Treatment of Ectopic Calcification in Fahr's Disease or Syndrome

The dosage of etidronate is 20 mg/kg for twee weeks and ten weeks off. Etidronate is given in capsules of 200 mg. Etidronate capsules are administered orally. During the study, participants will receive etidronate in four periods of two weeks during the twelve months of follow-up.

Placebo is given in capsules and are administered orally. During the study, participants will receive placebo in four periods of two weeks during the twelve months of follow-up.