A slap to the back of the neck: An antidote for pressure point TKO?

The other week, I received a fantastic question from a gentleman named Bill. He wanted to know whether there was any neurological basis in (what is apparently) a common technique for recovering a martial arts practitioner from a knock out induced by a strike to pressure points. 

Here's Bill's question in full:

In martial arts that make use of so called “pressure points” in self-defense, a technique for recovering someone from a TKO often involves one or two quick slaps to the back of the neck, just lateral to the spinal column and just below the hairline.

A fairly common explanation of this action is “to activate the Reticular Activating System (RAS)”. Less frequently the explanation offered is to stimulate the “wake-up nerve” (Spinal Accessory Nerve).

I guess most people just accept what they’re told and leave it at that, but I like to know what’s going on “under-the-covers” so to speak, so I tried doing some research on RAS and SAN. I must admit it got too deep for me and I got lost amongst the neuroscience terminology.

But from what I could understand it seems that the RAS is located high up on the brain stem, so I have my doubts about that explanation because of its apparent inaccessibility. The Spinal Accessory Nerve sounds more feasible. I have been unable to find reference to any connection between the SAN and the RAS.

Can you throw any light on the neurological effects of the slaps as indicated above, in relation to recovering someone from a semi-unconscious state.

I should mention that the knockouts, blackouts, TKOs that I refer to are not caused by concussive impact, but by manipulating well researched nerve centres.
— Bill Hely

As I've pretty much forgotten everything I ever knew about spinal nerves, I pulled a "Who Wants to be a Millionaire", and phoned (read: emailed) a friend. Well, three friends. One of whom contacted a neurology resident. 

The common response was a deep skepticism for the premise of the "slaps". 

First to respond was graduate student Jennifer Esch, who did some quick research into both pressure points and the “recovery slaps”. On the subject of the “recovery slaps”, she wrote:

… Basically, I think the answer is that the hitting on the back of the head is BS and doesn’t do anything.
— Jennifer Esch

However, since the question was of a medical bent, Jenn had the excellent suggestion that I contact a medical student. Luckily, I know 2 MD/PhD students who I thought were particularly bribable, so I emailed them:

I’ve never heard of this technique being employed. Probably if only because you’d be worried about exacerbating a cervical spine injury in someone who may be unconscious due to trauma. I think Jenn Esch’s bs radar is probably right.
— MD/PhD No. 1

MD/PhD No. 2 claimed to have no helpful knowledge, but forwarded on the question to a Neurology resident she knows. He wrote back:

The RAS is nestled up in the posterior pons/midbrain and would not be affected of any direct hits to the neck (probably a good thing). As far as I know, the SAN doesn’t have any significant sensory afferents so I can’t see how that explanation makes sense. Slapping the neck certainly provides some sensory input to the brain via typical pathways (cervical spinal roots, C2-C4) but I doubt they would have any sort of privileged input to reticular structures, any more so than any other sensory nerves would. ... My BS alarm is sounding a little bit, too. That being said, the brain is infinitely interesting and I wouldn’t be astonished to find out that I’m totally wrong!”
— Stanford Neurology Resident

So there we have it. None of us have ever heard of that particular technique; we are all rather skeptical that hitting on the back of the neck will be effective at reversing the TKO. And we are all unified in cautioning martial arts enthusiasts against providing additional trauma, that might exacerbate a potential spinal injury.

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Astra Bryant

Astra Bryant is a graduate of the Stanford Neuroscience PhD program in the labs of Drs. Eric Knudsen and John Huguenard. She used in vitro slice electrophysiology to study the cellular and synaptic mechanisms linking cholinergic signaling and gamma oscillations – two processes critical for the control of gaze and attention, which are disrupted in many psychiatric disorders. She is a senior editor and the webmaster of the NeuWrite West Neuroblog