Diabetic Neuropathy

Topic Highlights

●    Hyperglycemia or diabetes damages the nerves and affects their ability to transmit signals.

●    Diabetes may also damage the blood vessels supplying the nerves.

●    This results in disruption of signals leading to neuropathic pain.

●    This visual presentation explains the occurrence of diabetic neuropathy, associated complications, risk factors, and  various treatment options.

Transcript

Diabetic neuropathy occurs in nearly half of patients with diabetesThis debilitating disorder has significant impact on the social and psychological welfare of patients. The financial burden of diabetic neuropathy due to costs of health care and loss of productivity is very high.

Nerves carry messages back and forth between the brain and other parts of the body. High levels of blood glucose or hyperglycemia linked with diabetes causes chemical changes in nerves. The nerve coatings are damaged which affects their ability to transmit signals. Hyperglycemia may also injure the blood vessels supplying oxygen and nutrients to the nerves. This results in incorrect nerve signals being sent to the brain causing chronic pain called neuropathic pain.

Injury to nerves such as carpal tunnel syndrome, genetics and factors such as smoking, high cholesterol and high blood pressure can contribute to diabetic neuropathy.

Diabetic neuropathy primarily affects the peripheral nervous system. Peripheral neurons can be categorized broadly as motor, sensory, or autonomic. Motor neurons carry impulses from the brain and spinal cord to muscles or glands. Sensory neurons carry impulses from the sense organs to the brain and spinal cord. Autonomic neurons consist of sympathetic and parasympathetic nerves that control involuntary body functions.

Sensory neuropathy affects the distal extremities. Sensorimotor neuropathy involves both sensory and motor function, pain (described as burning, aching, lancinating or 'knife like', shooting or 'like electric shock' in quality) numbness or 'dead-feeling', and paresthesias (or abnormal sensations of 'pricking' or 'tingling' or 'pins and needles' that occur without an outside stimulus) can occur along with decreased strength and atrophy in the lower limb muscles. The feet of patients with neuropathy often lose sensation, and are highly susceptible to ulcers. Autonomic neuropathy involves the cardiovascular system, gastrointestinal system, and the genitourinary system.

Approximately 50% of diabetic patients have some form of neuropathy. Neuropathy is associated with pain in about one third of these patients. Nearly 10%-16% of all diabetic patients have painful neuropathy. About 12% of diabetics have neuropathy at the time of diagnosis of diabetes. Diabetics with neuropathy also have about 15% chance of having an ulcer during their lifetime. About 15% of those with ulcers undergo amputation. This accounts for approximately 3% of all diabetics. Nearly half will have an ulcer in the opposite foot within three years. This can occur even with a good effort to keep the blood sugar under control.

People with diabetes for over 25 years are at the highest risk for having neuropathy. Diabetic neuropathy also appears to be more common in people who have poor blood glucose control, elevated blood lipid levels and high blood pressure. Overweight individuals and patients over the age of 40 also have an increased risk for developing neuropathies. In Type-1 diabetes mellitus, neuropathy occurs after many years of chronic hyperglycemia, however in Type-2, it presents after only a few years of poor glycemic control.

Diabetic neuropathies can be classified as peripheral, autonomic, proximal, and focal, depending on the part of the body and nerve affected. Often, symptoms are minor at first, mild cases may go unnoticed for a long time.

Peripheral neuropathy damages nerves in the arms and legs. The feet and legs are likely to be affected before the hands and arms. Symptoms of peripheral neuropathy may include numbness or insensitivity to pain or temperature, a tingling, burning, or prickling sensation, sharp pains or cramps, extreme sensitivity to touch and loss of balance and coordination. This may lead to falls and fractures of the hip or wrist. Painful symptoms often worsen at night. Peripheral neuropathy may also cause muscle weakness and loss of reflexes, especially at the ankle, leading to changes in gait. It can also lead to foot deformities. Blisters and sores may appear on numb areas of the foot because pressure or injury goes unnoticed. If not treated, the infection can spread to the bone, and in severe cases, require amputation.

A diabetic person would normally experience symptoms such as shakiness when the blood glucose levels drop below 65 mg/dl. Autonomic neuropathy can completely mask these warning symptoms, making hypoglycemia (or low blood glucose) difficult to recognize. Damage to nerves in the cardiovascular system interferes with the body's ability to adjust blood pressure and heart rate. Blood pressure may drop sharply when the patient moves from a standing to a reclining position, causing the patient to feel dizzy or faint. Damage to the nerves that control heart rate can result in a constant high heart rate.

Autonomic neuropathy can cause nerve damage to the digestive system resulting in constipation and diarrhea. It can also cause gastroparesis, a condition that causes the stomach to empty slowly. Severe gastroparesis can lead to persistent nausea, vomiting, bloating, and loss of appetite. It can also cause wide fluctuation in the blood glucose levels. Nerve damage to the esophagus can make swallowing difficult. While nerve damage to the bowels can cause constipation alternating with frequent, uncontrolled diarrhea. Digestive problems may lead to weight loss.