Apparatus is provided for applying current to a nerve, including a housing, configured to be placed in a vicinity of the nerve. At least one electrode is fixed to the housing such that the at least one electrode does not come in direct physical contact with the nerve when the housing is placed in the vicinity of the nerve, and such that the electrode surrounds greater than 180 degrees of a circumference of the nerve after the placement of the housing. Two end insulating elements are fixed to the housing such that the at least one electrode is between the end insulating elements, and the end insulating elements come in contact or practically in contact with the nerve when the housing is placed in the vicinity of the nerve. Other embodiments are also described.