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Autonomic control of cardiovascular function: clinical evaluation in health and disease.

The high- and low-pressure baroreceptor reflexes are integral to the control of blood pressure by the autonomic nervous system. Tests of the integrity of these baroreflexes make it possible to identify the site of autonomic dysfunction in patients with orthostatic hypotension. Clinical characteristics and typical results of autonomic testing in patients with autonomic failure, with carotid sinus hypersensitivity, and with hyperadrenergic autonomic dysfunction are described in this review.

Adrenergic alpha-Agonists↗

[What are the physical complaints without pathological clinical signs in patients with diabetes mellitus?].

UNLABELLED: In previous research it was found that patients with diabetes mellitus suffer from multiple physical symptoms even early in their disease course. Such complaints may relate to blood glucose levels or can be understood as a sign of distress in respect to the diagnosis of a chronic disease. PURPOSE: This study was performed to evaluate in a cross-sectional analysis all the symptoms that patients may complain of and to relate these symptoms to a possible dysfunction of the autonomic nervous system. METHOD: We assessed the complaints of 66 patients with diabetes mellitus and compared these variables with those of patients with psychological disturbances (n = 794) or somatic disease (n = 162). The symptoms were recorded by means of several questionnaires such as the "Giessener Beschwerdebogen" (GBB), "the Freiburger Persönlichkeitsinventar" (FPI), the German version of the State Trait Anxiety Inventory (STAI) and the German version of the State Trait Anger Expression Inventory (STAXI). The autonomic nervous system was assessed using resting and mental stress conditions in a subset of patients with diabetes mellitus (n = 29) and psychological disturbances (n = 44). RESULTS: Patients suffering from diabetes mellitus and psychological disturbances showed a tendency to higher scores in GBB, STAI and STAXI. As far as psychological disturbances are concerned, the complaints experienced by patients with diabetes mellitus were found to be similar to those with somatic diseases. Both groups, however, rate clearly below those with psychological disturbances. The results of autonomic testing showed a significant disturbance in patients with diabetes mellitus with reduced sensitivity of the baroreceptor indicating autonomic neuropathy. CONCLUSION: Some of the physical complaints of patients with diabetes mellitus can be understood in connection with autonomic dysfunction. Moreover, an explicitly psychological view of these complaints may not be correct.

Adult↗

Cardiovascular autonomic function and sympathetic skin response in chronic inflammatory demyelinating polyradiculoneuropathy.

Quantitative cardiovascular autonomic function tests (AFTs) and sympathetic skin response (SSR) were performed in 12 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Parasympathetic autonomic function was examined by Valsalva ratio and R-R interval variation during rest and deep breathing. Sympathetic autonomic function was evaluated by blood pressure responses to sustained handgrip and active standing. Using quantitative AFTs, subclinical autonomic dysfunction was demonstrated in three (25%) patients. Abnormal SSR was seen in six (50%) patients. Thus, mild autonomic dysfunction is present in many CIDP patients. The autonomic abnormalities involve parasympathetic or sympathetic components; in the sympathetic nervous system, both vasomotor and sudomotor fibers may be involved.

Adolescent↗

[A severe case of acute autonomic and sensory neuropathy].

Acute autonomic and sensory neuropathy (AASN) is a rare neuropathy characterized by acute autonomic dysfunction and objective sensory disturbances. A 26-year-old pregnant woman with severe autonomic and sensory dysfunction is reported. This patient suddenly developed marked nausea and vomitting in about 2 days after having a sore throat. She then developed signs of autonomic dysfunction including dilated non-reactive pupils, dryness of the eyes and oral mucous membranes, generalized anhidrosis, paralytic ileus, orthostatic hypotension, and continuous tachycardia. She also had severe generalized sensory impairments of all modalities, and all deep tendon reflexes were absent. Sensation was almost totally lost for all modalities below the neck. There was marked pseudoathetosis and sensory ataxia in all extremities. Motor examination was normal. She had inability to urinate. At this time she was 38 weeks pregnant, and when she showed signs of fetal distress, a Caesarean section was performed. Albumino-cytological dissociation was seen in the CSF. Serum noradrenaline was reduced, no sensory nerve action potentials could be elicited, and reduced coefficient of variation of the R-R interval on electrocardiography was observed. Plasma exchange was performed every other day for 3 days for about 3 weeks after the onset of the illness, but no favorable effects. Seven months after the onset, her autonomic dysfunction slightly improved, but there was no recovery from the sensory disturbances. Many symptoms and signs that characterize AASN occurred in this patient, and each was severe. The patient developed SIADH, sleep apnea, personality change, and amenorrhea in the course of the disease. We suggest that AASN patients might have both peripheral and central nervous system manifestations including seizures and personality changes.

