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PubMed1999

[The assessment of sudomotor function for diagnosis of autonomic diseases. Principles and methods].

Thermoregulatory and emotional sweating can be distinguished in humans. While the first is organized via feed back mechanisms involving thermoreceptors, thermoregulatory centers in the brain and the effector system (sympathetic nervous system and sweat glands), the latter is generated directly by cortical and limbic mechanisms without any feed back. Sweat glands on the hairy skin can be stimulated by thermoregulatory mechanisms (rising body temperature), the emotional sweating on the glabrous skin as a result of an arousal reaction and they can be stimulated by peripheral acting cholinergic agents, which initiate direct or axon reflex mediated sweating. To evaluate sweating there are qualitative methods that visualize the sweat response or indirect methods like the registration of skin potentials. Alternatively sweat output can be quantified by evaporative measurement. For best results these methods should be combined. In this way autonomic dysfunction e.g. after nerve lesions, in polyneuropathies, central lesions and certain pain disorders can be assessed. The sudomotor function tests complete the conventional electrophysiological methods.

Animals↗

PubMed2000

Orthostatic Hypotension in the Elderly: Contributions of Impaired LV Filling and Altered Sympathovagal Balance.

Orthostatic hypotension, which occurs in 5%-18% of the elderly, may contribute to age-related disability. While autonomic dysfunction and alterations of cardiac structure and function likely to impair postural maintenance of blood pressure are common in the elderly, these have not been jointly studied in large cohorts. The authors evaluated the association of orthostatic hypotension with echocardiographic measures of cardiac structure and function, and with autonomic function determined by analysis of heart rate variability, in a large population of community-dwelling elderly. A total of 5201 men and women, aged 65-100 years and living in four geographically separate communities, were recruited from Medicare eligibility lists. In this prospective, observational cohort study, measurements included clinical questionnaires, standing and supine blood pressures, mini-glucose tolerance testing, echocardiography, and 24-hour Holter recording for assessment of heart rate variability. Orthostatic hypotension, defined as a decrease in standing systolic blood pressure of 20 mm Hg or more, was positively associated in bivariate analyses with left ventricular wall thickness, peak velocity of late diastolic filling, vagal tone on heart rate variability analysis, supine systolic pressure, supine diastolic pressure, age, and diabetes, and inversely associated with body weight. After statistical adjustment for the presence of myocardial infarction, stroke, and use of antihypertensive medication, the associations were maintained, and a previous trend toward an association with decreased left ventricular cavity size became statistically significant. The data suggest that in elderly, community-based individuals, orthostatic hypotension is associated with increased blood pressure and decreased weight; it possibly acts mechanistically via altered sympathovagal balance, increased left ventricular wall thickness, decreased left ventricular preload, and alterations of left ventricular diastolic filling. (c) 2000 by CVRR, Inc.

Journal Article↗

PubMed1998

Determinants of ventricular arrhythmias in hemodialysis patients. Evaluation of the effect of arrhythmogenic substrate and autonomic imbalance.

BACKGROUND/AIMS: In chronic hemodialysis patients, we evaluated determinants of repetitive ventricular tachyarrhythmias which included late potentials and heart rate variability. METHODS: We compared the presence of late potentials and heart rate variability obtained by ambulatory electrocardiogram (ECG), findings of echocardiography, and laboratory data between patients with and those without ventricular arrhythmias of Lown class 4A or 4B. Ambulatory ECG was recorded for 24 h from the beginning of hemodialysis. Heart rate variability was evaluated by the standard deviation of the normal RR interval (SDNN). RESULTS: Thirty patients (17%) had ventricular arrhythmias of Lown class 4A or 4B. They were older than patients without such arrhythmias (p=0.0021). Left-ventricular wall motion score (2.0+/-3.9 and 0.3+/-1.2, respectively, p < 0.0001) and left-ventricular mass index (167 +/-59 and 140+/-44 g/m2, respectively, p=0.0053) were larger in patients with ventricular arrhythmias of Lown class 4A or 4B than in those without. Stepwise logistic regression analysis was performed to select variables related to ventricular arrhythmias of Lown class 4A or 4B from the following 8 candidate variables; age, sex, presence of ischemic heart disease, diabetic nephropathy as the primary renal disease, presence of late potentials, SDNN, left-ventricular wall motion score and left-ventricular mass index. Higher left-ventricular wall motion score (p < 0.0001), older age (p=0.0022) and male sex (p=0.0235) were the variables associated with ventricular arrhythmias of Lown class 4A or 4B. CONCLUSION: In patients receiving hemodialysis, predominantly with chronic glomerulonephritis, ventricular arrhythmias of Lown class 4A or 4B were not associated with arrhythmogenic substrate revealed by late potentials or autonomic dysfunction assessed by heart rate variability. Left-ventricular wall motion abnormalities, age and sex were significant factors.

