Neuropathy

The type of nerve involved determines the symptoms.

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 freezing
• Tightness or squeezing
• Sensation that something is under your foot or toes
• Sensation of walking on pebbles or blocks of wood
• Heightened sensitivity to touch making it uncomfortable or 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 trouble
• Sweating too much or too little
• Sexual dysfunction or reduced libido
• Vision impairment
• Dry mucous membranes

• Diabetes. Diabetic neuropathies can affect any type of peripheral nerve and cause any neuropathy symptom. Thyroid and kidney disorders also can cause neuropathy.
• Genetic abnormalities can cause inherited neuropathies such as Charcot Marie Tooth disease and Fabry’s disease.
• Exposure to chemicals such as alcohol or chemotherapy can cause nerve injury and toxic neuropathies.
• Deficiency syndromes, especially of vitamins B12, B6 and B1.
• Autoimmune disorders like Sjögren's Syndrome, lupus, rheumatoid arthritis, fibromyalgia, Guillain-Barré Syndrome and chronic inflammatory demyelinating polyradiculoneuropathy cause inflammation that can damage nerves and lead to neuropathy.
• Mechanical trauma such as Carpal Tunnel Syndrome. Nerves also can be damaged during surgery or by trauma, compression or overuse.
• Cancerous tumors can compress a nerve or grow in the nerve. Cancer also can prompt the immune system to mistakenly identify the nerve as foreign and attack 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.

Because peripheral neuropathy has many potential causes, your doctor may order a variety of tests, in addition to a physical and neurologic exam and full medical history.

You may need to get some of the following tests:

• Blood tests. We look for vitamin deficiencies, diabetes, abnormal immune function and other signs of conditions that can cause peripheral neuropathy.
• Imaging tests. Using CT or MRI scans, we can find compressed nerves, tumors or other abnormalities.
• Nerve tests. The most common is electromyography (EMG), which tracks electrical activity in muscles to find any nerve damage. For this test, we will insert a thin needle/electrode into the muscle and have you contract the muscle. In the same appointment, we will place flat electrodes on the skin and send a low electric current through to stimulate the nerves. This nerve conduction study tells us the nerves' response.
• Sweat test. We will examine your body’s ability to sweat.
• Sensory tests. These record how your body feels touch, vibration and temperature.
• Nerve biopsy. For this, we must remove a small piece of a nerve to look for abnormalities.
• Skin biopsy. By removing a small piece of skin, we can see if there are fewer nerve endings than there should be.

Neurodiagnostics