# 1) Define CNPAS: embryology & epidemiology ## a) What CNPAS is (and why it matters) - **Definition:** Bony narrowing of the pyriform aperture from overgrowth of the **nasal process of the maxilla**, causing clinically significant **anterior** nasal obstruction in neonates/infants. - **Key CT threshold:** **PA < 11 mm** (term infant) on thin axial CT (1.5–3.0 mm). Symptomatic/operative cohorts often **≈3–6 mm**. - **Flow implication:** Tiny radius changes → big resistance changes (**A = πr²**). A PA of **4–6 mm** can be functionally obstructive. **Typical consequences:** feeding difficulty, cyclical cyanosis (worse with feeding, better with crying), apnea, FTT, extubation failure. **Differentiate from choanal atresia:** - CNPAS = **anterior** block (within ~1 cm of nares); **fails 5–6 Fr** anterior catheter or 2.2 mm scope. - Choanal atresia = **posterior** block; **NG/8 Fr** fails to reach nasopharynx. **Management overview:** - Mild → humidification, saline, short-course decongestant, topical steroid, feeding aids (McGovern nipple/oral airway). - Severe/failed conservative/extubation failure → **surgical widening** (sublabial drill-out ± stent) or **minimally invasive dilation** (Hegar/balloon). - Surgical endpoint often: **bilateral passage of 3.5 cuffless ETT** or **8 Fr suction catheter**. **High-yield numbers:** - Diagnostic CT: **PA < 11 mm**. - Predicts surgery: **PA ≤ 5.7–6 mm** (use as a **flag**, not an absolute). - Common stents: **2.5–3.5 mm I.D. ETT** (O.D. ~3.5–4.8 mm), typical dwell **~5–14 days** (historic range 5–28 d). **Pitfalls:** assuming posterior disease, injuring mucosa during drilling, unsecured/overlong stents, **prolonged stenting → pressure necrosis/ulcers**. ## b) Embryology (succinct) - **Primary palate** (anterior to incisive foramen) from **fused medial nasal prominences**; **lateral palatal shelves** from **maxillary prominences**. - **Maxillary ossification ~8th week**; nasal process forms **lateral PA boundary**. - Two mechanisms → CNPAS: 1. **Over-ossification/dysostosis** of maxillary nasal process. 2. **Primary palate hypoplasia** (triangular small palate) narrowing the inlet. **Holoprosencephaly spectrum link:** CNPAS is a **midline field** anomaly. Look for **SMMCI**, palatal ridge, olfactory/pituitary abnormalities. **Implications:** If **SMMCI** or midline signs → **MRI brain (pituitary protocol)** + **endocrine eval**; consider chromosomal microarray. ## c) Rarity & presentation - Less common than choanal atresia; presents **hours–days** after birth, later if mild. - Many centers trial conservative care; **median first procedure ~1–2 months** in some series (reflects initial medical trial). - **Red flags:** cyclical cyanosis, feeding failure, failure to pass **5–6 Fr** anteriorly, extubation failure. --- # 2) Clinical presentation & initial assessment ## a) What you’ll see - **Cyclical cyanosis** relieved by crying, tachypnea/retractions, feeding difficulty, FTT, apnea/desats.tachypnea/retractions, feeding - **Look for SMMCI** (≈40–60%); if present → MRI/endocrine. **Objective anchors:** - **Bedside:** inability to pass **5–6 Fr** catheter through anterior nares. - **CT:** **PA < 11 mm** diagnostic; **≤5.7–6 mm** raises surgical likelihood. ## b) Bedside localization (quick) 1. Try **lubricated 5 Fr**, then **6 Fr** along nasal floor. **Hard stop in first ~1 cm** = anterior (CNPAS). 2. 2.2 mm scope: if cannot pass anteriorly with firm resistance → supports CNPAS. 3. If **NG/8 Fr** can’t reach nasopharynx → think **choanal atresia** (posterior). **Do not force**; document largest size passed and depth of resistance. ## c) Immediate stabilization (priorities) - **Airway & nutrition:** McGovern nipple or nipple or**oropharyngeal airway**, humidification (oxyhood/blow-by), orogastric feeds. - **NICU monitoring** if respiratory or feeding compromise. --- # 3) Imaging: how to do it & what to measure ## a) CT technique (bone detail) - **Thin axial 1.5–3.0 mm**, **parallel to hard palate** (avoid obliquity). Reconstruct coronal/sagittal; small FOV; ALARA. - **Measure** minimum **bony** PA width **between inner cortices** at standardized level; report mm and level. ## b) Thresholds (interpretation) - **<11 mm** (term) = CNPAS. - **≤5.7–6 mm** → higher odds of surgery; still integrate with clinical course. ## c) What else to note - **SMMCI**, midline palatal ridge, nasolacrimal duct/tooth buds, turbinate position/soft tissue.nasolacrimal duct/tooth buds, turbinate position/so - **MRI brain (pituitary protocol)** if SMMCI/midline signs/abnormal neuro exam. --- # 4) Associated anomalies & multidisciplinary workup ## a) Common associations - **SMMCI (~34–60%)**, holoprosencephaly spectrum (~15–27% in series), holoprosencephaly spectrum (~15–27% in**pituitary dysfunction (~15–25%)**. ## b) Workup checklist - **ENT/NICU, Endocrine, Genetics, Ophthalmology, Radiology**. - **Labs (baseline):** glucose, electrolytes, **AM cortisol/ACTH**, **TSH/free T4**, **prolactin** (consider IGF-1/IGFBP-3 later). - **Genetics:** microarray; holoprosencephaly panel if