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Results for “Autonomic dysfunction”

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PubMed1997

[The effect of phototherapy on psychoautonomic disorders of a neurotic nature].

Bright white light therapy was applied to 51 patients with syndrome of autonomic dysfunction of neurotic origin (1 hour of light exposure every day in the morning, during 2 weeks, 60 sm from the lamp, 3300 lux). Improvement occurred in 52% of the patients (responders--group 1, nonresponders--2). Changes occurred in nearly all symptoms: neuroendocrine, motivation, psychoautonomic, pain, psychopathologic. After the treatment in group 1 there was an increase of power of EEG spectrum, intensification of manifestations of the slow activity and decrease of the fast one from the two sides, an approach of the coefficient of asymmetry to the control levels as well as elevation of the urine excretion of metabolites of both catecholamines and serotonin. Initially higher power of EEG spectrum in group 2, became still more increased due to intensification of manifestations of theta and beta-2 rhythms from the two sides. Meanwhile coefficient of asymmetry was sharply decreased as well as general secretory activity inhibited. There were such symptoms and indices which had changed either negatively or positively under the influence of phototherapy.

Adult↗

PubMed1996

[Acute hepatic porphyria and its neurological syndrome].

Certain of the hepatic porphyrias are classified as belonging to the acute hepatic prophyrias, namely acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP) and ALA-dehydrase deficiency. The common feature of all acute hepatic porphyrias is the sudden onset of neurological symptoms. The whole syndrome consists of acute abdominal pain crises with autonomic dysfunction, global or focal central nervous system involvement and a predominantly motor polyneuropathy. Mono- or oligosymptomatic manifestations of acute porphyrias occur and are probably underestimated. The laboratory diagnosis of porphyria depends on the measurement of porphyrin precursors in urine, whereas the measurement of porphyrins in urine and feces is essential for evaluation of the porphyria type. Enzyme measurements are used to identify asymptomatic family members whose quantitative excretions of porphyrins are normal. At present the pathogenesis of neurological manifestations of acute porphyrias remains an unsettled question. The major hypotheses are discussed in this paper. The most important precipitating factor in acute hepatic porphyrias is drug ingestion. As many new drugs have not been in use for sufficiently long periods to assess their porphyrogenic activity, it is safer to avoid drugs in patients with porphyria. The most effective treatment of porphyria attacks is the administration of heme. Among the porphyria patients with epileptic seizures requiring antiepileptic medication, treatment with bromides should be taken into consideration.

Abdomen, Acute↗

PubMedDate not supplied

The "Harlequin Sign". Case description and review of the literature.

Asymmetrical facial sweating and flushing has been named the "Harlequin Sign". This is a rare feature, as evident from only 12 cases described up to date. The "Harlequin Sign" represents a local autonomic dysfunction due to a cervical sympathetic deficit located at the pre or postganglionic level on the non-flushing side. We observed slow onset and progression of the "Harlequin Sign" in a 19-year-old man, with preexisting slight miosis on the non-flushing side. The differential diagnosis included other forms of dysautonomia and a secondary origin of this partial Horner's syndrome. Both pupils normally reacted to light, convergence, and pilocarpine eye-drop instillation, but the affected side showed supersensitivity to phenylephrine. Deep tendon reflexes were normal, thus excluding Adie's syndrome. The absence of cholinergic supersensitivity in the iris muscles indicated normal function of the ciliary ganglion and excluded the ocular parasympathetic deficit, also evident for the coexisting Horner's syndrome. The clinical features could be explained by assuming that the lesion was located at the level of postganglionic sympathetic fibers, probably due to trans-synaptic postganglionic neuronal degeneration at the level of the stellate ganglion, thus determining the onset of the hemifacial symptoms.

Adult↗

PubMed2001

Effect of beta-blockade on heart rate variability in decompensated heart failure.