Autonomic Nervous System Diseases↗

PubMed1993

Cardiac autonomic function in fibrocalculous pancreatic diabetes.

Cardiac autonomic function was evaluated in 23 patients with fibrocalculous pancreatic diabetes (FCPD). Though none of the patients had any symptoms referable to autonomic dysfunction, 5 had abnormal heart rate responses. The variability in the heart rate in response to deep breathing was the earliest abnormality found in our patients. Four of the 5 patients had clinical evidence of neuropathy while all 5 had retinopathy and overt nephropathy. We therefore conclude that the autonomic nervous system can be involved in patients with FCPD even as early as 2 years after the onset of the disease, and thus that evaluation of the autonomic nervous system should be part of the routine evaluation of all patients with FCPD.

Adolescent↗

PubMed1996

Blood pressure and heart rate variability in autonomic disorders: a critical review.

Spectral analysis (SA) of blood pressure (BP) and heart rate (HR) fluctuations has been proposed as a unique approach to obtain a deeper insight into cardiovascular regulatory mechanisms in health and disease. A number of studies performed over the last 15 years have shown that autonomic influences are involved in the modulation of fast BP and HR fluctuations (with a period <1 min), particularly at frequencies between 0.2 and 0.4 Hz [high frequency (HF) region or respiratory frequency] and around 0.1 Hz [mid frequency (MF) region]. In patients with secondary or primary autonomic dysfunction, SA of BP and HR signals recorded at rest or during orthostatic challenge in a laboratory environment have shown the occurrence of a reduction in the power of MF and/or HF, BP and HR components. Such a reduction is associated or may even precede the clinical manifestation of autonomic neuropathy. However, the above results collected in standardized laboratory conditions cannot reflect the features of neural cardiovascular control during daily life in ambulant individuals with autonomic failure. To investigate this issue, SA techniques have been applied to 24 h beat-to-beat intra-arterial and non-invasive finger BP recordings obtained in elderly subjects and in pure autonomic failure patients, respectively. In these conditions, HR powers displayed a reduction over a wide range of frequencies (from 0.5 to below 0.01 Hz). Conversely, BP powers underwent a complex rearrangement characterized by a reduction in the power around 0.1 Hz and by an increase in the powers at the respiratory frequency and at frequencies below 0.01 Hz. Dynamic quantification of the sensitivity of the baroreceptor-heart rate reflex by combined analysis of systolic BP and pulse interval (i.e. the interval between consecutive systolic peaks) powers around 0.1 Hz (alpha technique) has shown that in elderly subjects, and even more so in pure autonomic failure patients, baroreflex sensitivity is markedly reduced over the 24 h, and is no longer characterized by its physiological day-night modulation. In conclusion, although in some instances SA of cardiovascular signals may fail to fully reflect the features of autonomic cardiovascular control, the evidence discussed clearly demonstrates that this approach represents a promising tool for a dynamic assessment of the early impairment of neural circulatory control in autonomic failure. This is particularly the case when these analyses are performed on 24 h continuous BP and HR recordings in ambulant subjects.

Autonomic Nervous System Diseases↗

PubMed1995

Assessment of autonomic function in myotonic dystrophy by spectral analysis of heart-rate variability.

We analyzed by means of autoregressive spectral analysis the spontaneous beat-to-beat heart-rate variability (HRV) of 10 myotonic dystrophy (MD) patients (4 men and 6 women, aged 37-53 years) and 10 age- and sex-matched healthy, sedentary humans (control) at rest in the supine position. All MD patients had no cardiac conduction disturbances (i.e., atrioventricular or intraventricular conduction defects) on 12-lead electrocardiogram and were able to walk and perform daily activities. In the MD group, the total power, the power of the low-frequency component (a marker of sympathetic and vagal modulation of heart rate) and that of the high-frequency component (a marker of vagal modulation of heart rate) were smaller than those in the control group (P < 0.01, P < 0.05 and P < 0.05, respectively). The results of this study suggest that the cardiovascular autonomic nervous system contributing to the HRV may be disturbed even in the MD patients who can walk and perform daily activities. Therefore, one must give careful consideration to the cardiovascular autonomic dysfunction, as well as the cardiac conduction disturbance in the MD patients.

