Analysis Of Diabetic Neuropathies Biology Essay

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Diabetic neuropathy affects diffent parts of the nervous system. It is a group of diseases that affects all types of nerves, the peripheral, autonomic and spinal nerves. This is common on patients with diabetes that is more than 25 years already. The most common cause is elevated blood glucose for a period of years. This is also regarded as by continual loss of nerve fibers. In here, hyperglycemia will cause demyelization of nerves that will cause the reduction of conduction or nerves. There are three types of diabetic neuropathy, the sensory neuropathy and autonomic neuropathies.

There are two classifications of sensory neuropathy, the acute and chronic. Acute sensory neuropathy is uncommon and occurs after periods of poor metabolic control like pulmonary acidosis or it may also be caused by imbalance in insulin production. The clinical manifestations are acute onset of severe sensory symptoms and marked nocturnal exacerbation. Chronic sensory neuropathy is the most common neuropathy for diabetes. Half of the population is asymptomatic. Symptomatic patients experience burning, stabbing and deep aching pain and paresthesia. Neuropathic pain is most felt at night especially on the lower extremities. An examination of the extremities will show absence of reflexes, sensory loss of vibration, pressure and pain. As the neuropathy continuous, numbness of the foot can be felt and decrease sensation of light touch. To help for the diagnosis, the patient must undergo annual clinical examination including physical examination and blood chemistry. Several pain managements can be rendered and examination of the feet is a must to see if there are calluses, ulcers or deforminties.

Autonomic neuropathy results to high morbidity that can cause death. The symptoms can be identified through thorough history taking since the symptoms can be treated. In caring of patients with autonomic neuropathy, the nurse must observe abnormal signs from the cardiovascular, gastrointestinal and genitourinary systems. Cardiovascular autonomic neuropathy should be taken into consideration because of its critical complications and the accessibility to the direct tests of cardiovascular autonomic function. There are various tests to test the cardiovascular autonomic neuropathy of a patient, this includes resting and stess thallium myocardial scintigraphy, R-R variation, Valsalva maneuver, postural blood pressure testing and the measurement of heart rate variability. Pharmacological therapies of Angiotensin-converting enzyme and Beta-blockers are proven to help patients with cardiovascular autonomic neuropathy. When planning for the exercise regimen of a patient, thorough cardiac autonomic function testing must be performed. Gastroparesis is suspected to people with inconsistent insulin control and gastric emptying should also be evaluated. Barrium studies or endoscopy can also be done. For the genitourinary, bladder dysfunction should be evaluated.

Recall Output

Learning Objective

1. List the lobes of the brain and their associated functions.

1

2. How does the aging process impact the neurological system?

5

3. Compare and contrast the sympathetic and parasympathetic nervous systems in terms of function.

3

List the lobes of the brain and their associated functions.

Frontal-for concentration, abstract thought, information storage or memory, motor function. It is also responsible for affect, judgment, personality and inhibitions. It is also responsible for motor speech.

Parietal-this is responsible for conduction of sensory information to hypothalamus for further analyzation. It is also essential to proprioception and spatial relations.

Temporal-contains auditory receptive areas. It has interpretive area that provides integration of somatization, visual and auditory areas and plays the most dominant role of any area of the cortex in thinking.

Occipital-this assist in coordination of laguange generation and visual interpretation.

How does the aging process impact the neurological system?

The structure and function of nervous system change through advancing age and reduction of cerebral blood flow in the brain. There will be degeneration of nerve cells that will cause loss of brain mass, and reduction of synthesis and metabolism of the neurotransmitters. Older people tends to respond and react later than normal adult people. This changes can affect the gait and balance of the older people that can alter mobility and safety.

Older people experience sensory deprivation or the lack of stimuli from the

environment or the incapability to understand presented stimuli.

Compare and contrast the sympathetic and parasympathetic nervous systems in terms of function.

Sympathetic nervous system prepares the body to manage danger. It increases

heart rate and blood pressure. It helps us to respond better whenever there is emergency or threat. It made us confront the threat or just run away. Parasympathetic nervous system is very active during at rest. It calms the body after a threat. It maintains the homeostasis and helps the body to save energy through the decrease of demand of the cardiovascular system.

