Your brain controls virtually everything your body does, from thinking, feeling and breathing, to eating, sleeping, moving and making love. It performs this remarkable task by sending messages through your spinal cord and to organs throughout your body through a network of nerve cells. This network of nerves is much like a series of wires that transmits electrical impulses. Like electrical wires, nerves can become damaged or frayed. When this happens, components of the system connected by the wires can malfunction. This type of damage to the nerves is called neuropathy.
No one knows why for certain, but too much glucose in the blood can, over time, damage the nerves of your body. It may be because proteins coated with glucose directly harm the nerve cells. Or it could be that the extra amount of glucose in the blood upsets the chemical balance within nerves. Or it might be that too much glucose interferes with blood circulation and the nerves are unable to get the oxygen they need.
Whatever the reason, people with diabetes are more likely to develop nerve problems than people without diabetes. The good news is that keeping tight control over your blood glucose levels can reduce the risk on neuropathy by 60%.
Fortunately, the nerves of the central nervous system—the brain and spinal cord—are not usually affected by high blood glucose. But the nerves of the peripheral nervous system, which reach out to muscles, to sensory cells and organs, and to internal organs, can become damaged over time. Sensorimotor neuropathy refers to damage to the sensory nerves, those nerves that send information about how things feel from the skin and from internal organs to the brain.
Motor neutrons send information from the brain to the muscles of the body about how to move. For instance, if you put your hand down on a hot pot, the sensory neurons send a signal to your brain that you are hurting your hand. Your brain then sends a message through your motor neurons that tells you to move your hand. But when you have neuropathy, these nerve cell transmissions don’t work well. You don’t always feel pain or things you should be feeling, and your muscles don’t always get the message to move the way you want them to move.
There are different types of neuropathies, depending on what nerves are damaged. Neuropathy can affect sensory neurons, motor neurons, or autonomic neurons—those that control internal organs or automatic processes in your body that you don’t even need to think about. Nerves are made up of both small fibers and large fibers. Small fibers control sensitivity to heat and cold and to touch. Large fibers control your sense of balance and position.
When small fibers are damaged you may feel pain or a loss of sensitivity to heat and cold and to touch. When large fibers are damaged, you may lose your sense of balance and position. Often both small and large fibers are affected by neuropathy.
Neuropathies can also be classified as focal or diffuse. Diffuse neuropathies develop slowly, and over time spread from one set of nerves to another. For example, initially only the sensory and motor nerves may be damaged, but over time, your autonomic system may also become affected.
Diffuse neuropathies can affect several different parts of the body at the same time, such as the feet and hands, usually affecting both sides of the body. Focal neuropathies tend to come on suddenly and affect only one nerve or group of nerves. Focal neuropathies can affect very specific parts of the body, such as the wrist in carpal tunnel syndrome. Often diffuse and focal neuropathies can occur together. Fortunately, most types of neuropathies improve with better blood glucose control.
Mononeuropathy, or focal neuropathy, is caused by damage to a single nerve or group of nerves. Many mononeuropathies come on quite suddenly and are painful. Nerve damages does spread from the nerve originally affected and it usually goes away after a while. However, some mononeuropathies have symptoms similar to life-threatening conditions such as heart attack and strike, and should not be dismissed without first discussing your symptoms with your doctor. Unlike other mononeuropathies, entrapment syndromes, such as carpal tunnel syndrome, often develop more gradually and persist for long period of times.
Cranial neuropathy is caused by damage to a single nerve from the brain. Cranial neuropathy is rare in younger people, but occurs frequently in elderly people with diabetes
Symptoms of cranial neuropathy include severe headaches, drooping of one side of the face, double vision, or difficulty opening one eyelid. Cranial neuropathy is not usually painful.
What You Should Do
If you experience any of the symptoms listed above, call your doctor. Your doctor will want to rule out the possibility of stroke or other life-threatening conditions. Cranial neuropathy can be frightening, but it usually goes away in a few days or weeks. However, make sure to contact your doctor for an accurate diagnosis and to rule out the possibility of something more serious.
