From When the Sociopath Stonewalls You by Steve Becker, LCSW
For more on stonewalling, see this page.
The stonewaller isn’t necessarily a sociopath, but the act of intentional stonewalling contains the cold, callous attitude of the sociopath. Absence of empathy is characteristic of stonewallers, and they may relish a sadistic pleasure in watching their target twist, squirm, and make humiliating efforts and bids to be heard. Stonewallers, whether sociopaths or not, are seriously disturbed communicators. Their indifference to the stonewalled party’s experience, as noted, can be chilling. Stonewalling often reflects character pathology, in which case they won’t change—they will always be stonewallers.