Does multiple intraluminal impedance monitoring have a role in evaluating children with neurological impairment before percutaneous endoscopic gastrostomy?

Abstract

The study by Toporowski-Kowalska et al.1 addresses an important clinical problem – providing safe and effective enteral nutrition for children with neurological impairment. Neurological impairment is the most common indication for percutaneous endoscopic gastrostomy (PEG) in children, usually attributable to decreased oral intake from lack of oropharyngeal coordination or dysphagia.2 Furthermore, gastro-oesophageal reflux (GER) is commonly seen in patients with neurological impairment. This is a particularly challenging and controversial issue in these patients due to the discrepancy in the literature as to the risk of worsening GER after PEG placement. The data in this study is consistent with other series including that of Razeghi et al.3 who prospectively studied 68 pediatric patients (most of whom had cerebral palsy) using pH monitoring alone. This group demonstrated that pH monitoring after PEG did not differ significantly from results before PEG, but further described poor correlation between clinical signs of reflux and pH findings. While combined multichannel intraluminal impedance/pH (MII/pH) monitoring is a more sensitive diagnostic tool capable of detecting a substantially larger number of reflux events, its implications for clinical management of patients have not been well established. For instance, in this study GER was detected in fewer children after PEG, yet oesophagitis was more common after PEG. In fact, of those with oesophagitis after PEG, MII/pH testing was normal. One of these patients subsequently underwent a PEG-jejunostomy conversion. The relevance of the shift to more acidic versus weakly acidic reflux events after PEG is also uncertain. It raises some possibility of change in oesophageal motility and acid clearance (acid refluxate in general is slower to clear than non-acid), but it is beyond the scope of the current study to draw any definitive conclusions. While this report strives to define GER in patients with neurological impairment more objectively, the study is somewhat confined to the diagnostic findings of MII/pH monitoring and endoscopy with limited detail of other pertinent clinical patient characteristics. The authors discussed a nutritional benefit after PEG placement as evidenced by an increase in caloric intake and body weight; however, it was a bit unclear as to the degree of body mass index for age z-scores improvement and correction of severe malnutrition. The study would also be strengthened by a deeper understanding of a participant’s severity of neurological impairment and quality of life to better determine the clinical significance of MII/pH findings. As an example, in a study of gastrostomy tube placement in children with neurological impairment by Sullivan et al.,4 nearly all parents reported a perceived improvement in their child’s health after the tube was placed underscoring the importance of defining quality of life as well as diagnostic findings in patients with neurological impairment. The MII/pH data would have greater impact if symptoms such as dysphagia, aspiration, and chronic cough were defined in greater detail before and after PEG. These symptoms are common in patients with neurological impairment and one of the major reasons why GER can have more devastating consequences in this population. Better understanding of these symptoms may have greater implications than MII/pH monitoring. Data from Johns Hopkins Children’s Center, for instance, raised the concern regarding the association between a preoperative history of dysphagia or aspiration on modified barium swallow study and GER, with 10.6% and 11.2% respectively of these patients requiring fundoplication after PEG.5 Furthermore, a retrospective review by Rosen et al.6 concluded that MII/pH testing (acid, non-acid, or total events) was not a useful tool in predicting fundoplication outcome. One aspect of MII/pH monitoring for future consideration in children with neurological impairment and potential aspiration may include a more detailed analysis of the characteristics of individual reflux events; specifically, the number of events reaching the proximal oesophagus. While the absolute number of reflux events may not predict the outcome of a PEG or need for anti-reflux surgery, those which pass as high as the oropharynx may be more relevant particularly in patients with dysphagia. In summary, the authors of this report have taken a very important step by contributing a prospective evaluation of GER in a poorly characterized and very difficult patient population. While the study clearly adds to our understanding of GER in children with neurological impairment, it emphasizes the need for further investigation and will hopefully generate future prospective, hypothesis-driven studies.