iguanabill:

thanks for your post. Your questions are helping sort through the details of tdcs.

I would guess that you need to give ballerina a more specific description of of the location on the head you are placing your anodes/cathode...

from reading the research papers, I think the accepted paradigm to use is the EEG 10-20 system... most the researchers have put the For example, many researchers put the anode over the “C3” area (which correlates to the hand position for the Penfield brain map (I cannot post Web addresses yet -- I don't have enough postings)..

I'm curious about the same things you are. I am about ready to start some trials.

Thanks a lot for posting your information about the electrodes etc!! The part about the adapters to the banana plugs, etc. threw me for a loop for a while.. .. I kept on trying to figure out if I needed to order what other parts etc. etc.

So, anybody else reading this and also using the Square Amrex type rubber edged sponge electrodes---pay attention to the adapter part that iguanabill has stated. I ended up going down to a local electronic supply store and buying some banana plugs cutting the leads off the wires, and soldering banana plugs through the wire ends. I then tested the device on my multimeter to ensure the device was working correctly in putting out a steady 2ma.........but if I could have found some adapters -- I probably would've used the adapters that iguanabill used...

The adaptors are very inexpensive. I just got a PM from Ballerina, so it looks like I can communicate that way. PM me and I'll give you the exact links for purchasing them (if I am allowed to do so)...but in the meanwhile you can probably find them yourself online at the following companies:

(1) 3" x 3" Amrex rubber pad w/ sponge insert (actually 2" x 2" contact surface with skin; 25.8 cm2) - Austinmedical
(2) pin to banana pin adaptors (to insert into the rubber pad) - Austinmedical
(3) snap to pin converters (to connect between the electrophoresor's wires and the pin to banana pin adaptor) - Balegoonline

These accessories worked for the particular stimulator I purchased. They attached to the (button?) snaps on the end of the leads that came with my stimulator. Ballerina listed sources for her purchases; I don't recall how similar they were to mine.

voner: for the motor cortex position, we use the "C3" position on the top of the head between the ears, but as my wife's worst pain is below the waist and near the midline of her body, I keep the electrode close to the midline of her skull rather than more lateral, closer to the ear. If you check out a homunculus image online, you'll see where the different parts of the body correspond to the motor cortex (I've taught Anatomy and Physiology for many years, so I knew the homunculus would be informative). But bear in mind that the precise position isn't real important given the wide distribution of the electrical charge.

Many people use special elastic bands to secure the electrodes, but we use self-adhering ace wrap, which you can readily find at a drug store. We first secure the cathode (black) lead in the supra-orbital position on her left forehead with about a 20" strip of ace wrap. We then secure the anode (red) lead to the motor cortex using a similar stip of ace wrap. The ace wrap works perfectly fine.

I'll throw out one more suggestion. tDCS does not penetrate deep in the brain. There is a remarkably simple, non-invasive, cost-free method to stimulate deeper brain structures: it's called (caloric) vestibular stimulation.

You simply lie down in bed with a towell beneath your head, and then put ice cold water (using an eyedropper) into the ear contralateral to (on the opposite side of) your worst pain for 30-60 seconds. The cold stimulation will provoke nystigmus (eyes rapidely darting back and forth) and vertigo; you will probably want to keep your eyes closed, and you definitely do not want to be on your feet during this procedure! Functional imaging shows that the procedure activates a number of deeper brain structures, including the insula which are involved with pain processing.

You can search for the handful of papers exploring this form of stimulation at PubMed. Ramachandran's group claims remarkable and lasting pain relief from a single treatment in several CRPS patients. Most of the papers consist of case reports (an exception being central post-stroke pain). The lack of a definitive study for CRPS invites some doubt, but the procedure is definitely worth a try. Unfortunately, it appears to work much better for upper-body pain, so it hasn't benefitted my wife's condition.

My suggestion is to consider this treatment in combination with tDCS. I see no reason why you can't do the ice-water treatment once a day over an extended period of time.

