Tomacula, Conduction Block, and Axonal Constriction


After reading through the Orphanet journal review on PMP22 mediated neuropathies in the last post, I came across a very interesting statement about the effects of tomacula on nerve conduction.

In a mouse model heterozygous for Pmp22, conduction block was more rapidly induced by mechanical compression on the nerve in comparison to normal nerves and recovery was slower. They found focal axonal constrictions within tomacula. Reduced axonal diameter raises resistance to action potential propagation and thus predisposes these axons to conduction block. When the nerve is compressed, it may cause even further thinning of axons.

I did a search this morning for “Tomacula, Conduction Block, and Axonal Constriction” and came across a study which delves deeper into the subject. In fact, had I just followed the reference in the orphanet study I could have got there sooner, which goes to show that I am not a researcher by any stretch of the imagination.

Even better the very good people at PMC (which I think stands for PubMed Central) have made the study fully and freely accessible.

Conduction Block in PMP22 Deficiency

(Link embedded in title)

Much of the study flies way above my head, passes me by to the left and right and leaves my head spinning, but it still makes a very good read.

I was pleased to see that the conclusion I came to yesterday that axonal thinning within tomacula might lead to eventual axonal loss and that brought into mind the axonal loss during  military training study, is also the final conclusion reached in the article. But as they say, ‘pride comes before a fall’, so I’d better put on my rubber bouncy suit.

I can’t help feeling a bit irritated though, because so much of what I’ve read in this article seems to bear out and reinforce what most people with HNPP have been saying on forums to each other for years, only for it all to be dismissed at the neurologist clinic. I suppose it’s good that these researchers are doing this work, and they are able to get good experimental data, but if only they could listen to us a bit more, after all the poor mice can’t talk. Although I’m not sure I’d want to be cut up and sliced up for a microscope slide either….

Another point which thunders out from this is how important it is for physical therapist or fitness trainers to listen to us when we say that a certain activity is doing us harm. Often, I feel that they just think we’re shirking, and that all we need to do is try a bit harder… pah! no chance, you can’t push a palsy, and the evidence from this study reinforces that fact, and clearly states that if you do you will pay for it, perhaps with permanent irrepairable axonal nerve damage.


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