Peripheral Neuropathy

Anatomy

Peripheral nerves are soft tissue structures that carry signals between the brain and spinal column to the rest of the body. Peripheral nerves carry signals to the foot and ankle and control functions including sweating, ability to sense pain, and muscle movement.

Condition

Peripheral neuropathy (also called polyneuropathy) is a term used to describe damage to multiple peripheral nerves.

Symptoms

1. Burning, tingling, and numbness in both the hands and feet
2. Pain, typically burning in nature
3. Dry skin
4. Muscle weakness
5. Toe deformities including hammertoes, mallet toes, and claw toes
6. In advances cases, joint dislocation, also known as Charcot foot

Keys to understanding Peripheral Neuropathy

The nervous system is divided into 3 components, each with a unique function.

1. Autonomic nervous system
1. Allows skin to sweat
2. With peripheral neuropathy, the skin is dry and is more prone to cracking and open wounds. This provides an entry point for bacteria leading to infection
2. Sensory nervous system
1. Allows us to feel pain, sharp/dull, temperature, and sense of joint orientation
2. With peripheral neuropathy, patients are unable to sense pain and are unaware of injury to the foot. Injuries include and are not limited to burns, stepping on a foreign body such as glass, and joint dislocation. Unfortunately, due to the inability to sense pain, patients frequently don’t recognize a problem until limb threatening infection sets in
3. Muscular nervous system
1. Controls muscle balance
2. With peripheral neuropathy, muscle imbalance leads to prominent bone therefore leading to corns and calluses that are precursors to foot ulcers and infections

Peripheral neuropathy is highly associated with foot ulcers, particularly in diabetic patients. A foot ulcer is defined as a loss of the both layers of skin. Foot ulcers create a portal of entry for bacteria that can lead to infection and amputation. Diabetic foot ulcers cause 85% of all non-traumatic lower extremity amputations and 15% of diabetic foot ulcers result in lower extremity amputation.  These statistics demonstrate how important it is for diabetic patients to be aware of the risk factors associated with the disease.

Diagnosis

Diagnosis is made by a comprehensive foot and ankle exam by Dr. Stewart. In certain circumstances, electromyogram (EMG) and nerve conduction studies as well as a neurology referral are utilized.

Common causes

Peripheral neuropathy commonly occurs with certain medical conditions and can also result from nerve damage secondary to trauma. In some cases the cause is unknown and this is referred to as idiopathic peripheral neuropathy. Peripheral neuropathy is commonly associated with the following medical conditions:

1. Diabetes mellitus
2. Alcohol abuse
3. HIV/AIDS
4. Treatment with chemotherapeutic agents
5. Vitamin deficiencies
6. Thyroid disorders
7. Autoimmune conditions including rheumatoid arthritis and lupus

Treatment

Treatment for peripheral neuropathy is generally based on the underlying cause of the neuropathy. Optimal control of the underlying medical condition, managed by the primary care provider or medical specialist, is key to successful treatment. For example, diabetics that maintain tight glycemic control can prevent or delay progression of peripheral neuropathy.

The key to preventing complications associated with peripheral neuropathy is patient awareness and routine visits with a podiatrist. Dr. Stewart routinely evaluates and treats patients with peripheral neuropathy.

Conservative treatment for peripheral neuropathy includes:

1. Routine foot care including reduction of nails and trimming of corns and/or calluses
2. Oral medications including tricyclic anti-depressants, Lyrica, and Cymbalta
3. Topical medications such as Capsaicin cream
4. Medical management of the underlying cause of the neuropathy
5. Steroid injections
6. Custom foot orthotics
7. Extra-deep and extra-wide shoes
8. In certain circumstances, surgery may be required to correct structural deformities