October 2, 2016

Peripheral Neuropathy: An Overlooked Adverse Effect of Long-Term Use of Carbidopa-Levodopa for Parkinson's

“Did we miss something? Is it conceivable that for 40 years we have overlooked an insidious long-term levodopa treatment adverse effect, such as neuropathy, in idiopathic Parkinson's disease?" -- from the online journal "Neurology

"This intriguing study demonstrates a somewhat unexpectedly high prevalence of peripheral neuropathy in Parkinson's disease patients…. Peripheral neuropathy in Parkinson's disease could substantially contribute to gait disturbances and disability in some patients with Parkinson's, and prevention of peripheral neuropathy would be an important advance." -- from the online journal "Medscape

Toward the end of this past “Summer from Hell,” I started to wonder if some of the malaise I was experiencing might be due to something other than Washington's summer heat and humidity. As I mentioned in a recent post, one of my questions was: “Might I be experiencing peripheral neuropathy (PN)?"

A test last month by my new neurologist confirmed that I did have PN. Blood work also showed a vitamin B12 deficiency, not unusual for people with PN.

Normal values for vitamin B12 are 200 to 900 picograms per milliliter (pg/mL). Older adults with vitamin B12 levels between 200 and 500 pg/mL may also have signs of vitamin B12 deficiency. My reading was 346 pg/mL

When I started researching this subject, I was surprised to find studies like the two cited at the top of this post. I hadn’t known that Parkinsonians like me who are longtime users of carbidopa-levodopa (brand name Sinemet) often end up with peripheral neuropathy.

Peripheral Neuropathy
Here's an overview of PN from the Mayo Clinic:
Peripheral neuropathy, a result of damage to your peripheral nerves, often causes weakness, numbness and pain, usually in your hands and feet. It can also affect other areas of your body. 
Your peripheral nervous system sends information from your brain and spinal cord (central nervous system) to the rest of your body. Peripheral neuropathy can result from traumatic injuries, infections, metabolic problems, inherited causes and exposure to toxins. One of the most common causes is diabetes mellitus. 
People with peripheral neuropathy generally describe the pain as stabbing, burning or tingling. In many cases, symptoms improve, especially if caused by a treatable condition. Medications can reduce the pain of peripheral neuropathy.

Fortunately, my version of PN manifests as tingling, not pain.

PN, Parkinson's Disease, and Carbidopa-Levodopa
My research suggests that long-term use of carbidopa-levodopa -- and age -- are the main risk factors for ​peripheral neuropathy in those of us with Parkinson's. See this abstract on PubMed.
  
Treatment of PN
My neurologist recommended I take 1000mg of vitamin B12 every day. Now, after two weeks, I feel less tingling in my feet, less fatigue, and slightly better balance.

Click here for the Mayo Clinic's ​​discussion of treatment options for peripheral neuropathy. Most of those options are designed to relieve the pain (not my symptom) that typically accompanies PN.

I'll check with my neurologist about this supplement mentioned by Mayo:
Alpha-lipoic acid. This has been used as a treatment for peripheral neuropathy in Europe for years. Discuss alpha-lipoic acid with your doctor because it can affect blood sugar levels. Other side effects can include stomach upset and skin rash.

The Foundation for Peripheral Neuropathy has an excellent website with helpful background information and suggestions for dealing with PN. Click here.



1 comment:

Stepan Pachikov said...

Thank you. It looks like it explain why I walk like a drunk man. I also have tingling

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