Diagnosis of Peripheral Neuropathy

Diagnosis of Diabetic Neuropathy

The diagnosis of diabetic neuropathy (DN) can be difficult to determine. Diabetic neuropathy is highly underdiagnosed both by endocrinologists as well as other physicians because its symptoms can be subclinical and not interfere with daily living (e.g. ankle jerk test or vibration perception may be affected). The diagnosis of diabetic neuropathy is basically a diagnosis of exclusion since there is not any single test which can confirm it. The diagnosis is usually based on a minimum of two signs, symptoms, or tests. Objective testing may find signs of DN in up to 60% of patients with type I and type II diabetes. Most patients are unable to distinguish neuropathic from nonneuropathic pain, which adds to the importance of testing to determine the origin of the symptoms.

Diabetic patients should be evaluated annually for clinical evidence of diabetic peripheral neuropathy. This should include a careful inspection of both feet, palpation of the feet for pulses, evaluation of gait and proper shoe size/fit, and a thyroid function test. The American Diabetes Association recommends annual comprehensive foot examination for asymptomatic diabetic patients and more frequent examinations for diabetics who have developed signs and symptoms of diabetic neuropathy.

Signs and Symptoms of Diabetic Neuropathy

Acute Painful Neuropathy

This type of neuropathy is usually caused by small fiber neuropathy and presents as pain and paresthesia early in the course of diabetes. It is sometimes called "insulin neuritis", since frequently it appears after the initiation of insulin therapy. Symptoms are more prominent in the feet than in the hands and are usually worse at night. It typically lasts less than 6 months but the episodes of pain can be extremely severe and disabling. Pain may be of any quality (e.g., burning, stabbing) and accompanied by paresthesia (e.g., tingling, pins and needles). The skin (particularly of the lower legs) may be hypersensitive to any touch and even the slightest disturbance (e.g., light breeze) may be excruciating.

The symptoms of acute painful neuropathy can be successfully treated in many patients. The neuropathy may resolve spontaneously or may become chronic.

When symptoms are extreme, they may lead to weight loss and depression. This situation is called diabetic neuropathic cachexia and it occurs more often in diabetic males than in diabetic females. Diabetic neuropathic cachexia usually responds to symptomatic treatment.

Chronic Painful Neuropathy

This type of neuropathy often occurs up to several years after the onset of diabetes and persists longer than 6 months. It is also very debilitating and treatment may lead to addiction or abuse of powerful drugs used in an attempt to alleviate the pain. It may be resistant to treatment and, understandably, has a strong negative impact on the quality of life of the sufferer.

Diabetic Mononeuropathy

This is usually caused by vasculopathy where tiny blood vessels that supply the nerve become clogged. It may be accompanied by a deep aching pain followed by numbness or weakness.

Regional Neuropathic Syndrome

Groups of nerves in a specific region are damaged. It is seen in adult onset diabetes and is associated with diabetic amyotrophy (a disease of the nerves leading to the muscles). Symptoms usually begin with an aching in the leg which is followed by weakness.

Diabetic Autonomic Neuropathy

The symptoms of autonomic neuropathy, described above, affect up to 50% of diabetic patients.

Usually, symptoms of diabetic neuropathy begin with numbness and paresthesia in the foot and ascend up the leg. Over months or years, sensory loss usually intensifies and may eventually affect the arms and hands. The development of numbness in the feet is very important to note since it is usually the precursor to foot problems which can ultimately lead to ulceration, gangrene, and/or amputation. Loss of sensitivity to light touch and temperature is often an early symptom and may be followed by ataxia (lack of coordination). This increases the risk of falls and fractures.