Arachnoid cyst w/mass effect on right aspect of medulla in posterior cranial fossa measuring 15x13mm.what probs might it cause if any? treat or watch?

Arachnoid cysts: Arachnoid cysts rarely cause problems. Posterior fossa arachnoid cysts may have headaches and vertigo ascribed to them but it is likely that other problems such as arthritis in the neck or inner ear pathology are the actual cause. Most arachnoid cysts are observed. Creating windows in the cysts to drain to other cerebrospinal fluid pathways or placing a shunt is performed for symptomatic cysts.

Good question: Was this found on an MRI scan incidentally? Why was the scan obtained? We are typically taught in training that arachnoid cysts are congenital and benign..even if big and even if pressing on things. I don't think that's always true. I've had patients with severe headaches (migraines) and imbalance who we've sent for resection and have gotten instantly better.