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Partial improvement after chemo?

Partial improvement after chemo?

“Some of my neuropathy improved after chemotherapy but my feet still feel (numb, tingly, painful, whatever)”
In another posting we looked into why chemotherapy induced neuropathy might persist even after treatment is completed.
I get my ideas of what to write about from the conversations I have with my patients. And since neuropathy is a complicated topic, I don’t foresee having troubles coming up with writing ideas for the near future (fingers crossed).
So this week when speaking to a new person who is in for a consultation, they asked why some of the symptoms of their neuropathy improved after the end of chemotherapy and other symptoms didn’t. I get asked that quite a bit. The answer could lie in the way the nerves work themselves. Now we are going to do a little nerve anatomy but it will be easy. The main part of a peripheral nerve (a nerve outside the brain and spinal column) is its cell body or nerve root, which sends nerve branches out to the rest of the body. The nerve roots in your neck and upper most back send branches down your arms to your fingers. The nerve roots in your lower back and pelvis to down your legs to your toes.
Everything is made there and then gets shipped to the rest of the nerves in a process call axoplasmic transport.

For nerves, the nerve roots are the grocery stores, the Home Depot, the gas station and the Target all rolled into one.

So who is at the end of this supply chain? The ends of the nerves in the feet/toes and the fingers. The fancy name for nerve damage that can happen because of this is, “length dependent sensorimotor polyneuropathy”. “Length dependent” means the longer a nerve is, the more vulnerable to damage. Since the nerves in the feet are the longest (They come aaaaaall the way from the low back), they are most likely to be involved.
One way to think about it is that the further away from the nerve roots you go, the harder it is for the body to fix nerve problems.
Keep in mind that compared to the rest of your body cells, nerves are HUGE! For example, if a skin cell, a white blood cell, a muscle cell, or what have you, is the size of a cat, a nerve cell would be as big as a blue whale! Many people kind of think of nerves as almost being microscopic, but hey aren’t. Your sciatic nerve by your butt is about as big around as one of your fingers. You have single nerve cells that run from your beltline all the way to your toes. We are talking huge nerves.
And they are all dependent on what is produced in the cell body, which is right next to your spine.
That seems to be a reasonable explanation as to why some symptoms (most commonly those in the legs or shins or whatever) tend to improve while leaving remaining symptoms down in the feet, toes, or fingertips.

Nerve Endings:

• They are the furthest from “home base” of the nerve roots next to the spinal cord.
• Most vulnerable to damage.
• Hardest for the body to fix.

To me, this seems like a reasonable reason why there might be only partial improvement after cessation of chemotherapy.

Ps. If you are like me and want to know a little more about the nerve cells themselves here is a nice little page to peruse. Click Here

Chemo is Forever?

Chemo is Forever? 

    Chemotherapy induced neuropathy is a common occurrence during cancer treatment.  Generally the chance of developing neuropathy is dependent on what type of chemo was used and what the total dosage over time has been.

    There is some thought that having other illnesses could be damaging to nerves and make one more susceptible to neuropathy.  To me, it makes sense that the human body can accommodate to a certain degree, but eventually, something has to give.

Other Potential Risk Factors:

-Alcoholism-

-Diabetes-

-Family history of nerve damage-

    In general, an Oncologist’s main goal is the patient’s survival – To get rid of the cancer.

    That is exactly how it should be.

    But what about quality of life after?  We hear from patients that during care they were told that the neuropathy would go away after treatment – and for many it does.  Or it at least improves enough that it is no longer bothersome.

But perhaps up to one third of cancer survivors have ongoing and significant issues with Chemotherapy Induced Peripheral Neuropathy (CIPN )

    Those who find this article of great interest can probably state that yes, peripheral neuropathy can persist after chemotherapy is done.

    So why would the neuropathy persist?  If someone is off of chemotherapy and chemotherapy is what caused the neuropathy, shouldn’t it go away?  I recently read an interesting journal that might explain, for at least one family of chemotherapy agents, why it might never go away.

    A 1992 study by the American Society of Clinical Oncology examined the nerves of patients treated with chemotherapy agents which contained platinum.  There are several of these agents and they all end in “-platin” and contain a form of platinum. 

    They are the chemotherapy of choice for treating many types of cancer and the main goal above all others is survival of the patient.  Please do not infer that I believe there is something wrong with these agents or the physicians that prescribe them.  Nothing could be further from the truth.

We are just exploring why the neuropathy could persist even after chemo is done.

    Okay, back to what the journal found.  Read this line from the journal abstract:

    That part about the platinum being retained in the nerve?  That means even after chemo, the platinum was found in a “toxic” form within the nerve.

So the platinum from the chemo could stay within the nerves forever

    I read that and a lightbulb went off in my head.  It makes total sense.  Many heavy metals, like lead, stay in our systems forever and many heavy metals are neurotoxins.  The romans used to flavor their wines with lead and went nuts.  Mercury is a heavy metal.  Ever hear of mad hatter’s disease?  Hatters used to use mercury to make felt.  Mercury is a neurotoxin.  Bam, mad hatter.  Does it make sense that platinum would be the same way?  In the last line it states that the patients with clinical evidence of neuropathy also had the highest levels of platinum. 

   This is a very interesting development, at least for the platinum containing compounds.  They might never be gone.  It might just depend on the individual person and whether or not their body can overcome that toxicity.

Citations

Quasthoff S and Hartung HP.  Chemotherapy-induced peripheral neuropathy.  J. Neurol. 2002: 249 (1): m9-17

Gregg RW, Molepo JM, Monpetit VJ, et al. Cisplatin neurotoxicity: The relationship between dosage, time, and platinum concentration in neurologic tissues, and morphologic evidence of toxicity. J Clin Oncol1992;10:795-803.

https://neuropathyjournal.org/cancer-related-neuropathies/

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