link between apnea and periodic limb movement/restless leg?

[guest2006]

I have both PLM and apnea. After several years of browsing apnea/PLM forums, I find there is a large percentage of apnea sufferers (seems well over 75%) who also have some type of restless leg/periodic limb movement syndromes. Does one cause the other? I think the RLS and PLM might evolve from lack of oxygen during apnea, or that there is some chemical change from the apnea to oxygen/blood levels that affects the brain, and thus brings on the RLS. I asked a sleep specialist at Stanford if there were any studies of this phenomenon, or if the fact that the two seem to go hand in hand, and she hadn't heard of any, or even considered the possibility herself.

I'm not really smart, so the fact that I noticed what appears to be a causal action makes me believe that some of you with more experience might have heard something or developed your own theories. I think that forums like this, could definately help advance medical studies, as doctors may not be privy to their patient's total sleep history, whereas on these forums folks seem to be much more open and forthcoming.

[bassett]

I have personally found that using a CPAP has zero effect on my RLS. Without my Requip, the RLS appears. The sleep study tech suggested there's a correlation but my doctor told me there was not, to the best of his knowledge.

[Guest]

The following was posted by deltadave. He manages an accredited sleep lab and is an RT, RPSGT:

Hi all:
PLMS and OSA are entirely separate entities. A leg movement that is caused by the termination of a respiratory event should not be scored as a PLM, but rather an LM (Limb Movement). The disappearance of PLMS following successful CPAP titration would undoubtedly mean that the PLMS were not PLMS at all, but simply part of an overall body jerk accompanying the respiratory arousal. Actually, PLMS often increase in successful CPAP titration as the body is able to enjoy continuous sleep and the PLMS allowed to come to full fruition.
Since PLMS can be medically treated, it becomes important to be sure to differentiate them from LMs, which can not.
Further, PLMS by themselves are harmless. It is only when they cause arousals (listed in the sleep study as PLMAI, Periodic Limb Movement Arousal Index) that they need to be addressed. Usually we're looking at an index of >5.0 for treatment, and/or certainly, a complaint of excessive daytime sleepiness.
deltadave

and

<snip>

PLMs and OSA are not related. For a snapshot of a PLM take a look here:
PLMS
Limb movements that occur following respiratory events are called exactly that, LMs. And if all the LMs disappear with CPAP, then you KNOW they weren't PLMs. If anything, PLMs get much worse as the CPAP allows you continuous sleep and the PLMs are allowed to come to full fruition. You treat PLMs with drugs.
And actually, PLMs themselves are harmless, unless they cause an arousal, so look for your PLMAI. If it's >5.0 and you have EDS, think about treating the PLMs.
Did you see that subtle difference? Arousals don't cause PLMs, PLMs (may) cause arousals.

[kteague]

I just returned from Cleveland Clinic for a consult. The perspective of the doc there as relates to my treatment was that there are cases sometimes where therapeutic treatment of OSA results in improvement of RLS and/or PLMs. With other cases, treating a low Ferritin level improves or resolves the same. (Therapeutic is >50. Mine was 26.) The remaining cases that don't respond to either of the above are treated with medication, most commonly Requip or Mirapex. Their viewpoint was that I was on too high of a dose of Mirapex, without even knowing for certain that I needed medication. Although my blood counts in a routine CBC were normal, my Ferritin level was low and it had never been tested in almost 8 years of treatment by at least 4 doctors. Also, I had never had a follow-up sleep study with all my EDS to see if my cpap treatment is effective. After we back-track to be certain about the above, then they will reassess my daytime sleepiness for any further diagnosis.