Picture this:
The blackness abates and startled your eyes snap open. Immediately your vision focuses on the worried face of your comrade. Like a crashing wave the sound of battle rushes in -
WAKE THE %^& UP!
In the background you hear the familiar soothing voice of [cleric]: "sssleep..."
Your head turns just as the body of the foul orcish caster crumples to the ground - a bit of poetic justice granted by the Gods perhaps. Without a moment's hesitation your hand, sure in its grip on your favored weapon even in unconsciousness, whips around trailing the deadly spikes with it. Much like streamers in the wind, your spiked chain dances through the air and along the ground almost caressing the throat of the soon to be corpse lying next to you. With a jerk of your back and snap of your wrist you too begin to spin and the spiked links lock in place as your chain fully wraps around the head. Each spike is like a barb securing with a sure grip around the underside of the chin, the awkward cheek bones, the temple and the pinnacle of the skull. Completing your spin you kick out off the body of the orc tearing its head to an unnatural angle. Breathing heavily, you can hear the sounds have died down around you. The battle is done. The gore that was once this creature's face and the full 6' extension of its cervical vertabrae are evidence enough to tell the tale of how this one met its fate.
...
I think the legitimacy of any combat action in terms of its realism merely has to do with how one perceives the outcome. In truth, a maneuvar that winds up doing critical damage and results in a fortitude save vs that damage is a very deadly maneuver. It will probably kill almost anything that is used against. As such, there, in my mind, are many ways of describing this. One such way is to suggest that a vital area has been pierced. However, it seems perfectly reasonable, to me, that alternative descriptioins are coherent, and perhaps sometimes better - as I have described above.