INTRODUCTION

Stridor in children with subglottic cyst is rare. It is one of the potential life threatening conditions seen in the Emergency Department (ED), which jeopardize the airway. An acquired subglottic cyst is a condition resulting from previous trauma to glottic mucosa during intubation (Agada et al. 2006). Its clinical manifestations vary considerably from being asymptomatic to an airway obstruction and respiratory failure. Therefore, high index of suspicion is the key to early identification for prompt intervention from multidisciplinary teams. We highlight an important but an under-recognised case of acquired post-intubation subglottic cyst during a neonatal period presenting with stridor. The challenges encountered for identification and management of this case are being discussed.

CASE REPORT

A 6-month-old baby girl, presented to ED of an academic hospital at day 3 of illness for worsening stridor with cough, rhinorrhea and poor oral intake. However, she had no fever. She was born prematurely at 27 weeks. Her birth weight was 855 gms and required ventilation support at 10 hrs of life for respiratory distress. The process of intubation was uneventful. She was initially extubated after 3 95days but required repeat intubation for recurrent apnoeic episodes due to sepsis for another 3 days. She was noticed to have stridor since the age of 4 months, and was diagnosed for acute bronchiolitis at 5 months of age. During initial assessment, she appeared irritable. She was in respiratory distress with evidence of chest recession, and biphasic stridor, loud on inspiration. She appeared pink, and well perfused with capillary refilled time of less than 2 secs. Her respiratory rate was 56/min, blood pressure was 90/50 mmHg, heart rate was 196/min, afebrile, and oxygen saturation under room air (SpO2) was 85 %, which picked up to 100% on supplemental oxygen of 1l/min. There was transmitted sound over the lungs and reduced air entry at both bases. Other systemic examination was unremarkable. Laboratory findings showed that the total white cell count (WCC) was 9.3 x 109/l (normal range, 4-10x109/l), neutrophils 35.7%, lymphocytes 58.1%, haemoglobin 12.1g/dl (12-15 g/dl), and the platelet count was 334 x 109/l (150-410 x 109/l). Blood electrolytes were normal except that there was evidence of hyperkalaemia with serum potassium of 5.9 mmol/l (3.5-5.0). Her C-reactive protein was not raised <0.003 mg/dl (<1.0). Capillary blood gases on room air were as follows: pH 7.34, PaCO2 59.6 mmHg, PaO2 44.6 mmHg, HCO3 29.3 mmol/L. The infant was treated at the critical area as moderate to severe croup. However, she did not respond to intravenous dexamethasone at 2.5 mg and 2 mg of inhaled budesonide. A bolus intravenous adrenalin (1:1000) was delivered to her as she became progressively breathless and the stridor became worsened by the next few hours. She was then transferred to the Paediatric Intensive Care Unit (PICU). The patient was subjected to intubation due to worsening respiratory acidosis (Capillary Blood Gases: pH 7.25, pCO2 60.6 mmHg, pO2 61.3 mmHg, HCO3 22.5 mmol/l). However, there were difficulties with the intubation attempts. The vocal cord appeared oedematous with an unexplained resistance, which prevented the tube from passing thorough the trachea. She was urgently sent to the operating theatre for an emergency advance airway procedure. A direct laryngoscopy showed subglottic cyst (Figure 1). Subsequently endolaryngeal microsurgery (ELMS) was performed in emergency setting. Histopathological report showed benign epithelial cyst. Intravenous dexamethasone was continued for 9 days in tapering fashion. With all the efforts made, she was discharged well after 10 days of admission.

DISCUSSION

Subglottic cysts can be either congenital or acquired and can present as single or multiple cysts, but it is often difficult to distinguish, as most paediatric patients coming in with respiratory distress generally requires endotracheal intubation based on clinical judgment without prior endoscopy. The first-reported case was in 1968 with the patient’s death due to subglottic cysts (Wigger & Tang 1968).

The challenges remain in diagnosing subglottic cysts as early detection and intervention play a crucial role in improving a patient outcome and reducing the need for tracheostomy. A subglottic cyst clinical presentation varies depending on the size and location of the cyst. Inspiratory stridor and expiratory stridor suggest airway obstruction above and below the glottis, respectively. Biphasic stridor on the other hand, suggests of glottic or subglottic lesions. In the present case, the premature infant presented with biphasic stridor. Apart from that, she had a previous neonatal history of intubation. This condition should prompt the clinicians to narrow down the possible cause of stridor and to look for possible underlying cysts in infants’ larynx.

A review from previous literature showed that the development of subglottic cysts has a strong association with past history of neonatal intubation (Johnson et al. 2005). However, the duration of intubation has limited value in predicting the risk of development of subglottic cyst. A study showed that it could develop even after a period of intubation of less than 24 hrs (Johnson et al. 2005). A majority of the cases developed in premature infants (Lim et al. 2003). Agada et al. (2006) found 7 cases of subglottic cyst in a large cohort of 12,240 premature newborns. All 7 cases had history of intubation with an average intubation period of 20.6 days. The development of subglottic cyst is not always associated with history of prematurity and previous intubation. Aksoy et al. (2012) found in their study that 6 out of 9 children had no history of previous intubation.

Direct laryngoscopy is accepted as a gold standard tool to diagnose subglottic cysts (Zawadzka-Glos et al. 2009). In this patient, direct laryngoscopy was done on the next day when the infant’s condition deteriorated and endotracheal intubation faced difficulty. Subglottic cysts are treatable as they can be decompressed by needle puncture and aspiration. It can safely be removed with laryngeal microdebrider with a low recurrence rate (Ransom et al. 2009). However, long-term follow-up should be planned for patients treated for subglottic cysts as there is still risk of recurrence (Lim et al. 2003).

CONCLUSION

In the present case, we highlighted the need to have a high index of suspicion to diagnose subglottic cyst in premature infant with biphasic stridor and previous history of neonatal intubation. Early diagnosis is vital to successfully manage the airway without complications.

ACKNOWLEDGEMENT

The authors thank the doctors, paramedics and administrative support staff in the ED, Universiti Kebangsaan Malaysia for the assistance.