Friday, February 13, 2009

Brainstem Stimulation - cranial nerves

There are some novel therapies such as vagal nerve stimulation or deep brain stimulation, which can improve symptoms of depression. These treatments may be increasingly important sources of relief for chronically suffering depressed patients-- particularly as the technology advances, becomes safer and more refined.

Here are a few links to references about these treatments:

Of greater interest to me in an outpatient office psychiatry practice, is an idea based on looking at trivially available techniques to accomplish "deep brain stimulation" or "vagal nerve stimulation", etc. All parts of the brain -- even the "deep brain", and even the vagal nerve -- are connected to all other parts of the body! Specific life events can obviously affect deep brain or vagal nerve stimulation, without requiring an implanted electrical device or neurosurgery! Some of these life events could be deliberately sought out as therapeutic strategies.

Something I've noted about some of these new, radical techniques, is that they involve stimulation of brainstem structures, often involving the cranial nerves. It seems to me that the cranial nerves are an extremely visceral set of portals through which stimuli are exchanged between the environment and the deep structures of the brain which regulate mood and consciousness. Here's a summary of all the cranial nerves, with speculations about techniques to "stimulate" them in a way that might be therapeutic:

Cranial Nerve I (olfactory): Stimulation of this nerve requires exposure to different scents. Aromatherapy is a familiar component of alternative health strategies. Here is some evidence from the mainstream medical literature, showing that aromatherapy can be helpful:
(a review article)
(a randomized study showing that the scent from lemon oil improves mood, compared to water or lavender, and regardless of expectancies or past experience with aromatherapy)
(a study showing improvement with lavender oil aromatherapy vs. controls in neuropsychiatric symptoms of elderly dementia patients)
(another study showing improvements in dementia patients with lavender)

Given the fact that there is virtually no risk to aromatherapy treatments, why not give it a try? It could help with sleep, relaxation, studying, or as a conditioning device (e.g. associating a particular odor with sleep, or with studying a particular subject, etc.)

Cranial Nerve II (Optic): Bright light therapy has a considerable evidence base. Probably looking at beautiful things in nature is good for your mood (I'll need to find a reference to prove this!). These images would have to pass through Cranial Nerve II, on their way to your brain.

Cranial Nerves III, IV, and VI: these innervate the muscles which move the eyes. There is a type of therapy called "EMDR" which calls upon patients to move their eyes back and forth as an essential part of the therapeutic technique. I suspect this acts as a conditioning phenomenon, which at once distracts the person, while perhaps permitting exposure therapy regarding uncomfortable thoughts or PTSD symptoms to take place in a more relaxed state, or in a state associated with therapeutic benefit. But maybe the "brainstem stimulation" from eye movements is an integral part of EMDR's therapeutic effect.

Here are some links to review papers or meta-analyses looking at EMDR:
(here, EMDR and CBT are both shown to be substantially and similarly effective in the treatment of post-traumatic stress disorder)

(a Cochrane review also showing EMDR and CBT to be the psychological treatments of choice in post-traumatic stress disorder)

Cranial Nerve V (trigeminal): this nerve transmits tactile sensations from the face into the brainstem. I do not know of any deliberate psychiatric therapy involving this nerve. But there is acupuncture. Also, there is massage, and in particular "facial treatments" (involving massage, aromatherapy, moisturizing creams, etc.) available in health spas--these seem to have a positive effect on overall well-being. I'd be curious to see a controlled study on this: in the meantime, though, it seems another risk-free thing to try.
(well, this is a pretty weak study -- but it's a start, and it involves a totally harmless treatment -- it shows reduction of anxiety in women receiving facial massage)

Cranial Nerve VII (facial): this nerve innervates the muscles of the face. As noted in a previous post, actions which affect facial musculature can affect emotion, just as emotion changes facial muscle tone (it's always interesting how these phenomena can work both ways). A branch of Nerve VII also conducts information about taste (gustatory sensation) from the tongue to the brain. I have no doubt that enriching one's culinary sensations in life has a positive impact on mood. But I'll have to look for a study to prove it.