indicated.holoprosencephaly panel i ## c) Longitudinal monitoring - Growth surveillance (0–12 mo frequent; annually thereafter), periodic thyroid/adrenal/GH axis checks if risk. - Ophthalmology/neurology follow-up as indicated. - **Low threshold to re-test** if poor growth at ~1 year or symptoms. --- # 5) Conservative management ## a) Medical therapies - **Saline** drops/irrigation (frequent while stented: often **Q2–Q3H**). - **Topical steroid** drops (e.g., dexamethasone ophthalmic 0.1%) **short course**; monitor for adrenal suppression. - **Short-term decongestant** (oxymetazoline/xylometazoline) for procedures or brief relief.oxymetazoline/xylometazoline) for proc ## b) Temporizing airway - **McGovern nipple** or **oropharyngeal airway** for mouth breathing support; **oxyhood** for humidification (stent-friendly). - OG feeds as needed; escalate to CPAP/intubation if inadequate. ## c) When conservative care has failed - Typical trial **~2–3 weeks** if stable. - **Early surgery** if persistent distress, failure to wean support, extubation failure, or FTT. --- # 6) Indications for surgery & timing ## a) Operate when - **Apnea/cyanosis** despite medical care, **failure to extubate/wean**, persistent distress, or **poor weight gain** from obstruction. ## b) Imaging as a guide (not the boss) - **PA width** confirms diagnosis; **≤5.7–6 mm** suggests higher surgical need but **clinical course rules**. ## c) Comorbidities & timing - Holoprosencephaly/SMMCI → coordinate **MRI/endocrine**; consider minimally invasive or staged plans. - **Immediate/early repair** if unstable; **delayed/minimally invasive** if stable and growing. --- # 7) Open sublabial drill-out (maxillary vestibular) - **Steps:** gingivobuccal sulcus incision → subperiosteal elevation → incision**limited lateral drilling** of maxillary nasal processes with diamond burr. - **Priorities:** **preserve mucosa**, protect **inferior turbinate**, **nasolacrimal duct**, and **tooth buds**. - **Endpoint:** **bilateral 3.5 cuffless ETT** or **8 Fr** passes smoothly; meticulous hemostasis and closure. --- # 8) Minimally invasive dilation (Hegar or balloon) ## a) Concept - Controlled **outfracture of inferior turbinate** / anterior wall → **+1–3 mm** effective diameter (clinically meaningful). ## b) When to choose it - Failed medical therapy, anatomy allows instrument passage, desire to **minimize OR time**. - **Operative time** can be much shorter (balloon ≈ **~27 min** vs open ≈ **~104 min** in series). - Can repeat or convert to open if needed. ## c) Technique specifics - **Balloon:** commonly **7 mm** balloon; endoscopic placement; reported parameters include inflation to **~10 atm for ~5 min** (vary by device/protocol) × **2 inflations/side**. - **Hegar:** serial **2.0 → 5–6 mm** under visualization as able. - **Endpoint:** 3.5 ETT or clear endoscopic patency. **Stent optional**; practice varies. --- # 9) Stents & fixation ## a) What to use & how long - **ETT stents** (I.D. **2.5–3.5 mm**, length **~4–5 cm**). - Typical dwell **~5–14 days** (historic **5–28 d**). Choose smallest effective size that permits **8 Fr suction**. ## b) Securement options (complication-aware) - **Retroseptal bridle** (suture medial to stents looped around posterior septum) **± small ETT bridge** anteriorly → **less columellar pressure**, easy bedside removal. - **Transcolumellar sutures:** simple but higher risk of **columellar/septal ulceration**; use cautiously and briefly. ## c) Benefit vs risk - **Benefit:** maintain lumen while mucosa heals, facilitate suctioning.mucosa heals, facilitate suctioni - **Risks:** stent **obstruction**, columellar/alar **pressure necrosis**, **septal ulcers (~up to mid-20% in some older series)**, granulation/synechiae. - **Mitigation:** shortest safe duration, **frequent saline + measured suction**, humidification (oxyhood), pressure-sparing fixation. --- # 10) Post-op care, complications, and follow-up ## a) Standard regimen - **NICU/PICU** monitoring; **oxyhood** humidification (often until ≥POD5 and ~48 h after stent removal). - **Saline**: start **Q2H**, then **Q3H** as improving. - **Measured suctioning** to documented depth (use intraop stent length).stent length) - **Short steroid drops**, selective antibiotics if stented per institutional practice. - Discharge when off oxyhood ≥48 h, feeding well, caregivers trained. ## b) Common issues & fixes - **Stent crust/plug:** saline + measured suction; if persistent or desats → urgent removal/debridement. - **Ulceration/granulation/synechiae:** adjust fixation, topical steroid; OR debridement/dilation if needed. - **Restenosis:** office lysis/balloon dilation; reserve open revision for refractory bony stenosis. ## c) Stent removal & surveillance - **Timing:** individualized; many remove **POD5–7** with close observation (or longer if heavy dissection). - **Technique:** cut anterior knot (if bridled), remove gently at bedside; irrigate/suction; **observe 48 h**. - **Long-term:** monitor for restenosis; ensure **endocrine/neurologic** follow-up when midline findings present.