Needles and Nerves: How Neuropathy Challenges Notions of a Single Self

This feels like my ordinary nighttime routine: yellow light, static screen, wooden chair, pins and needles. Needles and pins? My foot has fallen asleep again – and yet, as that thought comes to me, I immediately question it: has my foot itself really turned off, or is it just that my mind has stopped registering the foot? Is my foot ignoring stimuli from the outside world, or is it simply unable to deliver the stimuli it does receive to my brain? I wonder what the relationship is between numbness and neurology. If I don’t feel a body part, does that automatically mean the part isn’t working? What if no “part” even exists outside of my brain’s conscious realization of it? I wonder which comes first, the foot or the brain that moves the foot. I wonder what’s lost in those few seconds in which I realize that the foot’s asleep. At that point, the brain seems to have kicked into high gear again, and I know what I am lacking. Does that mean, then, that what I lack is not, after all, just consciousness? And what does it mean that even consciousness isn’t enough to bring the foot back – that there’s a lag, while the foot wakes up, while I feel prickling pain and ticklishness and all sorts of sensitivity? Can my nerves be half-working? Can my foot be half-part-of-me, then three-fourths, then whole again?

One clue to the cause of temporary numbness comes when one looks at the scenario that causes it. My foot does not fall asleep while it’s in use; instead, it tends to happen when it’s tucked beneath me, or under my other leg, or dangled out to the side. I have ignored the foot while inadvertently placing a lot of pressure on it – extra weight, the lazy burden of my lazing body. The website HowStuffWorks.com explains that the added pressure interferes with the communication between the brain and the limbs and often puts so much pressure on nerve passageways that impulses cannot travel through them properly or at all (1). This explanation suggests that neither the foot nor the brain is totally at fault; instead, it’s the wiring between them that’s getting blocked. (Of course, it’s probably the brain that decided to sit in a compromising, unknowingly numbing position in the first place . . .)

The reason for the uncomfortable period during which the foot “wakes up” is, according to HowStuffWorks, due to differences in the types of neurons, with thicker pathways taking longer to re-read information again after being squeezed (1). I’m beginning to suspect that it does make more sense to think of the foot as a combination, or concept, than to think of it as a single part – that’s why parts of it can receive and deliver stimuli while others are still recovering from numbness. An MSNBC feature highlights the usefulness of the pins-and-needles sensation, or paresthesia, caused by misfiring or jumbled signals sent between the nerves and the brain: they remind you to move your foot (2), thereby opening up nerves – and often arteries as well – so that oxygen, blood, and nerve signals can flow regularly again. Seeming benign, the pressure that causes numbness could actually cause serious harm if we let it go on for too long and cut off circulation and stimuli completely!

Nerve anesthesia and paresthesia could be either the cause or the effect of a larger problem. The Neuropathy Association cites several types of neuropathy – or damage to peripheral nerves – and explains that in most cases the cause of random neuropathic symptoms is unknown. Sometimes, however, diabetes, autoimmune disorders, and toxic disease can cause neuropathy (3). In the case of diabetes, explains the National Diabetes Information Clearinghouse, the exact cause of neuropathy still isn’t clear, since diabetes causes and encompasses several smaller problems. For example, imbalances in the metabolic chemicals traveling through the nerves – those affecting blood sugar, blood fat, and insulin – may cause nerve damage. However, the actual structure of the nerves may also be at fault, since diabetes can cause neurovascular problems. If the nerves don’t get enough blood and oxygen, they function improperly, regardless of what they are connected to or the quality of the electrochemical impulses they carry. Disorders that cause injury to or inflammation of the nerves, like carpal tunnel syndrome, could also be involved in nerve damage (4). With such a wide range of factors, it would be difficult to pinpoint a single element of diabetes as the cause of neuropathy.

Moreover, nerve damage can (of course) occur in nondiabetic patients. Nerve damage could be a symptom of chronic inflammatory demyelinating polyneuropathy (CIDP), which results from damage to the myelin sheath of nerves. Without proper insulation, nerves may be susceptible to damage or may not carry impulses properly (5). Guillain-Barré Syndrome, another possible cause, is an autoimmune disorder that causes nerve malfunction, leading to weakness and paralysis (6). As in the case of CIDP, the major risk, when symptoms become apparent, is that the nerve damage will be permanent and that function will not be recovered. Major limbs and organs could become inaccessible to the brain.

Yet it could be even worse – what if parts of the brain were themselves off limits? What if a very large nerve were damaged? That’s one potential cause of stupor or, worse, coma – when nerve fibers connecting peripheral organs and the brain become damaged. Since consciousness and wakefulness are affected by the nerves in the brain stem, the loss of awareness may be the result of damage to brain stem damage (7). With the brain influenced by, connected to, and comprised of so many other systems and anatomical features, one would be hardpressed to cite nerve damage as the only cause of temporary or permanent unresponsive states. But I shudder to think of the effects of damaging the nerves involved in brain stem function or interrupting the communication between them and peripheral areas of the body.

It’s scary enough to feel pins and needles and wonder how long I’ve forgotten my foot (or my foot has forgotten me). What if I lost connection to my thoughts, my worldview, my conceptions of the space around me, my image of myself? In the case of my foot, the diversity of nerves and nerve connections makes me lose and regain different sensations, or impulses, at different rates. Perhaps something analogous to pins and needles – like intermittent blackouts, perhaps? – occurs in the case of more severe nerve damage. But just think if the pressure to the nerve connections were greater, if they were cut off because of a sudden blow or a big fall. And just think how easy it is not to notice the gradual, if temporary, loss of a foot. Would I know if I were suffering from serious, irrevocable neuropathy? Or, to ask a more daunting question, would I be able to do anything about it? Am I the conductor of my nerves or am I simply dependent on them?

References

1. HowStuffWorks: “What makes your arms, legs and feet fall asleep?” http://health.howstuffworks.com/question552.htm

2. MSNBC: “What makes our feet fall asleep?” http://www.msnbc.msn.com/id/3076701

3. The Neuropathy Association, Inc.: “About Peripheral Neuropathy: Facts.” http://www.neuropathy.org/site/PageServer?pagename=About_Facts

4. National Diabetes Information Clearinghouse: “Diabetic Neuropathies: The Nerve Damage of Diabetes.” http://diabetes.niddk.nih.gov/dm/pubs/neuropathies/

5. CureResearch.com: “Introduction: Chronic Inflammatory Demyelinating Polyneuropathy.” http://cureresearch.com/c/chronic_inflammatory_demyelinating_polyneuropathy/intro.htm

6. CureResearch.com: “Introduction: Guillain-Barre Syndrome.” http://cureresearch.com/g/guillain_barre_syndrome/intro.htm

7. The Merck Manuals Online Medical Library: “Stupor and Coma.” http://www.merck.com/mmhe/sec06/ch084/ch084a.html