Acute Disease↗

Mineralocorticoid receptor blockade: new insights into the mechanism of action in patients with cardiovascular disease.

Mineralocorticoid receptor (MR) blockade is effective in reducing total mortality and the incidence of heart failure in patients with systolic left ventricular dysfunction (SLVD) associated with chronic heart failure or post myocardial infarction. Pre-clinical and clinical studies in SLVD have shown that MR blockade reduces sudden cardiac death, left ventricular remodelling, left ventricular hypertrophy, endothelial dysfunction, autonomic imbalance, renal dysfunction and improves fibrinolysis. While MR blockade promotes sodium excretion and the combination of an angiotensin-converting enzyme inhibitor and a MR blocker have been shown to be more effective than either alone in causing natriuresis, it is unlikely that their beneficial effects can be explained solely on this basis. Aldosterone has been shown to have a number of adverse effects, including activation of other neurohumeral mediators, stimulation of active reactive oxygen species (ROS), activation of the NF-Greek small letter kappa kappabeta and AP-1 signalling pathways, vascular inflammation and fibrosis, myocardial hypertrophy, autonomic imbalance, and a decrease in fibrinolysis. MR blockade is, however, effective both in situations with and without an increase in serum aldosterone level, since the MR can be occupied and activated by cortisol as well as by aldosterone. In view of these mechanisms, MR blockade may play an important role not only on SLVD, but also in essential hypertension with normal systolic function, diastolic heart failure, valvular heart disease, vascular stiffening with ageing, progression of renal disease, and diabetes mellitus. This hypothesis will, however, require further prospective evaluation.

Animals↗

Evaluation of cardiac sympathetic neuronal integrity in diabetic patients using iodine-123 metaiodobenzylguanidine.

Autonomic dysfunction is associated with increased mortality in diabetic patients. To evaluate the cardiac autonomic dysfunction in these patients, a prospective study was undertaken using iodine-123 metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPET). The study groups consisted of ten diabetic patients with cardiac autonomic neuropathy (group I) and six without autonomic neuropathy (group II). Autonomic nervous function tests, thallium scan, radionuclide ventriculographic data including ejection fraction and wall motion study, and 24-h urine catecholamine levels were evaluated. 123I-MIBG SPET was performed at 30 min and 4h following injection of 3 mCi of 123I-MIBG in groups I and II and in normal subjects (n=4). On planar images, the heart to mediastinum (H/M) ratio was measured. Defect pattern and severity of MIBG uptake were qualitatively analysed on SPET. Compared with control subjects, diabetic patients had a reduced H/M ratio regardless of the presence of clinical autonomic neuropathy. There was no difference in H/M ratio between groups I and II. On SPET images, focal or diffuse defects were demonstrated in all patients in group I, and in five of the six patients in group II. The extent of defects tended to be more pronounced in group I than in group II. In conclusion, 123I-MIBG scan was found to be a more sensitive method than clinical autonomic nervous function tests for the detection of autonomic neuropathy in diabetes.

3-Iodobenzylguanidine↗

Autonomic and somatic peripheral nerve function and the correlation with neuropathic pain in diabetic patients.