BACKGROUND: One of the putative mechanisms for the salutary effects of beta-blockers in patients with congestive heart failure is their ability to improve autonomic dysfunction. However, patients with profound neurohumoral abnormalities derive little survival benefit from beta-blockers. The purpose of the current study was to evaluate the effect of beta-blockers on heart rate variability in decompensated heart failure. METHODS: Time and frequency domain heart rate variability indices were obtained from 24-h Holter recordings and compared to assess the role of beta-blockade in 199 patients (mean age 60+/-14 years [range 21 to 87]) with decompensated heart failure (New York Heart Association functional class III [66%] and IV [34%]). RESULTS: All heart rate variability indices were markedly suppressed but were substantially higher in patients who were on beta-blockers. Time domain measures of parasympathetic cardiac activity, the percentage of RR intervals with >50 ms variation (4.9+/-0.6 vs. 7.7+/-1.2%, P=0.006) and the square root of mean squared differences of successive RR intervals (22.7+/-2.0 vs. 31.6+/-4.1 ms, P=0.004), were higher in the beta-blocker group. Spectral analysis revealed that the total power and the ultra low frequency power were significantly higher in patients on beta-blockers (82% and 59%, respectively). The high frequency power, a spectral index of parasympathetic modulation, was 41% higher in the beta-blocker group (121+/-25 vs. 171+/-27 ms(2), P=0.02). Multiple linear regression, adjusted for clinical parameters and drug therapies, revealed a strong positive relationship between beta-blockade and higher values of time and frequency domain measures. The mean number of ventricular tachycardia episodes were significantly lower in patients on beta-blocker therapy (3.6+/-1.5 vs. 19.0+/-5.3, P=0.04). CONCLUSIONS: beta-blockers improve the impaired cardiac autonomic regulation during high sympathetic stress of decompensated heart failure.

Adrenergic beta-Antagonists↗

PubMed2001

Differentiation in the angiotensin II receptor 1 blocker class on autonomic function.

Autonomic function is disordered in cardiovascular disease states such as chronic heart failure (CHF) and hypertension. Interactions between the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) may potentially occur at a number of sites. These include central sites (eg, rostral ventrolateral medulla), at the level of baroreflex control, and at the sympathetic prejunctional angiotensin II receptor 1 (AT(1)) receptor, which is facilitatory for norepinephrine release from the sympathetic nerve terminal. Therefore, drugs that block the RAAS may be expected to improve autonomic dysfunction in cardiovascular disease states. In order to test the hypothesis that RAAS inhibition directly reduces SNS activity, a pithed rat model of sympathetic stimulation has been established. In this model, an increase in frequency of stimulation results in a pressor response that is sympathetically mediated and highly reproducible. This pressor response is enhanced in the presence of angiotensin II and is reduced in the presence of nonselective AIIRAs that block both AT(1) and AT(2) receptor subtypes (eg, saralasin). AT(1)-selective antagonists have also been studied in this model, at pharmacologically relevant doses. In one such study, only the AT(1) blocker eprosartan reduced sympathetically stimulated increases in blood pressure, whereas comparable doses of losartan, valsartan, and irbesartan did not. The reason(s) for the differences between eprosartan and other agents of this class on sympathetic modulation are not clear, but may relate to the chemical structure of the drug (a non- biphenyl tetrazole structure that is chemically distinct from the structure of other AIIRAs), receptor binding characteristics (competitive), or unique effects on presynaptic AT(1) receptors.

Acrylates↗

PubMedDate not supplied

[Hereditary sensory and autonomic neuropathies. The neurophysiological and pathological aspects of two cases with congenital insensitivity to pain].

AIM: Two patients suffering from congenital insensitivity to pain were studied. They corresponded to types IV and V of the 'hereditary sensory and autonomic neuropathies' (HSAN) classification. CASE REPORTS: The first case showed important autonomic dysfunctions, such as anhidrosis, hyperthermia, skin and bone trophic impairment, and mental retardation; the second one only exhibited alterations in pain and temperature sensibilities. In both, chronic indolent corneal ulcers were also present. Conventional neurophysiological evaluation of the neuromuscular system was normal, but an afferent disturbance of the blink reflex (BR) was evident in both. The sympathetic skin response was absent in the HSAN type IV case and normal in the HSAN type V. Notable reduction of the small myelinated fibres, associated to almost no unmyelinated fibres in the first case, were found in the sural nerve biopsies. CONCLUSIONS: So far there haven't been described BR abnormalities in patients with congenital insensitivity to pain, which should be related to a trigeminal sensory impairment, which could explain the corneal ulcers that suffered these cases. BR studies should be included in the neurophysiological evaluation of the suspected small fibre neuropathies even when there are no facial symptoms shown.

