Peripheral Neuropathy

What is peripheral neuropathy?

Peripheral neuropathy is a disease that affects the peripheral nerves in a length depended fashion.

Peripheral neuropathy is sometimes also called:

• Peripheral polyneuropathy
• Length depended symmetrical peripheral neuropathy

What are the symptoms of peripheral neuropathy?

The symptoms of peripheral neuropathy can vary, depending on the type of nerve signals that are affected.

Symptoms are grouped into three main types:

Motor symptoms

Signals are sent from the brain to the muscles, allowing us to move and function properly. If motor nerves are affected, symptoms may include:

• Muscle atrophy: Loss of connection between nerves and muscles can cause them to weaken and shrink.
• Muscle weakness and paralysis: May cause difficulty moving many parts of the body, including the hands and the feet.
• Uncontrolled muscle movements: When nerves lose connection to the brain, they may become hyperactive and lead to cramps.

Sensory symptoms

Information about the world around us is converted into nerve signals by our peripheral nerves. The brain processes these signals so we can understand what is happening. If peripheral neuropathy damages these nerves, it can disrupt what our senses notice around us or the way the senses are communicated with the brain. Sensory symptoms include:

• Imbalance: Nerves carry sensations which allow the brain to locate the hands and feet. If peripheral neuropathy affects these nerves, it causes problems with balance and coordination.
• Numbness: If nerves can’t send sensory signals, it can cause a loss of certain sensations.
• Pain: Peripheral neuropathy can cause problems with the ways our nerves send pain signals. It can make them too intense (hyperalgesia) or too sensitive (allodynia). It can also cause our nerves to make pain signals when no pain is actually experienced. This is called neuropathic pain.
• Tingling: Caused by a problem with the nerves which carry signals to the brain.

Autonomic symptoms

Autonomic processes are functions that the body does without thinking, such as digesting food or sweating. If peripheral neuropathy affects the autonomic nerve fibers, it can disrupt signals and these processes don’t work properly. Autonomic symptoms can include:

• Bowel/bladder problems: Nerve disruption can affect bowel or bladder control.
• Changes to blood pressure: Damage to peripheral nerves may cause a sudden increase or decrease in blood pressure or heart rate.
• Sexual dysfunction: Problems with the autonomic nervous system can cause sexual dysfunction.
• Sweating: Nerve damage may lead to too much or too little sweat being produced.

If an injury has caused peripheral neuropathy, then the symptoms can develop instantaneously or very quickly afterward. Inflammation-based cases may develop after several days or weeks. Most other cases of peripheral neuropathy take months or years to develop.

What causes peripheral neuropathy?

Causes of peripheral neuropathy can include:

• Type 2 diabetes: If blood sugar levels are too high for too long, damage to peripheral nerves can occur. A loss of feeling in the feet is common in people with unmanaged type 2 diabetes.
• Vascular disorders: A lack of blood flow to a part of the body can cause serious and permanent nerve damage.
• Vitamin deficiencies: If we don’t get enough of certain vitamins and nutrients, it can cause nerve damage.
• Excessive alcohol use: Over time, alcohol use can damage nerves.
• Genetic conditions: Some conditions that are inherited from your parents can cause peripheral neuropathy.
• Idiopathic neuropathy: This type of peripheral neuropathy happens for unknown reasons.
• Infections: Certain viruses or bacteria can cause nerve damage. A common example is shingles which causes nerve pain.
• Medications: Some medications, including chemotherapy, some antibiotics and medications (to treat gout and arrhythmia) can cause peripheral neuropathy.
• Toxins: Exposure to some industrial chemicals and heavy metals can cause peripheral neuropathy.

How is peripheral neuropathy diagnosed?

History and neurological exam

Diagnosing peripheral neuropathy will first involve your doctor asking you, in detail, about your symptoms and medical history as well as any medication you are taking or other health conditions that you are living with. Your doctor will then perform a physical exam to look for signs of peripheral neuropathy.

To confirm a diagnosis of peripheral neuropathy, a number of different tests may be performed, including:

• Electromyogram
• Skin biopsy

Diagnostic tests to find the cause of peripheral neuropathy include:

• Glucose tolerance test (GTT)/HbA1c
• Vitamin B12 with methylmalonoic acid
• Serum protein electrophoresis with immunofixation
• Comprehensive metabolic panel
• Complete blood count
• Rheumatology and thyroid testing-low yield

Other specific tests may be performed in certain clinical situations.

How is peripheral neuropathy treated?

Treatment of peripheral neuropathy focuses on managing the underlying condition. In addition, treatment of the associated symptoms can significantly improve the patient's quality of life.

Nonpharmacologic strategies such as proper foot hygiene, wearing appropriate footwear, weight loss, and physical therapy and gait training can help improve symptoms in those with lower extremity peripheral neuropathy.

Several oral medications help alleviate neuropathic pain. Gabapentinoids, pregabalin, and antidepressants appear to be moderately effective and are recommended as first-line options.

Topical medications, including lidocaine and capsaicin, can be added as adjuvants to oral medications.

Evidence for opioids role for peripheral neuropathy pain control is limited.