ARTICLE

DIABETIC NEUROPATHIES

The diabetic neuropathies are heterogeneous, affecting different parts of the nervous system that present with diverse clinical manifestations. They may be focal or diffuse. Most common among the neuropathies are chronic sensorimotor distal symmetric polyneuropathy (DPN) and the autonomic neuropathies. DPN is a diagnosis of exclusion. The early recognition and appropriate management of neuropathy in the patient with diabetes is important for a number of reasons. 1) Nondiabetic neuropathies may be present in patients with diabetes. 2) A number of treatment options exist for symptomatic diabetic neuropathy. 3) Up to 50% of DPN may be asymptomatic, and patients are at risk of insensate injury to their feet. As >80% of amputations follow a foot ulcer or injury, early recognition of at-risk individuals, provision of education, and appropriate foot care may result in a reduced incidence of ulceration and consequently amputation. 4) Autonomic neuropathy may involve every system in the body. 5) Autonomic neuropathy causes substantial morbidity and increased mortality, particularly if cardiovascular autonomic neuropathy (CAN) is present. Treatment should be directed at underlying pathogenesis. Effective symptomatic treatments are available for the manifestations of DPN and autonomic neuropathy.

This statement is based on two recent technical reviews to which the reader is referred for detailed discussion and relevant references to the literature.

DEFINITIONS AND CLASSIFICATION

An internationally agreed simple definition of DPN for clinical practice is "the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after the exclusion of other causes". However, the diagnosis cannot be made without a careful clinical examination of the lower limbs, as absence of symptoms should never be assumed to indicate an absence of signs. This definition conveys the important message that not all patients with peripheral nerve dysfunction have a neuropathy caused by diabetes. Confirmation can be established with quantitative electrophysiology, sensory, and autonomic function testing.

Numerous classifications of the variety of syndromes affecting the peripheral nervous system in diabetes have been proposed in recent years. The classification shown in is based on that originally proposed by Thomas.

DIAGNOSTIC CRITERIA AND BRIEF CLINICAL ASPECTS

A) Sensory neuropathies: clinical features

1) Acute sensory neuropathy.

Acute sensory neuropathy is rare, tends to follow periods of poor metabolic control (e.g., ketoacidosis) or sudden change in glycemic control (e.g., "insulin neuritis"), and is characterized by the acute onset of severe sensory symptoms (as detailed below) with marked nocturnal exacerbation but few neurologic signs on examination of the legs.

2) Chronic sensorimotor DPN.

This is the most common presentation of neuropathy in diabetes, and up to 50% of patients may experience symptoms, most frequently burning pain, electrical or stabbing sensations, parasthesiae, hyperasthesiae, and deep aching pain. Neuropathic pain is typically worse at night, and the symptoms are most commonly experienced in the feet and lower limbs, although in some cases the hands may also be affected. As up to half of the patients may be asymptomatic, a diagnosis may only be made on examination or, in some cases, when the patient presents with a painless foot ulcer. Other patients may not volunteer symptoms but on inquiry admit that their feet feel numb or dead. Examination of the lower limb usually reveals sensory loss of vibration, pressure, pain, and temperature perception (mediated by small and large fibers) and absent ankle reflexes. Signs of peripheral autonomic (sympathetic) dysfunction are also frequently seen and include a warm or cold foot, sometimes with distended dorsal foot veins (in the absence of obstructive peripheral vascular disease), dry skin, and the presence of calluses under pressure-bearing areas

3) Diagnosis.

The diagnosis of DPN can only be made after a careful clinical examination, and all patients with diabetes should be screened annually for DPN by examining pinprick, temperature, and vibration perception (using a 128-Hz tuning fork), 10-g monofilament pressure sensation at the distal halluces, and ankle reflexes. Combinations of more than one test have >87% sensitivity in detecting DPN. Loss of 10-g monofilament perception and reduced vibration perception predict foot ulcers. Indeed, longitudinal studies have shown that a simple clinical examination is a good predictor of future foot ulcer risk. The feet should be examined for ulcers, calluses, and deformities, and footwear should be inspected. Different scoring systems have been developed for monitoring progression or response to intervention in clinical trials.

Other forms of neuropathy, including chronic inflammatory demyelinating polyneuropathy (CIDP), B12 deficiency, hypothyroidism, and uremia, occur more frequently in diabetes and should be ruled out. The practitioner may wish to refer the more complex patient, or those in whom diagnosis needs confirmation, to a neurologist for specialized examination and testing.

The diagnosis of chronic DPN is therefore a clinical one and involves the exclusion of nondiabetic causes: investigations should be ordered as dictated by clinical findings and might typically include serum B12, thyroid function, blood urea nitrogen, and serum creatinine. A combination of typical symptomatology and distal sensory loss with absent reflexes, or the signs in the absence of symptoms, is highly suggestive of DPN.

B) Autonomic neuropathy

Diabetic autonomic neuropathy (DAN) results in significant morbidity and may lead to mortality in some patients with diabetes. The most common dysautonomic features are listed in together with their associated symptoms and management. The symptoms of autonomic dysfunction should be elicited carefully during the history, particularly since many of these symptoms are potentially treatable.

