At present there are no studies or data directly measuring extraoesophageal reflux and its correlation to oesophageal pH monitoring in children. As a result there is no baseline data for a paediatric population and subsequently no measureable definition of a significant extraoesophageal reflux event. There is a poor correlation between reflux events measured with an oesophageal probe and extra-oesophageal symptoms of reflux. Studies have demonstrated that 51% of patients without pharyngeal reflux had abnormal distal oesophageal pH studies.