What is Peripheral Neuropathy?
Peripheral neuropathy is a medical condition characterized by nerve damage in the lower limbs that results in burning pain and sensory loss. It most frequently caused by diabetes mellitus types I and II – but there are a variety of other important causes. Loss of sensation in the feet is especially concerning in patients with diabetes because it can lead to unrecognized foot ulcers that may get infected. Most patients are bothered by the pain, which can be severe and debilitating.
What Causes Peripheral Neuropathy?
Peripheral neuropathy is caused by damage to the nerves, which results in impaired nerve function and symptoms such as pain, sensory loss, and weakness. Nerve damage occurs due to various genetic and environmental factors.
The most common systemic diseases and conditions associated with peripheral neuropathy include:
- Diabetes mellitus types I & II
- Vitamin B12 deficiency
- Syphilis infection
- Thyroid disease
- Long term alcohol use
- Multiple myeloma
- AIDS – HIV infection
- Chemotherapy – vincristine, cisplatin
These conditions lead to inflammation and injury to the nerve tissue. Sometimes peripheral neuropathy is caused by pressure or nerve trauma. This can occur in the setting of ulnar neuropathy – funny bone pain – usually in patients that rest their elbows on flat surfaces for prolonged periods of time. This is also the case with carpal tunnel syndrome – a very common cause of wrist pain. The median nerve is a nerve that courses underneath the wrist. Any condition that puts pressure on the wrist - such as obesity, pregnancy, wrist overuse – can lead to nerve injury and wrist pain.
How Common is Peripheral Neuropathy?
Peripheral neuropathy is a common condition that is frequently evaluated in the primary care clinic. This disease often requires referral to a neurology specialist. Approximately 2.4% of Americans have peripheral neuropathy. In the United States, the prevalence of the condition is about 8% in people age 65 years or greater.
Signs and Symptoms
The most common symptom of include:
- Burning or shooting pain
- Loss of sensation
- Tingling (paresthesias)
- Loss of proprioception - trouble balancing
- Muscle weakness
Pain can be precipitated by touch and may be worse at nighttime. Symptoms often affect a “stocking glove” distribution – in other words, the same areas where stockings and gloves cover the skin – the hands and feet.
Your doctor will often evaluate for certain findings on your physical examination such as:
- Sensory loss
- Ability to feel vibration in the hands and feet
- Ability to sense where your joint is in space
- Muscle strength and bulk
- Muscle tone
They may perform a Romberg test, in which they ask you to stand with the arms at the sides and close your eyes. They will be evaluating your ability to balance. Problems with this are highly suggestive of peripheral neuropathy and posterior spinal column disease.
Peripheral neuropathy is diagnosed based on symptoms and physical examination. If the diagnosis is not clear, your doctor will likely order nerve conduction studies to identify the specific nerves that are damaged or affected. They may even perform needle electromyography (EMG) - study whereby they insert needles into muscle tissue to determine if muscle weakness is caused by the muscle itself instead of the nerve.
Sometimes, they will also obtain an MRI of the spine evaluate for any spinal cord abnormalities could be contributing to your symptoms.
Your doctor will also likely order blood tests such as a CMP (comprehensive metabolic panel) and CBC (complete blood cell count). They will also check your cholesterol levels and screen for diabetes. The following tests are often ordered to determine the specific cause of your peripheral neuropathy:
- Hemoglobin A1c – diabetes screening
- Vitamin B12 level, methylmalonic acid level
- Thyroid stimulating hormone and free T4 (thyroid hormone)
- Rapid plasma reagin (RPR) – syphilis screening
- HIV antibody
- Serum and urine immunoglobulins - SPEP & UPEP
Peripheral Neuropathy Treatment
Patients with peripheral neuropathy should first be treated for the underlying cause of their condition. For example, if you have diabetes, you and your doctor should work together in optimizing your sugar levels. Patients with vitamin B12 deficiency should receive oral or injectable forms of B12 supplementation.
If you have thyroid disease, you may have to take synthetic thyroid hormone or undergo thyroid surgery. Patients with alcohol dependence are encouraged to cut down and eventually completely refrain from alcohol use.
Sometimes, there is no identifiable cause of peripheral neuropathy. If you have pain with peripheral neuropathy, you may benefit from some of the following medications:
Sometimes topical creams or gels can be beneficial. These may include:
These medications are only effective against pain caused by peripheral neuropathy – they do not usually improve symptoms like sensory loss or muscle weakness.
- Azhary H, Farooq MU, Bhanushali M. Peripheral neuropathy: differential diagnosis and management. Am Fam Physician. 2010 Apr 1;81(7):887-92.
- Watson JC, Dyck PJ.Peripheral Neuropathy: A Practical Approach to Diagnosis and Symptom Management. Mayo Clin Proc. 2015 Jul;90(7):940-51.
The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.