This paper says....rare:
http://www.neurology.org/content/20/2/177.extract

But you know anything that reduces oxygen to the tissues, is suspect. Poor circulation is one thing that reduces oxygen to the tissues. Axonal, can also be autoimmune and those antibodies also attack the axon typically.

Just look at the faces/skin of people who smoke. They often look much older than they are because of the chronic monoxide in cigarette smoke.

I'd say most toxins do damage to us one way or another.

Most of what I found on a quick search just now, discusses acute poisoning with monoxide.

This paper is more specific and newer... suggesting some demyelination for subacute exposures:
http://www.ncbi.nlm.nih.gov/pubmed/21242286