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PF or nerve entrap? Question re diagnostic shot

Posted by chrisb on 6/25/03 at 10:18 (122892)

I said I'd report back on this so here goes. I'd appreciate feedback from one of the docs or anyone who has this experience.
I am a resistant 2.5 year case and they're wondering if now most of my problem may be trapped nerve and only to a lesser extent PF. I was thinking of ESWT and have been told that since ESWT does nothing for nerve entrap, it would be good to rule this out first. I currently have an odd flare happening, so my doc thinks this may be a good time to try a diagnostic shot to find out. (footpain.org describes calcaneal nerve entrapment as 'pain can mimic PF but does not increase with first morning step. Diagnosis is made by numbing point of max tenderness and determining if pain disappears while anaesthetic is working') I'm not a medical pro but this approach seems quite logical to me.

2 hours ago my doc injected marcaine to the area where the nerves sweep around the ankle under my instep, i.e not at fascia insertion point but a bit above and to the side. I'm keeping mostly off the foot but now feel no pain walking carefully around the house. Sensation in my foot appears to be normal, except for the frozen area about the size of a Canadian Toonie right at the fascia insertion point. The maracaine will wear off in 4 hours or so, and I'm reporting back to my doc Friday.

Here's my BIG QUESTION: since the fascia insertion point is frozen, wouldn't this also freeze any pain from a micro-tear in the fascia? In other words how do I know for sure that this points to nerve inflammation and not fascia micro-tear?

My doc's intention here is to try to tell if nerve inflam is happening. If this shot is diagnostic and I'm interpreting it correctly, then I guess this helps the diagnosis. As result I think he will probably inject cortisone Friday. The shot will be to the nerve area not the insertion point. I trust my doc on this one but would very much like to hear input.

Re: PF or nerve entrap? Question re diagnostic shot

Ed Davis, DPM on 6/25/03 at 15:23 (122923)


A Canadian Toonie? I think that is a little bit bigger than a US quarter.

You have bought up a good point. If one blocks the medial calcaneal nerve, then the origin of the plantar fascia would also go numb and it would be hard to distinguish between medial calcaneal nerve entrapment and plantar fascial insertional pain. One way around this is to mix a steroid (cortisone) in with the marcaine. Once the numbing wears off, one would expect some persistence of pain relief to occur. Since the steroid was only placed in the area of the nerve, persisting pain relief would point to the medial calcaneal nerve as the culprit.


Re: PF or nerve entrap? Question re diagnostic shot

chrisb on 6/25/03 at 16:55 (122937)

Thank you Dr Ed for your reply.
In this scenario (marcaine & steroid mix) do you mean that any persisting pain relief (after the marcaine wears off) would therefore be due to the cortisone bringing down inflammation around the nerve?
If that is the case, then will a separate followup injection of cortisone to the same area equally prove this point?
And yes, a $2 Toonie is bigger than a US quarter. Its bigger than the $1 Loonie, if you you know what I mean. So I guess I should say thanks for your 2 bits.

Re: PF or nerve entrap? Question re diagnostic shot

Dr. Z on 6/25/03 at 18:19 (122943)

Why not get an ultrasound and see if the plantar fascia is thickened . Compare the good foot with the painful foot. This would determine if the it is insertional pf very quickly

Re: PF or nerve entrap? Question re diagnostic shot

Ed Davis, DPM on 6/25/03 at 21:52 (122957)

The answer to your first question is yes.
As for the second question -- it depends where the follow up injection is intended to go --- if it is going into the medial calcaneal nerve, it can be used to help rule out (or in) medial calcaneal neuritis as the culprit.

Re: PF or nerve entrap? Question re diagnostic shot

chrisb on 6/26/03 at 07:49 (122976)

Thank you Drs Z & Ed. I have actually had an ultrasound which shows the fascia at 5.8 thickness which I know is PF indicative.
My doc may give me cortisone to the calcaneal nerve area tomorrow, and I hope that will help with my current flare and get me off crutches. If not then i guess I could try ESWT?
An MRI result will come in 2 weeks.