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Iguanabill :

thanks for your posts. Pretty darn informative and educational.
I'd love to see you, ballerina & whoever else feels confident enough, discuss your best guesses as to what's going on in tDCS…

I'm actually reasonably well-educated on the theories of electromagnetic wave propagation, etc. but what's going on with the brain and tDCS still baffles me. I'm a practical person – so I don't need to know what's going on -- but I'm a curious person, so I'd like to hear some ideas from people who don't have to consider all the ins and outs of a research publication to express their ideas.

On another note -- I'm curious if anybody has any simple and inexpensive techniques for vagal nerve stimulation? One of my other symptoms is that my autonomic system is messed up – ramped towards the sympathetic side…

Thanks!

In a nutshell, tDCS modulates spontaneous neuron activity by increasing or decreasing the thresholds that determine whether the neurons send a signal. The relatively local effects of tDCS can spread throughout the brain by networks of interconnecting neuron circuits.

There are some forms of vagal stimulation you could try: gagging, holding your breath while bearing down (Valsalva maneuver), immersing your face in ice-cold water (stimulating the diving reflex), and coughing. I'm not sure whether these would have a lasting effect. Sympathetic blocks (injecting lidocaine or bupivicaine) can help reduce sympathetic activity; though they are most effective regionally (placed near the sympathetic ganglion chain), some patients respond to i.v. (total body) infusions. My wife's sympathetic issues always improved with ECT. There are also more permanent but invasive approaches (implanting a stimulator).

Please see below for an overview of neuromodulation procedures.
http://www.ncbi.nlm.nih.gov/pmc/arti...3/?tool=pubmed

In the long term picture, tDCS is really in its infancy. Having posed this question to the top three tDCS folks in the country the bottom line is no one really understands exactly how and why tDCS or why it works for some and not for others.

Did you happen to ask him what experience he has with treating CRPS patients who have failed spinal cord stimulators?

How do I say this gently? We used the ice water injection into the ear to test for brain activity ' as in brain death, about 30 years ago in ER, checking the pupils reactions, before we stopped CPR, we stopped if there was no reaction. I am not sure how this would relate to pain suppression...

Here is a smattering of publications (there are others) that answer your questions:

Miller SM, Ngo TT. 2007. Studies of caloric vestibular stimulation: implications for the cognitive neurosciences, the clinical neurosciences and neurophilosophy. Acta Neuropsychiatrica 2007: 19: 183–203

full review article available here: http://www.pcng.org.au/IMG/pdf/CVSreview2007.pdf

McGeoch PD, Williams LE, Lee RR, Ramachandran VS. 2007. Behavioural evidence for vestibular stimulation as a treatment for central post-stroke pain. J Neurol Neurosurg Psychiatry 2008;79:1298–1301.

abstract here: http://jnnp.bmj.com/content/79/11/1298.abstract

Williams LE, Ramachandran VS. 2006. Novel experimental approaches to reflex sympathetic dystrophy/complex regional pain syndrome type 1 (RSD/CRPS -1) and obsessive-compulsive disorder (OCD). ABSTRACT. Neuroscience Meeting Planner. Atlanta, GA: Society for Neuroscience, 2006.

excerpt from the abstract (only the abstract was published): "...we irrigated the ear of a patient with RSD with cold water to produce vestibular caloric stimulation accompanied by nystagmus. The procedure produced a striking reduction of pain from a 7 to 4 on a visual analog scale. No such reduction occurred in two placebo controls, lukewarm water in the ear or ice cube placed on the forehead. This patient reported no reduction in pain from previous treatments with a spinal cord stimulator, a pain pump, ganglion blocks, or a transcutaneous electrical nerve stimulation (TENS) unit. We postulate the caloric stimulation activates the vestibular cortex and other areas which then “mask” the sympathetic pain in the adjacent insular cortex."

Ramachandran VS, McGeoch PD, Williams L, Arcilla G. 2007. Rapid Relief of Thalamic Pain Syndrome Induced by Vestibular Caloric Stimulation. Neurocase (2007) 13, 185–188.

full article available here: http://cbc.ucsd.edu/pdf/rapid%20relief%20caloric.pdf