Adult↗

PubMed2006

Autonomic nervous system control of the cardiovascular and respiratory systems in asthma.

Patients with asthma have exaggerated bronchoconstriction of their airways in response to certain indirect (e.g. cold air, allergens, dust, exercise) or direct (e.g. inhaled methacholine) stimuli. This 'hyper-reactivity' usually co-exists with airway inflammation, although the pathophysiological mechanisms underlying these changes are not fully understood. It is likely that this hyper-reactivity is associated with abnormal autonomic nervous system (ANS) control. In particular, the parasympathetic (vagal) component of the ANS appears to be implicated in the pathogenesis of asthma. In addition, several studies have suggested the existence of differential alteration in ANS function following exercise in asthmatics compared with non-asthmatic individuals. Several early studies suggested that the altered autonomic control of airway calibre in asthma might be reflected by a parallel change in heart rate. Cardiac vagal reactivity does indeed appear to be increased in asthma, as demonstrated by the cardiac response to various autonomic functions tests. However, other studies have reported a lack of association between bronchial and cardiac vagal tone, and this is in accord with the concept of system-independent ANS control. This review provides a discussion of cardiovascular-autonomic changes associated with either the pathophysiology of asthma per se or with asthma pharmacotherapy treatment. Previous investigations are summarised suggesting an apparent association between altered autonomic-cardiovascular control and bronchial asthma. The full extent of autonomic dysfunction, and its clinical implications, has yet to be fully determined and should be the subject of future investigation.

Adrenergic beta-Agonists↗

PubMed1990

Autonomic function in Holmes Adie syndrome.

Autonomic function was studied in a group of 11 patients with Holmes Adie Syndrome. Autonomic function was assessed by the measurement of cardiovascular reflexes. Heart rate responses to respiration, valsalva manoeuvre and standing were studied. The change in systolic blood pressure on moving from the lying to the standing position was measured. Abnormalities of parasympathetic function were found in three patients, compared with matched controls. Autonomic dysfunction in Holmes Adie Syndrome may be more widespread than previously suspected.

Adie Syndrome↗

PubMed2006

Pediatric autonomic disorders.

The scope of pediatric autonomic disorders is not well recognized. The goal of this review is to increase awareness of the expanding spectrum of pediatric autonomic disorders by providing an overview of the autonomic nervous system, including the roles of its various components and its pervasive influence, as well as its intimate relationship with sensory function. To illustrate further the breadth and complexities of autonomic dysfunction, some pediatric disorders are described, concentrating on those that present at birth or appear in early childhood.

Adrenal Insufficiency↗

PubMed2005

Autonomic nervous system dysfunction predicts poor prognosis in patients with mild to moderate tetanus.

BACKGROUND: Autonomic nervous system (ANS) dysfunction is present in up to one third of patients with tetanus. The prognostic value of ANS dysfunction is known in severe tetanus but its value is not well established in mild to moderate tetanus. METHODS: Medical records of all patients admitted with tetanus at two academic tertiary care centers in Karachi, Pakistan were reviewed. The demographic, clinical and laboratory data was recorded and analyzed. ANS dysfunction was defined as presence of labile or persistent hypertension or hypotension and sinus tachycardia, tachyarrythmia or bradycardia on EKG. Patients were divided into two groups based on presence of ANS dysfunction (ANS group and non ANS group). Tetanus severity was classified on the basis of Ablett criteria. RESULTS: Ninety six (64 males; 32 females) patients were admitted with the diagnosis over a period of 10 years. ANS group had 31 (32%) patients while non ANS group comprised of 65 (68%) patients. Both groups matched for age, gender, symptom severity, use of tetanus immunoglobulin and antibiotics. Twelve patients in ANS group had mild to moderate tetanus (Ablett I and II) and 19 patients had severe/very severe tetanus (Ablett III and IV). Fifteen (50%) patients in ANS group required ventilation as compared to 28 (45%) in non-ANS group (p = 0.09). Fourteen (47%) patients died in ANS group as compared to 10 (15%) in non ANS group (p= 0.002). Out of those 14 patients died in ANS group, six patients had mild to moderate tetanus and eight patients had severe/very severe tetanus. Major cause of death was cardiac arrhythmias (13/14; 93%) in ANS group and respiratory arrest (7/10; 70%) in non ANS group. Ten (33%) patients had complete recovery in ANS group while in non ANS group 35(48%) patients had complete recovery (p= 0.05). CONCLUSIONS: ANS dysfunction was present in one third of our tetanus population. 40% patients with ANS dysfunction had only mild to moderate tetanus. ANS dysfunction, irrespective of the need of mechanical ventilation or severity of tetanus, predicted poor outcome.

