Pupillary Abnormalities Mark a Higher-Risk CCHS Phenotype
In pediatric congenital central hypoventilation syndrome (CCHS), pupillary signs were linked to a markedly higher likelihood of later recognition of Hirschsprung disease and malignant neoplasm of the adrenal gland. The signal was not subtle: children with coded pupillary abnormalities had substantially higher adjusted hazard ratios for both outcomes at five years, pointing to a broader autonomic and neural crest phenotype rather than an isolated ocular finding.
CCHS is already known as a disorder of autonomic failure tied to disrupted ventilatory responses to carbon dioxide and hypoxia, most often through PHOX2B-related developmental abnormalities. The same embryologic pathway reaches the enteric nervous system, the adrenal medulla, and the ocular autonomic apparatus. When the pupils are abnormal, the bedside finding may be carrying information about how far that developmental disruption extends.
Cohort Signals From a Rare Pediatric Disorder
The cohort drew on 680 pediatric CCHS patients identified through the TriNetX US Collaborative Network across 68 healthcare organizations, with records spanning 2004 through 2024. Mean age was 3.4 years, and 38 children, or 5.6%, had pupillary abnormalities coded in the record. Those codes included pupillary abnormalities, anomalies of pupillary function, and Horner syndrome, used here as a composite exposure because the administrative data platform does not support a finer clinical subtype analysis.
Children with pupillary signs were compared with those without them after exclusion of patients who already had Hirschsprung disease or adrenal neoplasm before the index date. The analysis also excluded several tumor predisposition syndromes and congenital malformations that could distort the association. Follow-up was then used to estimate outcomes at three and five years, with adjustment for age, sex, race, and ethnicity.
The effect estimates were large. At five years, pupillary signs were associated with a higher risk of subsequent Hirschsprung disease diagnosis, with an adjusted hazard ratio of 4.93 and a 95% confidence interval of 2.72 to 8.84. The association with malignant neoplasm of the adrenal gland was even stronger, with a five-year adjusted hazard ratio of 5.72 and a 95% confidence interval of 2.31 to 14.33. Both findings were statistically significant with p values below .001.
The timing of the finding matters clinically. Hirschsprung disease is congenital, so later diagnosis in a CCHS child does not imply new disease; it reflects delayed recognition of a condition already present. In a child whose respiratory disease dominates the early clinical picture, autonomic clues may be the reason the enteric diagnosis is eventually made.
Why the Eye May Track Neural Crest Burden
The biological logic is straightforward. CCHS is rooted in abnormal neural crest development, and the pupillary apparatus sits on the same developmental map as the gut innervation and adrenal structures. Parasympathetic pupillary dysfunction reflects ciliary ganglion involvement, while Horner syndrome reflects disruption along the sympathetic pathway. Both pathways are neural crest-derived and both can be affected when PHOX2B-related dysregulation is more extensive.
This is why a pupil exam can carry more weight than a routine neurologic observation. A dilated, sluggish, or asymmetric pupil in CCHS may not simply be an ocular curiosity; it may signal a deeper autonomic phenotype with more extensive neural crest involvement. In practical terms, the examination can push clinicians toward earlier vigilance for intestinal aganglionosis and adrenal tumors, particularly when molecular testing is delayed or unavailable.
That clinical value is reinforced by the study design itself. Genetic data were not available in the TriNetX network, so the analysis relied on real-world diagnostic coding rather than genotype-based stratification. Even with that limitation, the association remained strong enough to justify closer phenotypic surveillance rather than reassurance based on an apparently isolated pupil finding.
Systematic Review Strengthens the Phenotypic Link
The cohort analysis was paired with a PRISMA-compliant systematic review of ocular manifestations in CCHS. Eight studies totaling 32 patients were included. Among tumor-positive patients in that review, pupillary signs were present in all cases, and pupillary abnormalities co-occurred with Hirschsprung disease in 56%.
The review is small, but it points in the same direction as the larger database analysis: ocular autonomic signs repeatedly appear in patients with broader neural crest disease. The consistency across real-world cohort data and published case-level evidence gives the signal added weight, even if it still falls short of proving causality.
A single bedside sign may identify a child who needs broader surveillance.
What Pediatric Teams Should Do With This Signal
The study argues for structured pupillary assessment as part of the multidisciplinary evaluation of children with CCHS. That means the pupil exam should be documented deliberately, not left to casual observation. In a syndrome already defined by autonomic dysregulation, the ocular exam becomes one more way to map the degree of developmental involvement.
For pediatric clinicians, the implications are immediate but still bounded by the data. Pupillary abnormalities should not be treated as proof of Hirschsprung disease or adrenal malignancy, yet they can justify a lower threshold for targeted workup and ongoing surveillance. The association is especially relevant in settings where PHOX2B testing is not readily available and where phenotype remains the main guide to risk assessment.
The study also shows the limits of administrative data in a rare disease. Examination-level detail was unavailable, the pupillary codes were grouped into a composite exposure, and the platform could not support more granular adrenal subcoding. Competing-risk analysis was not available either. Even so, the association was strong and reproducible enough to move the finding into clinical attention rather than leaving it as an incidental observation.
What remains unresolved is prospective validation. A forward-looking study with standardized pupillometry, genotype confirmation, and protocolized surveillance for enteric and adrenal disease would be needed to determine how well pupillary signs perform as a true risk marker. Until then, pediatric CCHS care should treat abnormal pupils as a potential flag for a wider neural crest disorder, not as a minor autonomic footnote.