Adolescent↗

PubMedDate not supplied

[A trial of the use of aekol in preventing psychoautonomic disorders].

Autonomic dysfunction in chronic emotional stress is well documented. The aim of this study was to analyze the effects of natural antioxidant vitamin E (aekol). Twenty persons (16 women and 4 men, mean age 38 +/- 4 years) who reported recent occurrence of emotional stress were examined before and after a 4-week treatment with aekol (5 ml twice a day). Heart rate variability (taking into account very low-frequency (VLF, 0.003-0.04 Hz), low-frequency (LF, 0.04-0.15 Hz), and high-frequency (HF, 0.15-0.40 Hz) components) was computed from the power spectra (5-min epochs) of the EKG recorded in the patients in supine position. After the treatment, the HF power of the heart rate variability (an index of cardiac parasympathetic activity) increased (p < 0.05), whereas the VLF power (an index of the cerebral sympathetic activity) decreased (p < 0.01). The decrease in the VLF was accompanied by a reduction of anxiety level (p < 0.01). According to our hypothesis, the absolute and relative power of the VLF can be used as an index of anxiety or cerebral sympathetic activity, which significantly decreases after the aekol treatment.

Adult↗

PubMed2004

Type 2 diabetes mellitus, etiology and possible treatment: preliminary report.

BACKGROUND: Insulin resistance has been proposed as the initial step in the cascade toward type 2 diabetes mellitus. The mechanisms underlying the development of insulin resistance are not fully understood. We hypothesize that neurovascular interactions, in particular arterial elongation, causes compression of the right lateral medulla, triggering a state of autonomic dysfunction including hyperactivity of pancreatic endocrine function, and predisposes to insulin resistance and the development of type 2 diabetes. METHODS: The clinical and operative findings were reviewed retrospectively in 15 patients with primary diagnoses of various right-sided cranial rhizopathies, but with a common diagnosis of type 2 diabetes mellitus. After microvascular decompression was performed for the primary diagnosis, arterial compression was observed of the lateral medulla and cranial nerve X and treated with microvascular decompression. Known duration of the diabetes ranged from "new" (patient was diagnosed as a result of preoperative blood work) to 16 years (mean 7.3 years). Duration of diabetes diagnosis was unknown in 2 patients. Follow-up was from 3 to 113 months (mean 29.9 months). RESULTS: Ten of the 15 patients (66%) showed improvement in their blood glucose control; 5 of those 10 (50%) did so with no (4 patients) or less (1 patient) diabetes medication. CONCLUSIONS: We have shown that arterial compression of the right lateral medulla is consistently present in patients with diabetes mellitus and that microvascular decompression can be performed safely. Further studies are necessary and are under way.

Adult↗

PubMedDate not supplied

Synergetic interpretation of patterned vasomotor activity in microvascular perfusion: discrete effects of myogenic and neurogenic vasoconstriction as well as arterial and venous pressure fluctuations.

Synergetic concepts allow to identify emergent coordination phenomena between interacting physiological systems, for example between the cutaneous microcirculation, the sympathetic nervous system and the cardiac and pulmonary systems. The temporal patterns (oscillations of various frequencies) that are found in the data obtained with laser-Doppler anemometers (LDA; e.g. Periflux 2 used in the study) can be investigated by simultaneous recording of photoplethysmographic data obtained in the identical region of interest, as well as in cutaneous regions treated with vasoparalytic procedures which permit to record the dynamics of the arterial system. These strategies were applied to studies in the cutaneous microcirculation (volar side of the index fingers) as well as to mucosal microcirculation (maxillar gingiva) in healthy subjects and in patients suffering from autonomic dysfunction (cutaneous microcirculation) or gingivitis. By this procedure, it could be corroborated that - contrary to popular notions - the temporal fluctuations in the LDA records do not necessarily reflect myogenic vasomotion, but can have multiple causes. In a confirming recent study [Schmid-Schönbein et al., J Auton Nerv Syst, 57, 136-140, 1996], we have demonstrated that the LDA fluctuations under conditions of normal ambient temperature and hand position most likely reflect neurogenic vasoconstriction. Under exceptional conditions, different patterns emerge. Prolonged exposure to ambient temperature (18 degrees C) leads to marked vasoconstriction, with occasional vasodilator escape ('miniature hunting reaction'). Normal subjects under gravitational load and in warm environment (28 degrees C ambient) silence their neurogenetic vasoconstriction reactions, which allows sinusoidal vasomotion to dominate. A similar phenomenon is seen in neuropathic patients at 21-24 degrees C (presumably due to structural defects). Fluctuations in LDA signal taken from the healthy gingiva are entrained to arterial, those taken from inflamed gingiva to respiratory activity. The theory and practice of nonlinear analysis is discussed, and data compression procedures allowing to portray characteristic temporal patterns for future diagnostic procedures are presented.

