Meralgia Paresthetica

[docnyc]

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Any suggestions?

Have already tried LFCN block, lidoderm, neurontin, loose clothing. Sent patient to PT today to try TENS unit.

 

[Ligament]

Any suggestions?

Have already tried LFCN block, lidoderm, neurontin, loose clothing. Sent patient to PT today to try TENS unit.

concur with what you have tried already. Was there relief during the anesthetic phase of the block? If yes, then cryo, pulse RF or botox the nerve. If that fails, could try L2 and L3 transforaminals or pulsed RF of the DRG.

If no response to block, did you use a nerve stimulator to localize the nerve? Are you certain of the diagnosis?

 

[docnyc]

concur with what you have tried already. Was there relief during the anesthetic phase of the block? If yes, then cryo, pulse RF or botox the nerve. If that fails, could try L2 and L3 transforaminals or pulsed RF of the DRG.

If no response to block, did you use a nerve stimulator to localize the nerve? Are you certain of the diagnosis?

Thanks for the input. I did consider L2,L3 TFESI but his pain pattern almost completely fits classic meralgia paresthetica. No back pain complaints whatsoever, and no anterior thigh pain but rather lateral anterior and lateral. Troch bursa was fine.

He states that it is numb with some dysesthesia. He has some findings of facet arthropathy at L3 but no sign of any nerve root irritation either by disc or facet capsule. I will definitely try the block with nerve stimulator. He did get relief with the local block but the steroid didnt do much. If no success I may try tfesi to see if anything improves and maybe its atypical radicular pain.

Have you had success with botox'ing the nerve?

 

[caedmon]

The LFCN is also easily visualized with Ultrasound. I've done ultrasound guided as well as US guided with needle stim.

I've done US guided pulsed RF with mixed results.

 

[nvrsumr]

I've done US guided pulsed RF with mixed results.

Same

 

[PinchandBurn]

Any suggestions?

Have already tried LFCN block, lidoderm, neurontin, loose clothing. Sent patient to PT today to try TENS unit.

This could be attempted

http://www.ncbi.nlm.nih.gov/pubmed/19787014

 

[Ligament]

I did consider L2,L3 TFESI but his pain pattern almost completely fits classic meralgia paresthetica.

Just to clarify, I am not implying that it is L2/L3 radiculopathy, but rather the LFCN originates from the L2 and L3 roots. Therefore, you can sometimes treat pain of the LFCN by blocking its contributing branches which are L2 and L3.

Similarly, I have had some successes blocking L1 and L2 to treat genitofemoral neuropathy.

 

[Jeff05]

Any suggestions?

Have already tried LFCN block, lidoderm, neurontin, loose clothing. Sent patient to PT today to try TENS unit.

try nortriptyline and lyrica (i don't love neurontin's bioavailability).


also, if it's a true MP - the LFCN block would be diagnostic and should work. which means that you either did not get the LFCN or this is not MP. so try to block it again or go up to the spine.

 

[docnyc]

Thanks for the input guys. He did get temporary relief with local from LFCN but it did not last (no sustained effect from steroid).

I may consider going up the spine to see if better long lasting treatment.

 

[NOSfan]

Just to clarify, I am not implying that it is L2/L3 radiculopathy, but rather the LFCN originates from the L2 and L3 roots. Therefore, you can sometimes treat pain of the LFCN by blocking its contributing branches which are L2 and L3.

Similarly, I have had some successes blocking L1 and L2 to treat genitofemoral neuropathy.

I would also like to add the relationship between the L2 DRG and sympathetics which may play a role here and would opine a direct relationship between MP and sympathetic dysfunction.

p.s. L2 DRG TFESI have helped some of my patients with MP!

