The silent treatment effectually cuts the victim off from the abuser; it sends a clear message to the victim about how insignificant they are and how easy it is for the abuser to live without them. It is utilized by insecure people with a poor self image who cannot keep up their end of a relationship through dialogue. When the victim does something that displeases the narcissist, they cease to exist for a certain period of time-most often extensive and disproportionate amounts of time.
The narcissist also uses the silent treatment, apathy or a general current of hostility to throw their partner off balance. The narcissist does this to find out exactly how much control they have over their victim. The most typical reason is to “punish” their partner for something they failed to do or some wrong they did (and probably are unaware of). Of course, if the partner directly asks the narcissist about it they will deny it.
It seems plausible that the narcissist also uses the silent treatment as a way to get a reaction from his partner. All narcissists use the silent treatment as a way to validate and assess the amount of control they have over a person. Typically, the victim would ask a narcissist what is wrong, why are you ignoring me, etc. This gives the narcissist power and control. It allows him or her power to do whatever they wish; if the partner doesn’t accept their behavior, or rejects their behavior, narcissists will then use the silent treatment again to draw them back in to the cycle.