Differentials
Asthma
SIGNS / SYMPTOMS
Variable severity and periodicity of cough, expiratory wheeze, dyspnoea, hyper-secretions, chest tightness, and tachypnoea.
Symptoms show reversibility.
INVESTIGATIONS
Spirometry: measurement of FEV1 and FVC. Ratio of FEV1/FVC is reduced (expressed as a percentage), indicating airway obstruction.
PEFR: reduced, most markedly on waking, and improving through the morning. Compared against predicted value based on sex, age, and height.
Bronchodilator challenge: reversibility of airflow obstruction with inhaled beta-2 agonist. Improvement of FEV1 or PEFR of 20% or greater following inhalation of salbutamol is diagnostic.
Methacholine provocation test: airway hyper-responsiveness leading to narrowing of the bronchi and subsequent reduced FEV1 in response to inhaled methacholine (bronchoconstrictor). It is possible to obtain a false positive test on methacholine provocation for asthma.
Laryngomalacia
SIGNS / SYMPTOMS
Congenital disorder, rarely seen in older children, characterised by inspiratory stridor.
INVESTIGATIONS
Flexible fibre-optic nasendoscopy: decreased laryngeal tone and supra-glottic collapse.[82]
Vocal fold paresis/paralysis
SIGNS / SYMPTOMS
Abnormal voice changes, including increased phonatory effort and altered quality (breathy, hoarse, with possible changes to volume and/or pitch). Damage to both vocal cords (rare) causes difficulty breathing.
INVESTIGATIONS
Flexible fibre-optic nasendoscopy: weakness or fixation of the arytenoid complex unilaterally or bilaterally.
Laryngeal electromyography: decreased or absent nerve input to the thyroarytenoid and/or cricothyroid muscles.[83]
Laryngeal space-occupying lesion (Reinke's oedema, laryngeal carcinoma, laryngeal web, vocal fold polyp, vocal fold papilloma)
SIGNS / SYMPTOMS
Voice changes including increased phonatory effort, altered quality and/or loudness, difficulty breathing, shortness of breath, and vocal fatigue secondary to a space-occupying lesion.
INVESTIGATIONS
Flexible fibre-optic nasendoscopy: visible space-occupying lesion (e.g., Reinke's oedema, laryngeal carcinoma, laryngeal web, or vocal fold polyp).[84]
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