Interhypothalamic adhesions: prevalence, structure, and location-based classification map in pediatric patients undergoing MRI.

Purpose: Interhypothalamic adhesions (IHAs) have been reported only in the pediatric population, with unknown prevalence and histological composition. We aim to demonstrate their prevalence, assess their persistence through longitudinal imaging, classify IHAs by anatomical distribution, explore their structure, and report associated pathologies.

Methods: A retrospective review was conducted on consecutive pediatric brain MRI studies obtained between January 2012, and December 2013. The presence of an IHA was only confirmed when observed on at least two planes. For each IHA, cross-sectional area was calculated, and signal intensities were measured at the center on sagittal T2WIs. Signal intensities were also measured in both cerebral white matter and gray matter for normalization and comparison. Patient demographics and clinical information were collected from electronic charts.

Results: Out of 1550 patients (0-17.9 years), 33 (19 males, 14 females) had an IHA, resulting in a 2.13% prevalence. Follow-up images were available for 19 IHA-positive patients, and IHAs were again seen in 92% of the follow-up scans (71/77). Normalized IHA signal highly correlated with normalized gray matter signal (r = 0.83, P < 0.001), but not with normalized white matter signal (r = -0.16, p = 0.494). Common co-occurring pathologies included hydrocephalus (n = 9), prematurity (n = 8), and corpus callosum abnormalities (n = 7). All type 3 IHAs (3/3) were accompanied by pituitary pathologies.

Conclusion: IHAs have a prevalence of 2.13% in our cohort, and the majority persist in longitudinal studies. They showed gray matter signal intensity and Type 3 IHAs exclusively accompanied pituitary abnormalities.