Endolymphatic sac tumors are virtually always benign, but may appear on MRI or CAT scans like acoustic neuromas or meningiomas. They can grow quite large before detection. Like acoustic neuroma, early symptoms include hearing loss, ear noise, imbalance, and vertigo. A careful evaluation of the CAT scan and the MRI scan allow preoperative diagnosis. Perhaps ten percent or so are associated with an hereditary syndrome called von Hippel Lindau disease.