The purpose of the study is to investigate how best to screen for Endolymphatic sac tumors (ELSTs) in von Hippel-Lindau (vHL) patients in order to diagnose the ELSTs while they are still small so that hearing loss can be prevented. Up to 16% of vHL patients are known to develop endolymphatic sac tumors in the inner ear that can cause permanent hearing loss. However, the ELSTs are often not found before hearing loss has already occurred. The challenge for doctors is to diagnose the ELSTs at early stages before they cause often irreversible deafness. In order to find ELSTs before they cause hearing loss, it is important to screen for the tumors prophylactically, that is screen all vHL patients regardless of whether or not they have symptoms. Who can join? Persons diagnosed with vHL who are at least 15 years old. The investigators include patients WITH OR WITHOUT a diagnosed ELST. What does it involve? You need to have a hearing test and an MRI of the brain, where the inner ear can be seen, most vHL patients have already had this done as part of their surveillance program. Participants will be asked to participate in follow up examinations (hearing test and/or MRI of the brain) after 2, 5, and 10 years. How can I join? A doctor has to be responsible for the study in each country where vHL patients participates. Ask the doctor who manages your vHL examinations to contact us or contact us yourself and the investigators will help you find a doctor in your country who will participate in the study.