Unlike airway stenosis in adults, which is usually the result of having a tube placed in the windpipe for artificial ventilation, airway problems in children generally result from abnormalities of the development of the larynx (voice box) or trachea (windpipe) in the womb. These problems tend to come to light as a result of noisy breathing or recurrent infections in early life. In the most severe cases, the child may have episodes of rapid breathing or even stop breathing momentarily or develop a bluish tinge to the lips. However, in many cases much milder symptoms are present, and certain types may even resolve as the child grows.
One of the most common developmental abnormalities of the airway in infants is laryngomalacia, where the part of the voice box above the vocal cords is vulnerable to collapse during inspiration. As with other causes of airway stenosis, the first and most obvious sign is often a noise made predominantly during inspiration, called ‘stridor’. In the case of laryngomalacia, the stridor may be worse when the child lies on their back and improve when they turn on their front; it may worsen during respiratory infections such as colds or when the child feeds or cries. Sometimes the sound is only present when they are sleeping. The symptoms of laryngomalacia are typically most pronounced when the child is 4-8 months old, and often disappear within one year, requiring no treatment. If the symptoms are mild, the best approach is usually to closely observe the child through regular appointments with a specialist, such as an Ear, Nose and Throat Surgeon. Acid reflux commonly occurs with this condition and may worsen its symptoms, so this specialist may recommend that a medication is taken to control acid reflux (called a proton pump inhibitor, or PPI). Symptoms that suggest a more serious case include rapid breathing, laboured breathing in which the upper part of the stomach or spaces between the ribs are drawn in during inspiration, or a bluish tinge to the lips (known as ‘cyanosis’). If these are present, a simple and generally very safe operation can be performed to remove excess tissue at the front of the voice box (an ‘aryepiglottoplasty’). However, this should not be performed unless absolutely necessary, because it has the potential to result in scar formation that can lead to adult forms of subglottic stenosis (see previous article on this topic). The presence of laryngomalacia is rarely associated with other congenital abnormalities.
A less common cause of stridor in children is the presence of a vallecular cyst, which is a mucus-containing cyst that bulges into the larynx. These can be treated by being laid open, such that the ‘roof’ of the cyst cannot seal itself, a technique known as ‘marsupialisation’. This can be done either by an incision in the front of the throat, or endoscopically via a flexible telescope camera. Aside from cysts, abnormal ‘pouches’ may be present in the voice box that can intermittently fill with air, producing similar symptoms. If such a pouch is continuous with the inside of the voice box, it is referred to as a laryngocele; if this is not the case, it is referred to as a ‘saccular cyst’.
A more serious airway condition that can be catastrophic if not detected at birth is ‘laryngeal atresia’. Part of the airway is formed by the ‘hollowing out’ of a solid tube, and if this process fails during development, a child can be born with no connection between its lungs and its nose and mouth. Sadly, if this is not identified before birth, or shortly thereafter, the child will not survive. Aside from total occlusion of the airway as a result of atresia, a lesser form may present in an older child were a remnant of this process is left in the form of a partially-perforated membrane across the beginning of the windpipe, called a ‘laryngeal web’. Respiratory problems in infants may also be caused by the same narrowing of the airways seen in adults who have been artificially ventilated for long periods, called ‘subglottic stenosis’. In children who have not been artificially ventilated, this is usually a problem that was present from birth, and unlike the adult ‘acquired’ form, generally improves with age. The condition can sometimes be ameliorated by endoscopic laser treatment, or an operation called an ‘anterior cricoid split’.
In addition to narrowings of the airway, abnormal connections within the respiratory system have the potential for equally serious consequences. Just such a problem is posed by a condition called ‘laryngeal cleft’. The windpipe and gullet begin life as a single tube, and as development progresses ridges on either side of the longitudinal axis of this tube form and eventually join in the midline to form two separate tubes, the windpipe anteriorly, and the gullet behind. If this process fails to occur completely, a cleft (slit-like opening) may remain in the wall that separates these two structures, allowing milk and potentially regurgitated stomach acid to enter the lungs. This may present with ‘cyanotic attacks’ (turning blue) during feeding, or recurrent respiratory infections due to aspiration of food and stomach acid; stridor may also occur. It is often associated with other developmental abnormalities and learning difficulties.
Finally, another potential cause of breathing difficulties in infants is a ‘haemangioma’ (plural ‘haemangiomata’). These are more commonly seen on the face, for instance as ‘strawberry naevi’ or ‘port wine stains’, which are examples of haemangiomata on the skin, but they also occur in the larynx, where they have the potential to be fatal. Like haemangiomata on the skin, they tend to grow rapidly, reach a certain size, and eventually undergo ‘involution’ and disappear. Around 50% of those present at birth will regress by the age of five, with virtually 100% regressing by the age of 12. Oral steroids or local injection of steroids via an endoscope may hasten their regression. Once detected, these swellings, which appear blue-purple under endoscopic vision, tend to be closely monitored. The dogma is that they should also be treated with ‘tracheostomy’, which is a tube inserted into the windpipe via the front of the neck as a safeguard against complete airway occlusion, until they are confirmed to have resolved.
Any of these diagnoses may be the cause of noisy or laboured breathing in a very young child. Some of them are benign and require only careful observation. Should they pose a risk to the airway, many can be safely corrected by simple surgical procedures. The most common cause for laboured breathing in a child is asthma, although this tends to occur on exertion, or in the presence of certain triggers, vary with the time of day, and respond well to standard medical therapy in the form of inhalers. Due to the rarity of many of these conditions, they are easily missed, and are occasionally misdiagnosed as asthma, or recurrent ‘croup’ (viral infection causing stridor). Doctors should have a high index of suspicion for an anatomical cause of ‘wheeze’ in those children whose noisy breathing does not have the classic features of asthma or does not respond to standard therapy.
Written by Dr Adam Nunn
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