Plexopathy involves damage to any of the nerves plexi or the peripheral nervous system. A nerve plexus is a sort of electrical junction box that sends out groups of nerves from the spinal cord to various parts of the body. The major plexi include the cervical plexus of the neck, which distributes nerves to the arms, and the lumbosacral plexus of the lower back, which sends out nerves to the pelvis and legs. People with diabetes, especially elderly people, sometimes experience a type of plexopathy known as femoral neuropathy, which affects nerves in the thigh.
Symptoms of femoral neuropathy include pain in the thigh and in the calf. The pain is often worse at night. You may also experience weakness in the thigh muscle, which makes it difficult to move your hip and knee
What You Should Do
If you experience any leg pain, tell your doctor. Your doctor will want to distinguish it from sciatica. To do this, you will be asked to straighten your leg and raise it. If you have sciatica, this will be very painful, but if you have a plexopathy, you should be able to do this without pain. Usually, this condition is diagnosed by excluding other conditions. Plexopathies, including femoral neuropathy, usually heal spontaneously without treatment. However, it may take several years before you regain muscle strength, and the condition can recur.
Radiculopathy is caused by damage to a nerve or group of nerves in the trunk of the body. It affects both men and women with diabetes and is more common in older people.
If you have radiculopathy, you may experience pain in the chest or abdomen. The pain usually comes on suddenly and can get worse at night. This could lead you or your doctor to suspect an emergency situation such as a heart attack, ulcer or appendicitis. The pain of radiculopathy does not usually get worse when you cough or exercise, however.
What You Should Do
Call your doctor if you experience any chest or abdominal pain. You may need immediate treatment to rule out the possibility of something more serious, such as heart attack, pneumonia, appendicitis, gastrointestinal disease, or ulcer. Your doctor may need to perform several different tests to correctly diagnose the condition. If you do indeed have radiculopathy, it will go away in a few months on its own. Talk to your doctor if you need help dealing with the pain.
Several types of entrapment neuropathies are common in people with diabetes than in the general population. Researchers do not know for sure why this is true, but they think that diabetes somehow affects nerve transmission. This makes nerves more susceptible to mechanical damage, such as compression. When an already vulnerable nerve is compressed, then damage can occur more readily than in a patient without diabetes. Nerves commonly affected with entrapment include the median nerve in the wrist, which leads to carpal tunnel disorder, the ulnar nerve of the elbow, the radial nerve of the upper arm, the lateral cutaneous nerve of the thigh and the peroneal nerve of the knee.
Carpal tunnel syndrome is twice as likely to occur in people with diabetes and more likely to affect women than men. It can be caused by repeated motion that compresses the nerve, by changes in metabolism, and by fluid that accumulates within the confined space of the carpal tunnel. People who frequently subject their wrists to forceful repetitive movements such as using a screwdriver or typing at a computer terminal are especially at risk
Symptoms of carpal tunnel syndrome include numbness, tingling, pain and odd sensations in the thumb, index finger and middle finger of one hand. Sometimes pain and a tingling or burning sensation also occurs in the arm and shoulder. You may find it more painful while sleeping because of the position of your hand.
What You Should Do
If you have any of the symptoms of carpal tunnel syndrome, talk to your doctor about what you can do to relieve the pain. You may want to first try to avoid the positions and motions that compress the median nerve. Avoid overextending your wrist or putting extra pressure on your wrist. Using a wrist splint might help. If your problem is as a result of overusing your computer keyboard, for example, you might try adjusting the angle or position of the keyboard.
Your doctor may prescribe anti-inflammatory drugs to reduce inflammation and help with the pain. In some cases, injection of a corticosteroid can bring temporary relief from pain. You may also be a candidate for physical therapy.
