PNE vs. Posterior Femoral Cutaneous Nerve Entrapment

[Faith]

In trying to research and understand post femoral cutaneous nerve (PFCN) in relation to the pudendal nerve I ran across this article published by Dr. Hibner this September 2011 in Global Library of Women's Medicine http://tinyurl.com/3vs8y9v

There is a section on the PFCN (which divides into the inferior cluenal/perineal branch of the PFCN) and it says,

"To differentiate pudendal neuralgia from PFCN entrapment, a CT guided block can be performed at the entrance to Alcock's canal to isolate the pudendal nerve. Failed alleviation of symptoms would suggest PFCN entrapment. Treatment for neuropathy of the PFCN consists of CT guided nerve blocks at the ischial spine to access the PFCN or an injection 4 cm inferior to the ischial tuberosity to block the PBPFCN."

"The advantage of CT guided injection is that it allows placement of the block into Alcock’s canal. Placing blocks into the Alcock’s canal allows differentiation between pudendal neuralgia and inferior cluneal neuralgia."

I am concerned now because I have some symptoms of inferior cluneal neuralgia (particularly pain around the ischial tuberosities). I had 2 blocks via Xray and Ultrasound(transgluteally) and then a block (anesthetic only) transvaginally by Hibner when I had my botox. One of my ultrasound guided blocks caused some short-term weakness in my posterior thigh which now looking back makes me feel like that block also probably hit my PFCN. That block numbed my butt and the lower half of my perineum. The second ultrasound guided block I had numbed me all the way up to the clitoris which caused a very strange feeling and and I didn't get as good of relief with that one. Interestingly the one I had transvaginally by Hibner numbed me up through the clitoris as well, but I had better relief with that one (or was it because I also had the left over effects of general anesthesia from botox in my system?).

I found a couple of articles including this one (abstract only link)http://tinyurl.com/3kvy6vj that say "An isolated posterior femoral cutaneous nerve lesion is rare."

It seems more likely that there would be both PNE and PFCNE than just PFCNE alone and with my history/symptoms Dr. Hibner feels PNE is more likely, but I do not want to have PN decompression only to really be entrapped at the PFCN/inferior cluneal nerve. Of course in the article above Dr. Hibner also talks about the communication between the PBPFCN and inferior rectal branch of PN so it is possible some of my symptoms are from that as well. But maybe I should have a CT guided PN block at Alcock's canal to be "sure".

Any thoughts?

[Faith]

Also in Dr. Hibner's article http://tinyurl.com/3vs8y9v he says about PN

"Interestingly, most patients report absence or improvement of pain when sitting on a toilet seat,6 as the body weight in this position is supported by the ischial tuberosities, thereby relieving pressure from the pelvic floor."

and about PFCN

"worsening pain when applying pressure to the ischial tuberosities such as sitting on a toilet seat."

Maybe I am just a small person, but when I sit on the toilet my ischial tuberosities do not touch the toilet seat so the pressure is relieved from them just like my pelvic floor!

I spoke to Hibner recently about my concerns about PFCN involvement (unfortunately I hadn't seen this article yet though) and he said some people who have symptoms of PFCN are helped with PN decompression (they don't really know exactly why) and he felt my blocks were diagnostic enough for PNE, but if I wanted another one I could have a CT-guided one.

It sure seems like a lot of people with PN also have ischial tuberosity pain. My pain is more medially to the ischial tuberosities, like along the ischial ramus,(which could very well be coming from the PN) but I am thoroughly confused after reading this article!

[carolynm]

Faith,

First off, I'm wondering where your blocks were placed, i.e. did you have one into Alcock's canal? where does he think you are entrapped from the information he got from the blocks?

I'm not trying to be condescending, we are both nurses here, but couldn't the weakness in the thigh be some leakage over to the sciatic n.?

