Abstract: A method is disclosed for treating brain tissue with cryotreatment. A surgical tool, such as a catheter is disposed proximate to a target region of brain tissue. The tool or catheter provided includes a cryotreatment element. The cryotreatment element may be a cryochamber for enclosing the flow of a fluid refrigerant therein. The cryotreatment element is disposed at the situs of brain tissue to be treated, either through endovascular insertion, or via an opening in the cranium. A refrigerant flow within the cryochamber creates endothermic cooling with respect to the surrounding brain tissue, inducing hypothermia and forming iceballs proximate said tissue. The cooling may be reversible and non-permanent, or may be permanent leading to cell death, necrosis, apoptosis and/or surgical excision or ablation of tissue.