Polyneuropathy is the medical term used when there has been a change in the general health of our nerves. Polyneuropathy is commonly just referred to as neuropathy. We can think of nerves as relatively large cables connecting our brain and spinal cord from our spine to the muscles and skin of the arms, legs, trunk, and face.  A single nerve cell that extends all the way from our spine to our toes is called a neuron.

Like an electrical cable there are many small hair-like extensions like the small copper threads within an electrical cable.  These microscopic hair-like extensions called axons extend all the way from the spine to the tips of the fingers and toes.  It takes a tremendous amount of body energy for these neurons to function and maintain themselves. 

When your body has developed a metabolic problem it commonly affects the health of the nerves. The nerves that are the longest in the body take up the most energy because they do the most work.  Those are the nerves that go all the way from your spine down to your toes.  It is for this reason that people with neuropathy first experience symptoms in their toes and feet. 

Nerve like symptoms can be experienced in a variety of ways including numbness, tingling, burning, brief shooting pains, occasionally aching, and skin hypersensitivity.  Some people feel like their feet are cold even when they are warm to the touch. In polyneuropathy the symptoms are often worse when someone is trying to go to sleep and can even wake somebody from sleep.

The hypersensitivity (termed allodynia) can cause even the feeling of bedsheets rubbing the feet to be painful.

In some people this nerve type pain continues to bother them when they are walking and they will often describe the sensation as walking on gravel. 

Muscle cramps in the feet and the calves are commonly associated with this condition.  Often people experience muscle cramps in their feet or calves in the evening/night prior to them beginning to experience the numbness and tingling of neuropathy. 

In some forms of neuropathy it may cause damage to the nerve connections to muscles resulting in ankle weakness.

What causes polyneuropathy?

Polyneuropathy can be hereditary or be due to acquired medical diseases. Hereditary neuropathy often will be seen to run in families. It commonly presents more as ankle weakness, clumsiness, and balance problems rather than the more common tingling, burning, or numbness sensations. Most forms of hereditary neuropathy are called CMT (Charcot-Marie-Tooth Disease).

Acquired neuropathy in theory has a long list of potential causes but most often is caused by just a few factors. These factors can be additive meaning that a bit of each of them can work together to cause nerve damage. Common factors contributing to nerve health:

Alcohol – a potent nerve toxin. Can Cause direct nerve damage as well as influence vitamin levels in your blood that can further affect nerves. How much regular consumption of alcohol is needed before nerve damage starts to occur varies from person to person.

Vitamin B12 deficiency. This is a common problem that can affect nerve health and contribute to polyneuropathy.

Metabolic syndrome: While diabetes is the most commonly cited reason for polyneuropathy it has become clear that other factors of metabolic syndrome including elevated lipid levels (especially high triglycerides), abdominal obesity, and lack of aerobic exercise strongly influence the deterioration in nerve function.

Vitamin B6 (pyridoxine) toxicity: While not common I wanted to emphasize the dangers of taking high doses of this vitamin which has been proven to cause nerve damage. It is a vitamin crucial for nerve health and body metabolic processes but taken in high doses can be toxic. Doses as low as 50 mg per day taken regularly can cause nerve damage in some individuals. It is present in low doses in a multivitamin but is present in higher doses in a straight B6 supplement, B complex, B50, B100. It is also a listed ingredient in many other supplements (especially those marketed to improve nerves). Consult with a physician before starting this supplement.

How is polyneuropathy diagnosed?

The diagnosis first begins with the patient story (history) of the kinds of experiences described above. This will include an assessment of neuropathy risk factors (see above). This will prompt the medical team member to perform a physical examination checking the lower extremity (leg) strength, reflexes, and sensation. Blood tests will be done to assess for common treatable causes of polyneuropathy. If the blood tests are normal, or the neuropathy seems severe or unusual then the patient will often be referred to a neuromuscular(nerve and muscle) disease specialist for more in depth assessment as well as EMG and Nerve Conduction Studies.

What are the consequences of polyneuropathy?  How will it affect me and my function?

Pain: For some people neuropathy is just an odd sensation.  For some it becomes a pain that interferes with their life.  When this happens it is termed neuropathic pain.  This is that quality of neuropathy where people feel tingling, burning, shooting pain sensations, or skin hypersensitivity (such as the sheets of the bed irritating their skin). 

