Burning Feet

[Biohazard685]

I wanted to pick the collective mind of IPM on SDN.

I have an 85 year old female. Chief complaint burning pain of bilateral feet (specifically the soles). Pain is worse at night.

Worked up relatively well by her PCP, podiatrist, and two neurologists.

Has had adverse effects with gabapentin, Lyrica, and duloxetine.

BMP, CBC, B12, folate, TSH, A1C, all unremarkable.

EMG of upper and lower extremities shows sensory neuropathy and what is most likely mild carpal tunnel of the wrist.

She was recently diagnosed with lung cancer and is on a new monoclonal antibody medication but the time of diagnosis doesn't fit with onset of neuropathy. Doesn't fit the mold of a paraneoplastic process to me.

Going to try her on a TCA and if that doesn't work then will plan to go on a deep dive of diagnostic work up.

She is not on opioids and prefers not to be on any "strong" medications. I suggested OTC capsaicin and some socks. Surprisingly, it helped with the pain but doesn't last very long.

What am I missing?

Plantar fasciitis? Skin biopsy for small fiber neuropathy? Lyme titers? MRI of the feet for Morton's neuroma? Tarsal tunnel syndrome (wouldn't an EMG pick this up)? Am I missing some cryoglobulinemia or IgM/IgG blood dyscrasia since the pain is worse at night and "gravity dependent"?

She's not on any opioids and she is hesitant to take any.

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[Orin]

Some of the new monoclonal immunotherapies like Keytruda that activate the immune system to fight the cancer can flare up neuropathic pain states significantly. The treatment there is to leave it alone as it should get better after the cancer therapy flares down, but if she's looking at a lifetime of that, stim it.

 

[Biohazard685]

Some of the new monoclonal immunotherapies like Keytruda that activate the immune system to fight the cancer can flare up neuropathic pain states significantly. The treatment there is to leave it alone as it should get better after the cancer therapy flares down, but if she's looking at a lifetime of that, stim it.

Plan is to continue the monoclonal as long as she needs it (probably the rest of her life).

I want to see how she does with the TCA and make sure it's nothing reversible before committing to intervention.

 

[callmeanesthesia]

I wanted to pick the collective mind of IPM on SDN.

I have an 85 year old female. Chief complaint burning pain of bilateral feet (specifically the soles). Pain is worse at night.

Worked up relatively well by her PCP, podiatrist, and two neurologists.

Has had adverse effects with gabapentin, Lyrica, and duloxetine.

BMP, CBC, B12, folate, TSH, A1C, all unremarkable.

EMG of upper and lower extremities shows sensory neuropathy and what is most likely mild carpal tunnel of the wrist.

She was recently diagnosed with lung cancer and is on a new monoclonal antibody medication but the time of diagnosis doesn't fit with onset of neuropathy. Doesn't fit the mold of a paraneoplastic process to me.

Going to try her on a TCA and if that doesn't work then will plan to go on a deep dive of diagnostic work up.

She is not on opioids and prefers not to be on any "strong" medications. I suggested OTC capsaicin and some socks. Surprisingly, it helped with the pain but doesn't last very long.

What am I missing?

Plantar fasciitis? Skin biopsy for small fiber neuropathy? Lyme titers? MRI of the feet for Morton's neuroma? Tarsal tunnel syndrome (wouldn't an EMG pick this up)? Am I missing some cryoglobulinemia or IgM/IgG blood dyscrasia since the pain is worse at night and "gravity dependent"?

She's not on any opioids and she is hesitant to take any.

Does she have sensory loss, testing with sharp/dull and temperature? Feel like a sock is bunched up under her feet, or like she’s walking on gravel? Those descriptors seem almost universal with the true sensory neuropathy. Their pain is almost always worse at night and length dependent so you probably don’t need to be hunting zebras based on that unless you’ve exhausted all else. I’d say it’s worth testing B12 because that’s easily treatable and common in the elderly, unless she’s already on B12 shots.
Are you sure about TCA in an 85 yo with the anticholinergic side effects? I know there is poor evidence for them but maybe a compounded cream with gabapentin?

 

[paindoc007]

I hate TCAs personally. She seems like a good scs candidate

 

[Biohazard685]

Does she have sensory loss, testing with sharp/dull and temperature? Feel like a sock is bunched up under her feet, or like she’s walking on gravel? Those descriptors seem almost universal with the true sensory neuropathy. Their pain is almost always worse at night and length dependent so you probably don’t need to be hunting zebras based on that unless you’ve exhausted all else. I’d say it’s worth testing B12 because that’s easily treatable and common in the elderly, unless she’s already on B12 shots.
Are you sure about TCA in an 85 yo with the anticholinergic side effects? I know there is poor evidence for them but maybe a compounded cream with gabapentin?

On my exam, no major sensory loss. Could discriminate pretty well between point and dull.

Literally feels like her feet are burning mainly at night.

