Peripheral Neuropathy: a Functional Perspective

Lately I've been busy researching the mechanisms behind a disorder that has effected two important people in my life. The disorder is called peripheral neuropathy. Simply stated that stands for pathology of nerves in the peripheral nervous system. Remember that the peripheral nervous system (PNS) is what brings information from "out there" into "in here". In other words, the PNS is what connects us with the world around us. All the sensations of cold, hot, pain, and vibration are carried by this system. Not only that, but the PNS is the data-gathering part of the central nervous system (CNS). The CNS is the main frame computer that runs the human experience and the PNS is all the sensors and data collectors that feed it. Just a simple explanation to help set the stage for what I'm about to talk about next.

The PNS also performs a very important task of telling the CNS where the body is in space. This may seem minor but it is a huge factor. The PNS has sensors all over the outside shell, or soma, of the body. Thousands of these sensors exist per square inch of skin and they also innervate the fascia, muscle, and joint surfaces of the body. If only we could conceive of a computer with this much sensitivity and intelligence!

Now it is important to note that the basic histology, or design, of the PNS nervous system involves a nerve body and axon. The nerve body serves as the brain of the individual neuron as it houses the nucleus, organelles, mitochondria, DNA, etc. This nerve body exists adjacent to the spinal cord in what is termed the dorsal root ganglion. The axon then grows during our fetal and infant development from the spinal cord to say, the outside of our foot. What I'm saying is that axon can be several feet long, traveling all the way from the outside of our feet or tips of fingers to the very edge of the spinal cord. The important point to get here is not to remember all this terminology but to start to build a picture in your mind of what we are talking about when we explain peripheral neuropathy.

What happens during peripheral neuropathy is that the nerve transmissions from far away places like the feet start to malfunction. Peripheral neuropathy affects the distal portions of our body first because the farther things are away from the core viscera, the more difficult it is to maintain healthy tissue. Its like when a plant dries out, it starts at the tips of the leaves farthest from the center and then dries out towards the stem. It is the same with the human body as those with peripheral neuropathy know that it begins in the feet but can progress to make its way up the ankle, then knee, then hip, etc. Its just a simple fact that providing nutrition to and removing toxins from areas of the body becomes more difficult as we get further from the heart. This is why when people start to lose neurological sensation like touch and vibration in their feet it is a warning sign that potentially could lead to more serious complications. Peripheral neuropathy is serious because of its effect on our activities of daily living - try walking and exercising when you cannot feel your feet!

The cause of the neuropathy can be multi-factoral but likely it is due to either a compromise in microvascular circulation and/or a dysregulation of fat metabolism. When nerves are injured they lose their function first in the most distal portion as we have already pointed out. This is why pain, tingling, and numbness in the feet are warning signs that PNS neurons are malfunctioning. As an example, in type 2 diabetes patients suffer from a multitude of symptoms including peripheral neuropathy that is often so severe that limbs are progressively amputated. Basically the nerve supply and blood supply are so compromised that no oxygen gets into tissues in the feet and large infections begin to take hold. This is a worse case scenario but does happen to many diabetics.

In the case of the two important people in my life, neither one are diabetics per se, but clearly there is an underlying set of metabolic conditions that is promoting the dysfunction of their peripheral nerves. Lets examine briefly by what mechanisms the nervous system can be affected in peripheral neuropathy and what measures can be taken by your astute chiropractor and natural healer to correct the underlying issues without resorting to dangerous drugs and surgeries.

Looking at the compromise in circulation we can understand how this will stress the nervous system because without the ability to expel toxins and take in nutrients the nerve cell will become toxic. More likely the Schwann cells that surround the axon will deteriorate which causes the transmission to be interrupted. Its just like losing the insulation of any electrical wire - without the high resistance and low capacitance of the insulating material, the electrical signal will leak out of the wire. And in the case of human nerves, the signal for vibration may be lost somewhere between the foot and the spinal cord because the nerve tissue has lost is insulation called myelination.

This loss of myelination is key in thinking about peripheral neuropathy. Once a clinician has ruled out upper motor neuron lesions, CNS problems, MS, etc. we are left with basic dysfunction of peripheral nerves. Losing the insulation of the nerve is possible when there is a great deal of inflammation in the body. As the blood inflames the body reacts to suppress it, releasing cholesterol and other blood-born anti-oxidant molecules. All of this is fine but when the blood becomes inflamed, all sorts of reactive molecules are present. This makes the blood "thicker" and more sludge like which makes it harder to pump into small vessels as effectively. So the big idea here is that with increased systemic inflammation, due to low anti-oxidant levels combined with modern high sugar, high fat, nutrient-deficient foods, the micro-vascular does not get as much blood. Less blood means less nutrition and less removal of toxins. It also alters the pH, creating more acidosis locally since CO2 is removed by hemoglobin. All these factors - thick blood, acid pH, high oxidation - will make it hard for the Schwann cells to keep the nerve properly insulated. This is one source of PNS dysfunction.

