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Unnerving Truth About Diabetic Neuropathy

Consider this as your daily fare – pins and needles piercing your toes or a hundred critters crawling under your skin or tiny blades dicing your soles or the sensation of treading barefoot on coal. Today it could be that irksome numbness on your fingers, tomorrow it could be an irrepressible burning pain in your feet. In no time, you turn into a nervous wreck. Literally. But sans the hysteria.

As many as 20 to 50 percent of persons with diabetes are afflicted with some form of neuropathy, or nerve damage from long-standing diabetes mellitus. Neuropathy is considered as the most common complication of diabetes. The reported incidence varies for several reasons. Firstly, the number of people suffering from neuropathy rises with time, with one large study pegging the increase at a rate of 0.5 to 2 percent annually. Secondly, not all patients with neuropathy complain of symptoms. Some forms of nerve dysfunction are only detected after intensive testing, in which case the incidence can be as high as 95 percent.

Too much sugar can be unnerving
The main risk factor for diabetic neuropathy is chronic hyperglycemia, or high blood sugar over a prolonged period of time. Within our bodies is an intricate and highly specialized network of millions of nerves that control every organ and function. Nerves allow us to feel physical sensations and to move our muscles. Tiny blood vessels nourish and maintain the integrity of these nerves.

Elevated blood sugar levels form metabolic by-products that injure the blood supply to the nerves. Ischemia or inadequate blood flow ensues. Nerves that lack the necessary blood supply eventually malfunction. As can be expected, the consequences of injury to the nervous system are myriad and multi-systemic. Other factors that likewise lead to blood vessel injury, such as hypertension, cigarette smoking, and high cholesterol levels, also pose substantial danger to the nerves.

There’s variety in neuropathy
Different types of nerves perform different functions in the body. Not surprisingly, there are as many types of neuropathy, and an even greater number of manifestations of neuronal (nerve) damage.

Sensorimotor or peripheral neuropathy is the variety most diabetics complain of. Longer nerve fibers are affected to a greater degree than are shorter ones, leading to a loss of sensation (paresthesia or dysesthesia) in the legs and feet. Symptoms typically follow a glovestocking distribution, which initially affects the fingers and toes then progresses upward towards the torso, and may range from numbness to pain.

Pins-and-needles sensation, tingling, or burning or dull aches are among the common manifestations. Pain may worsen at night, or may be unrelenting in more severe cases. Likewise, motor function may be affected and may lead to weakness in and wasting (atrophy) of one or more muscle groups. Again, the more distal (farther from the torso) muscles are affected earlier.

Gaunt hands and feet are a common sight among diabetics. Sometimes an imbalance in the strength of opposing muscle groups results in contracture deformities and joint problems. Proprioception, or the sense of a limb’s position in space, is impaired as well. Diabetics whose sensation, motor function, and proprioception are compromised by neuropathy may step on a foreign object, develop calluses from ill-fitting shoes, or sustain a wound, without being aware of the injury.

Consequently, these patients are at risk for developing foot ulcers and infections, which may subsequently lead to limb amputation. The neurovascular (nerve and blood vessel) dysfunction of diabetes mellitus and the resulting foot ulcers and infections are the leading cause of limb amputations in the developed world.

While sensorimotor neuropathy is often quite evident, autonomic neuropathy is its less recognized yet equally morbid counterpart. Autonomic ‘nerves innervate and control the heart, blood vessels, gastrointestinal tract, and urinary and genital organs. They regulate involuntary bodily functions such as digestion, urination, sweating, sexual and stress responses, and blood pressure and heart rate control, among others. Autonomic dysfunction may present in multifarious ways.

Cardiovascular neuropathy is the most significant manifestation, since dysfunction in this organ system may prove fatal. Symptoms include a rapid resting heart rate, orthostasis or the sensation of dizziness and fainting upon standing up, easy fatigue and exercise intolerance. These symptoms arise from a failure of the heart and blood vessels ‘ to maintain an adequate supply of blood to the brain and muscles during standing or exertion. More importantly, patients with cardiovascular neuropathy may lose their ability to feel the chest pain associated with a heart attack. “Silent ischemia” becomes lethal in this setting, as the absence of a warning symptom precludes prompt diagnosis and treatment. An ongoing heart attack may in fact be overlooked!

