Tectal breaking is seen in -

Arnold Chiari malformation  : It is herniation of tonsils of cerebellum and medulla oblongata through Foramen magnum into vertebral canal. This results in blockage of exits in the roof of the fourth ventricle (foramen of Magendie & Luschka) causing hydrocephalus. Schwartz mentions that — "there is a dorsal kink in the cervicomedullary junction and breaking of the Quadrigeminal plate." The quadrigeminal plate is the dorsal part of the midbrain and its another name is Tectum.