Dysphagia as a risk factor for sudden unexplained death in infancy

The TRIAD of encephalopathy, subdural haemorrhages, and retinal haemorrhages is commonly considered diagnostic of Shaken Baby Syndrome, but the original paper describes a statistically linked QUADRAD of features, the fourth of which is a previous history of feeding difficulties (dysphagia). Recent reviews of giving pacifiers (dummies) to infants during sleeping periods have found a significant reduction in the incidence of Sudden Infant Death Syndrome. Stimulation of swallowing is a possible connection with dysphagia, which is examined here, illustrated by a well documented case. Although amniotic fluid passes freely through the larynx of fetal mammals during fetal breathing, application of pure water to the laryngeal epithelium in infants causes choking and laryngeal closure. "Water sensors" in the surface respond to lack of chloride ions and adapt very slowly or not at all. Others have found in puppies that following application of pure water only 32% resume breathing in less than 30-40s. The rest needed at least one saline flush, and some required artificial ventilation in addition. These receptors also respond to high potassium concentrations and acid or alkaline solutions. Normally, airway closure during swallowing or vomiting prevents entry of feed or oesophageal reflux, but in some forms of dysphagia leakage can occur, causing paroxysmal coughing, reflex laryngeal closure, and so prolonged apnoea. Recently, it has been realised that the TRIAD injuries can also result from high intracranial vascular pressures transmitted from intra-thoracic pressure surges during paroxysmal coughing, choking, etc. Triggering of such pressure surges by dysphagic accidents provides a physiological link to injuries commonly considered diagnostic of Shaken Baby Syndrome, completing the statistically identified QUADRAD of features. Further dysphagic research might reveal predictive factors, and preventative measures such as feeds of optimal pH.