 

[CB1Antagonist]

try topical doxepin cream 5%. messy but often effective

 

[joshmir]

There is a paper in a NS journal where they tested the hypothesis that if you push down on the ASIS from the lateral aspect it would impart slack into the inguinal ligament, so if you have MP from the nerve being entrapped under the ligament, even though you are bending their bone, they should get relief

this test was predictive of benefit from surgical exploration and release of the inguinal ligament

i have tried this diagnostic test a couple times and it works, suprisisngly

i sent one young girl to a NS who released the ligament and she is doing great now

sorry i don't remember the reference, couldn't find it when i tired to google it

 

[FLK 1]

I'm among those who have been pleasantly surprised by the positive response to pRF of L2, L3 DRG in patients with MP confirmed by LFCN block. Injected local and steroid, billed as TFESI, ate cost of RF cannula.

 

[lobelsteve]

I am amused and disturbed at proximal treatments for distal entrapment neuropathies. I will wager that all who got better with this treatment were destined to get better with tincture of time.

Can someone refute this is the exact same thing as doing a CESI for carpal tunnel? Proximal treatment for distal entrapment. Makes no sense to me, but I'm willing to learn.

 

[drf]

depends what we think pRF actually does.

At some point the nociception from the groin passes through the DRGs to get to the cord and brain. Only putting steroids on the DRG with the lesion in the groin doesn't necessarily make sense, but maybe pulsing that DRG modulates the nociceptive pathway and does something magical.

 

[drf]

I guess I could also add that I sometimes do a series of diagnostic blocks to figure out where a lesion is located, then I pulse proximal to that lesion. Most nerves are n = 1-2, but I do have a series of saphenous neuralgia patients (s/p TKA or knee scope) that get better when I pulse the nerve at the mid-thigh.

 

[Jcm800]

I am amused and disturbed at proximal treatments for distal entrapment neuropathies. I will wager that all who got better with this treatment were destined to get better with tincture of time.

Can someone refute this is the exact same thing as doing a CESI for carpal tunnel? Proximal treatment for distal entrapment. Makes no sense to me, but I'm willing to learn.

I agree... i have said this for years...

i used ask why a sciatic block would help for a distal peroneal injury. people looked at me like i was crazy.

 

[NOSfan]

I am amused and disturbed at proximal treatments for distal entrapment neuropathies. I will wager that all who got better with this treatment were destined to get better with tincture of time.

Can someone refute this is the exact same thing as doing a CESI for carpal tunnel? Proximal treatment for distal entrapment. Makes no sense to me, but I'm willing to learn.

.Not too crazy when you think about it...Why does a proximal sympathetic block help for a CRPS II patient? What about radiosurgery at the trigeminal nucleus for trigeminal neuralgia?

Besides, CTS and MP are not always secondary to an entrapment phenomemon or else they would have all gotten better after surgery and......I would not have to see them 🙂.

 

[lobelsteve]

.Not too crazy when you think about it...Why does a proximal sympathetic block help for a CRPS II patient? What about radiosurgery at the trigeminal nucleus for trigeminal neuralgia?

Besides, CTS and MP are not always secondary to an entrapment phenomemon or else they would have all gotten better after surgery and......I would not have to see them 🙂.

I believe cts and mp are always defined as entrapment neuropathoes whereas the tn and crps 2 are entirely different neuropathic phenomenon with no entrapment. Similar, but different.

Would not treat peripheral neuropathies with any procedures.

 

[FLK 1]

Can someone refute this is the exact same thing as doing a CESI for carpal tunnel?

Doing TFESI for MP would be the same as doing CESI for carpal tunnel. Pulsing the DRG to treat MP is more akin to pulsing a thoracic DRG to treat post-thoracotomy pain.

As I said, I was surprised by the good response. The initial patient was desperate, and had little or no response to meds and loose-fitting clothing. Transient benefit from LFCN block. I reluctantly gave it a try, and the patient had 80% resolution x 9 months before we had to repeat it. Same result the second time. I've used it a few more times since then with similar results in other patients. Just sharing my experience. Anecdotal evidence is no evidence.