Autonomic Nervous System Diseases↗

PubMed2001

The use of baclofen in cluster headache.

Cluster headache is a rare, clinically well-characterized disabling disorder that occurs in both episodic and chronic forms. The very painful short-lived unilateral headache attacks are associated with autonomic dysfunction. A large number of drugs such as ergotamines, steroids, methysergide, lithium carbonate, verapamil, valproate, capsaicin, leuprolide, clonidine, methylergovine maleate, methylphenidate, and melatonin are considered beneficial for prophylaxis. Nevertheless, this extremely painful condition is occasionally refractory to conventional treatment. The antispastic agent baclofen has been shown to possess an antinociceptive activity. Its efficacy in neuralgias, central pain following spinal lesions, painful strokes, migraine, and medication misuse chronic daily headache suggests that it may be useful for prevention of cluster headache attacks. Therefore, we treated 16 symptomatic patients with cluster headache with daily baclofen, 15 to 30 mg, in three divided doses for the cluster period and 2 weeks after. Within a week, 12 patients reported the cessation of attacks. One was substantially better and became attack free by the end of the following week. In the remaining three patients, the attacks worsened and corticosteroids were prescribed. One of these was also given verapamil. Three of the 16 patients had an additional cluster period, which cleared with a second course of baclofen. In this pilot study, baclofen seemed to be effective, safe, and well tolerated for cluster headache, and seemed to retain its efficacy on repeated clusters.

Adrenal Cortex Hormones↗

PubMed2005

Is lumbar spondylosis a cause of urinary retention in elderly women?

OBJECTIVES: Lumbar spondylosis (LS) is a common spinal degenerative disorder which causes various types of lower urinary tract dysfunction (LUTD). However, it is not certain whether LS may cause urinary retention in elderly women. METHODS: In a period covering the past 3 years, we retrospectively reviewed: a) urodynamic case records of women with urinary retention (post-void residuals, PVR > 100 ml), b) the records of women with LUTD due to LS (cauda equina syndrome and spinal canal narrowing by MRI), and c) uro-neurological features of women who belonged to both a) and b). RESULTS: a) One-hundred women with a mean age of 58 years had urinary retention. The most common underlying disease was multiple system atrophy [19], followed by multiple sclerosis [13] and cervical/thoracic tumours [8]. LS was the fourth most common [5], with the highest age (71 years) of all diseases. b) Nineteen women with LUTD had LS (12, canal narrowing of 50-70%; 7 > 70 %), with a mean PVR volume of 60 ml. A fourth [5] of them had urinary retention, with severe spinal canal narrowing (all 5 > 70%). c) Thus, 5 women belonged to both a) and b). In 4 of these women, LUTD followed or occurred together with typical cauda equina syndrome symptoms such as sciatica and saddle anesthesia. However, one elderly woman presented with painless urinary retention, and absent ankle reflexes were the sole neurological abnormality. The urodynamic abnormalities underlying urinary retention included an underactive detrusor in all 5, bladder sensory impairment in 3, an unrelaxing sphincter in 2, a low compliance detrusor in one, neurogenic sphincter motor unit potentials in 2 of 4 studied, and cholinergic supersensitivity of the detrusor in one of 3 studied. Surgical decompression ameliorated urinary retention in 1 of 2 women who had surgery. CONCLUSIONS: In our series, only 5 percent of the women with urinary retention had LS, but LS poses a potential risk for retention, particularly in elderly women with severe spinal canal narrowing. Preganglionic somato-autonomic dysfunctions underlie this condition. It may appear as the sole initial complaint in cases in which no other obvious neurological abnormalities are found.

