Diabetes mellitus is the most common cause of peripheral neuropathy worldwide. In clinical practice, the two conditions often seem to be synonymous: more than half of all patients with diabetes have neuropathy, and half the patients with neuropathy have diabetes. Disease-related changes in diabetic individuals with neuropathy cause a wide range of presentations, reflecting acute or chronic symptoms in a variety of anatomic locations, such as skin, nerve root, vasculature, and autonomic nervous system. The discussion that follows focuses on three characteristic presentations: distal symmetric polyneuropathy, diabetic amyotrophy, and diabetic autonomic neuropathy. Characteristic features of each are contrasted in Table 17–1. Focal mononeuropathy caused by diabetes produces symptoms similar to those of compressive or entrapment neuropathies, which are discussed at the end of this chapter.
Table 17–1Key features of polyneuropathies ||Download (.pdf) Table 17–1 Key features of polyneuropathies
|Polyneuropathy ||Symptoms and Signs ||Electrodiagnostic Findings ||Treatment |
|Distal symmetric polyneuropathy || |
Distal, symmetric sensory deficits
Numbness distally (stocking glove)
Slow nerve conduction
Can see fibrillations, positive waves distally
Good blood glucose control
Agents for neuropathic pain (eg, tricyclics, gabapentin)
|Diabetic amyotrophy || |
Weakness of pelvic muscles
|Can see fibrillations, positive waves proximally || |
Corticosteroids may be beneficial
|Diabetic autonomic neuropathy || |
Labile blood pressure
|Special techniques required ||Medications to stabilize blood pressure (eg, midodrine, fludrocortisone) |
DISTAL SYMMETRIC POLYNEUROPATHY
ESSENTIALS OF DIAGNOSIS
Most common form of peripheral neuropathy in diabetic patients as well as worldwide.
Findings are chronic, distal, symmetric, and sensory predominant.
Symptoms include tingling or burning pain, sensory loss, or numbness.
Electrodiagnostic studies show axonal demyelinating neuropathy.
Distal symmetric polyneuropathy (DSP) is the most common form of peripheral neuropathy in diabetic patients, and also the most common form worldwide. DSP is a major risk factor in foot ulceration and eventual limb amputation. Neuropathy, sensory loss, and distal weakness are major risk factors for falls, and the confluence of these findings in patients with DSP increases the fall risk sevenfold. For these reasons, DSP is a significant cause of disability and reduced quality of life. Neuropathy may progress even in patients who achieve excellent glycemic control. Additional risk factors for neuropathy in diabetic patients, independent of glucose control, include obesity and dyslipidemia.
Typical findings in DSP are chronic, distal, symmetric, sensory predominant, and very painful. DSP can cause a variety of positive and negative symptoms or it can be asymptomatic. Positive symptoms include prickling, tingling, or burning. Negative symptoms consist of sensory loss or numbness. Severe neuropathy can result in painless injury. Pain is length dependent and involves the feet, toes, calves, and hands. Pain is worse with walking but is most severe at ...