- sensorimotor polyneuropathy
Peripheral neuropathy (PN) is a loss of function in the peripheral nerves, that is, the nerves that branch out from the brain and spinal cord to the rest of the body. Typically, PN is a term used to refer to damage of the smallest nerves, those farthest from the spinal cord.
What is going on in the body?
Peripheral neuropathy occurs when the peripheral nerves are damaged. The damage is usually caused by a loss of myelin, the protective coating of the nerve; however, the axon (the actual nerve fiber) is commonly affected as well.
The damage may be focal or limited to one nerve (mononeuropathy), usually from nerve injury, or more diffuse (polyneuropathy) involving multiple nerves. Polyneuropathy may be due to a toxin, to a system-wide disease such as diabetes, or can be inherited.
What are the causes and risks of the condition?
Diffuse peripheral neuropathy (polyneuropathy) can be caused by a number of factors and may be inherited. Acquired polyneuropathies are more common and usually are related to a systemic disease, such as:
diabetes mellitus (the most common cause)
uremia, severe chronic kidney disease
celiac disease or sprue from poor absorption of nutrients
chronic severe liver disease
HIV or AIDS
- hepatitis C
Conditions that may cause neuropathy from a toxic effect or vitamin deficiency include:
excessive alcohol intake
exposure to radiation
heavy metal exposure (lead, mercury etc.)
medication side effects (especially from cancer chemotherapy)
- nutritional deficiencies such as vitamin B12 deficiency
Guillain-Barré disease is an example of polyneuropathy with an acute onset.
A similar syndrome that pursues a more chronic course is known as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).
A focal peripheral neuropathy (mononeuropathy) can result from trauma to a nerve caused by:
direct injury to the nerve itself, as from a gunshot or knife wound
entrapment of the nerve, as in carpal tunnel syndrome, where the nerve is injured as it travels through a tunnel at the wrist
- prolonged compression from staying in one position too long
What can be done to prevent the condition?
Some cases of peripheral neuropathy can be prevented by avoiding or controlling the underlying problem. For instance, individuals with diabetes can lower their risk by controlling their blood glucose levels.
Individuals with chronic diseases affecting vitamin intake should be on multivitamin supplements. Following sports safety guidelines for children, adolescents, and adults can help prevent some nerve injuries.
How is the condition diagnosed?
Diagnosis of peripheral neuropathy begins with a medical history and physical exam. The healthcare professional may detect muscle weakness and decreased sensation. Unfortunately, the cause for a polyneuropathy is frequently never found. The cause for a mononeuropathy is much easier to determine.
The healthcare professional may order tests, including:
blood tests to look for underlying diseases
electromyography, or EMG, which measures the electrical activity of the involved muscles
nerve conduction velocity studies, or NCV, which measure the nerve's ability to carry messages
- X-rays, CT or MRI to look for underlying conditions
Long Term Effects
What are the long-term effects of the condition?
Without treatment, peripheral neuropathy may worsen over time. The individual may lose muscle function and sensation. There may even be muscle wasting, or atrophy. The person may have chronic pain that worsens at night. Skin injuries may not heal properly and may become infected.
What are the risks to others?
Peripheral neuropathy is not contagious and poses no risk to others.
What are the treatments for the condition?
Treatment of peripheral neuropathy varies, depending upon the underlying problem. Some examples include:
avoiding alcohol when the cause is thought to result from to chronic alcohol use
controlling blood glucose, for people with diabetes
vitamin supplementation for those thought to have a PN related to a vitamin deficiency
discontinuation of a medicine that is known to cause a PH
getting physical therapy and occupational therapy if needed
undergoing surgery to relieve pressure on a nerve
- using splints and other devices to relieve pressure on a nerve
If an individual has significant pain, medications may be recommended. These include the following:
Someone who has polyneuropathy is at increased risk for injury. Decreased sensation increases the risk for burns. A person with muscle weakness may fall easily.
Some measures to prevent injuries include:
Participating in an exercise program designed to improve balance.
Removing throw rugs and any other objects that could cause slips and falls.
Testing bath water with a thermometer before getting into the tub.
- Using handrails and tub rails as needed to prevent falls.
The person should examine all areas of decreased sensation on a daily basis. Any cuts, bruises, or pressure sores should be reported to the healthcare professional.
What are the side effects of the treatments?
Medications used to treat neuropathy may cause stomach upset or allergic reactions. Some can also cause dizziness, drowsiness, dry mouth, and constipation.
What happens after treatment for the condition?
If the underlying cause is effectively treated, the person may recover some or all of the nerve function. Recovery is slow and complications are common. The person may lose sensation and movement to a part of the body.
How is the condition monitored?
Any new or worsening symptoms should be reported to the healthcare provider.