Neuropathy: Causes, Types, Treatment and Medications

What is Neuropathy?

Neuropathy affects about 8 percent of people over age 55.

Your nervous system consists of two parts: the central nervous system and the peripheral nervous system.

The nerves of your peripheral nervous system transmit messages between your central nervous system your brain and spinal cord and the rest of your body.

These nerves regulate a large range of functions throughout the body, including voluntary muscle movement (motor nerves), involuntary organ activity (autonomic nerves), and the perception of stimuli (sensory nerves).

Peripheral neuropathy, which is often simply referred to as “neuropathy,” is a condition that occurs when your peripheral nerves become damaged or disrupted.

It is estimated that neuropathy affects about 2.4 percent of the general population, and about 8 percent of people older than age 55.

However, this estimate doesn’t include people affected by a neuropathy resulting from physical trauma to the nerves.

Causes of Neuropathy

Approximately 30% of neuropathies are ‘idiopathic’, or of an unknown causes.

Many different conditions can lead to peripheral neuropathy.

• Diabetes – the commonest cause of chronic peripheral neuropathy. High blood sugar levels in people with poorly controlled diabetes damage nerves.
• B12 or folate vitamin deficiencies can cause nerve damage and peripheral neuropathy.
• Drugs – such as some chemotherapy medication and medicines used to treat HIV can cause damage to peripheral nerves.
• Poisons (toxins) – insecticides and solvents can cause peripheral nerve damage.
• Cancers – peripheral neuropathy can occur in people with some cancer E.G: lymphoma and multiple myeloma.
• Alcohol excess – high alcohol levels in the body cause nerve damage.
• Chronic kidney disease – if the kidneys are not functioning normally, an imbalance of salts and chemicals can cause peripheral neuropathy.
• Chronic liver disease.
• Injuries – broken bones and tight plastercasts can put pressure directly on the nerves.
• Infections – damage can be caused to peripheral nerves by some infections including shingles, HIV infection and Lyme disease.
• Guillain–Barré syndrome is the name given to a specific type of peripheral neuropathy triggered by infection.
• Connective tissue diseases – rheumatoid arthritis, Sjögren’s syndrome and systemic lupus erythematosus.
• Certain inflammatory conditions – conditions including sarcoidosis and coeliac disease can also cause peripheral neuropathy.
• Hereditary diseases – Charcot-Marie-Tooth syndrome and Friedreich’s ataxia.
• Idiopathic – in a few people, no specific cause is found for their peripheral neuropathy. This is known as idiopathic peripheral neuropathy.

Types of Neuropathy

Peripheral neuropathy: Peripheral neuropathy is when the nerve problem affects the nerves outside of the brain and spinal cord. These nerves are part of the peripheral nervous system. Accordingly, peripheral neuropathy is neuropathy that affects the nerves of the extremities- the toes, feet, legs, fingers, hands, and arms. The term proximal neuropathy has been used to refer to nerve damage that specifically causes pain in the shoulders, thighs, hips, or buttocks.

Cranial neuropathy: Cranial neuropathy occurs when any of the twelve cranial nerves (nerves that exit from the brain directly) are damaged. Two specific types of cranial neuropathy are optic neuropathy and auditory neuropathy. Optic neuropathy refers to damage or disease of the optic nerve that transmits visual signals from the retina of the eye to the brain. Auditory neuropathy involves the nerve that carries signals from the inner ear to the brain and is responsible for hearing.

Autonomic neuropathy: Autonomic neuropathy is damage to the nerves of the involuntary nervous system. These nerves that control the heart and circulation (including blood pressure), digestion, bowel and bladder function, the sexual response, and perspiration. Nerves in other organs may also be affected.

Focal neuropathy: Focal neuropathy is neuropathy that is restricted to one nerve or group of nerves, or one area of the body.