 

[NOSfan]

I believe cts and mp are always defined as entrapment neuropathoes whereas the tn and crps 2 are entirely different neuropathic phenomenon with no entrapment. Similar, but different.

Would not treat peripheral neuropathies with any procedures.

CTS and MP, as well as other neuropathies are not always secondary to entrapment....I would submit other etiologies: RA, leprosy, Raynaud's, dysproteinemia, DM, and vitamin deficiencies to name a few.

 

[lobelsteve]

CTS and MP, as well as other neuropathies are not always secondary to entrapment....I would submit other etiologies: RA, leprosy, Raynaud's, dysproteinemia, DM, and vitamin deficiencies to name a few.

I disagree baed on the definition of CTS and MP. I believe they are defined as entrapment neuropathies and while DM and RA and pregnancy are associated and are risk factors, they are not the underlying etiology.

Nerve entrapment is different than nerve dysfunction. Maybe a continuum like Sunderland and Seddon reports would be more applicable.

 

[axm397]

Besides, CTS and MP are not always secondary to an entrapment phenomemon or else they would have all gotten better after surgery and......I would not have to see them 🙂

I don't believe in over-utilizing EMG/NCS but confirming CTS can actually be a good use of NCS. I have been fooled many times this year by history and physical exam very suggestive of CTS which turned out not to be CTS. The hand surgeon in the group told me he didn't think NCS was necessary and that he felt he could diagnose based on H&P - he has been wrong more times than some of the other general orthopods based on NCS.

I just do median motor and sensory and ulnar motor and sensory. no EMG if no weakness. will do CSI if borderline. no f-waves or H reflex if CTS on NCS, will needle pronator teres, APB, FDI

 

[clubdeac]

I guess I could also add that I sometimes do a series of diagnostic blocks to figure out where a lesion is located, then I pulse proximal to that lesion. Most nerves are n = 1-2, but I do have a series of saphenous neuralgia patients (s/p TKA or knee scope) that get better when I pulse the nerve at the mid-thigh.

I've got a few patients I could try this on. Where do you pulse drf? You do it the same as a saphenous nerve block? What's your techniques/landmarks? Thanks

 

[drf]

I've got a few patients I could try this on. Where do you pulse drf? You do it the same as a saphenous nerve block? What's your techniques/landmarks? Thanks

There is a number of papers on subsartorial/adductor canal blocks. Here is one example with some good pictures.

Feasibility and Efficacy of Ultrasound-Guided Block of
the Saphenous Nerve in the Adductor Canal
Baskar Manickam, MD, FRCA,* Anahi Perlas, MD, FRCPC,Þ Edel Duggan, MB, FCARCSI,*
Richard Brull, MD, FRCPC,Þ Vincent W.S. Chan, MD, FRCPC,Þ and Reva Ramlogan, MBBS*
Background and Objectives: Saphenous nerve (SN) block can be
technically challenging because it is a small and exclusively sensory
nerve. Traditional techniques using surface landmarks and nerve stimulation
are limited by inconsistent success rates. This descriptive prospective
study assesses the feasibility of performing an ultrasound-guided
SN block in the distal thigh.
Methods: After the research ethics board’s approval and written informed
consent, 20 patients undergoing ankle or foot surgery underwent
ultrasonography of the medial aspect of the thigh to identify the SN in
the adductor canal, as it lies adjacent to the femoral artery (FA), deep to
the sartorius muscle. An insulated needle was advanced in plane under
real-time guidance toward the nerve. After attempting to elicit paresthesia
with nerve stimulation, 2% lidocaine with 1:200,000 epinephrine
(5 mL) and 0.5% bupivacaine (5 mL) were injected around the SN.
Results: The SN was identified in all patients, most frequently in
an anteromedial position relative to the FA, at a depth of 2.7 T 0.6 cm and
12.7 T 2.2 cm proximal to the knee joint. Complete anesthesia in the SN
distribution developed in all patients by 25 mins after injection.
Conclusions: In this small descriptive study, ultrasound-guided SN
block in the adductor canal was technically simple and reliable, providing
consistent nerve identification and block success.
(Reg Anesth Pain Med 2009;34: 578Y580)


