Diabetic neuropathy history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Diabetic neuropathy affects all peripheral nerves: pain fibers, motor neurons, autonomic nerves. It therefore necessarily can affect all organs and systems since all are innervated. There are several distinct syndromes based on the organ systems and members affected, but these are by no means exclusive. A patient can have sensorimotor and autonomic neuropathy or any other combination. Symptoms vary depending on the nerve(s) affected and may include symptoms other than those listed. Symptoms usually develop gradually over years.
History and Symptoms
Usual symptoms may be
- Numbness and tingling of extremities
- Dysesthesia (decreased or loss of sensation to a body part)
- Diarrhea
- Erectile dysfunction
- Urinary incontinence (loss of bladder control)
- Impotence
- Facial, mouth and eyelid drooping
- Vision changes
- Dizziness
- Muscle weakness
- Dysphagia (swallowing difficulty)
- Speech impairment
- Fasciculation (muscle contractions)
- Anorgasmia
Sensorimotor polyneuropathy
Longer nerve fibers are affected to a greater degree than shorter ones, because nerve conduction velocity is slowed in proportion to a nerve's length. In this syndrome, decreased sensation and loss of reflexes occurs first in the toes bilaterally, then extends upward. It is usually described as glove-stocking distribution of numbness, sensory loss, dysesthesia and nighttime pain. The pain can feel like burning, pricking sensation, achy or dull. Pins and needles sensation is common. Loss of proprioception, that is, the sense of where a limb is in space, is affected early. These patients cannot feel when they are stepping on a foreign body, like a splinter, or when they are developing a callous from an ill-fitting shoe. Consequently, they are at risk for developing ulcers and infections on the feet and legs, which can lead to amputation. Similarly, these patients can get multiple fractures of the knee, ankle or foot, and develop a Charcot joint. Loss of motor function results in dorsiflexion contractures of the toes, loss of the interosseous muscle function and leads to contraction of the digits, so called hammer toes. These contractures occur not only in the foot but also in the hand where the loss of the musculature makes the hand appear gaunt and skeletal. The loss of muscular function is progressive.
Autonomic neuropathy
The autonomic nervous system is composed of nerves serving the heart, gastrointestinal system and urinary-genital system]]. Autonomic neuropathy can affect any of these organ systems. The most commonly recognized autonomic dysfunction in diabetics is orthostatic hypotension, or the uncomfortable sensation of fainting when a patient stands up. In the case of diabetic autonomic neuropathy, it is due to the failure of the heart and arteries to appropriately adjust heart rate and vascular tone to keep blood continually and fully flowing to the brain[failure of the sensitivty of the baroreceptors]. This symptom is usually accompanied by a loss of sinus respiratory variation, that is, the usual change in heart rate seen with normal breathing. When these 2 findings are present, cardiac autonomic neuropathy is present.
GI tract manifestations include delayed gastric emptying, gastroparesis, nausea, bloating, and diarrhea. Because many diabetics take oral medication for their diabetes, absorption of these medicines is greatly affected by the delayed gastric emptying. This can lead to hypoglycemia when an oral diabetic agent is taken before a meal and does not get absorbed until hours, or sometimes days later, when there is normal or low blood sugar already. Sluggish movement of the small instestine can cause bacterial overgrowth, made worse by the presence of hyperglycemia. This leads to bloating, gas and diarrhea.
Urinary symptoms include urinary frequency, urgency, incontinence and retention. Again, because of the retention of sweet urine, urinary tract infections are frequent. Urinary retention can lead to bladder diverticula, stones, reflux nephropathy.
Cranial neuropathy
When cranial nerves are affected, oculomotor (3rd) neuropathies are most common. The oculomotor nerve controls all of the muscles that move the eye with the exception of the lateral rectus and superior oblique muscles. It also serves to constrict the pupil and open the eyelid. The onset of a diabetic third nerve palsy is usually abrupt, beginning with frontal or periorbital pain and then diplopia. All of the oculomotor muscles innervated by the third nerve may be affected, except for those that control pupil size. This is because pupillary function within CNIII is found on the periphery of the nerve (in terms of a cross sectional view), which makes it less susceptible to ischemic damage (as it is closer to the vascular supply). The sixth nerve, the abducens nerve, which innervates the lateral rectus muscle of the eye (moves the eye laterally), is also commonly affected but fourth nerve, the trochlear nerve, (innervates the superior oblique muscle, which moves the eye downward) involvement is unusual. Mononeuropathies of the thoracic or lumbar spinal nerves can occur and lead to painful syndromes that mimic myocardial infarction, cholecystitis or appendicitis. Diabetics have a higher incidence of entrapment neuropathies, such as carpal tunnel syndrome.
This condition is affiliated with erectile dysfunction and epigastric tenderness which in turn results in lack of blood flow to the peripheral intrapectine nerves which govern the movement of the arms and legs.