Adolescent↗

PubMed1995

Smoking induced differences in autonomic responses in military pilot candidates.

The effects of smoking on autonomic function, the renin-angiotensin-aldosterone system, plasma catecholamine and 11-dehydro-thromboxane B2 values were studied in 37 young male military pilot candidates, 19 smokers and 18 non-smokers. There was a higher diastolic blood pressure at rest and higher systolic blood pressure after 5 min during the orthostatic test in smokers. Smokers also had higher diastolic blood pressure levels after exercise in the hand-grip test. Smokers had a lower Valsalva ratio and higher tachycardia ratio in the modified Valsalva manoeuvre, suggesting a degree of autonomic dysfunction. Plasma renin levels at rest and plasma noradrenaline levels after hand-grip test were significantly higher in smokers, implying increased sympathetic activity and enhanced activation of the renin-angiotensin system. Our findings indicate that smoking in fit young men increases sympathetic activity and changes physiological responses to autonomic tests.

Adolescent↗

PubMed2006

Recent clinical advances in diabetic polyneuropathy.

PURPOSE OF REVIEW: Recent dramatic increases in the incidence and prevalence of diabetes make an understanding of chronic symmetric sensorimotor diabetic polyneuropathy, the most common and problematic of chronic diabetic complications, essential for a wide range of medical practitioners. RECENT FINDINGS: The demonstration of neuropathic dysfunction in patients with prediabetes or impaired glucose tolerance emphasizes the susceptibility of peripheral nerve fibers, especially small A delta fibers and C fibers, to relatively mild, short-duration hyperglycemia. New testing can reveal peripheral nerve dysfunction prior to clinical neuropathic symptoms and signs. In the absence of effective medications to halt or reverse nerve damage or promote nerve regeneration, early diagnosis of diabetic polyneuropathy, followed by tight glycemic control with diet and exercise, offers the best opportunity to prevent progressive symptoms of sensory loss, pain, autonomic dysfunction, ulcerations, and amputations. Some patients with impaired glucose tolerance have a reversal of neuropathic features with tight glycemic control. Nonpharmacologic therapies for neuropathic pain in diabetic polyneuropathy appear promising. SUMMARY: Tight glycemic control, especially early in diabetes, is the best approach to minimizing the prevalence and severity of diabetic polyneuropathy and makes research into the deleterious effects of even mild hyperglycemia imperative.

Analgesics↗

PubMed2002

Decreased cutaneous vasodilatation to isometric handgrip exercise in Alzheimer's disease.

BACKGROUND: Cutaneous active vasodilatation is a cholinergic nerve mediated function of the sympathetic nervous system and the disturbed function of cholinergic neurotransmission is known as a prominent feature of Alzheimer's disease (AD). METHODS: To assess this relationship, skin blood flow (SkBF) and other haemodynamic parameters were determined by a simple vasodilatory test, isometric handgrip exercise (IHG), in 22 late-onset sporadic type AD and 20 aged control persons (AC). RESULTS: Significantly higher cutaneous vascular resistance and decreased SkBF were found after the stimulus in the AD group. A smaller reduction (p < 0.03) of R wave intervals on the electrocardiogram was observed in the AD group compared to the AC one. After IHG, change in systolic blood pressure was less in the AD (p < 0.01) than in the AC group. CONCLUSION: Our results suggest that autonomic dysfunction affecting active vasodilator sympathetic, as well as parasympathetic functions is present in AD.

Aged↗

PubMed1976

Ocular manifestations of acute pandysautonomia.

