Linear nevus sebaceous syndrome (LNSS) is characterized by the association of a large sebaceous nevus, usually appearing on the face or on the scalp, with a broad spectrum of abnormalities that may affect every organ system, including the central nervous system (brain neoplasms, hemimegalencephaly and lateral ventricle enlargement).

Distance between the inner canthi more than two standard deviations above the mean (objective); or, apparently increased distance between the inner canthi.