Pupillary and cardiovascular autonomic functions were examined in 25 diabetic patients with and 25 diabetic patients without painful neuropathy. There were no significant differences between the groups with regard to age, duration of diabetes or glycaemic control. Vibratory perception, reflecting peripheral large fibre function, was more severely disturbed in the symptomatic group (P = 0.003). Thermal discrimination thresholds (TDTs), reflecting somatic small fibre function, were abnormal in all symptomatic patients and the difference between patients with and without symptoms was more pronounced (P less than 0.0001), than for large fibre function. The latency of the constriction reaction of the pupil (parasympathetic function) was prolonged in 17 symptomatic patients and in 6 patients without pain; it proved to be significantly more prolonged in the group with painful neuropathy (P = 0.001). Cardiovascular autonomic neuropathy was present in 29 patients, especially in patients with painful neuropathy (22 in the group with painful neuropathy, 7 in the group without pain). There was a significant correlation between results of TDT and respectively pupillary and cardiovascular autonomic function tests (kappa coeëfficient: 0.63 and 0.56, respectively, P less than 0.0001). We conclude that autonomic dysfunction is often present in patients with painful neuropathy. However, thermal sensory dysfunction is better correlated with the presence of symptoms than cardiovascular and pupillary autonomic dysfunction.

Adult↗

Early use of intrathecal baclofen in brain injury in pediatric patients.

BACKGROUND: The Food and Drug Administration (FDA) approved the use of intrathecal Baclofen for spasticity from traumatic brain injury in June of 1996 based on a Phase III clinical trial that documented efficacy in patients one year post injury. The FDA approval is only for patients who are one year post injury based on the Phase III study. We have found use of ITB in the first few months after injury very effective in a subgroup of severe traumatic brain injury (TBI) pediatric patients with spasticity, dystonia and autonomic storming following brain injury. METHOD: The author's database of over 250 patients receiving intrathecal baclofen was reviewed. Retrospective chart review was undertaken of the 6 patients identified with brain injuries over a three year period that were given ITB less than one year post injury. The patients' diagnosis included asphyxia, traumatic brain injury and stroke. The ages were one year to fourteen years of age. ITB was offered after all conventional therapy had been exhausted and the patient's spasticity remained intractable. These patients also all experienced autonomic dysfunction with severe autonomic storms. FINDINGS: All of the patients had a decrease in their spasticity of at least 2 points on the Ashworth score. The autonomic storms ceased in all 6 patients when adequate dosages of ITB were reached. The patients could be weaned from all oral and intravenous medications for tone, storming and fever. Many of the patients became much more alert and interactive when the medications were stopped. Five of the six are still using their pump for their tone one to five years post implant, the sixth had the pump stopped at the parents' request for religious reasons. INTERPRETATION: Early use of ITB can play a significant role in the rehabilitation of brain injury in children.

Adolescent↗

The sympathetic skin response: normal values, elucidation of afferent components and application limits.

The sympathetic skin response (SSR), recorded at the hand and foot, was elicited using different classes of stimuli in 20 normal controls and 10 patients with peripheral neuropathy. We found that SSR latencies changed significantly with different recording sites, but not with different stimulation sites. Additionally, after ischemic conduction block of the arm in 3 normal controls, the previously obtainable SSR recorded at the hand became unobtainable with median nerve stimulation. Also, in one patient with subacute ganglionitis and 3 patients with demyelinating neuropathies, the SSR could not be elicited by electrical stimulation, but it could with deep inspiration. These results suggest that large diameter myelinated fibers may serve as afferents for the SSR. Furthermore, these findings imply that an unobtainable SSR by electrical stimulation may be due not only to dysfunction of the autonomic efferent nerve fibers, but also to abnormalities of the sensory afferents of the reflex. Therefore, investigations of autonomic dysfunction utilizing the SSR must be interpreted with caution in patients with peripheral neuropathies.

Acoustic Stimulation↗

Contralateral hyperhidrosis after cerebral infarction. Clinicoanatomic correlations in five cases.

