Sensory sensitivities: research and theories?

Does anyone know of research into sensory sensitivities in ME? (I know MERUK have something in motion, but is there anything already published?) Or anything that outlines possible causes?

 

I don't know of any specific research, but as sensory sensitivity occurs in many illnesses – all the way from life-threatening conditions to hangovers and colds – might it be difficult to characterise it specifically in ME? (I don't actually know the answer, that's just the first thing that popped up in my brain!)

 

Michael van Elzakkar at his recent talks at Harvard is studying the brain doing neuroimaging. He mentioned the similarities between post concussion cognitive dysfunction and sensitivities and gave a chemical reason for this in those conditions (I think!) and said it might be the same In ME. Previously in a talk to llewllen king he said his neuro imaging research was finding low activity of the thalamus. He suggested the thalamus had an important stimulus filtering role in the brain including in sleep which might be why we are light sensitive etc and also wake at the slightest noise, I do anyway. Please check yourself as I’m going by my interpretation and memory but he is one of leading CFS researchers doing neuro Imaging afaik and it’s encouraging he’s very aware of our sensitivity issues in relation to his findings, even if not researching them directly.

 

Thanks very much. I’ll look into this.

 

Migraine can cause light sensitivity.

Also, some ingested drugs can cause the pupils to dilate, which I would assume would cause light sensitivity similar to the topical dilation you'd receive from an optometrist in a retinal exam.

So, there'd be at least two possible mechanisms for light sensitivity - over-sensitivity of the nervous system (like in hangover), and actual pupil dilation that allowed in too much light.

 

From the Michael van elzakjar talk from about 9mins in : might not be fully accurate

 

I had a test a few years ago that used an eye drop that dilates the pupils and it didn't make light particularly more sensitive, just blurry. I doubt this part is mechanical, most likely lowered neuron firing threshold or something that amplifies the normal signal.

 

Do you mean something similar to what happens in epilepsy? Just affecting perception of, well, perception?

 

That's interesting. Sensitivity to the eye drop may vary from person to person. Every time my eyes are dilated (most recently a month ago), I'm effectively blinded by the bright sunlight when I step out of the optometrist's office. I have to wear one of those disposable sun shields they give you and a pair of sunglasses over that (and it's still pretty bright).

Apparently, people with blue eyes are more sensitive to the atropine drop than those with brown eyes.



A few years ago my doctor offered to give me an eye drop that would - mostly - reverse the dilation before I left the office. I think it was either new or experimental. I got the impression that it might be expensive, too - but he didn't charge me for it. He just seemed interested in seeing how effective it was. It probably cut the light sensitivity in half and shortened its duration. The "reversing" drop may not have caught on, since I was never offered it again.

[I believe a dilated eye is blurry for the same reason that a camera lens with a wide aperture can be blurry if not carefully focused, i.e. reduced depth of field. Atropine probably also inhibits the muscles that adjust the lens of the eye, making you farsighted.]

 

I don't think it's perception, more of an excess signaling. Like lighting a fire with way too much gas, a small match will make a big boom. Likely a similar process to whatever happens in a migraine, ordinary headache, hangover or being suddenly woken up from REM. It's probably a common process that just goes uncontrolled.

 

My unreliable memory tells me it was cloudy that day, no bright sun, but I really did not notice any difference at all. Even if it hadn't been painful, it should at least have been noticeably brighter but it wasn't. Also blue eyes.

 

I don’t think so. Because the sensory sensitivity that appears in other conditions is very different to that which appears in ME, and especially in severe and very severe ME. As far as I know, in no other condition does it cause drastic and severe deterioration, ie a few minutes or seconds (in v severe) causing extreme distress but also leading to reduced / inability to talk, sit up, eat, swallow, etc.. severe increases in pain... reduction in functioning. And then that can carry on for many days or weeks etc.

I really think there’s something here that should be looked at more because this seems completely unique to ME. What possible mechanism can there be - for sound, light, movement, touch to affect someone in this way? For example in migraines people are affected by similar things but the symptoms and functioning issues are quite different when looked at overall. In the hospital admission film Dr Speight says it’s so important for doctors to do everything they can to reduce the stress on the patient. Again, how and why can stress - both emotional and physical, and sensory, cause such rapid deterioration?

