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Diabetic Neuropathy

Diabetic neuropathy refers to nerve damage caused by diabetes. It can affect different parts of the body, including the legs, feet, bladder, heart, and stomach. There are several forms of diabetic neuropathy:

Peripheral neuropathy: This affects the legs, feet, arms, and hands. It causes numbness, pain, tingling, and weakness. It is the most common form of diabetic neuropathy. Over time, it can lead to painless injuries and sores.
Autonomic neuropathy: This affects the autonomic nervous system which controls organ functions like blood pressure, digestion, urination, sexual arousal, and sweating. It can cause problems like orthostatic hypotension, gastroparesis, diabetic diarrhea or constipation, bladder problems, and sexual difficulties.
Focal neuropathy: This affects specific nerves, usually in the head, torso, or leg. It causes sudden pain, weakness, and paralysis in the affected area. It is usually temporary but may recur.
Proximal neuropathy: This affects the thighs, hips, or buttocks. It causes pain in the lower back or pain from the hip down to the knee. It makes it difficult to stand up or climb stairs.

The main causes of diabetic neuropathy include:

High blood glucose levels: Elevated glucose over time damages nerves. Keeping blood sugar in the target range can help prevent or slow progression.
Vascular damage: Diabetes damages blood vessels that carry oxygen and nutrients to nerves. This deprives nerves of nourishment and leads to nerve damage.
Autoimmune factors: In some cases, the body's immune system may attack nerve fibers and contribute to nerve damage.
Diabetic kidney disease: Kidney disease leads to a buildup of toxins that may damage nerves.
Lifestyle factors: Smoking, alcohol, lack of exercise and being overweight also contribute to nerve damage.

Treatment focuses on controlling blood sugar, medications for pain relief, addressing lifestyle factors, and sometimes other treatments like vitamin/dietary supplements. The earlier diabetic neuropathy is diagnosed and treatment started, the more likely progression can be slowed or prevented.

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.

Autonomic neuropathy also affects the organs that control urination and sexual function. Nerve damage can prevent the bladder from emptying completely, allowing bacteria to grow in the bladder and kidneys and causing urinary tract infections. Damage to the nerves of the bladder can cause urinary incontinence, because the patient may be unable to sense when the bladder is full or even control the muscles that release urine. Neuropathy may also affect sexual function in both men and women.

Autonomic neuropathy can affect the nerves that control sweating. When nerve damage prevents the sweat glands from functioning normally, the body cannot regulate its temperature. Nerve damage can also cause profuse sweating at night or while eating. Neuropathy affects the pupils of the eyes, making them less responsive to changes in light.

Proximal neuropathy, also known as diabetic amyotrophy, is characterized by pain in the thighs, hips, buttocks, or legs, usually on one side of the body. This is more common in those with Type-2 diabetes and in older patients. It causes weakness in the legs. The patient would find it difficult to stand up from a sitting position.

Focal neuropathy affects specific nerves, most often in the head, torso, or leg. It may occur suddenly affecting the eye, causing difficulty in focusing, double vision and aching behind a single eye. Focal neuropathy may cause paralysis on one side of chest, abdomen and flank. It may cause foot drop. Focal neuropathy is painful and unpredictable and occurs most often in older patients. However, it tends to improve over weeks or months and does not usually cause long-term damage.

Neuropathy is diagnosed on the basis of symptoms and a physical exam. The doctor may check blood pressure and heart rate, muscle strength, reflexes, and sensitivity to position, vibration, temperature, or a light touch. A comprehensive foot exam assesses skin color, circulation, and sensation. To assess feeling in the foot, a nylon monofilament attached to a wand is used to touch the foot. Other tests include checking reflexes and assessing vibration perception with a tuning fork.

A complete blood test, including glucose levels is done to assess the severity and control of diabetes and to rule out other causes for neuropathy. In over 95% of cases a neuropathic diagnosis can be made by clinical exam only. Rarely nerve conduction studies may be required. Nerve conduction studies check the transmission of electrical current through a nerve. Weaker impulses indicate possible damage. Very rarely, MRI of the brain, cervical, thoracic, and/or lumbar region may help rule out secondary causes of neuropathy. CT myelogram is an alternative to exclude compressive lesions and other pathology in the spinal cord.

The first step for managing neuropathies is to monitor and control blood glucose, meal planning, exercise, oral drugs or insulin injections. Pain caused due to diabetic neuropathy is usually treated with tricyclic antidepressant medications such as amitriptyline, imipramine, and nortriptyline; new antidepressants such as duloxetine; and anticonvulsant medications such as carbamazepine, gabapentin and pregabalin. More severe pain is treated by opiate derivatives such as tramadol, oxycodone and morphine. There are marked side effects with all of the above medications and treatment must be started at a small dose.

Transcutaneous Electronic Nerve Stimulation, which uses small amounts of electricity to block pain signals, is also used. Intractable pain that doesn’t respond to drug treatment is managed by the insertion of an Electrical Spinal Cord Stimulator into the epidural fat space over the spinal cord.

Autonomic neuropathy can be treated based on the nerve affected and the symptoms. Eating small, frequent meals, avoiding fats, and eating less fiber can help reduce symptoms of gastroparesis, such as indigestion, belching, nausea, or vomiting. Gastroparesis can be treated with erythromycin, metoclopramide and domperidone. Severe gastroparesis can be treated by the injection of botox to the outlet of the stomach or by surgical implantation of gastric pace-maker. Diarrhea and other bowel problems are treated with antibiotics such as tetracycline.

Walking regularly may also help reduce leg pain. Sitting or standing slowly may help prevent dizziness associated with blood pressure. Raising the head of the bed may also help. Some patients may benefit from a fluid retaining medication called fludrocortisone. Physical therapy can help treat muscle weakness. Urinary tract infections are treated with antibiotics. Drinking plenty of fluids helps prevent infection. Erectile dysfunction in male patients can be treated with vasodilators. Vaginal lubricants are prescribed for women to treat vaginal dryness. Patients with diabetic peripheral neuropathy require more frequent follow-up care, paying particular attention to foot care.