PERIPHERAL NEUROPATHIES – Causes and Risk Factors, Clinical Manifestations, Diagnostic Evaluations and Management

                Peripheral neuropathy is a common neurological disorder resulting from damage to the peripheral nerves. Peripheral nerves, located outside of the brain and spinal cord, provide the means of communication between the brain and other parts of the body, including muscles, skin, internal organs and blood vessels.

                Some form of neuropathy involves damage to only one nerve and are called mononeuropathies. More often though,  multiple nerves affecting all limbs are affected- called polyneuropathy. Occasionally, two or more isolated nerves in separate areas of the body are affected- called mononeuritis multiplex.

                Peripheral neuropathy often causes numbness and pain in hands and feet. People typically describe the pain of peripheral neuropathy as tingling or burning, while they may compare the loss of sensation to the feeling of wearing a thin stocking or glove.

CAUSES AND RISK FACTORS

                Peripheral neuropathy is caused by nerve damage. There are many possible causes of peripheral neuropathy, including:

• Injury or sudden trauma from automobile accidents, falls, and sports-related activities
• Shingles (post herpetic neuralgia)
  
• Metabolic and endocrine disorders (Diabetes Mellitus)
  
• Vitamin B deficiencies and alcoholism
  
• Vascular damage and blood diseases
  
• Autoimmune diseases, including lupus, rheumatoid arthritis or Guillain-Barre syndrome
  
• AIDS, whether from the disease or its treatment, syphilis, and kidney failure
  
• Inherited disorders, such as amyloid polyneuropathy or Charcot-Marie-Tooth disease
  
• Cancer therapy drugs such as vincristine (Oncovin, Vincasar)
  
• Other medications such as metronidazole (Flagyl), and isoniazid
  
• Exposure to toxins, such as heavy metals, gold compounds, lead, arsenic, mercury, and organophospate pesticides
  

CLINICAL MANIFESTATIONS

                Symptoms are related to the type of affected nerve and may be seen over a period of days, weeks, or years. Muscle weakness is the most common symptom of motor nerve damage. Although there are numerous causes of peripheral neuropathies, they do share some common symptoms, including:

• Weakness, numbness and pain in the hands, legs and or feet
• Paresthesia or abnormal sensations such as burning, tickling, pricking or tingling
  
• Extreme sensitivity to touch, even light touch
  
• Lack of coordination
  
• Painful cramps and fasciculations (uncontrolled muscle twitching visible under the skin)
  
• Muscle loss, bone degeneration and changes in the skin, hair and nails
  
• Muscle weakness or paralysis if motor nerves are affected
  
• Bowel or bladder problems if autonomic nerves are affected
  

DIAGNOSTIC EVALUATIONS

                A crucial part of diagnosing neuropathy is to identify the cause of the underlying condition. Both physical and neurological exams will be performed. A number of tests may be used to determine the underlying cause of neuropathy and rule out other conditions. Along with blood and urine tests, the following also may be performed:

• Electroencephalography (EEG)
• Spinal Tap
  
• Computed Tomography (CT)
  
• Magnetic Resonance Imaging (MRI)
  
• Nerve Conduction Velocity (NCV) Studies
  
• Electromyography (EMG)
  
• Nerve biopsy and Skin biopsy
  

MANAGEMENT

                No medical treatments now exist that can cure inherited peripheral neuropathy. Therapy for peripheral neuropathy focuses in treating the underlying cause. Vitamin deficiencies can be corrected. Diabetes can be controlled, although control may not reverse the neuropathy. The goal with diabetes is early detection to prevent the occurrence of neuropathy. Neuropathies that are associated with immune diseases can improve with treatment of the autoimmune disease. Immunosuppressive drugs such as prednisone, cyclosporine, or azathioprine may be beneficial. Plasmapheresis – a procedure in which blood is removed, cleansed of immune system cells and antibodies, and then returned to the body- can limit inflammation or suppress immune system activity. High doses of immunoglobulins, proteins that function as antibodies, also can suppress abnormal immune system activity. Neuropathy caused by nerve entrapment can be treated by physical therapy, injections or surgery. Prompt treatment with sympathetic injections can minimize the chance of shingles progressing to post herpetic neuralgia.

                The simplest treatment is acetaminophen, ibuprofen, or aspiring. Tricyclic antidepressants such as amitriptyline (Elavil) and anti-seizure medications, such as carbamazepine (Tegretol) have been used to relieve the pain of neuropathy. Mild symptoms may be relieved by over-the-counter pain medications. For more severe symptoms, your doctor may recommend prescription painkillers. Pregabalin (Lyrica) has recently been approved by the FDA for the treatment of post herpetic neuralgia and diabetic peripheral neuropathy, while duloxetine (Cymbalta) has been approved for diabetic peripheral neuropathy.

                Mechanical aids can help reduce pain and lessen the impact of physical disability. Hand or foot braces can compensate for muscle weakness or alleviate nerve compression. Orthopedic shoes can improve gait disturbances and help prevent foot injuries in people with a loss of pain sensation. If breathing becomes severely impaired, mechanical ventilation can provide essential life support.

 

PERIPHERAL NEUROPATHIES – Causes and Risk Factors, Clinical Manifestations, Diagnostic Evaluations and Management