Peripheral neuropathy is a disease state of the peripheral nerves, those found outside the spinal cord. This disorder commonly affects nerves in the arms and legs. It is a disease state characterized by sudden or progressive damage to the peripheral nerves and can affect sensation, motor function, organs, or glands. Peripheral neuropathy can involve different types of nerves simultaneously. It can be reversible or irreversible/permanent.
One of the most common causes of peripheral neuropathy is diabetes. Additional causes include toxic chemicals, heredity, cancer and HIV medications, kidney disease, alcoholism, lack of appropriate nutrition, autoimmune diseases, infections, connective tissue diseases, vitamin B12 or folate deficiency, and protein abnormalities.
Symptoms depend on the type of nerve involved. One or multiple nerves can be involved. Sensory neuropathy results when sensory nerves are damaged, resulting in tingling and numbness, inability to detect temperature changes, impairment of coordination, and burning or shooting pain that can be worse at night. Sensory neuropathy typically starts in the hands and feet and progresses centrally.
Motor neuropathy results when motor nerves are damaged. Muscle stimulation is diminished and can lead to:
Muscle weakness
Muscle wasting
Twitching
Cramps
Muscle paralysis
Autonomic nerve involvement leads to autonomic neuropathy. Symptoms include:
Dizziness
Fainting
Reduction in the ability to sweat
Intolerance to heat
Loss of bladder control leading to urinary incontinence
Bloating
Constipation
Diarrhea
Impotence
The diagnosis of peripheral neuropathy starts with a thorough history. The physician will ask questions about symptoms, factors that cause or alleviate symptoms, work history, alcohol intake, history of infections, and family history.
On the physical exam, the physician will look for evidence of systemic disease such as diabetes. Neurologic tests are utilized to test the amount of nerve damage.
Body fluid tests are used to test for causes of peripheral neuropathy such as diabetes, infections, immune disorders, metabolic disorders, vitamin deficiencies, liver dysfunction, and kidney disease.
Additional tests may include genetic tests and tests for atypical proteins or immune cells.
Nerve functions tests include nerve conduction velocity (NCV) testing and electromyography (EMG).
A nerve biopsy can provide detailed information on the types of nerve cells affected.
A neurodiagnostic skin biopsy can be used to diagnose small fiber neuropathies that may remain undetected by nerve function tests.
The QSART test is an autonomic test that measures the ability to sweat in the arm and leg. Abnormalities found in this study are associated with small fiber polyneuropathies.
An MRI can show nerve root compression or tumors among other anatomic abnormities.
A CT scan can reveal herniated discs, spinal stenosis, and other bony irregularities affecting nerves.
New techniques under development include muscle and nerve ultrasound.
In many instances, peripheral neuropathy cannot be cured. Treating and managing peripheral neuropathy involves trying to control the underlying cause. For diabetic peripheral neuropathy, blood glucose should be improved as much as possible. Over-the-counter pain medications such as Tylenol or NSAIDS can help to some degree. Prescription medications include mexiletine and antiseizure drugs such as carbamazepine and gabapentin. Tricyclic antidepressants can help as well. Lidocaine injections and patches can be beneficial as well.
Lifestyles changes such as smoking cessation, meticulous foot care, and braces for the hand and foot and relation techniques can offer significant symptomatic relief.