Neuropathic Symptoms

The most common symptom of a motor nerve neuropathy is muscle weakness, but you may also experience numerous other symptoms, including:

• Muscle pain
• Muscle cramping
• Uncontrolled muscle twitching
• Muscle loss
• Bone degeneration
• Changes to the skin, hair, and nails

Neuropathies affecting the sensory nerves often result in more complex symptoms, including:

• Numbness
• Loss of coordination and balance
• Hampered reflexes
• Burning sensations
• Heightened sensitivity to pain or touch, or the inability to feel pain
• Tingling or so-called “pins and needles” sensations
• Neuropathic pain (nerve pain)

And if the autonomic nerves are affected, you may experience:

• Diarrhea or constipation
• Incontinence
• Altered heart rate
• Abnormal blood pressure, which results in dizziness and lightheadedness, especially when rising from a standing position
• Erectile dysfunction (ED)
• Overactive or underactive sweat glands
• Dryness of the eyes and mouth
• Difficulty eating or swallowing

Treatments for Neuropathy

Whether single or multiple nerves are affected by neuropathy, the underlying cause can often be targeted for treatment, but if the background condition cannot be corrected, treatment takes the form of symptomatic pain relief.

• Treat any underlying cause
• Control the symptoms of neuropathy
• Stop it getting any worse

Addressing the underlying cause is also a preventive strategy, particularly against diabetic neuropathy, where addressing the high blood sugars can prevent nerve damage.

For toxic causes, simply removing the exposure to a suspect toxin, or stopping a culprit drug, will halt further nerve damage behind the neuropathy.

Medications to relieve pain and reduce burning, numbness and tingling are available. Some of these are known for their use in other conditions but they still seem to help those with nerve damage.

What medications are used to treat Neuropathy?

A number of medications have been useful in controlling the pain of peripheral neuropathy.

What Are Neuropathy Medications?

Typical pain medications sold over-the-counter such as acetaminophen (Tylenol and others) and ibuprofen (Motrin and others) are not generally effective for controlling the pain of neuropathy. These drugs may be effective for lessening pain or joint damage and deformities associated with neuropathy, but they should be used with caution because there is some concern that these drugs may worsen nerve injury.

Certain prescription medications have been shown to bring relief for those with neuropathy. In severe cases, a combination of medications may be necessary. Oral medications that have been successfully used to help the pain of neuropathy include:

• Antidepressants: Antidepressants including the tricyclic antidepressants amitriptyline (Vanatrip), imipramine (Tofranil, Tofranil-PM), and desipramine (Norpramin, Pertofrane) as well as other antidepressants such as duloxetine (Cymbalta), venlafaxine (Effexor, Effexor XR), bupropion (Wellbutrin), paroxetine (Paxil), and citalopram (Celexa). Duloxetine has been approved by the U.S. Food and Drug Administration (FDA) specifically for treating diabetic peripheral neuropathy.
• Anticonvulsants: Anticonvulsants such as pregabalin (Lyrica), gabapentin (Gabarone, Neurontin), carbamazepine (Carbatrol, Equetro, Tegretol, Tegretol XR), and lamotrigine (Lamictal). Pregabalin has been FDA-approved for the treatment of diabetic neuropathy.
• Opioids and opioid-like drugs such as controlled-release oxycodone and tramadol (Ultram)

Topical medications that may bring pain relief include capsaicin cream and lidocaine patches (Lidoderm, Lidopain). Alternative or complementary therapies like acupuncture, biofeedback, and physical therapy have been shown to be helpful in some cases.

The antioxidant alpha-lipoic acid (ALA, taken in one oral 600 mg dose daily) has been shown to be effective in treatment of diabetic neuropathy in several short-term trials; evidence for its effectiveness over the long term is not yet available.

For those whose pain is not controlled by medications, a procedure known as trans-cutaneous electrical nerve stimulation (TENS) may be an option. Although data are limited on the effectiveness of this method, a 2010 guideline issued by the American Academy of Neurology stated that TENS is probably effective for reducing pain from diabetic neuropathy.