BACKGROUND: Excessive sweating from cerebral infarction has been reported rarely in the available stroke literature, and its pathophysiological mechanisms and clinical significance have remained obscure. In addition, there have been no reports that medullary infarction results in only contralateral hemihyperhidrosis without ipsilateral Horner's syndrome. In the hope of increasing recognition of this phenomenon, we describe five patients with hyperhidrosis, including two patients with medullary infarction, and discuss the clinicoanatomic correlations. CASE DESCRIPTIONS: Contralateral hyperhidrosis occurred in two patients with large strokes involving both superficial cortical and deep subcortical structures of the middle cerebral artery territory and in two patients with medullary infarctions. Bilateral hyperhidrosis of the face was noted in one patient with basilar artery thrombosis and bilateral cerebellar and pontine infarctions. The hyperhidrosis typically involved the face and arm and was transient, lasting from 2 days to 2 months. No associated Horner's syndrome, hypothalamic dysfunction, or other autonomic dysfunction was observed. CONCLUSIONS: The phenomenon of hyperhidrosis might be attributed to a lesion of a putative sympathoinhibitory pathway that controls sweating. This pathway might originate in the cortex, possibly in the operculum, and make terminal connections with the contralateral thoracic spinal cord. Our observations suggest that the fibers of this putative pathway may be very close to the corticospinal tract.

Brain↗

Cardiovascular reflexes and low long-term exposure to mercury vapour.

Subjective symptoms related to autonomic dysfunction and quantitative non invasive tests measuring both sympathetic and parasympathetic functions of the autonomic nervous system were studied among a group of 41 chlorine-alkali workers with low long-term exposure to mercury (Hg degree) vapour and their matched referents. The test battery included measurements of pulse rate variation in normal and deep breathing, in the Valsalva manoeuvre and in vertical tilt as well as blood pressure responses during standing and isometric work. The exposure time had been 16 years on average, and the mean exposure to Hg vapour was estimated to have been about 30 micrograms/m3 of air. Only a tendency for a subtle reduction of cardiovascular reflex responses and a slight increase of subjective symptoms were seen in the exposed group, but no significant autonomic dysfunction was associated with the low level of exposure.

Adult↗

Sympathetic and parasympathetic pupillary dysfunction in familial dysautonomia.

Objective assessment of autonomic dysfunction in familial dysautonomia (FD) is largely based on the analysis of cardiovascular responses to challenge maneuvers such as orthostatic stress. Infrared pupillometry (IPM) provides an additional reliable method for cranial autonomic evaluation and has the advantage of requiring minimal cooperation.This study was performed to determine whether IPM contributes to the assessment of autonomic function in FD patients. In 14 FD patients and 14 healthy controls, we studied absolute and relative light reflex amplitude, pupillary constriction velocity (v(constr)), pupillary diameter, early and late pupillary re-dilatation velocity (v(dil 1), v(dil 2)) after dark adaptation. Prior to IPM, all patients had an ophthamological examination to evaluate refraction and corneal integrity. In comparison to controls, patients had a significant reduction of the parameters reflecting parasympathetic pupillary function (absolute light reflex amplitude 1.34 +/- 0.21 vs. l.86 +/- 0.14 mm, relative light reflex amplitude 22.74 +/- 7.11% vs. 30.76 +/- 3.57%, v(constr) 3.75 +/- 1.09 vs. 5.80 +/- 0.59 mm/s) and of the parameters reflecting sympathetic pupillary function (diameter 5.69 +/- 0.66 vs. 6.35 +/- 0.60 mm, v(dil 1) 1.29 +/- 0.23 vs. 1.95 +/- 0.23 mm/s, v(dil 2) 0.64 +/- 0.13 vs. 0.72 +/- 0.l2 mm/s; Mann-Whitney U-test: p<0.05). The non-invasive technique of IPM demonstrates dysfunction not only of the cranial parasympathetic, but also of the cranial sympathetic nervous system and, thus, further characterizes autonomic dysfunction in FD.

Adolescent↗

Autonomic mediation of glucagon secretion during hypoglycemia: implications for impaired alpha-cell responses in type 1 diabetes.

