An Update in the Magnetic Resonance Imaging Features, Classification, and Associated Brain Abnormalities in Hypothalamic Hamartomas

Background Hypothalamic hamartomas (HH) are rare, non-neoplastic malformations associated with gelastic seizures and, less frequently, precocious puberty. Recent classifications have linked HH subtypes with clinical features, and emerging evidence suggests that HH may co-occur with other brain abnormalities. Objective This study investigates the imaging characteristics of HH, the prevalence of concurrent structural abnormalities, and metabolic alterations using magnetic resonance spectroscopy (MRS). Methods We retrospectively analyzed MRI and MRS findings in 18 patients with HH (mean age, 9.24 ± 8 years). Lesions were classified per Li et al., assessing morphology, signal characteristics, associated abnormalities, and MRS-derived choline-to-N-acetylaspartate (Cho/NAA) ratios. Results Fourteen patients (77.8%) had gelastic seizures, while four had non-seizure-related HH, including precocious puberty (n = 1) and NF1 (n = 3). HH lesions were isointense on T1-weighted MRI; 88.9% were isointense and 11.1% hyperintense on T2. Concurrent brain abnormalities were found in 50%, including focal cortical dysplasia, amygdala enlargement, and corpus callosum hypoplasia. MRS in three cases showed elevated Cho/NAA ratios. Conclusion HH is frequently associated with structural abnormalities and metabolic alterations, particularly in seizure-related cases. These findings support the broader spectrum of HH-related brain abnormalities and highlight the need for further research. Advances in Knowledge This study provides new insights into the imaging and metabolic characteristics of hypothalamic hamartomas (HH), highlighting the significant association between HH subtypes, brain abnormalities, and metabolic alterations. Additionally, it introduces the elevated choline-to-N-acetylaspartate (Cho/NAA) ratio as a potential biomarker, contributing to a deeper understanding of the underlying pathophysiology and diagnostic approach for HH.