PAEDIATRIC LARYNGOLOGY 199 develop enough firmness in the laryngeal structures for the condition to disappear by the age of 2. The condition is distinguishable from lesions affecting the vocal cords by the fact that the cry is normal. The diagnosis can only be made at direct laryngoscopy which excludes other causes of inspiratory stridor. The treatment is to reassure the parents that it will be self-resolving and to advise them to pay more attention than usual to upper respiratory tract infections in the infant because these are more prone to develop into bronchitis or bronchopneumonia. INFLAMMATORY CONDITIONS These are described more fully in Chapter 33. Simple acute laryngitis is a condition to bs taken seriously because of the danger of oedema. Supraglottic oedema begins in the arytenoids and spreads to the ary-epiglottic folds and the false cords. Subglottic oedema occurs only below the vocal cords in the lax subglottic submucosal spaces. In neither case do the vocal cords become oedematous. Similar dangers exist in acute epiglottitis and acute laryngotracheobronchitis but to a much greater extent. In epiglottitis the supraglottic oedema may obstruct breathing and the large surface area affected in the inflammatory process will make the patient very ill. Pain is a characteristic feature of the condition as is the pyrexia which is usually higher than that found in acute laryngotracheobronchitis. This latter condition carries with it the danger of subglottic oedema but, as well as this, the whole tracheobronchial tree is oedematous and efficient gas exchange may not be possible. Treatment consists of administering drugs such as ampicillin and hydro- cortisone to diminish the infection and oedema and also to employ local applications such as adrenaline sprays and steam inhalations. In any child presenting with stridor and a fever it is important not to forget the possibility of dipiitheria. LARYNGEAL TRAUMA Foreign bodies in the larynx are uncommon because they are either coughed out or cause fatal obstruction within a few minutes if help is not to hand. In the desperate acute situation the child should be turned upside down and its back slapped. If the child arrives at hospital with a foreign body lodged in the larynx it usually means that there is sufficient airway to allow of careful induction of general anaesthesia and removal at laryngoscopy. Scalds and burns of the larynx occur when a child inhales superheated steam, drinks a boiling liquid or is rescued from a fire. The supraglottic oedema may settle with conservative measures such as inhalations, sprays and steroids but intubation for 2-3 days may occasionally be required. Injury to the larynx is less common in children than in adults since there is more 'give* in the pliable laryngeal cartilages. The shortness of the neck makes laryngeal injury from an automobile accident rare in children. The commonest cause is from beatings, attempted strangulations and running into a 'neck high' wire or clothes rope during play.