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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 8 of 8. This is the beginning of the thread.
Posted by morganator on December 7, 2009, at 16:14:55
Does anyone have any idea how rTMS works? I would love if it could possibly help me but unfortunately I don't think it would given my particular illness.
Posted by Phillipa on December 7, 2009, at 16:45:42
In reply to rTMS, posted by morganator on December 7, 2009, at 16:14:55
Morgan is it OCD I'm sorry kind of forgot. Love Phillipa
Posted by SLS on December 7, 2009, at 16:55:37
In reply to rTMS, posted by morganator on December 7, 2009, at 16:14:55
> Does anyone have any idea how rTMS works? I would love if it could possibly help me but unfortunately I don't think it would given my particular illness.
Magnetic fields can produce electric currents through induction. That's how generators work. In excitable cells (neurons, muscle), the induced current produces action potentials - neuron firings. It takes a heck of a strong magnetic flux to penetrate the skull to produce this effect. The focus of effect is therefore not very deep, but is deep enough to work on temporal and prefrontal areas. It is sort of like a well-placed, localized, and minimal dosage of ECT. Placement of the coil is usually on the left side of the forehead, and the magnetic flux is focused on the left prefrontal cortex. The optimum frequency of the pulse train is 10Hz.
I don't know what the mechanism is by which rTMS treatment exerts an antidepressant effect. Perhaps it is similar to that of ECT. I think those pathways in the LPFC that are stimulated make their way to the limbic system. There might be a LTP thing going on here.
- Scott
Posted by morganator on December 8, 2009, at 1:20:53
In reply to Re: rTMS » morganator, posted by Phillipa on December 7, 2009, at 16:45:42
I'm fall somewhere under the bipolar umbrella. I do have OCD(mostly with thoughts) and major depression and anxiety. So my bipolar is very mixed. This is the first time in my life that I have suffered from a deep depression for this long.
Posted by morganator on December 8, 2009, at 1:21:17
In reply to Re: rTMS, posted by SLS on December 7, 2009, at 16:55:37
Thanks
Posted by Phillipa on December 8, 2009, at 19:44:08
In reply to Re: rTMS, posted by morganator on December 8, 2009, at 1:20:53
Morgan thanks for explaining easier to understand a person's message on babble to me. Love Phillipa
Posted by twinleaf on December 9, 2009, at 9:21:47
In reply to rTMS, posted by morganator on December 7, 2009, at 16:14:55
I think I can add a bit about how it works. The treatments are given to the left frontal area, and, as Scott says, although the electromagnetic current does pass through the skull, it doesn't go very far into the brain- about one to two cm. only. So. it initially affects the left prefrontal area only. It does"perk up" neurons there. This can be important, as blood-flow studies in depression usually show underactivity of the whole left prefrontal cortex. As this is the more hopeful, problem-solving area of the brain, activating it, so that it becomes more equal to the right pre-frontal cortex, which tends to contain our pre-conscious and unconscious memories of past social stressors- abuse, neglect, failures and losses- can result in a much less depressed or hopeless state of mind.
And it does more. Connections between the prefrontal areas and the limbic system are very numerous, so messages get sent from the neurons in the prefrontal areas to those in the hippocampus and nearby structures. In major depression, work done at the German Primate Center and elsewhere has shown that severe social stressors result in an overactive HPA axis, with excessive production of cortisol and glutamate in the brain. This stops the formation of new cells in the hippocampus (and elsewhere). We are supposed to produce several thousand new neurons in the hippocampus every day throughout life, When this stops happening because of the toxic effects of high levels of stress hormones, the hippocampus becomes smaller than normal, and individual cells appear shrunken and damaged. rTMS has the effect, indirectly, of lowering the levels of stress hormones, causing the individual neurons to regain a more healthy appearance, and allowing neurogenesis to begin again.
The depression model used in studying this is the social-stressor model, which would be comparable to the type of depression in humans caused by childhood abuse, neglect, loss, etc. However in bipolar depression, which at times appears to be less closely related to social stressors, and more closely related to hereditary factors, it has also been used successfully.
ECT has essentially the same beneficial effects as TMS does, but it is an "overkill", with quite a high risk of impairments in memory and cognition. TMS does not carry these risks. I think it is always worth trying it first. If it doesn't work, there is the possibility of considering ECT next.
Posted by morganator on December 9, 2009, at 11:44:39
In reply to Re: how it works... » morganator, posted by twinleaf on December 9, 2009, at 9:21:47
Thanks for the in depth explanation. I'm going to see my doctor today and will discuss rTMS with him. I just feel like my brain is such a wreck and I am way too depressed about things in my life to do what I used to in order to make a complete recovery.
Btw, I do think my bipolar depression is much worse because of my childhood.
This is the end of the thread.
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