Pupillometric assessment of dysautonomia in pediatric bowel and bladder dysfunction: a pilot study

Bowel and bladder dysfunction (BBD) refers to a heterogeneous group of voiding disorders, accounting for an estimated 40% of pediatric urology visits. Symptoms of BBD include enuresis, urgency, and urinary retention, often accompanied by constipation. The aim of this pilot study was to explore whether a pupillary response can be characterized for BBD, by examining the pupillary light reflex (PLR) before and after voiding among patients with BBD. A total of 28 patients aged from 7 to 21 years were recruited from the Wetting, Infections, and Stooling Help clinic at Children's National Medical Center. An infrared pupilometer was used to assess the PLR. Both baseline static and dynamic pupillometry assessments were obtained before and after voiding. Measurements were also taken after 5 min in the supine position, followed by 5 min standing to induce an orthostatic stressor. Visual inspection of the graphed data revealed a characteristic shape in 11 of 28 patients with voiding symptoms. In these 11 patients, the redilation arm of the PLR shows a 'notch,' or a brief reconstriction of the pupil before resting pupil size is reestablished (figure). This feature of the PLR has not been seen in previous and parallel studies using pupillometry to evaluate other populations. The results of this study suggest that a subset of patients with BBD may have a significant perturbation of autonomic regulation, identifiable through analysis of the PLR. To our knowledge, this 'notch' during redilation has not been previously described or seen in other patient populations and may represent a distinctive and readily identifiable physiologic marker of disease. These results are broadly aligned with results of other studies that have examined ANS activity in patients with BBD, although further study is needed to confirm the results of this pilot study and to assess relative contributions of sympathetic and parasympathetic function in producing pupillary abnormalities. This study has several limitations, including the small sample size, the absence of data on severity and duration of symptoms, and the absence of a control group of patients without any voiding symptoms. A simple tool for diagnosing BBD and for monitoring response to treatment could significantly improve the quality of treatment for one of the most common pediatric urologic complaints. Given the heterogeneity of symptoms under the BBD umbrella, pupillometric data could guide selection of treatment options, as well as assess adequacy of response to pharmacologic therapy.