Neuropathy: Conditions

What is Neuropathy?

Neuropathy refers to a disorder of one or more peripheral nerves. But, like there are many types of headaches, there are many kinds of neuropathies and many causes.

Studies estimate that 5 to 9 percent of the American population, or 16 to 30 million people, experience some degree of peripheral neuropathy. Neuropathy is much more common in people having diseases like diabetes. As many as 70 percent of people with diabetes have some form of neuropathy.

To understand a neuropathy, it helps to know the type of nerve involved. The nervous system is divided into two categories:

• Peripheral nervous system includes all nerves connecting the brain and spinal cord to the body. Motor nerves send signals from the brain to muscle, sensory nerves send sensations from the body to the brain for processing, and other nerves carry signals to and from internal organs to keep them working.
• Central nervous system includes the brain, brainstem connecting the brain to the spinal cord, and the spinal cord.

When ONE peripheral nerve is affected, it is called mononeuropathy. Examples are Carpal Tunnel Syndrome, in which the median nerve in the wrist is compressed, causing numbness, tingling and weakness in the hand, particularly the palm and thumb, index and middle fingers; and Cubital Tunnel Syndrome, in which the same type of symptoms result from compression of the ulnar nerve where it passes through the elbow.

When two or more peripheral nerves are affected, it is called polyneuropathy. One example is diabetic neuropathy, which typically starts in the toes and moves up the legs to the hands and arms.

Autonomic neuropathy

Many bodily functions – digestion, heart rate, blood pressure, sweating - occur without our conscious control as part of our autonomic system. These functions are controlled by nerves which can be affected by neuropathy. To diagnose autonomic neuropathies, we use a specific set of tests that evaluate many of these bodily functions, including tilt table testing, measuring the variability in heart rate and the skin’s production of sweat.

Signs of neuropathy

The type of nerve involved determines symptoms of the neuropathy.

• Neuropathy in motor nerves can cause:
  • Weakness
  • Loss of muscle tissue or atrophy
  • Muscle cramps
  • Fatigue

• Neuropathy in sensory nerves can cause:
  • Numbness or reduced sensation
  • Tingling, pin prick or stabbing sensations
  • Burning
  • Sensations of cold or even freezing
  • Tightness or squeezing
  • Sensation that something is under foot or under the toes
  • Sensation of walking on pebbles or blocks of wood
  • Heightened sensitivity making normal touch uncomfortable or even painful
  • Throbbing or aching
  • Trouble balancing

• Neuropathy in small fiber sensory nerves can cause a painful, burning sensation.

• Neuropathy in autonomic nerves can cause:
  • Lightheadedness, dizziness and fainting
  • Heart arrhythmias
  • Constipation or diarrhea
  • Bloating or feeling too full after small amounts of food
  • Bladder difficulties
  • Sweating too much or too little
  • Sexual dysfunction such as reduced libido
  • Vision impairment
  • Dry mucous membranes

Causes of peripheral neuropathy

• Diabetes. Diabetic neuropathies can affect any type of peripheral nerve and cause any neuropathy symptom. Other metabolic conditions that can cause neuropathy are thyroid and kidney disorders.
• Genetic abnormalities can cause inherited neuropathies such as Charcot Marie Tooth disease and Fabry’s disease. Sometimes, a family history can be identified when multiple members have a similar neuropathy.
• Exposure to chemicals causing nerve injury, such as alcohol or chemotherapy, can cause toxic neuropathies.
• Deficiency syndromes, especially of B12, B6 and B1.
• Autoimmune disorders like Sjögren's Syndrome, lupus, rheumatoid arthritis and fibromyalgia cause inflammation that can damage nerves and lead to neuropathy. This is the case with Guillain-Barré Syndrome and chronic inflammatory demyelinating polyradiculoneuropathy.
• Mechanical trauma such as Carpal Tunnel Syndrome. Nerves can also be damaged during surgery or by trauma, compression or overuse.
• Cancerous tumors can compress a nerve directly or grow within the nerve. Cancer can also prompt an autoimmune response in which the immune system mistakenly identifies the nerve as foreign and attacks it.
• Infection like HIV, hepatitis, West Nile virus and Lyme disease.
• Vasculitis, which can disrupt the blood supply to nerves.
• Up to 30 percent of the time, a neuropathy is considered “idiopathic” because no cause can be identified.

Check your feet 

Because many neuropathies reduce sensation in the feet, try to visually check them every day to be sure there hasn’t been an injury you didn’t feel. Even a puncture or break in the skin can cause infection that could spread and become dangerous. Through daily inspections, you will find and treat any injury or cut immediately.

Look at the soles of your feet and toes, inspecting between them. If you have trouble seeing the bottom of your feet, use a mirror or ask a family member to help. You may also want to consider regular visits to a podiatrist.