If your pain is severe or your muscles begin to weaken, and none of these measures helps, your doctor may suggest surgery to relieve pressure on the nerve. In this procedure, a surgeon sections a ligament called the volar carpal ligament, which should release the trapped nerve.
Ulnar Nerve Entrapment
The ulnar nerve is also vulnerable and can become entrapped, especially in people with diabetes. This nerve passes through the elbow near the surface of the skin and can become compressed if you repeatedly lean on your elbow or if you have any kind of abnormal bone growth in that area
Symptoms of ulnar nerve entrapment include pain and weakness in the pinkie and ring fingers and the forearm. You may also experience weakness and odd sensations in the hand. If the pain is severe and the nerve compression lasts a long time, then your muscles can atrophy, giving the hand a claw-like deformity.
What You Should Do
Surgery is generally not successful in relieving ulnar nerve entrapment. Treatment is usually aimed at avoiding pressure on the elbow, and physical therapy can help restore mobility and muscle tone.
The radial nerve runs beneath the bone of the upper arm. Pressure to this nerve can also cause an entrapment syndrome. This problem is sometimes called ‘Saturday Night Palsy’ because it often occurs in people who drink heavy and fall asleep with an arm draped over the back of a chair or under the head.
Symptoms of radial nerve entrapment include weakness and loss of sensation on the back of the hand. Often, the fingers curve and the wrist flops into a bent position (wrist-drop) when the wrist is extended
What You Should Do
If you suspect radial nerve entrapment, try to avoid any position or motions that put pressure on the underside of the upper arm. Usually the condition improves once the pressure is relieved. If this does not help, talk to your doctor about possible therapies.
The peroneal nerve runs along the surface of the skin at the top of the calf muscle, in the soft folds of tissue behind the knee. It is often found in people who are thin and bedridden, improperly strapped to a wheelchair, or who tend to cross their legs often and for long periods of time
Symptoms include a weakening of the muscle that lifts the foot. This causes foot-drop, an inability to raise or flex the foot and a loss of sensation at the outer foot.
What You Should Do
The first thing is to identify the cause of the nerve compression. If you cross your legs often, try to avoid doing so. If you are bedridden or wheelchair-bound, talk to your caregivers about finding a position that reduces pressure on the back of your knee. Talk to your doctor about other measures you can take.
Other nerves are also susceptible to entrapment. Pressure or damage to the lateral cutaneous nerve of the thigh causes pain and sensory loss in the upper thigh. Compression of the sciatic nerve in the buttock can cause sciatica, marked by pain in the lateral thigh, as well as foot-drop. And pressure on the medial and lateral plantar nerves in the foot can cause a decrease in sensation on the inside and outside of the foot. Treatments generally include relief of the pressure on the nerve, anti-inflammatory drugs, physical therapy, and in some cases, surgery. Talk to your doctor if you are experiencing any pain or unusual symptoms.
When people say they have neuropathy, they are usually talking about damage to the nerves to the leg, feet, arms and hands that control the way they walk, move and feel things in the environment. But nerves to the autonomic nervous system can also be damaged. The autonomic nervous system delivers messages from the brain to control all the internal organs that you don’t usually even think about—the heart, lungs, bladder, kidney, stomach, intestines and reproductive organs, for example. When these nerves are damaged, you may develop autonomic neuropathy. When this occurs, you may experience problems with some of the major organ systems in your body.
Autonomic neuropathy can cause problems with bladder control, with the stomach and gastrointestinal tract, with sexual function in both men and women, with our heart and blood pressure, with the nerves in the skin that control sweating, and with the way your eyes adjust to lightness and darkness. Autonomic neuropathy can also interfere with the warning signs of hypoglycemia and can contribute to hypoglycemia unawareness.
Sources and References
The Diabetes Problem Solver—Quick Answers to Your Questions About Treatment and Self-Care by Nancy Touchette
Diabetic neuropathy by Aaron Vinik, Henri Parson et al
Peroneal nerve decompression by Mark Corriveau, Jacob Lescher and Amgad Hanna