Understand that the frequency with which different infectious and inflammatory conditions of the larynx occurs are dependent on the age of the child, his/her immune status, other underlying medical conditions, and unknown risk factors.

1. Infectious causes of laryngotracheal diseases.
   • Croup.
     • Viral laryngotracheobronchitis: > 95% of cases, typically infants from 6 months to 2 years, most commonly in winter and early spring, classic “steeple sign” on anterior/posterior neck plain films; if recurrent or persistent consider endoscopy to rule out an underlying anatomic abnormality by visualization of the airway.
     • Spasmodic: no prodromal illness but typically occurs in the middle of the night, older children, may be related to gastroesophageal reflux disease (GERD), stress, allergy, or temperature changes.
   • Epiglottitis.
     • Young children between 2 and 7 years but now becoming very rare because of near-universal vaccination against Haemophilus influenzae type b (HiB).
     • Rarely seen but more frequent now in older children and adults because of non-typeable H. influenzae and other organisms but less severe of a disease process.
   • Bacterial tracheitis.
     • Associated with a recent upper respiratory infection or as a complication of another infection: Staphylococcus aureus,(methicillin-resistance and multi-drug resistance more common now),  Moraxella catarrhalis GABHS, H. influenzae are the most common organisms.
     • Bronchoscopy may be therapeutic as well as diagnostic.
   • Recurrent respiratory papillomatosis.
     • 75% diagnosed by 5 years of age with most common presentation in 2- to 5-year-olds. Classic triad of first born to young, sexually active mother delivered vaginally. Caused by HPV 6 and 11. Recurrences due to latent infection in surrounding tissues with predilection for areas of stratified squamous epithelium and iatrogenic areas of squamous metaplasia.
     • Juvenile form tends to be more aggressive than the adult form and leads to a greater need for frequent surgery, adjuvant medical therapy, and tracheotomy.
   • Bronchiolitis: acute respiratory illness affecting young infants causing inflammation and obstruction in the small bronchioles. Most commonly caused by respiratory syncytial virus. A major cause of morbidity and mortality in infants with underlying and congenital cardiopulmonary problems.
   • Other viral, bacterial, fungal, and mycobacterial infections.
     • Diphtheria, tuberculosis (typical and atypical), herpes, varicella, mucocutaneous candidiasis, histoplasmosis, pertussis.
        
2. Inflammatory causes of laryngotracheal diseases.

• Juvenile rheumatoid arthritis: autoimmune disease affecting children of all ages producing airway compromise due to involvement of the cricoarytenoid joint causing decreased abduction of the vocal folds.
• Dermatomyositis: inflammatory disease of striated muscle and skin with obliterative vasculitis involving small vessels.
• Allergic bronchopulmonary aspergillosis: usually occurs in atopic and asthmatic children.
• Pemphigus vulgaris: occasionally seen in children, affects cutaneous and mucosal surfaces.
• Bullous pemphigoid: an autoimmune disorder seen more frequently in the elderly but can occur in infants and young children. Mucosal involvement with blistering may cause upper airway obstruction.
• Stevens-Johnson syndrome: a form of erythema multiforme characterized by extensive mucosal erosions. More common in children than in adults and typically affects teenagers. Associated with immune response to a precipitating factor such as antibiotics.
   
• Anaphylaxis: a type 1 allergic reaction involving immunoglobulin E associated with allergic angioedema causing airway obstruction. Requires immediate treatment including securing the airway, administration of epinephrine, antihistamines, fluid resuscitation, H2 blockers, and corticosteroids. Prevention is critical in preventing subsequent episodes.
• Hereditary angioedema: a defect of the complement system involving a defect in C1 inhibitor, can occur in children as young as 2 years, related to precipitating factors such as airway trauma. Typically presents with multiple episodes of angioedema necessitating treatment.
• Wegener’s granulomatosis: a necrotizing vasculitis affecting the respiratory mucosa, more typically in the nose but also involving the larynx or subglottis.
• Polychondritis: autoimmune disorder typically involving the cartilage of the nose and ear in teenagers and young adults but also can involve the cricoid cartilage producing subglottic stenosis or vocal cord immobility

    3. Acquired neurogenic

• Traumatic: due to birth injury or as a consequence of surgery for cardiovascular or esophageal anomalies.
• Infectious: postnatal infections such as polio, rabies, Guillain-Barré, tetanus, botulism, syphilis, HIV, myasthenia gravis and polyneuritis may cause airway obstruction from their effects on cranial nerve X (vagus nerve)
• Supranuclear: multiple sclerosis and kernicterus can also cause neurogenic deficits in children.

    4.Trauma.

• Blunt and penetrating trauma are relatively rare because of the anatomy of the infant and pediatric airway. Clothesline injury (with potential for laryngotracheal separation), attempted suicide by hanging, and blunt trauma from striking anterior neck on objects such as coffee tables, sporting equipment (hockey puck, stick, ball) are most common presentations.
• Thermal injury: may occur at any age from steam, fire, or iatrogenic from laser airway fire.
• Caustic ingestion: may occur from either acidic or alkaline ingestions.
• Reflux: seems disproportionately present in children with subglottic stenosis, causes edema, erythema, mucosal posterior pharyngeal cobblestoning and “active” larynx appearance.
• Iatrogenic: can occur because of wrong size endotracheal tube or traumatic intubation with dislocation of arytenoids.
• Radiation effects: may occur in the context of treatment for laryngeal malignancies.
• Foreign body in the airway:  Most common entities are vegetable products such as peanuts and seeds.  Other foods include popcorn, hot dogs, grapes.  Most lethal are conforming foreign bodies such as balloons. Foreign bodies such as batteries in the airway can cause obstruction and caustic injury from the acidic nature of the battery.

     5. Postintubation stenosis.

• Associated with advent of neonatal and pediatric intensive care units and salvage of low-birthweight infants with bronchopulmonary dysplasia and children with congenital anomalies requiring prolonged ventilatory support or airway stenting.
• Related to tube size, movement, length of intubation, and associated inflammatory factors as well as intrinsic healing re-epithelialization in the cricoid region.

    6. Postoperative stenosis.

• Related to high tracheotomies, cricothyrotomy. or improper tracheotomy care. Although cricothyrotomy may be a life-saving procedure in the emergency room or out in the field, it has a high complication rate in children and should be converted to a tracheotomy as soon as patient is stable and it is possible to limit stenosis risk.
• Related to failed attempts at laryngotracheal reconstruction or any airway surgery occurring in the presence of an active larynx (uncontrolled reflux or infection).