Presence of an arachnoid cyst at craniospinal junction is not very common. This is a very rare anatomic site. with only seven other cases reported in the literature. We report a case of large intradural craniospinal arachnoid cyst presenting with obstructive hydrocephalus and cranial nerve palsy. https://www.bekindtopets.com/special-deal-Dermatomes-Foerster-Keegan-and-Garrett-map-Posterior-English-hot-value/