Is there no research working on this at the moment?

 

I had those dilating eye drops (while ill with ME but not as severe), it did make me slightly more sensitive to light but it was a totally different mechanism to whatever is going on with my light sensitivity imo. Just felt different. Like an added layer of light sensitivity but not the same as what I experience on a daily basis.

 

I suspect it's thought to be part of the whole 'broken battery' phenomenon, since sensory stimulation consumes a lot of energy resources. Even people who're not chronically ill find it becomes a great deal less tolerable when they're exhausted.

If we can find ways to increase energy levels in ME, that will tell us whether sensory sensitivity also improves. If it doesn't, then maybe it is something separate.

 

This is certainly my experience...I don’t know whether what I have is true sound “sensitivity”, but the inability to distinguish one sound from another, all sound just being “blah” and volume being disproportionate to normal seems to get worse in PEM and sometimes isn’t present at all when I’m having a good day. I frequently need ear plugs when others are talking if I need to concentrate on something.

For me this is cognitive fatigue rather than anything specific to do with sound or light (light “sensitivity” is similar for me). Perhaps this is a different experience to others and there is confusion in terminology for different experiences/symptoms?

maybe as a mild/moderate I’m only experiencing the tip of the iceberg?

 

@arewenearlythereyet my sensitivity is very different to that. I experience severe pain when exposed to light and sound, beyond my very narrow limits. It causes me pain to type on my phone now, with dark glasses and with the screen dimmed right down and the blue light off.

Also when it’s bad, causes physical deterioration in health and all parts of my functioning get worse. Which can continue to get worse for some time afterwards (days, weeks after hospital for example). I do have what you describe as well - like I need ear plugs too but not to concentrate - I need it to drown out the sound. Which unfortunately even noise cancelling earplugs + ear defenders don’t do completely!

Edit; we have a thread in the advocacy forum somewhere about what happens to you when you’re exposed to sensory stimulation which has different peoples experiences

 

Yes, it's pain and deterioration, as @lunarainbows says.

Much less of a deterioration in function for me, I suspect, as I'm not severely affected. It just burns though a day's energy in minutes.

However, my autism means that pain from sound – and especially light – can be as acute as someone piercing your skin with a nail.

 

I wonder if this is the cumulative effect of more than one problem.

I have blue/grey eyes and have always been a bit light sensitive.

I started having migraines as a pre - teen. The sensitivity became much more extreme and when a migraine was brewing soon became impossible to ignore or work around.

The ME sensitivity is quite different, though I doubt I am anything like as sensitive as @lunarainbows. In my own case I think the inability to filter unwanted stimuli to the brain that's part of how ME affects my cognition combines with the sensitivity.

I don't mean that in a behavioural way.

 

Yes I’m also not sure to what extent my autism is interacting with my ME. Before I got ill with ME, I did feel pain, but then there were also times that sensory stimulation would cause extreme hyperactivity and panic / adrenaline type feelings which actually would counter act any sort of sensitivity I was feeling. But then I would feel extremely unwell in crowded places. But I could still manage going out and about and living a “normal” life. Now I know that I continuously pushed myself a lot outside my comfort zone because I was told it was all anxiety, and so I ended up affecting my physical and mental health because of it.

I’ve also been told I have migraines - and that could be causing the light and noise sensitivity - I am a bit sceptical because I just tried some migraine meds which did do what they’re supposed to do (constrict the blood vessels), pushing my blood pressure up by 10-15 points, but did nothing for the light and sound sensitivity!

It’s just a completely different experience to Severe and very severe ME. Sensory stimulation is very frightening now - the deterioration (which wasn’t there before) and the level of pain (which also wasn’t there before - never to this extent) and my level of functioning. I think Kitty may be right it may be related to the “broken battery”, and energy is required to deal with sensory input, as it does drain my energy and functioning so quickly. Wasn’t there a research group looking specifically at sensory parts of ME, I think it was posted on S4ME a while ago.