“I have become comfortably numb.” Unknown
On a weekly basis, I get the question can PD cause numbness? Well today, I thought I would tackle this sensitive topic from a different angle than before. hopefully this will help so many of you who like me are plagued with this problem and are not sure where to turn.
First, let me explain a couple of things. we have learned in the last decade or so that Parkinson’s disease can cause pain and central sensory deficits. this means that the brain does not process sensation normally because these connections pass through the basal ganglia on their way to the thalamus (sensory control center in the brain). This usually manifest in abnormal sensations when touch is involved. Plus, this abnormal basal ganglia dysfunction is the source for what we call “central” pain in PD. This is a burning, searing, excruciating pain that is constant deep in the bone aggravated by touch and follows the normal pathways of the brain – usually unilateral but can become bilateral. But, this does not cause numbness or tingling typically. as you might recall one of my initial symptoms was pain- this central pain. I could not stand anyone to touch my limbs which started on my left side, showering was torture. I felt like the water touching me was pure acid.
However, peripheral sensory deficits like toe, feet, and hand numbness has not been shown to be caused by PD itself. The usual test we use to detect neuropathies called NCV (nerve conduction velocity) study are normal in PD. Yet, many of us have been down with severe numbness particularly in our lower extremities.
So, why is this?
Well you are neither alone nor crazy. Well, I think I have a logical explanation for these symptoms from my own experience, living with my Parkinson’s and also having treated many patients in the past who regularly complained of this problem.
The cause is a simple mechanical problem. I have had two herniated discs in the past and know full well the symptoms of radiculopathy – numbness and pain shooting down your leg along with accompanying weakness. Of course, the first time I had numbness in my feet and back pain I immediately thought I was having exacerbation of my injured back. however, I had no pain nor weakness only numbness. I discovered that the usual treatments for back spasm like Lidoderm patches, Nsaid’s (non-steroid anti-inflammatories), wearing a brace did not alleviate this problem completely. However, increasing dose of dopaminergic medication e.g. levodopa stopped symptoms instantaneously as soon as medicine kicked in. Also, over the years I have noticed that when muscles get very tight i.e. dystonia especially in the neck and arms it can mimic cervical radiculopathy, carpal tunnel syndrome, and ulnar neuropathy. as a matter of fact when I was in residency because I was starting to get dystonia carrying my heavy doctors bag I was erroneously diagnosed and given a splint for carpal tunnel. since it was difficult to carry my bag with the brace the symptoms stopped abruptly.
As far as foot and toe numbness, I know too well the feeling. Although not painful it is extremely uncomfortable and if severe it can lead to falls due to loss of proprioception (not knowing where floor is). The main cause for this as I stated earlier is a mechanical one. as we stiffen rather our backs get rigid it decreases the normal curvature of the spine putting tension in our back muscles which then in turn pull on our spine to maintain posture this stretches the space between the vertebra and compresses the nerves as they exit the foramen. end result, the nerves get stretched and compressed decreasing their function acting as if they were being pinched permanently. As I sit here writing my back is getting tighter and I begin to feel some discomfort in my feet telling me I have to move about. however, when someone is under-medicated you get the same effect severe rigidity of axial muscles ( neck and back) with loss of normal curvature and subsequently the entire nerve collection known as a plexus gets compressed and stretched causing numbness in feet because these are the biggest fibers- so get affected first. the key is that usually this occurs bilaterally simultaneously and without pain or weakness and gets better quickly after taking medication or realigning spine like laying down supine in a flat surface.
Of course this is not to say that Parkinson’s patients do not get neuropathies ( progressive nerve ending atrophy) from other common causes like B12 deficiency, diabetes, or vitamin deficiencies, or presenting symptom of cancer.
Talk to your physician and discuss problem. as they check for metabolic problems ask them to adjust your dose of medication ( up usually) before proceeding with any more invasive or expensive tests because in my experience this will remedy problem if caused by Parkinson’s-indirectly.
Finally, staying active and keeping muscles limber by doing exercises routinely- does not necessarily mean daily but at least couple of times a week, can reduce this problem dramatically. As an aside never start any vigorous exercise program like boxing, or other physical regimen before discussing with your physician especially if having numbness or other symptoms because you can seriously injure yourself.
So next time you have problems with feet being numb do not fret and follow these recommendations as you call your doctor to discuss further. However, if symptoms come on suddenly on one side of the body go to ER asap. This could be a stroke!
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