Balance: As neuropathy progresses it can affect the nerve function known as proprioception. This is the nerves telling your brain where your feet and legs are at all times. When this function has been affected it forces people to rely on their other senses (primarily vision) to compensate. Their balance seems particularly poor when they close their eyes (like taking a shower) or walk around in the dark (like when getting up in the middle of the night). This poor balance can progress to the extent that it results in falls and injury.

Skin injury and limb loss: Most commonly in people with diabetes (who also have reduced wound healing), they can become at risk for developing ulcers in their toes or feet that don’t heal. These skin ulcers can become infected. In the most serious cases this can result in limb loss (amputation). This most frightening complication usually only occurs in advanced cases of diabetic neuropathy, where people no longer feel sharp/pain sensation in their feet, and also have poor ability to heal wounds. People with normal sensation might walk just a few feet with a stone in their shoe before taking their shoe off and shaking it out. Someone who has lost sensation may walk a mile and only notice the injury to the skin when they take off their shoe at the end of the day.

How can neuropathy be prevented (from getting worse)?

The most important part of preventing neuropathy worsening is by identifying and addressing the risk factors that contribute to it.

STOP drinking alcohol

START regular aerobic exercise

WORK with your care provider to improve your general health including blood sugars, cholesterol, and obesity.

Vitamin D (sunshine vitamin) deficiency has been linked to worse neuropathy in patients with diabetes. For this reason it is recommended that all patients with diabetic neuropathy take at least 1000 units vitamin D daily. For patients with higher body mass index the vitamin D requirements are higher, and patients may need 2000 units per day.

How can the pain symptoms of neuropathy be treated?

Remember that the goal of these treatments is to reduce painful sensations like uncomfortable tingling, burning, shooting, and skin sensitivity (allodynia). It will not improve numbness, weakness, or balance problems which are caused by lack of nerve function.

1. Address the above polyneuropathy risk factors
2. Compression: Some people find that compression improves their pain experience. This can be just a tight fitting sock or a low grade compression sock can be tried. This option is relatively cheap and safe.
3. Topical creams: capsaicin (available over the counter as well as stronger prescribed strengths). Beware: this is the same chemical in chilli peppers. It operates by draining the pain chemicals from the nerve endings. When it is applied there is a burning sensation that lessens with repeated applications.
4. Topical creams: compounded creams. These are expensive prescribed formulations made by certain pharmacies often containing different combinations of medicines such as lidocaine, gabapentin, diclofenac
5. Supplements: Alpha Lipoic Acid has been studied in diabetic polyneuropathy and has been shown to improve nerve pain. It is a supplement available in many pharmacies and grocery stores. The dose studied was 600 mg daily. Vitamin D has also been shown to be important for nerve health in diabetics.
6. Oral medications: There are many medications tried for nerve pain. These includes SNRI (venlafaxine, duloxetine), gabapentinoids (gabapentin, pregabalin), and TCAs (amitryptiline, nortryptiline). Severe nerve pain might benefit from opiate medications for short periods of time. Choosing different medications with your doctor depends on what time of day your pain is worse, possible medication side effects, and cost.

Can anything be done to improve balance or falls?

A person’s balance is affected by nerve function, brain function, joint pain, muscle strength/endurance, vision, and inner ear (vestibular) function. Lost function in any one of these areas forces greater reliance on the others. Some of these can be compensated for or trained.

People with neuropathy are most at risk for falls in the dark or when their eyes are closed. Routinely turning on the lights before walking around at night (or going down the stairs) can assist your vision in maintaining your balance.

Some exercises have been shown to improve balance. These kinds of balance exercises can be found online or prescribed through a physiotherapist. Tai-Chi exercises have been shown to improve balance and reduce falls.

What can be done to prevent the most worrisome complications of foot ulcers?

Many resources exist online with detailed education on this topic such as here, and here.

Below is pasted from the Canadian Diabetes Website (www.diabetes.ca)

• Examining feet and legs daily

• Going to a health-care professional for treatment of any corns, cuts, ingrown toenails, and more

• Caring for toenails regularly

• Applying moisturizing lotion if feet are dry (but not between the toes)

• Wearing properly fitting footwear

• Testing bath water with elbow before stepping in, to make sure the water is not too hot