Characteristics and additional diagnostic techniques to differentiate the causes of stridor in children
| Characteristics | Additional diagnostic techniques | |
| Acute | ||
| Foreign body aspiration or ingestion [5–7] | Peak age 1–3 years Sudden-onset coughing and choking that might be followed by symptom-free period, and thus be misinterpreted as resolution Potentially life threatening | Chest radiography CT when suspected that negative result might avert bronchoscopy Bronchoscopy |
| Anaphylaxis | Potentially life threatening Possible additional symptoms (skin and/or gastrointestinal) | Detail history of the episode |
| Infection | ||
| Bacterial tracheitis [7] | Any age; most commonly, first 6 years ARVI-like prodromal period Croup-like symptoms that do not respond to standard croup therapy | Direct laryngoscopy and/or bronchoscopy gives a definitive diagnosis but is not routinely performed Specimens for aetiological diagnosis during endoscopy immediately after intubation; older patients might provide sputum |
| Epiglottitis [7] | Decreased incidence and increased age at presentation (previously 3 years, now 6–12 years) since Hib vaccine was introduced Sudden onset, rapid progression Hallmark: three D's (dysphagia, drooling and distress), fever, toxic appearance, hoarse voice, stridor, pharyngitis Various degrees of severity Young children: respiratory distress, anxiety, “tripod”/ “sniffing” posture, drooling; cough not characteristic Older children: might just have severely sore throat | Often clinical diagnosis Direct laryngoscopy (swollen epiglottitis) Lateral radiography of the neck, looking for the “thumb sign” Laboratory tests and microbiology only if the airways are safe Need for a very cautious examination is warranted in theatre with experienced anaesthetist and an ENT specialist capable of performing an emergency airway procedure |
| Diphtheria [7] | Presenting symptoms: malaise, sore throat, fever (low grade), cervical lymphadenopathy Mild pharyngeal erythema → isolated exudate (grey, white) → pseudomembrane (at least one third of cases); pseudomembrane can extend to lower parts of respiratory system Laryngeal diphtheria (pseudomembrane covers larynx) might be isolated (cough, hoarseness) or a part of malignant diphtheria (stridor, respiratory insufficiency) Systemic manifestations: myocarditis, neuropathies | Culture of Corynebacterium diphtheriae from respiratory tract Toxin detection Laryngoscopy: pseudomembrane |
| Airway burns | ||
| Thermal epiglottitis and upper airway burns [8] | Clinical presentation similar to that of infectious epiglottitis; might not correlate with severity, especially in younger children With/without cutaneous burn injury Risk of rapid airway obstruction (because of developing oedema) | Direct laryngoscopy Bronchoscopy |
| Caustic burns [9] | More common 1–3 years of age Upper airway involvement: hoarseness, stridor, nasal flaring, retractions Other symptoms: food refusal, drooling, dysphagia (oropharyngeal/oesophageal injury) Symptoms might not correlate with severity, especially in younger children May be misdiagnosed as anaphylaxis | Direct laryngoscopy Bronchoscopy |
| Subacute | ||
| Retropharyngeal abscess [7, 10, 11] | Peaks at 2–4 years of age Often after upper airway infection (tonsillitis, pharyngitis, lymphadenitis) Early stage: symptoms indistinguishable from uncomplicated pharyngitis Later stage: dysphagia, odynophagia, drooling, torticollis, neck pain, dysphonia, respiratory distress, stridor, trismus, fever, chest pain Symptoms might be similar to that of epiglottitis but progress slower | Lateral neck radiograph (might be false positive if the child is crying) CT scan with intravenous contrast |
| Peritonsillar abscess [7, 12] | More often in adolescents Severe sore throat (mainly unilateral), fever, muffled voice, trismus, drooling | Pus drainage from abscess confirms diagnosis Laboratory tests not necessary Imaging studies not routinely performed; might help differentiate peritonsillar abscess from cellulitis (intraoral or submandibular US), deep space neck infection (CT scan with contrast) and epiglottitis (direct laryngoscopy, lateral neck radiograph) |
| Chronic/recurrent | ||
| Congenital | ||
| Laryngomalacia [5, 7, 13] | Usually begins at neonatal period: 4–5 weeks, peaks at 4–8 months; may resolve by 12–18 months Inspiratory “wet” low-pitch stridor; hoarseness is atypical May worsen in the supine and improve in the prone position Worsens during respiratory infections Mild to moderate: louder when sleeping and feeding; may disappear when crying Severe: louder when crying. Severe: associated with other problems (sleep disordered breathing, failure to thrive etc.) Higher incidence of gastro-oesophageal reflux | Flexible laryngoscopy if associated problems are noted (failure to thrive, apnoea, significant/progressive stridor, etc.) Sleep endoscopy: suspicion of state dependent laryngomalacia (during sleep) |
| Tracheomalacia [5, 14, 15] | Usually manifests from 2–3 months of age More common in children with oesophageal atresia Barking or brassy cough, stridor Moderate: more frequent lower airway infections Severe: upper respiratory tract obstruction, cyanosis, apnoeic spells Symptoms might become more evident with activities (crying, eating) | Dynamic airway endoscopy: diagnostic tool of choice CT scan: end-expiratory and end-inspiratory images (endotracheal intubation needed in young kids) Free-breathing cine CT scan (can be used in young children, does not require breathing manoeuvres cooperation) Barium oesophagography (evaluating tracheal compression by oesophagus or other structures) |
