CONGENITAL NASAL PYRIFORM APERTURE STENOSIS AS A RARE CAUSE OF CYCLICAL CYANOSIS

further. We planned for computed tomography of the paranasal sinuses (CT PNS) as bilateral choanal stenosis was suspected. Subsequently, she was discharged home on DOL 17. At home, the mother claimed she was having intermittent noisy nasal breathing during episodes of rhinorrhea with no affected feeding and sleeping. There were no cyanosis episodes reported. She managed to undergo CT PNS as an outpatient. One week after the CT scan, she was readmitted to NICU due to rapid breathing at home associated with


Introduction
The nasal pyriform aperture is a pear-shaped opening located at the frontmost part of the nose.The lateral boundary of the structure is formed by the nasal process of the maxilla, the inferior boundary is formed by the horizontal process of the maxilla, the anterior boundary is formed by the nasal spine, and the superior boundary is formed by the nasal bones.Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of breathing difficulties in newborns, caused by an abnormal overgrowth of bone in the nasal area of the upper jaw.Due to its narrowness, any decrease in the diameter of the pyriform aperture can present significant risks to one's life.The first radiological features were described in 1988 by Ey et al. [1], before the initial clinical depiction was documented by Brown et al. a year later [2].

Case Report
A 3-month-old, full-term baby girl was born by elective lower caesarean section to a mother with established diabetes mellitus (DM) for a suspected macrosomic baby, with a good APGAR score.She was monitored in the Neonatal Intensive Care Unit (NICU) for fluctuating asymptomatic hypoglycemia.On DOL 3, she had history of sudden brief episodes of cyanosis and desaturation during sleep and relieved upon awakening and crying.She was then put on oxygen supplementation (NPO 2 2L/min) and then upgraded to high flow nasal cannula (HFNC) 6L/min FiO2 21% due to worsening respiratory distress secondary to congenital pneumonia, evidenced by perihilar haziness on the chest X-ray.Nasoendoscopy using a paediatric flexible scope 2.2mm was attempted twice, both before and after initiating oxymetazoline 0.01% nasal drop for three days.However, the scope could only be advanced up to the middle turbinate but could not pass through further.We planned for computed tomography of the paranasal sinuses (CT PNS) as bilateral choanal stenosis was suspected.Subsequently, she was discharged home on DOL 17.At home, the mother claimed she was having intermittent noisy nasal breathing during episodes of rhinorrhea with no affected feeding and sleeping.There were no cyanosis episodes reported.She managed to undergo CT PNS as an outpatient.One week after the CT scan, she was readmitted to NICU due to rapid breathing at home associated with rhinorrhea and nasal blockage for two days prior.She was put on nasal Continuous Positive Airway Pressure (CPAP) due to persistent respiratory distress.
CT PNS confirmed the diagnosis of CNPAS (Figure 1).The decision on surgical intervention was discussed with the parents and agreed to the operation.The patient was planned for examination under anesthesia (EUA) nose and CNPAS repair with stent insertion.Post operatively, she was kept intubated for 48 hours, with intravenous (IV) Cefuroxime 15 mg/kg TDS and IV Dexamethasone 0.5mg TDS for three days on board.Nasal suctioning with saline drops using a suction catheter size of 8 French, inserted at least 6cm, was performed at least once per shift through the nasal stent, which remained in place for one week.
Feeding was resumed according to requirement.
Upon follow-up at 2 weeks post-operation, she was well, with no respiratory symptoms.There was no noisy or difficulty in breathing and tolerating feeding.She was not tachypnoeic and had no stridor on examination.The Cottonwool test showed patent bilateral nostrils.Flexible scope demonstrated a clear nasal secretion and was able to pass through the scope into the nasal cavity to the nasopharynx (Figure 3).

Discussion
Newborns and infants are obligate nasal breather, particularly during feeding.Mouth breathing occurs between 3 to 6 months.CNPAS can cause significant obstruction, especially if pyriform orifices are very narrow, resulting in rapid onset of severe respiratory distress.The worsening of cyanosis during feeding and improvement when crying can indicate an obstructive origin of neonatal distress.
CNPAS may manifest as a singular malformation or be linked with additional craniofacial and encephalic abnormalities [3,4].It is frequently connected to other conditions such as solitary median maxillary central incisor, holoprosencephaly, and pituitary dysfunction.Holoprosencephaly is an infrequent condition characterized by an improper division of the developing forebrain, resulting in the absence of distinct cerebral hemispheres, diencephalon, optic, and olfactory bulbs.However, no abnormalities were detected in this patient, as evidenced clinically by the absence of premature dentition and central incisor anomalies, along with normal ultrasound brain showing no signs of holoprosencephaly.
Respiratory distress may manifest through various symptoms such as noisy breathing, desaturation, sternal recession, and cyclical cyanosis, with evidence of hypoxemia and acidosis.These symptoms might exacerbate during upper respiratory tract infection (URTI), as in our patient.Infants with this condition may experience feeding difficulties, cyclical cyanosis, or respiratory distress, which can temporarily improve when they cry and open their mouths.Additionally, if the nasolacrimal duct is affected by bony involvement, patients may present with epiphora.
In neonates, the larynx is positioned higher in comparison to adults.When swallowing occurs, it meets the nasopharynx and fits between the soft palate and the side of the nasopharynx.When the mouth is sealed during both inhalation and  The indications for surgical treatment include moderate-to-severe stenosis causing respiratory distress or failure to thrive, an aperture measuring less than 5mm on a CT scan, failure of conservative treatment and nasal stenting, and persistent symptoms despite initial interventions [11].In our present case, surgical widening of pyriform apertures was deemed necessary due to the patient's recurrent respiratory distress and prolonged requirement for oxygen support, even after being discharged home.Surgical approaches may include the sublabial or transnasal approach.In cases where signs of restenosis manifest and become symptomatic, reexpansion techniques such as a balloon or Liston dilator may be required, as it is mostly a soft tissue stenosis.

Figure 1 .
Figure 1.Axial non-contrast CT image depicts the abnormal narrowing of the pyriform aperture (yellow arrow) with measurement of the narrowest part of 0.5cm.

Figure 3 .
Figure 3. (a) Appearance of nostrils 2 weeks post operation during follow-up with normal nasal vestibular opening.(b) Flexible scope image of right nostril during follow-up with ability to pass through the scope without anterior bony obstruction (red arrow: middle turbinate).
exhalation, the soft palate exerts pressure on the soft tissue and the tongue within the oral cavity, potentially leading to obstruction of the oral airway.