Subglottic stenosis is concentric or asymmetric narrowing of the airway at the cricoid cartilage level (just below the vocal cords). The most common cause is prolonged endotracheal intubation (90%) — tube pressure on the cricoid cartilage results in mucosal ischemia, ulceration, granulation tissue formation, and ultimately fibrosis. Congenital subglottic stenosis is rare in neonates. Among autoimmune causes, GPA (granulomatosis with polyangiitis, formerly Wegener) is an important differential diagnosis. CT shows concentric wall thickening and lumen narrowing; MRI shows low-signal fibrotic tissue on T2.
Age Range
0-70
Peak Age
40
Gender
Female predominant
Prevalence
Uncommon
In acquired subglottic stenosis, the endotracheal tube exerts continuous pressure on the mucosa at the narrowest part of the cricoid cartilage (subglottic area 15-20mm diameter in adults). If this pressure exceeds local capillary perfusion (>30 mmHg), ischemic necrosis begins. Necrotic mucosa ulcerates and granulation tissue develops on the exposed cartilage surface. As granulation tissue matures, fibrosis and scar tissue form — collagen fibers organize concentrically to create a fibrotic ring narrowing the lumen. In advanced cases, cartilage may also be affected by the fibrotic process — cartilage resorption or deformity may occur. On imaging: mature fibrosis has low water content and shows low signal on T2 (collagen has short T2); on CT, fibrotic tissue appears as concentric thickening at soft tissue density with minimal enhancement (low vascularity). Active granulation tissue shows high signal on T2 and prominent enhancement — this distinction is important for assessing treatment response.
Concentric lumen narrowing at cricoid level on coronal reformat — 'hourglass' appearance. While normal subglottic space > interglottic lumen, in stenosis the subglottic space becomes the narrowest point.
On contrast-enhanced CT, concentric soft tissue thickening and airway lumen narrowing at the cricoid cartilage level. The thickened wall may have smooth or irregular contours. Stenosis length can be measured on coronal reformat (short segment vs long segment). Enhancement is minimal (mature fibrosis) or prominent (active granulation). Cotton-Myer grading is based on percentage of lumen diameter narrowing.
Report Sentence
Concentric soft tissue thickening and airway lumen narrowing at the cricoid cartilage level. The stenotic segment length is approximately __ mm with residual lumen diameter of __ mm (Cotton-Myer Grade __). Enhancement is [minimal/prominent]. Consistent with subglottic stenosis.
On MRI T2-weighted sequences, if subglottic thickening shows low signal, it favors mature fibrosis (collagen); if high signal, it favors active granulation tissue. This distinction is more prominent on STIR sequence. On post-contrast sequences, active granulation shows prominent enhancement while mature fibrosis minimally enhances. These MRI findings guide treatment strategy.
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Subglottic thickening shows [low signal — consistent with mature fibrosis / high signal — consistent with active granulation] on MRI T2. Enhancement on post-contrast sequences is [minimal/prominent].
Cricoid cartilage integrity is assessed on non-contrast CT — presence of deformity, resorption, or calcification. In advanced stenosis, cricoid cartilage deformity or incomplete cartilage ring may be seen. Normal cricoid cartilage has thicker posterior lamina and thinner anterior arch. In congenital subglottic stenosis, the cricoid lumen may be round instead of elliptical.
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Cricoid cartilage [is intact/shows deformity/shows resorption areas]. Cartilage ring is [complete/incomplete]. Cricoid lumen shape is [normal elliptical/circular].
Mature fibrotic subglottic stenosis does not show diffusion restriction on DWI. This is an additional helpful finding for distinction from malignant subglottic lesions like SCC. Active granulation tissue may show mild diffusion restriction.
Report Sentence
No significant diffusion restriction is seen in the subglottic lesion on DWI. No findings favor malignancy.
Coronal CT reformat best evaluates the craniocaudal length, shape (hourglass/conical/tubular), and location (glottic/subglottic/tracheal) of the stenotic segment. The upper and lower boundaries of the stenotic segment are defined using the vocal cords and carina as references. Coronal reformat also allows comparison of glottic and subglottic lumen diameters — while normal subglottic diameter is wider than glottic, this relationship reverses in stenosis (hourglass appearance). Stenosis length determines surgical approach selection: short segment (<1cm) suitable for endoscopic treatment, long segment (>1cm) may require open surgery. Virtual bronchoscopy (VB) can simulate the endoscopic appearance of stenosis with 3D endoluminal imaging.
Report Sentence
On coronal reformat, the subglottic stenotic segment craniocaudal length measures __ mm. Stenosis shape is [hourglass/conical/tubular]. Residual lumen diameter is __ mm (Cotton-Myer Grade __). Upper boundary is __ mm below the vocal cords, lower boundary is at [carina/specific vertebra] level.
Criteria
Lumen narrowing <50%
Distinct Features
Conservative follow-up. Most are asymptomatic.
Criteria
Lumen narrowing 51-70%
Distinct Features
Treatment with endoscopic dilation, laser, or steroid injection.
Criteria
Lumen narrowing 71-99% (Grade III) or complete occlusion (Grade IV)
Distinct Features
Requires surgical reconstruction. Laryngotracheal reconstruction or cricotracheal resection.
Distinguishing Feature
Acute findings in trauma (fracture, emphysema, hematoma); chronic fibrotic narrowing in stenosis.
Distinguishing Feature
Reinke edema at glottic level (vocal cords), stenosis at subglottic level (cricoid).
Distinguishing Feature
Epiglottitis involves supraglottic structures, acute; stenosis is subglottic, chronic.
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
3-monthCotton-Myer grading determines treatment decision. Grade I conservative, Grade II endoscopic (dilation/laser/steroid), Grade III-IV surgical (laryngotracheal reconstruction or cricotracheal resection). c-ANCA testing is mandatory for GPA differential. Active granulation vs mature fibrosis distinction (with MRI) guides treatment strategy.
Cotton-Myer Grade I (<50% narrowing) conservative follow-up, Grade II (51-70%) endoscopic dilation/laser, Grade III (71-99%) and Grade IV (complete occlusion) require surgical reconstruction (laryngotracheal reconstruction or cricotracheal resection). c-ANCA testing is critical for GPA diagnosis.