| Vocal cord paralysis [5, 7, 16] | Onset of symptoms: birth to 5 years Bilateral (birth trauma, neurological, unknown reason): stridor, respiratory insufficiency, cyanosis | Flexible fibreoptic nasopharyngolaryngoscopy Direct laryngoscopy Laryngeal ultrasound |
| Vascular ring [17] | Great clinical variability from critical airway obstruction to asymptomatic (incomplete vascular ring) Stridor (usually louder during expiration), wheezing, cough, respiratory distress, respiratory infections Digestive system complaints: dysphagia, feeding difficulty, vomiting (complete vascular ring) Associated anomalies: congenital heart disease, tracheo-oesophageal fistula, cleft lip/palate, subglottic stenosis, genetic or malformation syndromes | Anterior, posterior, lateral chest radiograph (compressed trachea, anterior bowing of the trachea) CT scan or MRA Echocardiography Bronchoscopy (not routinely performed) Barium swallow (not routinely performed) |
| Bronchogenic cyst [14] | Usually presents in adolescence with recurrent cough, wheezing (might simulate asthma), pneumonia Starting in infancy: respiratory distress, cyanosis, feeding difficulty | Chest radiograph CT scan, MRI |
| Laryngeal malformations [13] | Cyst (vallecular, saccular), laryngocele, stenosis, cleft usually present in infancy/early childhood Stridor, wheezing, noisy breathing, hoarseness, aspiration, recurrent respiratory infections, feeding difficulty, failure to thrive | Endoscopy |
| Infantile haemangiomas [5, 7, 13, 18] | Symptoms typically start at 1–3 months and resolve by 5–12 years of age Presentation similar to that of subglottic stenosis; recurrent croup, biphasic stridor (may progress to respiratory distress) Initially might be misdiagnosed as croup; response to standard croup therapy is transient Might be associated with other haemangiomas, especially in the “beard” distribution | Endoscopy Radiograph of the neck: asymmetric narrowing of the subglottis CT scan with contrast: delineating |
| Subglottic stenosis [5, 7, 13, 19] | Biphasic stridor, recurrent episodes of croup and barking cough Typically improves with time | Endoscopy |
| Acquired | ||
| VCD or paradoxical vocal fold motion [20, 21] | Transient improper adduction of the true vocal folds (inspiration and/or expiration) Great clinical variability; may also mimic other diseases (e.g. asthma attack), frequently misdiagnosed Various triggers: exercise, stress, irritants, infections, etc. Stridor, globus sensation, difficulty swallowing, chest tightness, aphonia/dysphonia, sensation of choking that can lead to stress, anxiety, panic Usually self limiting | VCDQ (symptom monitoring) Pittsburgh VCD index (differential diagnosis with asthma) Direct flexible laryngoscopy (if possible, after bronchoprovocation challenge) is the gold standard Pulmonary function testing (possible changes in inspiratory loop) Impulse oscillometry |
| Recurrent respiratory papillomatosis [22, 23] | Juvenile (usually more aggressive; most commonly 2–4 years of age) or adult (diagnosis after 12 years of age) onset Hoarseness: usually the presenting symptom, followed by stridor. Less often: failure to thrive, chronic cough, dysphagia, dyspnoea, acute respiratory distress, recurrent pneumonia. Often misdiagnosed as croup, asthma, allergies, bronchitis, vocal nodules. The diagnosis usually made 1 year after the onset of symptoms | Laryngoscopy |
| Vocal cord paralysis | Unilateral (usually iatrogenic): hoarse voice, crying affections; risk for aspiration | Flexible fibreoptic nasopharyngolaryngoscopy Direct laryngoscopy Laryngeal ultrasound |
| Subglottic stenosis [24] | Symptoms similar but less severe to that of congenital subglottic stenosis | Endoscopy |
| Hypocalcaemic laryngeal spasm [25] | Children with vitamin D deficiency and rickets (mostly); metabolic/endocrine disorders that result in hypocalcaemia Stridor: chronic intermittent or acute and severe; rarely as presenting symptom Other symptoms due to hypocalcaemia: muscle contractions, anticonvulsant-resistant seizures; in neonates: apnoea, lethargy, poor feeding, abdominal distension, tachycardia, vomiting | Chvostek or Trousseau sign Blood tests: electrolytes, alkaline phosphatase, phosphate, magnesium, PTH, vitamin D metabolites, liver function tests ECG: prolonged QTc Urine tests: pH, calcium, magnesium, phosphate, creatinine Urine calcium/creatinine ratio |
| Tumour [26] | Tumors that compress the airways may present with expiratory stridor, shortness of breath, cough, hoarse voice | Chest radiograph: mediastinal masses are commonly discovered on routine test |
| GORD [27, 28] | Nocturnal stridor and cough are atypical manifestations of GORD Other symptoms Infants: feeding refusal, poor weight gain, haematemesis, anaemia, respiratory symptoms Preschool: intermittent regurgitation, respiratory symptoms, decreased food intake and poor weight gain; Sandifer syndrome School-aged children and adolescents: postprandial cough, chronic cough, hoarseness, dysphagia, globus sensation, bitter taste in mouth, heartburn, nausea | Empiric treatment 24-h pH monitoring or impedance monitoring Endoscopy and histology |
CT: computed tomography; ARVI: acute respiratory viral infection; Hib: Haemophilus influenzae type b; ENT: ear, nose and throat; US: ultrasonography; MRA: magnetic resonance angiography; MRI: magnetic resonance imaging; VCD: vocal cord dysfunction; VCDQ: Vocal Cord Dysfunction Questionnaire; PTH: parathyroid hormone; QTc: QT interval; GORD: gastro-oesophageal reflux disease.