Subglottic Stenosis

SUBGLOTTIC STENOSIS
Subglottic stenosis is a congenital or acquired narrowing of the subglottic airway.
It can present as a life-threatening airway emergency.
CAUSES OF SUBGLOTTIC STENOSIS
Congenital subglottic stenosis is a birth defect.
Acquired subglottic stenosis generally follows as an after-effect of airway intubation, and in extremely rare cases as a result of gastroesophageal reflux disease (GERD). 
  •  Stenosis could also be secondary to foreign body, infection, inflammation, or chemical irritation.
  • Other causes include the following:
  1. External trauma, penetrating and blunt
  2. Tracheotomy, especially a high tracheotomy or cricothyroidotomy
  • Chronic inflammatory diseases include the following:
  1. Wegener granulomatosis
  2. Sarcoidosis
  3. Relapsing polychondritis
PATHOPHYSIOLOGY OF SUBGLOTTIC STENOSIS
  • In a case of congenital type,subglottic diameter is < 4 mm in full term neonate (normal 4.5 – 5.5 mm )or < 3 mm in a preterm neonate (normal 3.5 mm)
  • Congenital stenosis has two main types, membranous and cartilaginous.
  1. In membranous stenosis, fibrous soft tissue thickening is caused by increased connective tissue or hyperplastic dilated mucus glands with absence of inflammation. Membranous stenosis is usually circumferential and may extend upward to include the true vocal folds.
  2. In cartilaginous stenosis, a thickening or deformity of the cricoid cartilage most commonly occurs, causing a shelflike plate of cartilage and leaving a small posterior opening. Cartilaginous stenosis is less common than membranous stenosis.
SYMPTOMS IN A CASE OF SUBGLOTTIC STENOSIS
  • Dyspnea (may be on exertion or with rest, depending on severity of stenosis)
  • Stridor
  • Cry is normal in a case of congenital type.
  • Hoarseness
  • Brassy cough
  • Recurrent pneumonitis
  • Cyanosis.
  • Many cases improve as Larynx grows in congenital type.
DIAGNOSIS AND GRADING IN A CASE OF SUBGLOTTIC STENOSIS
  • Visualization of the larynx by flexible fiberoptic or rigid telescopic (90- or 70-degree scopes) in the clinic is crucial to the evaluation of airway lesions.
  • Myers and Cotton devised a classification scheme for grading circumferential subglottic stenosis from I-IV.
  • The scale is based on a percentage of stenosis established by the age of the patient and the size of the endotracheal tube that can be placed in the airway with an air leak less than 20 cm of water pressure.
  • This grading system mainly applies to circumferential stenosis.
  • The system contains 4 grades, as follows:

  1. Grade I - Obstruction of 0-50% of the lumen obstruction
  2. Grade II - Obstruction of 51-70% of the lumen
  3. Grade III - Obstruction of 71-99% of the lumen
  4. Grade IV - Obstruction of 100% of the lumen (ie, no detectable lumen)
MANAGEMENT IN A CASE OF SUBGLOTTIC STENOSIS
Medical:

  • Any underlying medical cause must be addressed (eg, control of infectious etiology, inflammatory causes such as Wegener granulomatosis).
  • Antireflux management
  • Steroids such as prednisone, which reduces the inflammation of the area for better breathing.
Surgical :
  • Long-term tracheostomy
  • Long-term intraluminal stent Endoscopic repair
  • Carbon dioxide laser or Nd:YAG laser can be used.
  • Dilation of the stenotic area.
  • Open Repair
  • Open repair is indicated following failure of the endoscopic approach
Exam Question
  • The Myer-Cotton grading system is used for Subglottic stenosis
  • A 38 year old man presents with stridor following a respiratory infection. Cotton's grading is used to classify the pathology.Subglottic stenosis is the diagnosis in this case. Subglottic stenosis in term infants is a subglottic diameter of less than 4 mm
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