I had the same hesitation with TCA but she didn't flinch at all with the capsaicin. This is probably just optimism on my part. She's aware of all the possible side effects and is pretty good with follow up communication so she would give me a heads up if there's ADRs.

I totally forgot about compounded creams. Thanks for the tip. If she had good response to topical capsaicin maybe she will respond to others.

 

[deleted993114]

I wanted to pick the collective mind of IPM on SDN.

I have an 85 year old female. Chief complaint burning pain of bilateral feet (specifically the soles). Pain is worse at night.

Worked up relatively well by her PCP, podiatrist, and two neurologists.

Has had adverse effects with gabapentin, Lyrica, and duloxetine.

BMP, CBC, B12, folate, TSH, A1C, all unremarkable.

EMG of upper and lower extremities shows sensory neuropathy and what is most likely mild carpal tunnel of the wrist.

She was recently diagnosed with lung cancer and is on a new monoclonal antibody medication but the time of diagnosis doesn't fit with onset of neuropathy. Doesn't fit the mold of a paraneoplastic process to me.

Going to try her on a TCA and if that doesn't work then will plan to go on a deep dive of diagnostic work up.

She is not on opioids and prefers not to be on any "strong" medications. I suggested OTC capsaicin and some socks. Surprisingly, it helped with the pain but doesn't last very long.

What am I missing?

Plantar fasciitis? Skin biopsy for small fiber neuropathy? Lyme titers? MRI of the feet for Morton's neuroma? Tarsal tunnel syndrome (wouldn't an EMG pick this up)? Am I missing some cryoglobulinemia or IgM/IgG blood dyscrasia since the pain is worse at night and "gravity dependent"?

She's not on any opioids and she is hesitant to take any.

 

[deleted993114]

Don't do the TCA- oldsters don't tolerate the anti-cholinergic side effects. We go down the rabbit hole of trying to find the "cause" of peripheral neuropathies and we fail most of the time. Nonetheless, we all order the same labs hoping that occasionally one will find a defined source of the neuropathy.

Try Zanaflex (just 4mg qhs) and caution about orthostatic hypotention in an oldster.

Low dose tramadol (25 mg increments) helps neuropathic pain, unlike a pure opioid.

Mexilitene is a fourth line drug (150 bid) which really helps the burning, dysesthetic pain of a peripheral neuropathy, but is less well tolerated in the elderly. Simply 150 mg qhs would be worth a try if the other meds fail.

Lastly (creams should he tried first), just topical lidocaine cream and or a compounded cream with ketamine and local. Creams, of course, should be tried first, as there is no downside (except expense).

It's hard to catch the feet reliably with a stim and one needs to be rational in dealing with an oldster, as going down the route of a retrograde stim would be too much.

PS- If a much younger person presents with burning pain in the feet, don't forget about HIV.

 

[Ducttape]

for an 85 year old - did she have a history of ethanol use?

if you do TCA, stick to desipramine only.

alpha lipoic acid is something simple she might try OTC. or, since everyone is using it, CBD oil topically.



but wait, lets as our initial therapy recommend a $45000 hail mary.

 

[clubdeac]

I’d check an SPEP/UPEP/SIF. You didn't say this had been checked but if she has seen two neurologists, chances are it has. Agree with everything else that has been said. You could try Effexor or another AED (Topamax, Zonegran, Keppra) before going to the TCA

 

[Orin]

I'm sorry. I don't see significant benefit in fiddling around for months to years in an 85 year old with nutraceuticals or high risk medications. I generally counsel to avoid steroids and certain nutraceuticals that are known to quiet the immune system down, but it really depends on the cancer agent. Nerve health agents are fine to try though.

You can always screen negative on a stimulator trial, and if you don't gate anyone out then you aren't doing enough or you shouldn't be trialing. If you're concerned about capture, there are folks that would consider a PNS stim in this case. I would not because of the bilateral nature of it, but it is cheaper and less invasive if you're concerned about that. I would argue against a DRG stim due to the need for MRIs unless the labelling has changed for the Abbott product.

I would though generally just do this with a T9/10 with paresthesia pants on the table and setting her for whatever high frequency program you like for 5 - 10 days, assuming all other options are reasonably excluded, there is anatomic space, and you've had some temporary benefit from a less invasive/expensive complementary therapy such as a lumbar sympathetic block.

 

[Ligament]

Sounds like a great workup and she has a great pain doc on her side.

Small fiber neuropathy worth working up as you said, but what to do about it if so?

DRG stim to get feet/compounded topicals

 

[Ferrismonk]

For completeness, you can try PoDiaPN, Metanx and the like.