Aged↗

PubMed2006

Decrease heart rate variability but preserve postural blood pressure change in type 2 diabetes with microalbuminuria.

BACKGROUND: This study compares the cardiovascular autonomic function in type 2 diabetes with and without microalbuminuria, in order to identify the possible links between early nephropathy and diabetic autonomic neuropathy (DAN). METHODS: Cardiovascular reflex tests were performed to determine the cardiovascular autonomic function. Thirty cases of type 2 diabetes with microalbuminuria were studied for evidence of DAN to compare with a normoalbuminuric group of 56 diabetic patients. RESULTS: There was an increased prevalence of autonomic dysfunction in patients with microalbuminuria (63.3% in the microalbuminuria group vs. 40.0% in the normoalbuminuric controls, p = 0.001). These patients had lower heart rate variability during single breathing tests (6.9 +/- 4.3 vs. 9.6 +/- 3.6 beats/minute, p = 0.005), during 6 consecutive breathings (5.8 +/- 3.6 vs. 8.2 +/- 3.3 beats/minute, p = 0.005), after standing up (12.2 +/- 4.6 vs. 15.0 +/- 5.2 beats/ minute, p = 0.012), and during the Valsalva maneuver (11.3 +/- 3.5 vs. 13.2 +/- 3.6 beats/minute, p = 0.022). The heart rate variability with these stresses was revealed to be less favorable in subjects with microalbuminuria. However, blood pressure (BP) changes from the sitting to standing position were not significantly different for systolic BP (11.5 +/- 10.7 vs. 10.7 +/- 7.8 mmHg, p = 0.741) and diastolic BP (5.2 +/- 4.4 vs. 5.9 +/- 4.0 mmHg, p = 0.451) between the 2 groups. CONCLUSION: Type 2 diabetic patients with microalbuminuria have diminished heart rate variability in response to deep breathing, change of position and the Valsalva maneuver, but they preserve BP response to postural change. Therefore, microalbuminuria seems to be associated with early DAN, but not with advanced DAN.

Aged↗

PubMed2002

Age-related sympathetic ganglionic neuropathology: human pathology and animal models.

Systematic studies of the autonomic nervous system of human subjects and development of well-defined animal models have begun to substantially improve our understanding of the pathogenesis of autonomic dysfunction in aging and may eventually provide strategies for intervention. Neuropathological studies of the sympathetic ganglia of aged human subjects and rodent models have demonstrated that neuroaxonal dystrophy involving intraganglionic terminal axons and synapses is a robust, unequivocal and consistent neuropathological finding in the aged sympathetic nervous system of man and animals. Quantitative studies have demonstrated that markedly swollen argyrophilic dystrophic axon terminals develop in the prevertebral superior mesenteric (SMG) and coeliac, but to a much lesser degree in the superior cervical ganglia (SCG) as a function of age, sex (males more than females) and diabetes. Dystrophic axons were immunoreactive for neuropeptide Y, tyrosine hydroxylase, dopamine-beta-hydroxylase, trkA and p75NTR, an immunophenotype consistent with their origin from postganglionic sympathetic neurons, and contained large numbers of highly phosphorylated neurofilaments or tubulovesicular elements. The sympathetic ganglia of aged rodents also showed the hallmark changes of neuroaxonal dystrophy as a function of age and location (many more in the SMG than in the SCG). Plasticity-related synaptic remodeling could represent a highly vulnerable target of the aging process. The fidelity of animal models to the neuropathology of aged humans suggests that similar pathogenetic mechanisms may be involved in both and that therapeutic advances in animal studies may have human application.

Aging↗

PubMed2006

Orthostatic decrease in cardiac chaos during the head-up tilt test in patients with vasovagal syncope.