I understand that you are needing to know a firm diagnosis before the big surgery date. Could you call again and tell him about your concerns, that you read his article and had some questions? I really think you should call. I don't know what his call-back times are, but it will before for surgery and could possibly put your mind at ease.

xx cari

[Lernica]

I understand that you are needing to know a firm diagnosis before the big surgery date. Could you call again and tell him about your concerns, that you read his article and had some questions? I really think you should call. I don't know what his call-back times are, but it will before for surgery and could possibly put your mind at ease.

xx cari

Faith,

I agree with Cari. Call Dr. Hibner! I can see that you are really struggling with your decision about surgery, and it must be taking an emotional toll on you. He will no doubt be able to answer many of your questions and address any remaining concerns that you have.

Thinking of you.

[Faith]

Faith,

First off, I'm wondering where your blocks were placed, i.e. did you have one into Alcock's canal? where does he think you are entrapped from the information he got from the blocks?

I'm not trying to be condescending, we are both nurses here, but couldn't the weakness in the thigh be some leakage over to the sciatic n.?

xx cari

According to my records, my blocks were done inferior to the the ischial spine. Only CT guided blocks are done at Alcock's to my understanding. The "spillover" could have been to the sciatic, but more than likely I think it was the PFCN because most of my lower butt was numb and the weakness only went down to my posterior mid thigh. Also the PFCN is closer to the PN than the sciatic. This picture is a good diagram that shows the PFCN's relation to the scatic and pudendalhttp://tinyurl.com/3fjb5su

[Faith]

I'm surprised I haven't gotten more responses to this as several people have talked about inferior cluneal nerve entrapment lately.

I was thinking though if someone gets a CT-guided nerve block in Alcock's canal (which is what Hibner does and maybe other PN docs I'm not for sure) and your pain is not relieved then that could lead someone to believe that they don't have PN and maybe have something else like PFCN entrapment. But in reality they could have PN entrament and just be entrapped at the ischial spine level or higher up, right? Because the block doesn't numb up "higher" than the injection site...only lower.

And again...am I the only one who's sit bones don't touch the toilet seat, but rather fall in the hole (like my perineum) when I sit down?

[Lernica]

And again...am I the only one who's sit bones don't touch the toilet seat, but rather fall in the hole (like my perineum) when I sit down?

Mine fall in the hole too.

[Karyn]

It seems more likely that there would be both PNE and PFCNE than just PFCNE alone and with my history/symptoms

I'm not a doctor but I agree with you, Faith. I'm beginning to learn that a good lot of us not only have PNE, but other pelvic neuropathies as well.

[helenlegs 11]

It's almost got my head done in. . . reading, trying to decipher,reading some more. . .AAArgh! wish I had paid more attention in biology. However faith I agree PN sufferers often have other nerve issues too. The cause may be because of the PN problem already existing and a development of CRPS or they may occur along with the onset of PN, especially if cause by trauma.
I also think that I may have PCFM involvement btw.
My theory is that because mine is because from a trauma (innocuous,fall onto buttocks) and I have one particularly 'exquisitely tender' site (sciatic notch end of piriformis) which is where it has been so painful from day one, and I had a lump there, now gone. I think I have nerve compression/entrapment issues at this one spot. I know that you have wondered if you have SI problems too which is the spot just above (I have wondered the same for myself too) So I am hoping that any surgery would be able to address everything at once.
With Dr Martin doing the surgery endoscopically, I wonder if he would be able to reach any further if that were needed.
You have done a lot more reading about PCFN and understand the whole thing far better than I do . . . but what I am asking is may you not be in a similar situation, in that once a surgeon is in there, they will be able to address your whole problem whether PN or PCFN or whatever in the op?
I can understand about the ischeal tuberosity pain though, again I have the same. That is a bit more confusing admittedly.
Where are the most problematic points that the PCFN can be compressed?
I think the printing of that report (although an excellent one ) Must be slightly wrong about the toilet seat thing. That is one of the signs of PN since the Nantes Criteria.

[FinalCountdown]

(No, I'm not okay; yes I'm still here.)

Is it possible that the sacrotuberous ligament could have adhesions and is mashing both of these nerves? This is kind of where my process-of-elimination "theory-du-jour" is taking me now.

I just had Botox in my piriformis which *absolutely* helped with sciatic nerve pain, but didn't touch my lower back (sacral area) or endless groin and perineal pain (I am male, btw).

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