 

[painj]

Not a doctor and would never, ever chime in with anything you are discussing about a patient-but I have a personal experience with this-after my back surgery a few years ago, at night extreme burning in feet, much worse when laying down. Ortho and my pain physician tried a number of things to no avail, but had me try the Icy Hot smart relief back TENS therapy before they did any stims. I put in on a fairly lower setting at night about ten minutes before bed and it helped considerably. After a month or so, the burning lessened and I am assuming because I could sleep easier and was able to do more physical therapy due to it-I am 50, not 80. Again, I don't want to overstep at all, or say anything on treatment--that patch helped me and symptoms sound the same as to what I had, so I thought I would mention in case.

 

[Ducttape]

so... you have an 85 year old, who probably still has a rotary dial up phone as her primary means of communication, who has lung cancer and is undergoing a type of chemo, and the first thing you want to do is stick metal leads in her that may effectively eliminate screening MRIs, and - ironically - a short trial of something like tramadol...

i like your previous statement - let it alone as it should get better. id spend a couple of months to exhaust all other measures that are safe and reasonable before putting a stim that she may have technical difficulties with, that does carry risk, particularly implantation. (if capsaisin helped... what about qutenza? that still available?)

now, in 10 years or so, our senior citizens will be much more computer savvy. i just spent the entire weekend trying to show my dad how to use the iphone map app... and he is considered an expert...

 

[cowboydoc]

Why are we looking for a small fiber neuropathy when the emg showed a peripheral neuropathy? Likewise, tarsal tunnel is difficult to isolate on emg, probably not possible if there is a significant underlying neuropathy, as in this case.

Treatment above (besides stim) is solid.

Unlikely to find cause with further workup. (I punt to Neuro if not done already and patient requests.)

 

[Biohazard685]

Sounds like a great workup and she has a great pain doc on her side.

Small fiber neuropathy worth working up as you said, but what to do about it if so?

DRG stim to get feet/compounded topicals

Thank you for the kind words.

I'm trying to pool ideas. She's not the best stim candidate.

But she is a sweet lady who deserves some relief.

I'll keep everyone up to date. But will exhaust topicals and other meds before bringing up anything invasive.

I appreciate the candor of the stim experts here.

 

[myrandom2003]

would you consider stimwave the S1 drg?
This way you dont have to implant an IPG?

I've never used it, but maybe beneficial for this situation?

 

[epidural man]

If stim is the choice - I would do StimWav (at least consider it).

Agree to avoid TCA - but try it topically, with some ketamine topically.

Also, in between stim aggressiveness and tramadol - would be Qutenza.

 

[paindoc007]

would you consider stimwave the S1 drg?
This way you dont have to implant an IPG?

I've never used it, but maybe beneficial for this situation?

What’s the issue with implantation of an ipg in this case?

 

[BobBarker]

Stimwave?? The probability of her aligning the felt pad is 0.

 

[Orin]

I don't consult for them yet, but the alignment with the Stimwave pad is a lot easier on an extremity than on the back. If you're using high frequency stimulation parameters, the capture/alignment is a lot less of an issue as well.

If the back is not ideal, or there are infection risks, I would consider putting a Stimwave, Bioness, or SPR system in the leg, but realize that it can be a bit hard to capture a large mixed nerve like the sciatic, so preferentially target the distal branches if possible.

SPR's system is probably the best if you had to try to capture the whole sciatic distribution, but that's more similar to magic beans as far as I can understand.

Also, you would ideally like to target the nerve above the level of the sensory deficit, but that's just me being mechanistic, and I have no evidence for that.

 

[Crybaby]

I have seen Stimwave used targeting peripheral nerves for neuropathy pain in feet. I have not used it yet for that but have twice for other issues with very good response about 1-2 months out.
I have a nice gentleman with terrible neuropathy I have discussed this with. Trying to decrease opiate load and he strongly opposes SCS/DRG. May potentially be an option.

 

[drusso]

How come you're not offering her DRG with BurstDR and a non-rechargeable battery?

 

[Biohazard685]

How come you're not offering her DRG with BurstDR and a non-rechargeable battery?

She's not ready to cross the device bridge yet.

 

[Biohazard685]

If stim is the choice - I would do StimWav (at least consider it).

Agree to avoid TCA - but try it topically, with some ketamine topically.

Also, in between stim aggressiveness and tramadol - would be Qutenza.

Do you have a compounding pharmacy you trust?

 

[Biohazard685]

Not a doctor and would never, ever chime in with anything you are discussing about a patient-but I have a personal experience with this-after my back surgery a few years ago, at night extreme burning in feet, much worse when laying down. Ortho and my pain physician tried a number of things to no avail, but had me try the Icy Hot smart relief back TENS therapy before they did any stims. I put in on a fairly lower setting at night about ten minutes before bed and it helped considerably. After a month or so, the burning lessened and I am assuming because I could sleep easier and was able to do more physical therapy due to it-I am 50, not 80. Again, I don't want to overstep at all, or say anything on treatment--that patch helped me and symptoms sound the same as to what I had, so I thought I would mention in case.

Thank you for the TENS recommendation. I'll pass it along.