Cranial Nerve VIII: the cochlear branch of this nerve transmits information about sounds from the ears to the brain. Hearing music, soothing sounds, and speech clearly affect mood and cognition. Noise, as I claimed in an earlier post, has a negative impact on mental health. Silence itself "rests" the cochlear nerve, which could itself be therapeutic (in moderation).
The vestibular branch of nerve VIII seems interesting to me as a prospective therapeutic target. This nerve transmits signals about balance, head position, and head movement to the brain. Sometimes individuals in an autistic or highly agitated psychotic state will stimulate their vestibular nerve by rocking repetitively. The action of a parent rocking a baby to sleep, or calming an agitated, crying baby, involves stimulating the baby's nerve VIII. It would be interesting to see if various stimulations of the vestibular nerve could be useful in adults, to treat anxiety, agitation, insomnia, or mood disorder. Balance exercises could be a start (perhaps some of yoga's therapeutic effects come from this). Maybe something like sleeping in a hammock, which would rock slowly, could be more soothing on this level, compared to a regular bed. Some people might find a boat to be very soothing (for others it would just cause nausea). If there are any engineers out there, reading this, it would be an interesting project to design a device which could be programmed to gently rock an adult back and forth (with different waveforms and frequencies).

Cranial Nerve IX: Glossopharyngeal. This nerve innervates your throat. The action of swallowing involves this nerve. People with anxiety states often have uncomfortable throat sensations, or problems with swallowing. It's hard to come up with therapeutic ideas directly relating to this one. Except perhaps the idea of eating really spicy food -- which stimulates not only taste buds but also sensory nerves (partly from Cranial Nerve V) in the mouth and throat. Strong culinary sensations can be a source of pleasure, and perhaps can also teach one to be more open about new things (I remember taking a long time getting used to wasabi on sushi after being introduced to Japanese food upon moving to Vancouver in 1995).

Cranial Nerve X: This is the vagus nerve that is stimulated electronically in an advanced surgical treatment for depression. The vagus nerve innervates the parasympathetic system of the body's viscera (e.g. it slows the heart, speeds up the bowel, etc.). One can train the vagus nerve through activities such as yoga, meditation, biofeedback, and through physical exercise.

Cranial Nerve XI: this nerve allows you to turn your head back and forth. Perhaps this could be an element not to forget in your exercise regime -- do some stretching and gentle exercises involving rotation of your head.

Cranial Nerve XII: this nerve allows you to move your tongue. Speech, singing, eating, and a variety of other pleasurable activities -- all involve your tongue. In anxiety states, people can have an exaggerated awareness of their tongue movements. Taking voice lessons or attending a voice coach can help build confidence, reduce social anxiety, literally help you "strengthen your voice"--a strong and clear voice, both metaphorically and literally, can be part of a healthy emotional life.

In conclusion, perhaps there are a variety of readily available techniques that can accomplish "deep brain stimulation" in ways that benefit your mental health, without actually requiring a neurosurgical procedure!


Anonymous said...

I thought that you had posted somthing on TransCranial Magnetic Stimulation.... but apparently not... or maybe I can't find it.

I was watching something last night that is really interesting.

It is basically the idea of of using TMS to "scramble" neurons in a particular brain region to change judgements (moral judgements). From the talk you can see that TMS causes us to revert to how we used to judge others when we were children.

Rebecca Saxe: How we read each other's minds

Lastly--- on a more therapy orientated issue. I was reading up on how TMS is now being used to decrease/temporarily cause abolishment of hallucinations (specifically auditory)in some severely depressed patients.

What haveyou heard about this therapy?

Super interesting...!!

GK said...

Thanks for the comment.

TMS seems like a really interesting idea. It is much easier to administer, with less medical risk, fewer side effects, and is less burdened by negative social perceptions and controversial history, compared to ECT. It also could be a useful research tool, to study the effects from selective stimulation of particular brain regions while the patient is conscious.

Unfortunately, research about its therapeutic benefits has so far not led to impressive results, in my opinion. But I haven't reviewed the literature in detail on this in the past while; I'll have to write a more detailed post about this in the future.