Major clinical manifestations of DAN include resting tachycardia, exercise intolerance, orthostatic hypotension, constipation, gastroparesis, erectile dysfunction, sudomotor dysfunction, impaired neurovascular function, "brittle diabetes," and hypoglycemic autonomic failure. CAN is the most prominent focus of autonomic dysfunction because of the life-threatening consequences of this complication and the availability of direct tests of cardiovascular autonomic function. However, neuropathies involving other organ systems should also be considered in the optimal care of patients with diabetes.

Cardiovascular

CAN is the most studied and clinically important form of DAN. The reported prevalence of CAN varies widely depending on the cohort studied and the methods of assessment. The presence of autonomic neuropathy may limit an individual's exercise capacity and increase the risk of an adverse cardiovascular event during exercise. CAN may be indicated by resting tachycardia (>100 bpm), orthostasis (a fall in systolic blood pressure >20 mmHg upon standing) without an appropriate heart rate response, or other disturbances in autonomic nervous system function involving the skin, pupils, gastrointestinal, or genitourinary systems. Sudden death and silent myocardial ischemia have been attributed to CAN in diabetes. Resting and stress thallium myocardial scintigraphy is an appropriate noninvasive test for the presence and extent of macrovascular coronary artery disease in these individuals. Hypotension and hypertension after vigorous exercise are more likely to develop in patients with autonomic neuropathy, particularly when starting an exercise program. Because these individuals may have difficulty with thermoregulation, they should be advised to avoid exercise in hot or cold environments and to be vigilant about adequate hydration.

Observational studies have consistently documented an increased risk of mortality in subjects with autonomic neuropathy, although these associations may be related in part to the presence of other comorbid complications. A recent meta-analysis of published data demonstrated that reduced cardiovascular autonomic function, as measured by heart rate variability (HRV), was strongly (i.e., relative risk is doubled) associated with increased risk of silent myocardial ischemia and mortality.

A patient's history and physical examination are ineffective for early detection of CAN, and therefore noninvasive tests that have demonstrated efficacy are required. Proceedings from a consensus conference in 1992 recommended that three tests (R-R variation, Valsalva maneuver, and postural blood pressure testing) be used for longitudinal testing of the cardiovascular autonomic system. Other forms of autonomic neuropathy can be evaluated with specialized tests, but these are less standardized and less available than commonly used tests of cardiovascular autonomic function, which quantify loss of HRV. The ability to interpret serial HRV testing requires accurate, precise, and reproducible procedures that use established physiologic maneuvers. The battery of three recommended tests for assessing CAN is readily performed in the average clinic, hospital, or diagnostic center with the use of available technology.

At time of diagnosis of type 2 diabetes and within 5 years after diagnosis of type 1 diabetes (unless an individual has symptoms suggestive of autonomic dysfunction earlier), patients should be screened for CAN. Screening should comprise a history and an examination for signs of autonomic dysfunction. Tests for HRV, including expiration-to-inspiration ratio and response to the Valsalva maneuver and standing, may be indicated. Early measurement of HRV can serve as a baseline from which interval tests can be compared. Regular HRV testing provides early detection and thereby promotes timely diagnostic and therapeutic interventions. HRV testing may also facilitate differential diagnosis and the attribution of symptoms (e.g., erectile dysfunction, dyspepsia, dizziness) to autonomic dysfunction. Finally, knowledge of early autonomic dysfunction can encourage patient and physician to improve metabolic control and to use therapies, such as ACE inhibitors and β-blockers, that are proven to be effective for patients with CAN.

Orthostatic measurement of blood pressure should be performed in people with diabetes and hypotension when clinically indicated.

Cardiovascular system and exercise.

Cardiac autonomic function testing should be performed when planning an exercise program for individuals with diabetes about to embark on a moderate- to high-intensity exercise program, especially those at high risk for underlying cardiovascular disease.

Gastrointestinal

Gastrointestinal disturbances (e.g., esophageal enteropathy, gastroparesis, constipation, diarrhea, fecal incontinence) are common, and any section of the gastrointestinal tract may be affected. Gastroparesis should be suspected in individuals with erratic glucose control. Upper-gastrointestinal symptoms should lead to consideration of all possible causes, including autonomic dysfunction. Evaluation of gastric emptying should be done if symptoms are suggestive. Barium studies or referral for endoscopy may be required. Constipation is the most common lower-gastrointestinal symptom but can alternate with episodes of diarrhea. Endoscopy may be required to rule out other causes.

