A control module for an electrical stimulation system includes a casing having an electrically-conductive portion; an electronic subassembly disposed in the casing; and a header portion coupled to the casing and including a connector for a lead or lead extension. The control module also includes a feedthrough assembly coupling the casing to the header portion. The feedthrough assembly includes a non-conductive ceramic block; conductive feedthrough pins passing through the ceramic block and electrically coupling the connector to the electronic subassembly disposed in the casing; a metal flange disposed around, and attached to, the ceramic block, and a non-conductive spacer attached to the metal flange and to the casing to raise the ceramic block above, and away from, the casing. Other control modules include a ceramic block that has a rim portion that raises the plate portion, through which the feedthrough pins pass, of the block away from the casing.