A 33-year-old white man developed premature presbyopia and anisocoria as initial manifestations of acute pandysautonomia. Nine months later signs and symptoms of generalized, severe autonomic dysfunction developed, and six years later only paralysis of pupillary reactions, presbyopia, and orthostatic hypotension were unresolved. Pharmacologic testing of the pupils demonstrated no mydriasis to cocaine 4% or hydroxyamphetamine 1% and hypersensitivity to epinephrine 0.1%, methacholine 2.5%, and pilocarpine 0.0625%, suggesting the presence of sympathetic and parasympathetic, postganglionic blockage of autonomic innervation of the iris.

Adult↗

PubMed1998

Altered autonomic cardiac control in hypertrophic cardiomyopathy. Role of outflow tract obstruction and myocardial hypertrophy.

AIM: The goal of this study was to investigate the role of left ventricular outflow tract obstruction and myocardial hypertrophy on autonomic cardiac function in patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: The sympatho-vagal function was evaluated by spectral analysis of heart rate variability in 28 patients with hypertrophic obstructive cardiomyopathy, 22 patients with hypertrophic non-obstructive cardiomyopathy, 12 with systemic hypertension and left ventricular hypertrophy and 28 healthy subjects. Left ventricular out-flow tract pressure gradient in patients with hypertrophic cardiomyopathy was evaluated by echo-Doppler methods and the quantitative assessment of left ventricular hypertrophy was based on an echocardiographic index. At rest, patients with hypertrophic non-obstructive cardiomyopathy showed normal spectral patterns, while in patients with hypertrophic obstructive cardiomyopathy and in patients with systemic hypertension we observed, respectively, a significant reduction and increase in the low frequency component relative to the control (P < 0.05). During tilt, the physiological increases in the low frequency component and in the low to high frequency ratio were markedly blunted, or even reverted, only in patients with hypertrophic obstructive cardiomyopathy. In these patients, the heart rate increase during tilt was delayed in comparison to the other groups. Finally, in the hypertrophic obstructive cardiomyopathy group, the impairment of sympathetic activation (lack of increase in the low frequency component during tilt) was significantly correlated to the echocardiographic index of left ventricular hypertrophy (r = -0.800, P < 0.001) rather than to the left ventricular outflow tract pressure gradient (r = 0.295, P: ns). CONCLUSION: Among patients with hypertrophic cardiomyopathy, only those with outflow tract obstruction show spectral signs of altered autonomic cardiac control. Within this group, the autonomic dysfunction appears to be correlated to myocardial hypertrophy rather than to left ventricular outflow tract obstruction.

Adult↗

PubMed1990

[Lambert-Eaton myasthenia syndrome--review with case report].

The pathogenetic and therapeutic concepts in Lambert-Eaton Myasthenic Syndrome (=LEMS) are changing. The disease has been proved to be an autoimmune reaction to voltage-dependent calcium channels of the presynaptic membrane at the neuromuscular junction. As pointed out in a case report, autonomic dysfunction can be an early sign and symptom of LEMS. The update review of the literature deals with the diagnosis, aetiology and therapy of the often but not exclusively paraneoplastic induced disease.

Autonomic Nervous System Diseases↗

PubMed1985

Mitral valve prolapse syndrome: etiology and symptomatology.

Mitral valve prolapse syndrome is the most common cardiac disorder today. However, it is relatively new in the medical literature and not well understood by most health care professionals. This article discusses the history, pathophysiology and etiology of the syndrome. An in-depth study of the psychological aspects of the disease is also presented. The syndrome is considered by some authors to be the same as soldier's heart and neurocirculatory asthenia. Mitral valve prolapse syndrome can produce disabling symptoms such as chest pain, chronic anxiety, syncope and many others. The cause of these symptoms is not well understood. Autonomic dysfunction and a congenital brain malfunction are proposed explanations for the symptoms. Nurse practitioners who are aware of and knowledgeable about this disease can provide an invaluable service to those afflicted with it.

Autonomic Nervous System Diseases↗

PubMed1977

Autonomic neuropathy in Black diabetic patients.

Seventy adult diabetic patients were assessed for the occurrence of autonomic neuropathy by means of simple clinical tests. Objective evidence of autonomic dysfunction was present in 72%, pure sympathetic dysfunction in 28%, pure parasympathetic dysfunction in 10% and impotence in 57% of patients. Approximately 10% of patients had nocturnal diarrhoea and gustatory sweating.

Black or African American↗