BACKGROUND: Autonomic dysfunction contributes to orthostatic intolerance in vasovagal syncope (VVS), but as it has not been identified by spectral analysis of heart rate variability (HRV) in previous studies, the present hypothesis was that nonlinear analysis of HRV would identify the orthostatic intolerance in VVS. METHODS AND RESULTS: Twenty-six patients with VVS and 14 matched controls were subjected to 80-degree head-up tilt test (positive: 13 patients; negative: 13 patients and 14 controls). There were no differences in the orthostatic changes in the indices of spectral analyses of HRV among the 3 groups. The Lyapunov exponent (LE) was calculated from 200 consecutive RR-intervals to investigate chaotic behavior, and cardiac chaos was defined as the incidence of the presence of a positive finite LE. Orthostatic decreases in cardiac chaos were observed in the VVS patients (both the positive and negative groups), although there was no orthostatic decrease in the control group (ANOVA: p = 0.008). The receiver-operator characteristic curve indicated that cardiac chaos during the tilt identified VVS regardless of the results of the tilt (p < 0.001, sensitivity: 85.7%, specificity: 96.2%). CONCLUSIONS: The decrease in cardiac chaos during the tilt test was specific to patients with VVS, even if their response to the test was negative.

Adult↗

PubMed2000

Baroreflex sensitivity determined by spectral method and heart rate variability, and two-years mortality in patients after myocardial infarction.

Sympathetic overactivity and low parasympathetic activity is an autonomic dysfunction (AD) which enhances cardiac mortality. In the present study, the impact of AD on the mortality in patients after myocardial infarction was evaluated. We examined 162 patients 7-21 days after myocardial infarction, 20 patients of whom died in the course of two years. Baroreflex sensitivity (BRS) was estimated by spectral analysis of spontaneous fluctuations of systolic blood pressure and cardiac intervals (Finapres, 5 min recording, controlled breathing 20/min). The heart rate variability was determined as SDNN index (mean of standard deviations of RR intervals for all 5-min segments of 24-hour ECG recordings). BRS < 3 ms/mm Hg and/or SDNN index < 30 ms were taken as markers of AD. The risk stratification was performed according to the number of the following standard risk factors of increased risk of cardiac mortality (SRF): ejection fraction < 40%, positive late potentials and the presence of ventricular extrasystoles > 10/h. No difference in mortality between patients with AD (4%) and without AD (4.5%) was found in 92 patients without SRF, the mortality in 6 patients with three SRF was 66.6%. Five of these patients had AD. Out of 64 patients with one or two SRF, 32 had AD. The mortality of patients without AD was 6.25% and 31.2% of those with AD (p<0.025). It is concluded that AD enhanced two-years mortality five fold in our patients with moderate risks.

Aged↗

PubMed2001

Heart rate variability in childhood obesity.

UNLABELLED: Obesity is characterized by hemodynamic and metabolic alterations. Autonomic control on cardiac function involvement is controversial. The aim of the study was to assess early sign of cardiac autonomic dysfunction in obesity, using time- and frequency-domain heart rate variability (HRV) analysis in a pediatric population. METHODS: 32 obese children (OB) (17 M, 15 F; 13.9 +/- 1.7 y) were compared with 13 healthy lean subjects (7 M, 6 F; 12.9 +/- 1.6 y). For each participant, the authors performed a clinical examination, laboratory testing, blood pressure (BP) measurements, and 24-hour electrocardiograph/ambulatory BP monitoring. The spectral power was quantified in total power, low-frequency (LF) power, index of sympathetic tone, high-frequency (HF) power, index of vagal tone, and LF/HF ratio. Low frequency and HF were averaged to obtain 3 measures: 24-hour, daytime, and nighttime levels. Total, long-term, and short-term time-domain HRV values were calculated. RESULTS: The obese children had higher casual and ambulatory BP, and higher fasting glucose, insulin, and triglyceride levels. Overall HRV values were not significantly lower in OB. The obese children had significantly lower 24-hour and nighttime high-frequency normalized units, and time-domain measures of vagal activity. Low-frequency power showed an inverse but not significant pattern. The OB group had significantly greater 24-hour and nighttime LF/HF ratios. CONCLUSIONS: The authors found an increase in heart rate and in BP associated with parasympathetic heart rate control decrease in stabilized obese normotensive children.

Adolescent↗

PubMed2003

Current pathophysiological views on vibration-induced Raynaud's phenomenon.