As I mentioned the other issue we deal with is fat metabolism gone awry. The same forces which compromise micro-circulation and promote inflammation in the blood will negatively effect how the neuron, way up by the spinal cord, will be able to produce energy. As we eat processed garbage, we get a huge amount of energy - glucose and fat - with very little anti-oxidants and vitamins to help us deal with all the energy. Too much energy is just as dangerous as too little. When you need to heat your house, you don't douse your fireplace with wood and gasoline just because more energy is better. You pick the right amount of logs and kindling and stay balanced between burning your house down and freezing. Your body is no different.

Insulin is required for the glucose and free fatty acids to enter most cells in the body. And we all know that Diabetes has "something" to do with insulin. Well as it turns out neurons are special cells who are so important to our survival that the innate intelligence of the human body designed them so they could get glucose into the cell without insulin. This is a blessing when blood glucose levels are low because this will guarantee that the CNS and PNS are fueled with energy so we can survive long enough to locate another source of food. However, this is a curse when we live in a world were people eat such toxic food.

As we consume processed food that is highly glycemic and high in energy but low in nutrition, our blood sugar spikes and remains elevated until we can secrete enough insulin to bring it down. Diabetics have insulin problems and they are not able to reduce their blood sugar effectively, which leads them to be susceptible to peripheral neuropathy. Excess blood sugar causes inflammation as discussed above, but it also forces neurons to absorb more glucose than they need. And when neurons are getting more glucose than they need, which happens via passive diffusion, they must convert the excess they do not need into free fatty acids. These free fatty acids are themselves converted into triglycerides which is the body's preferred method of energy storage - typical "fat" tissue.

As these neurons continually store more and more fats, the levels of free fatty acids inside the cell increase as the neuron begins to be saturated with too much energy. As these molecules are reactive, they start to create inflammation INSIDE the cell - a process called Lipotoxicity or toxic levels of fat. This results in damage to the mitochondria and other cell organelles. The net effect of this energy toxic scenario is that the neuron is both drowning in excess glucose and fat while at the same time losing the ability to effectively burn those molecules to create energy. This was all caused by the fact that the patient is consuming too many refined foods with high calorie loads while simultaneously not exercising or being physically active. This creates an environment where the neuron, just like other body cells, is forced to soak up this high blood sugar.

Now this neuron which has been drinking up blood glucose and storing it as fat eventually gets saturated with fats and this begins to interrupt the process of burning fat for energy. As the neuron becomes less efficient at producing energy, it can no longer effectively communicate with its most distal end. Thus as the neuron loses its ability to efficiently create energy, due to a lipotoxic effect, the transmission of nerve impulses along its axon is compromised.

In conclusion the reason for peripheral neuropathy in patients can be due to a lipotoxicity that is occuring in the neuron. The neuron is energy toxic with too much glucose entering the cell that must be converted to free fatty acids and stored as triglycerides. As this process occurs the cell cannot efficiently create energy. The oxidative stress and inflammation from excess energy in the cell (in the form of glucose and free fatty acids) damages organelles and mitochondria reducing the capacity for the cell to create ATP.

A natural practitioner will correct these deficits by directing the patient to alter their diet along the lines of the Modified Elimination Diet. Then the practioner will use the following supplements to help the neurons create energy efficiently and restore function to the peripheral nerve:

Acetyl L Carnitine - Helps cells burn fat by shuttling fats into the mitochondria to be burned for ATP.
Resveratrol - A powerful anti-inflammatory that quenches inflammation which is damaging the cells ability to efficiently oxidize energy.
Alpha Lipoic Acid - A power anti-oxidant that also protects the cell's membranes and promotes function of the mitochondria.

These supplements will aid the pathways of the cell which are involved in burning fat. This process is called beta oxidation and is different than the citric acid cycle. By using high doses of natural, safe vitamins and minerals a knowledgeable natural doctor can use the body's own systems to help heal it. Alpha lipoic acid and resveratrol will suppress inflammation while L-carnitine will help get the free fatty acids turned into useful ATP for nerve impulse transmission.

Using dietary changes and the above supplements in an intensive protocol, natural practitioners may be able to reverse the effects of peripheral neuropathy. The underlying cause of peripheral neuropathy may be that the neuron is toxic from excess energy consumption. By opening up the pathways inside the body that help cells burn fat more efficiently, neurons and other body cells will respond by lowering their toxic, pro-inflammatory burden. Once a doctor understands the complex nature of physiology, he or she can use simple, safe alternatives to expensive and risky drugs and surgeries to correct what is wrong with the human body.