With gastrointestinal dysfunction, movement of the intestines becomes sluggish because of damage to the nerves that control them. Patients may experience bloating, nausea, vomiting, indigestion, constipation, diarrhea or incontinence (inability to hold the urge to defecate). Meanwhile, incontinence, retention (incomplete urination), frequent urinary infections, vaginal dryness, impotence, and premature ejaculation are among the manifestations of genito-urinary neuropathy.

Not even the skin is spared by diabetic nerve damage, as patients can either have too much or too little perspiration. Not uncommonly, diabetics suffer from heat intolerance, because their blood vessels are unable to appropriately dilate and dissipate heat through the skin. Others experience gustatory sweating, which is excessive perspiration when eating. On the other hand, the skin on some parts of the body, particularly on the limbs, may produce too little sweat or lubrication, causing the skin over these areas to be very dry and be prone to damage.

Even stress responses, particularly the response of the body to very low levels of blood sugar, are impaired, with dangerous outcomes. Under the latter circumstance known as hypoglycemia unawareness, the diabetic who has very low blood sugar does not develop the usual warning symptoms (rapid heart beat, shivering, cold sweats, profound weakness, headache, extreme sensation of hunger, disorientation), fails to recognize this hazardous condition, and if untreated, may slip into a hypoglycemic coma.

Other types of neuropathy include focal neuropathy, wherein only one group of nerves on one side of the body or controlling a specific group of muscles is affected, and cranial neuropathy, which means damage to the nerves of the face.

Identifying the usual suspects
Who among the millions of diabetics are most likely to develop neuropathy? And hoO can they be recognized and diagnosed? Fortunately, they leave a trail.

The longer a person,is diabetic, the higher the blood sugar levels are, the greater is the probability of neuropathy. Sensorimotor dysfunction usually develops five years after a diagnosis of diabetes is made. But autonomic neuropathy, whose symptoms may be subtle or even silent, is said to be present even at the time of diagnosis of diabetes. Hence, all patients must be thoroughly examined as to the presence of the above-mentioned symptoms at every medical consult.

Feet must be comprehensively inspected and tested with simple clinic tools and procedures to identify those at risk for injury and amputation. If deemed necessary, more extensive and sophisticated tests of nerve function, such as nerve conduction velocity, electromyography, heart-rate variability tests and even a
nerve biopsy, must be performed.

Preserve the nerve!
The best way to prevent diabetic neuropathy is to maintain the blood sugar at normal or near-normal levels through proper nutrition, exercise, and medications. Large-scale clinical trials have proven that intensive blood glucose lowering delays the onset and slows the progression of neuropathy and other diabetic complications. Once diabetic neuropathy is present, few remedies are completely successful in arresting its progression or in controlling its symptoms

High doses of vitamin B are not necessarily useful; anticonvulsant (seizure) medications and anti-depressants may relieve pain but are not always effective. Still, motility agents for gastrointestinal symptoms, lubricants or vasodilators for sexual dysfunction, antihypertensive medication adjustment for orthostatic dizziness do have their benefits.

Lastly, the following practical guidelines are invaluable for the diabetic who wishes to hold his nerve for as long as it takes:

  • Be meticulous about foot care. Keep feet clean and dry, inspect feet daily for wounds or calluses, moisturize with lotion, cut toenails to the shape of the toes, wear shoes that fit properly, protect the feet from injury with the proper footwear
  • Eat smaller meals more frequently to avoid bloating and nausea and to prevent hypoglycemia
  • Avoid standing up too quickly or wear special elastic stockings to prevent orthostatic dizziness
  • Drink plenty of fluids to help flush bacteria out of the urinary tract
  • Urinate more frequently at regular intervals (every 3 hours) if retention and incontinence are existing problems
  • Exercise regularly for muscle conditioning
  • Quit smoking to prevent further damage to blood vessels and nerves
  • Avoid excessive alcohol intake which, in itself, damages the nerves
  • Consult your doctor to ascertain if referral to a specialist, or if other medications or modalities are indicated.

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