Peripheral neuropathy describes damage to the peripheral nervous system, which transmits information from the brain and spinal cord to every other part of the body. More than 100 types of peripheral neuropathy have been identified, each with its own characteristic set of symptoms, causes, pattern of development, and prognosis. Peripheral neuropathy can range from carpal tunnel syndrome (an injury common after chronic repetitive use of the hands and wrists, such as computer use) to Guillain-Barre syndrome (a rare, sudden paralysis). Impaired function and symptoms depend on the type of nerves — motor, sensory, or autonomic — that are damaged.
Symptoms of Peripheral Neuropathy
Some people may experience temporary numbness, tingling, and pricking sensations, sensitivity to touch, loss of balance or muscle weakness. While others may suffer more extreme symptoms, including burning pain (especially at night), muscle wasting, paralysis, or organ or gland dysfunction. Oftentimes, the symptoms are symmetrical and involve both hands and feet. Peripheral neuropathy may be either inherited or acquired.
Specific nerves can be involved in neuropathy. When a specific nerve is involved, the symptoms are limited to the distribution of that nerve. The most commonly involved peripheral nerve is the median nerve at the wrist in carpal tunnel syndrome. Essentially any peripheral nerve can become entrapped and cause the signs and symptoms of peripheral neuropathy. The ulnar nerve is commonly entrapped at the elbow. The peroneal nerve is exposed at the outer part of the knee. The pudendal nerve can cause pain in the perineum and is relieved by sitting on a toilet seat or an inflatable donut. Entrapment of the lateral femoral cutaneous nerve at the waist, called meralgia paresthetica, causes numbness at the outer part of the thigh.
Causes of Peripheral Neuropathy
Peripheral neuropathy may be either inherited or acquired. Causes of acquired peripheral neuropathy include diabetes, chemotherapy treatment, physical injury (trauma) to a nerve, tumors, toxins, autoimmune responses, nutritional deficiencies, alcoholism, and vascular and metabolic disorders. Acquired peripheral neuropathies are grouped into three broad categories: those caused by systemic disease, those caused by trauma, and those caused by infections or autoimmune disorders affecting nerve tissue. One example of an acquired peripheral neuropathy is trigeminal neuralgia (also known as tic douloureux), in which damage to the trigeminal nerve (the large nerve of the head and face) causes episodic attacks of excruciating, lightning-like pain on one side of the face. In some cases, the cause is an earlier viral infection, pressure on the nerve from a tumor or swollen blood vessel, or, infrequently, multiple sclerosis. In many cases, however, a specific cause cannot be identified. Doctors usually refer to neuropathies with no known cause as idiopathic neuropathies.
Possible causes of peripheral neuropathy, include:
- Diabetes mellitus
- Physical injury or trauma
- Repetitive Stress
- Metabolic and endocrine disorders
- Shingles (post herpetic neuralgia)
- Vitamin deficiency, particularly B12 and folate
- Vascular damage and blood diseases
- Connective tissue disorders and chronic inflammation
- 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
- Exposure to toxins, such as heavy metals
- Cancer therapy drugs such as vincristine (Oncovin and Vincasar)
While diabetes and postherpetic neuralgia are the most common causes of peripheral neuropathy, often times no cause is found. In these situations, it is referred to as idiopathic peripheral neuropathy.
Sometimes, peripheral nerve entrapments, such as carpal tunnel syndrome, are considered peripheral neuropathies. In these cases, pressure on the nerve rather than a disease state leads to nerve malfunction.
Diagnosis of Peripheral Neuropathy
Diagnosing peripheral neuropathy is often difficult because the symptoms are highly variable. A thorough neurological examination is usually required and involves taking an extensive patient history (including the patient’s symptoms, work environment, social habits, exposure to any toxins, history of alcoholism, risk of HIV or other infectious disease, and family history of neurological disease), performing tests that may identify the cause of the neuropathic disorder, and conducting tests to determine the extent and type of nerve damage.
A general physical examination and related tests may reveal the presence of a systemic disease causing nerve damage. Certain tests done during the physical exam, including vibration and monofilament testing, are very accurate in diagnosing certain types of peripheral neuropathy, such as large fiber peripheral neuropathy seen with diabetes. Blood tests for exposure to toxins and electrodiagnostic studies, such as nerve conduction studies (NCS) and electromyelography (EMG) are also very useful, although these tests will not help with the diagnosis of small fiber neuropathy. Either skin biopsies or quantitative sudomotor axon reflex testing (QSART) are occasionally used to help diagnose small fiber neuropathy.
Based on the results of the neurological exam, physical exam, patient history, and any previous screening or testing, additional testing may be ordered to help determine the nature and extent of the neuropathy.
Peripheral Neuropathy Treatments
The treatment for peripheral neuropathy depends on its cause. The first step in treatment is, therefore, to look for the cause.
- Vitamin deficiencies can be corrected.
- Diabetes can be controlled, although control may not reverse the neuropathy. The goal with diabetes is early detection and adequate treatment to prevent the occurrence of neuropathy.
- Neuropathies that are associated with immune diseases can improve with treatment of the autoimmune disease.
- 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 postherpetic neuralgia.
If a specific treatment isn’t available, the pain of the neuropathy can usually be controlled with medications.
At Neurological Associates of West Los Angeles Dr. Chang, Dr. O’Connor, Dr. Shimizu and Dr. Jordan all treat patients with peripheral neuropathy. If you have peripheral neuropathy and need a specialist contact one of our Los Angeles based neurologists to schedule an appointment 310-829-5968.