The present invention relates to an apparatus for the treatment of a brain affection, which comprises at least one implantable generator made of non-ferromagnetic material comprising a casing, an ultrasound generating treating device positioned into said casing to induce brain affection treatment by emission of ultrasound waves, and means for fastening the implantable casing into the skull. or higher and 50 to 300 parts by weight of metal hydroxide blended into 100 parts by weight of ethylene polymer. The catalyst comprises a central element, which is selected from germanium, tin and antimony, and at least one halogen atom, which is bound to the central element. The acoustic pressure wave serves to cause agglomeration of particles contained within the combustion stream for easy removal.