A neurostimulator implant includes an insulating member and an elongate circuitry unit. The circuitry unit includes (a) a first electrode, disposed on an outer surface of a first end portion of the circuitry unit； (b) a second electrode, disposed on an outer surface of a second end portion of the circuitry unit； and (c) circuitry, disposed inside the circuitry unit, and configured to be wirelessly powered to drive an electrical current between the first and second electrodes. The circuitry unit is disposed alongside a medial part of the insulating member, bulging away from the insulating member to define a generally arced portion of the implant. Lateral parts of the insulating member extend laterally outward from the medial part to define lateral zones laterally beyond the circuitry unit. The second side of the insulating member defines a generally flat side of the implant. Other embodiments are also described.