Genitourinary

DAN is also associated with genitourinary tract disturbances, including bladder and/or sexual dysfunction. Evaluation of bladder dysfunction should be performed in individuals with diabetes who have recurrent urinary tract infections, pyelonephritis, incontinence, or a palpable bladder. In men, DAN may cause loss of penile erection and/or retrograde ejaculation. A complete work-up for impotence in men should include history (medical and sexual); psychological evaluation; hormone levels; measurement of nocturnal penile tumescence; tests to assess penile, pelvic, and spinal nerve function; cardiovascular autonomic function tests; and measurement of penile and brachial blood pressure.

EPIDEMIOLOGY

DPN

DPN is a common disorder. Although estimates vary, it appears that at least one manifestation of DPN is present in at least 20% of adult diabetic patients. DPN has been associated with a number of modifiable and nonmodifiable risk factors, including the degree of hyperglycemia, lipid and blood pressure indexes, diabetes duration, and height. DPN has been less consistently associated with cigarette smoking and alcohol consumption.

DAN

Prevalence data for DAN range from 1.6 to 90% depending on tests used, populations examined, and type and stage of disease. Risk factors for the development of DAN include diabetes duration, age, and long-term poor glycemic control. DAN may cosegregate with factors predisposing to macrovascular events such as raised blood pressure and dyslipidemia. Thus, in addition to good glycemic control, lipid modulation and blood pressure control may be beneficial in the prevention of DAN. There are no true population-based studies using radioisotopic techniques that quantify gastric emptying in diabetic patients, but cross-sectional studies have indicated that ∼50% of outpatients with long-standing diabetes have delayed gastric emptying and up to 76% of diabetic outpatients indicate that they have one or more gastrointestinal symptom, the most common of which is constipation. Both upper- and lower-gastrointestinal symptoms occur more frequently in individuals with diabetes than in control subjects, but the symptoms are nonspecific and occur in the general population. Specific symptoms such as bloating after meals, vomiting of previously ingested food, and alternating constipation and explosive diarrhea should lead to further evaluation.

Genitourinary bladder dysfunction has been shown in 43-87% of individuals with type 1 diabetes. Diabetic women have a fivefold higher risk of unrecognized voiding difficulty compared with nondiabetic women. The history and physical are generally noncontributory, and the patient should be referred to a urologist for urodynamic studies.

The prevalence of erectile dysfunction in diabetic men ranges from 27 to 75% .

DIABETIC NEUROPATHIES

Diabetic neuropathy affects diffent parts of the nervous system. It is a group of diseases that affects all types of nerves, the peripheral, autonomic and spinal nerves. This is common on patients with diabetes that is more than 25 years already. The most common cause is elevated blood glucose for a period of years. This is also regarded as by continual loss of nerve fibers. In here, hyperglycemia will cause demyelization of nerves that will cause the reduction of conduction or nerves. There are three types of diabetic neuropathy, the sensory neuropathy and autonomic neuropathies.

There are two classifications of sensory neuropathy, the acute and chronic. Acute sensory neuropathy is uncommon and occurs after periods of poor metabolic control like pulmonary acidosis or it may also be caused by imbalance in insulin production. The clinical manifestations are acute onset of severe sensory symptoms and marked nocturnal exacerbation. Chronic sensory neuropathy is the most common neuropathy for diabetes. Half of the population is asymptomatic. Symptomatic patients experience burning, stabbing and deep aching pain and paresthesia. Neuropathic pain is most felt at night especially on the lower extremities. An examination of the extremities will show absence of reflexes, sensory loss of vibration, pressure and pain. As the neuropathy continuous, numbness of the foot can be felt and decrease sensation of light touch. To help for the diagnosis, the patient must undergo annual clinical examination including physical examination and blood chemistry. Several pain managements can be rendered and examination of the feet is a must to see if there are calluses, ulcers or deforminties.

Autonomic neuropathy results to high morbidity that can cause death. The symptoms can be identified through thorough history taking since the symptoms can be treated. In caring of patients with autonomic neuropathy, the nurse must observe abnormal signs from the cardiovascular, gastrointestinal and genitourinary systems. Cardiovascular autonomic neuropathy should be taken into consideration because of its critical complications and the accessibility to the direct tests of cardiovascular autonomic function. There are various tests to test the cardiovascular autonomic neuropathy of a patient, this includes resting and stess thallium myocardial scintigraphy, R-R variation, Valsalva maneuver, postural blood pressure testing and the measurement of heart rate variability. Pharmacological therapies of Angiotensin-converting enzyme and Beta-blockers are proven to help patients with cardiovascular autonomic neuropathy. When planning for the exercise regimen of a patient, thorough cardiac autonomic function testing must be performed. Gastroparesis is suspected to people with inconsistent insulin control and gastric emptying should also be evaluated. Barrium studies or endoscopy can also be done. For the genitourinary, bladder dysfunction should be evaluated.

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