This review attempts to summarize and discuss contemporary pathogenetic views on vibration-induced Raynaud's phenomenon assuming its multifactorial etiology. An increase in central and peripheral sympathetic nervous activity is discussed based on different physiological indicators of autonomic dysfunction and sympathetic hyperactivity. Local acral vasodysregulation is considered. Receptor and nerve endings dysfunction presented with predominance of alpha(2)-receptor function in the digital arteries and neuronal loss in those digital cutaneous perivascular nerves containing calcitonin gene-related peptide result in deficiency of endogenous release of this powerful vasodilator. Endothelial damage and dysregulation induced by vibration and increased shear stresses are demonstrated by the elevated plasma level of thrombomodulin and of von Willebrand factor and reduced endothelium-dependent vasodilator responses. The concentrations of endothelin-1 are high, the highest being in most advanced stages. Decreased plasma thiol level, indicating increased production and activity of free radicals, contribute to vasospastic paroxysms in vibration white finger patients. Dysbalance of local vasoactive factors with opposing effects on vascular smooth muscle like endothelin and nitric oxide, endothelin and calcitonin gene-related peptide, nitric oxide and superoxide anion are discussed. Disturbed smooth muscle response is supposed. Changes in hemostasis, fibrinolysis and hemorrheology, activation of blood cells with erythrocyte hyperaggregation and red cell hypodeformability, platelet aggregation with increased release of vasoconstricting thromboxane A(2) and serotonin as well as leukocyte activation, entrapment within capillaries and post-capillary venules and increased reactive oxygen species and lysosomal lytic enzymes release might also contribute to digital vasospasms and tissue damage. Elevated soluble intercellular adhesion molecule-1 levels involved in the adherence of leukocytes to endothelium and to other leukocytes have been found in patients with hand-arm vibration syndrome.

Autonomic Nervous System Diseases↗

PubMed1996

Impact of changes in respiratory frequency and posture on power spectral analysis of heart rate and systolic blood pressure variability in normal subjects and patients with heart failure.

1. Autonomic dysfunction is a major feature of congestive cardiac failure and may have an important role in determining progression and prognosis. The low-frequency/high-frequency ratio derived from power spectral analysis of heart rate variability has been proposed as a non-invasive method to assess sympatho-vagal balance. However, the effects of different respiratory rates or posture are rarely accounted for, but may be relevant in patients with heart failure in whom clinical improvement is accompanied by a fall in respiratory rate and an increased proportion of the day in the upright position. 2. We have assessed the effect of controlled respiration at different rates (10, 15, 20 breaths/min or 0.17, 0.25 and 0.33 Hz), while supine and standing, on power spectral analysis of heart rate and blood pressure variability in 11 patients with heart failure and 10 normal subjects. 3. Heart rate variance and low-frequency power (normalized units) were reduced in patients with heart failure (absent in six). During controlled breathing while supine, the power of the high-frequency component was significantly greater at 10 breaths/min than at 20 breaths/min in patients with heart failure, whether expressed in absolute units (P = 0.005) or percentage of total power (P = 0.03). 4. On standing, controlled breathing in patients with heart failure produced less change in high-frequency power (P = 0.054), but the low-frequency/high-frequency ratio at lower respiratory rates was reduced (P = 0.05). In normal subjects, as expected, respiratory rate had a highly significant effect on high-frequency power. Also, in normal subjects there was the expected increase in heart rate low-frequency power (P = 0.04) moving from supine to standing with an increase in the low-frequency/high-frequency ratio (P = 0.003), while in the patients with heart failure this was absent, reflecting blunted cardiovascular reflexes. 5. Systolic blood pressure low- and high-frequency components and their ratio were significantly affected by respiration (P < 0.03) and change in posture (P < 0.03) in both patients with heart failure and normal subjects, with a significant increase in the low-frequency/high-frequency ratio (P = 0.03) on standing in patients with heart failure, indicating that autonomic modulation of blood pressure is still operating in heart failure. 6. Thus, respiratory rate and changes in posture have a significant effect on measurements derived from spectral analysis of heart rate and blood pressure variability. Studies that use power spectral analysis as a measure of sympatho-vagal balance should control for these variables.

Adult↗