prove to be an independent prognostic factor on multivariate analysis. Taken together, these results indicate that, in most patients with symptomatic Chiari II malformations (including neonates), neurological deficits are potentially reversible if hindbrain decompression is performed expeditiously.

Anatomical progression of the Chiari II malformation

To evaluate whether anatomic change of the relationship of the Chiari II malformation and the cranial base was occurring, 22 children with meningomyelocele had serial MRI scans reviewed. A ratio (B/A) was established between the distance from the foramen magnum to the caudalmost portion of herniated cerebellum (B) and the diameter of the foramen magnum (A) and this ratio was compared on serial MRI scans. Eighteen children had an increase in the B/A ratio, two children had a decrease, and two had no change. This indicates that continuous anatomic change of the Chiari II malformation and the skull base is occurring. Clinical deterioration in the older child may be explained by a combination of compressive and traction forces due to this change.

Symptomatic Chiari malformations. An analysis of presentation, management, and long-term outcome

The Chiari malformation is a condition characterized by herniation of the posterior fossa contents below the level of the foramen magnum, and is categorized into three types based on the degree of herniation. The authors review their surgical experience between 1975 and 1985 with 50 patients afflicted with symptomatic Chiari malformations. Any patient with associated myelomeningocele, tethered spinal cord, lipoma, or diastematomyelia was excluded from this series. Forty-one patients had Chiari I malformations, seven were classified as having Chiari II, and two as having Chiari III. The presentation of pediatric and adult patients was identical. Treatment was directed at the posterior fossa pathology. Seven patients with accompanying ventral bone compression underwent transoral decompression of the cervicomedullary junction, 42 had posterior decompressive procedures, and six received ventriculoperitoneal shunts. The posterior decompression included opening the outlet foramina of the fourth ventricle, occluding any communication between the spinal cord central canal and the obex, shunting the fourth ventricle, and placing a dural graft. Postoperatively, 20% of the patients are asymptomatic, 66% improved, and 8% stabilized; in 6% the disease has progressed in spite of multiple procedures. Preoperative signs that are predictive of a less favorable outcome include muscle atrophy, symptoms lasting longer than 24 months, ataxia, nystagmus, trigeminal hypesthesia, and dorsal column dysfunction (p less than 0.05, chi-square test). A model based on the presence or absence of atrophy, ataxia, and scoliosis at the time of the preoperative examination has been generated that allows prediction of long-term outcome at the 95% confidence level.

Symptoms and signs of progressive hydrocephalus

The clinical features of 107 cases of children with hydrocephalus and measured raised intraventricular pressure were analysed retrospectively. Fifty one children had recently been diagnosed as having hydrocephalus, and the remainder had had shunts injected to direct the cerebrospinal fluid. The most common symptoms in the group were vomiting, behavioural changes, drowsiness, and headaches. The most common clinical signs were inappropriately increasing occipitofrontal head circumferences, tense anterior fontanelles, splayed sutures, and distension of the scalp veins. Half the infantile cases of hydrocephalus were without symptoms, and a quarter of the cases with cerebrospinal fluid shunts and measured raised intraventricular pressure were without signs. There were no fewer than 33 different clinical signs including several unusual ones, such as macular rash and sweating. We believe that the presentation of hydrocephalus with raised intraventricular pressure is sufficiently variable, unusual, or even absent to justify the direct measurement of intracranial pressure.

Abnormal ventilatory patterns during sleep in infants with myelomeningocele

Some infants with myelomeningocele, hydrocephalus, and Arnold-Chiari malformation have symptomatic apnea or hypoventilation. The incidence of abnormalities of the ventilatory pattern during sleep in asymptomatic infants with myelomeningocele is not known. Therefore we performed overnight pneumograms (recordings of ventilatory pattern and electrocardiogram) in 18 asymptomatic infants with myelomeningocele and compared them with pneumograms from 64 control infants. Infants with myelomeningocele had longer total sleep time (596 +/- 16 minutes vs 536 +/- 10 minutes, P less than 0.005), longer episodes of longest apnea (12.6 +/- 0.8 seconds vs 8.1 +/- 0.3 seconds, P less than 0.001), greater total duration of apnea greater than or equal to 6 seconds as percent total sleep time (1.02% +/- 0.18% vs 0.23% +/- 0.03%, P less than 0.001), and lower mean heart rates (120 +/- 5 vs 145 +/- 5, P less than 0.001) than did control infants. No abnormal bradycardia was observed in either group. Thirteen (72%) of 18 infants with myelomeningocele had abnormal pneumograms, compared with 4 (6%) of 64 control infants (P less than 0.0005). We conclude that asymptomatic infants with myelomeningocele have a high incidence of ventilatory pattern abnormalities during sleep.

Shunt placement and myelomeningocele repair: simultaneous vs sequential shunting. Review of 12 cases

The optimal management of patients with myelomeningocele and hydrocephalus is facilitated by a constant review of the patients with the aid of the sonogram and CT scan. Six infants treated with simultaneous shunt placement and myelomeningocele repair were compared with six other neonates treated with conventional sequential myelomeningocele repairs requiring a second separate procedure for shunt placement. Infants operated upon simultaneously experienced no increase in morbidity or mortality and appeared to benefit substantially.

An unusual form of laryngeal paralysis associated with Arnold-Chiari malformation

This paper alerts the otolaryngologist to a previously unreported type of laryngeal paralysis (adductor type) in association with the Arnold-Chiari malformation. A survey of the literature fails to reveal any similar documented cases of absent laryngeal sensory function in association with this neurological defect. All prior reports have dealt with abductor laryngeal paralysis associated with the Arnold-Chiari malformation in which airway obstruction was the predominant laryngeal symptom. In the patient reported here, aspiration was the predominant symptom and was due to total loss of laryngeal sensation. This report describes this patient's clinical findings in detail, reviews the literature, and discusses management.

Respiratory obstruction and apnea in infants with bilateral abductor vocal cord paralysis, meningomyelocele, hydrocephalus, and Arnold-Chiari malformation

This report describes 21 infants and children with bilateral abductor vocal cord paralysis and associated meningomyelocele, Arnold-Chiari malformation, and hydrocephalus. Two life-threatening forms of respiratory distress are distinguished: (1) upper airway obstruction due to bilateral abductor cord paralysis and (2) apnea. Clinically significant episodes of apnea were documented in 13 infants. Ten infants had evidence of aspiration and dysphagia. Vocal cord paralysis, apnea, aspiration, and dysphagia were frequently temporally related to increased intracranial pressure.