Figure 1. Delalande Classification of Hypothalamic Hamartomas.

Type I lesions have horizontal attachment inferior to floor of the third ventricle. Type II lesions have vertical attachment to the wall of third ventricle and are above the floor of the third ventricle. Type III lesions have horizontal and vertical attachments above and below the floor of the third ventricle. Type IV lesions are considered “giant” with volume 8 cm³ or larger (used with permission from Barrow Neurologic Institute, Phoenix, AZ).