My technique:
Place a linear probe on the medial thigh getting a short axis view. Scan anterior and posterior until you identify the femoral artery under the sartorius. The muscle on the lateral side of the sartorius is the vastus. As you get more distal the nerve starts to become more superficial in the fascial separation of those two muscles. As such I usually try to find it when it is still close to the femoral artery more mid-thigh. The nerve is usually on the superficial surface of the artery. The nerve does move from one side to the other as it descends with the vessel, so sometimes it will be medial and sometimes lateral to the vessel.

I insert the needle right over the US probe and go in-plane to the nerve. I always use a nerve stim as well as US for the diagnostic blocks to verify if the stimulation is concordant with the painful area. For pRF I poke at the nerve at two locations and pulse for 4 minutes each.

 

[Jcm800]

ultrasound for this block i guess could be needed perhaps in the situation where you describe, post TKA or knee scope and a proximal block is required, but in general for post-op pain or for surgical anesthesia? this is where i think ultrasound is getting silly.

Have you ever MISSED a saphenous block distal to the patella? there is no block that is simpler to do...I used to sciatic saphenous blocks for foot and ankle surgery every week for like 2 years, and never did i have anyone complain during surgery that they felt pain in the saphenous distribution.

i did not realize that this was a technically challenging block that has "inconsistent results" as cited in this article.

i used to do continuous cervical paravertebral catheters because i thought this block was "better, more dense" but a simpler, less invasive continuous interscalene block does the trick fine. why block higher unless you need for a saphenous?

i must be really bored tonight...

 

[drf]

A ring block is fine for ankle surgery. However it will miss the infrapatellar branches of the saphenous nerve for knee pain.

 

[Jcm800]

A ring block is fine for ankle surgery. However it will miss the infrapatellar branches of the saphenous nerve for knee pain.

i agree, which is why i said in the situation you are describing, for knee pain, but the article is for U/S guided block for ankle surgery, unless i read it wrong...

 

[drf]

i agree, which is why i said in the situation you are describing, for knee pain, but the article is for U/S guided block for ankle surgery, unless i read it wrong...

We agree. I just wanted any random article that had some pictures to describe my technique.

 

[NOSfan]

I believe cts and mp are always defined as entrapment neuropathoes whereas the tn and crps 2 are entirely different neuropathic phenomenon with no entrapment. Similar, but different.

Would not treat peripheral neuropathies with any procedures.

Steve,

I guess you missed my point. Basically, if it was as simple as compression on the nerve, or any root, trunk, division, cord or nerve branch and the compression removed/relieved, then the patient would be expected to always improve.

There is likely neuroplasticity at many levels; therefore, the efficacy of a more proximal block may benefit patients with peripheral pathology.

Brain. 1998 Sep;121 ( Pt 9):1785-94.
Neurophysiological evidence of neuroplasticity at multiple levels of the somatosensory system in patients with carpal tunnel syndrome.

Tinazzi M

 

[olafa]

You can also use minimum sensory threshold to verify you are in the best possible postion close to the nerve, which is important for getting a good lesion. We use 0.3 and pulse for 2 min.


To clarify what you guys are debating on CTS- Syndrome - isn't that actualy a collection of signs and symptoms, technically you need to name to nerve and the location of the pathology to be complete, ie median neuropathy at the wrist, which of course there are several risk factors already mentioned which I agree with, could also be entrapment but NCS only ID the location of the decreased CV or amp whatever.... without super secret laser vision how can tell that entrapment specifically is the problem??

My technique:
For pRF I poke at the nerve at two locations and pulse for 4 minutes each.