נאונטולוגיה

Quiz No. 24 is presented by Dr. Mila Barak – Lis Maternity Hospital, Tel-Aviv – ועכשיו גם התשובה

A female infant weighing 2700 gm was delivered at 40 weeks of gestation by a Cesarean Section to a HIV positive mother. The baby developed increasing breathing difficulties and was therefore admitted to the Neonatal Intensive Care Unit. Physical examination revealed tachypnea with subcostal and sternal retractions. The O2 saturation was 88-92% in room air. Two hours later, the oxygen saturation dropped, respiratory acidosis developed and the chest X ray showed right pneumothorax and pneumomediastinum. She was intubated and mechanically ventilated.

The next day, in spite of 100% O2 administration and pneumothorax drainage, she became even more hypoxic, requiring intensive mechanical ventilation. The echocardiography showed signs of pulmonary hypertension, therefore Nitric Oxide (NO) was administered with a significant improvement in oxygenation.

Five days later, after gradual improvement in her respiratory status, an extubation was performed but failed after a few hours due to increasing respiratory effort and respiratory acidosis. Over the next week, two additional extubation trials failed because of marked respiratory distress, mostly inspiratory, suggesting airway obstruction. Direct laryngoscopy and bronchoscopy did not reveal a possible cause for the respiratory distress.

A very simple – bed-side procedure was done that directed the clinicians towards an investigation that revealed the final diagnosis.

1. What bed-side procedure was done?

2. What was the investigation?

3. What is the diagnosis?

4. What is the treatment?


התשובה







1. The procedure was – passing an NG tube through the nose.

2. The investigation was – nasal endoscopy and CT scan.

3. Diagnosis: Congenital nasal pyriform aperture stenosis.

4. Treatment – surgery.

The infant underwent a surgical sublabial repair of the defect by enlarging the bony pyriform aperture. Tube stents were left in the place for one week and then removed, without any further adverse events.

Additional investigations included: head CT scan which did not show associated anomalies, kariotype which was normal and renal ultrasound examination which revealed significant enlargement of the right kidney pelvis. Further investigations of this problem were planned over the next month in the pediatric urology clinic.

The baby was discharged at the age of 4 weeks, without prominent respiratory problems, on full oral feedings.

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare and an unusual cause of airway obstruction in infants. Its radiologic appearance was first described by Ey et al. [1] in 1988 and its clinical findings detailed by Brown et al. [2] in 1989.

The nasal pyriform aperture is the bony inlet and represents the narrowest part of the nasal airway. Even a small change in its cross-sectional area can result in a significant increase in nasal airway resistance. This increase in airway resistance can increase the effort necessary to breathe to such a degree that it often leads to exhaustion. CNPAS can mimic the clinical findings of choanal atresia.

Presenting symptoms in infants may include respiratory distress, cyclical cyanosis, inability to nurse, or sudden total airway obstruction. Symptoms can occur immediately after birth or within a few months of life depending on the level of obstruction. The breathing problems may be triggered by an upper respiratory infection that further narrows an already compromised airway.

Physical examination may reveal extremely narrow anterior nasal fossas.

Passage of nasal catheters or endoscopes may be difficult.

Timely recognition and appropriate therapy are required for airway management.

Belden et al. [3] described the CT measurements and features of CNPAS patients compared with control population.

They felt a width less than 11 mm in a term infant is considered diagnostic for CNPAS. Findings of abnormal dentition or a bone ridge along the underside of the palate may also be confirmatory CT findings.

CT with contiguous thin sections (13 mm thick) through the midface from the palate to orbital roof is the study of choice.

The developmental embryology and etiology of CNPAS are still unclear. The development of the nose and nasal passages begins in the 3rd week of embryologic life. Maxillary ossification begins from the growth center above the canine teeth and at 4 months meets the cartilaginous nasal capsule and forms the lateral nasal walls. It has been postulated that an overgrowth of maxillary ossification at the area of the nasal process of the maxilla is responsible for the anomaly of pyriform aperture stenosis.

Congenital pyriform aperture stenosis can be isolated or it can occur as a part of other multiple abnormalities. Associated anomalies have been reported including: absence of the anterior pituitary gland, submucous cleft palate, hypoplastic maxillary sinuses, prominent central incisor (mega incisor) or as a manifestation of the holopresencephaly sequence .

Management of CNPAS depends on the severity of the symptoms. As with any neonate in respiratory distress establishing a safe airway is the primary goal. Oral airway and appropriate monitoring in an intensive care unit setting represents the initial intervention. Gavage feedings may be necessary for the beginning. Mild nasal obstruction can be managed conservatively with humidification, topical nasal decongestants and suctioning. However, the infant eventually required surgical intervention. If the infant is discharged with a McGovern nipple, home apnea monitoring and cardiopulmonary resuscitation training for the family should be considered. Infants who display cycles of cyanosis, apnea, significant nasal obstruction should be considered for surgical intervention

Two approaches to surgical repair of pyriform aperture stenosis have been described. The transnasal approach has been utilized in adults but is technically difficult with an inadequate visualization in infants .The sublabial approach utilizing magnification, ear drill with a wide selection of cutting and diamond burrs and micro-instruments is the preferred method.

Conclusions: CNPAS is a rare and an unusual cause of airway obstruction in infants. Timely recognition of the condition with appropriate airway management is essential to avoid a possible deadly outcome. Definitive surgical correction with attention to anatomic detail can be easily and safely accomplished at almost any age. Associated anomalies should be investigated, but this condition commonly occurs as an isolated deformity with no long-term sequelae.

References

1. E.H. Ey, B.K. Han, R.B. Towbin and W. Jaun, Bony inlet stenosis as a cause of nasal airway obstruction. Radiology 168 (1988), pp. 477479

2. O.E. Brown, C.M. Myer and S.C. Manning, Congenital nasal pyriform aperture stenosis. Laryngoscope 99 (1989), pp. 8691.

3. C.J. Belden, A.A. Mancuso and I.M. Schmalfuss, CT features of congenital nasal pyriform aperture stenosis: initial experience. Radiology 213 (1999), pp. 495501.


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