This article examines the role of the autonomic nervous system in mediating the increase of glucagon secretion observed during insulin-induced hypoglycemia (IIH). In the first section, we briefly review the importance of the alpha-cell response in recovery from hypoglycemia under both physiologic conditions and pathophysiologic conditions, such as type 1 diabetes. We outline three possible mechanisms that may contribute to increased glucagon secretion during hypoglycemia but emphasize autonomic mediation. In the second section, we review the critical experimental data in animals, nonhuman primates, and humans suggesting that, in the absence of diabetes, the majority of the glucagon response to IIH is mediated by redundant autonomic stimulation of the islet alpha-cell. Because the glucagon response to hypoglycemia is often impaired in patients with type 1 diabetes, in the third section, we examine the possibility that autonomic impairment contributes to the impairment of the glucagon response in these patients. We review two different types of autonomic impairment. The first is a slow-onset and progressive neuropathy that worsens with duration of diabetes, and the second is a rapid-onset, but reversible, autonomic dysfunction that is acutely induced by antecedent hypoglycemia. We propose that both types of autonomic dysfunction can contribute to the impaired glucagon responses in patients with type 1 diabetes. In the fourth section, we relate restoration of these glucagon responses to restoration of the autonomic responses to hypoglycemia. Finally, in the fifth section, we summarize the concepts underlying the autonomic hypothesis, the evidence for it, and the implications of the autonomic hypothesis for the treatment of type 1 diabetes.

Animals↗

Neural therapy.

Neural therapy is a treatment system to relieve chronic pain and illness through the injection of local anesthetics into scars, peripheral nerves, autonomic ganglia, trigger points, glands, and other tissues. Treatment is based on normalizing the dysfunctional autonomic nervous system, which initiates or propagates many chronic ailments. Neural therapy has been used widely by European physicians for over 50 years. Theories of action relating to a dysfunctional autonomic nervous system and chronic pain or illness are discussed.

Analgesics↗

Detection of autonomic sympathetic dysfunction in diabetic patients. A study using laser Doppler imaging.

OBJECTIVE: To study signs of the disturbed reflex autonomic sympathetic nerve function in type 1 and type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Measurements were made on 15 type 1 (duration 13-32 years) and on 50 recently diagnosed type 2 diabetic patients (duration 3-4 years). The vasoconstrictor responses in the distal phalanx of the middle finger (locally heated to 40 degrees C) to the cooling of the contralateral arm were measured using Laser Doppler Imaging (LDI). A vasoconstriction index (VAC) was calculated taking age into account and was compared with reference values obtained in 80 control subjects. The diabetic patients were also studied with deep-breathing tests (i.e., the heart-rate variation expressed as the expiration-to-inspiration [E/I] ratio, a test of parasympathetic nerve function). RESULTS: The vasoconstrictor responses to indirect cooling (VAC) were significantly reduced in the fingers of the diabetic patients, both type 2 (0.77 +/- 0.02 V; P < 0.01) and type 1 (0.83 +/- 0.04 V; P < 0.001), compared with the healthy control subjects (0.65 +/- 0.01); the age-corrected VAC (VACz) was slightly more impaired in type 1 than in type 2 diabetic patients. The frequency of an abnormal VACz corresponded well to the frequency of an abnormal E/I ratio in type 1 diabetic patients (approximately 50%), whereas the frequency of an abnormal VACz was significantly higher than an abnormal E/I ratio among type 2 diabetic patients (11/50 vs. 4/50; P < 0.05). CONCLUSIONS: Both type 1 and type 2 diabetic patients have impaired cutaneous blood flow regulation. The VAC index seems to be a promising tool for detection of subclinical changes in autonomic sympathetic function.

Adolescent↗

Autonomic-cardiovascular dysfunction accompanies sensory-motor impairment during acrylamide intoxication.

We investigated the effects of acrylamide monomer on autonomic-cardiovascular functions and simple sensory-motor behaviors. Rats were intoxicated by ip injections of acrylamide at a dose of 50 mg/kg/day for 10 days; control animals received an equivalent volume of saline. Heart rate (HR) and systolic arterial blood pressure (BP) were measured using the method of indirect tail plethysmography. Intoxicated animals showed fluctuating but significant increases in HR and BP after the first dose of acrylamide, during the course of the intoxication, and two days after the last dose. Deficits in sensory-motor behaviors appeared after the first dose of acrylamide and progressed steadily throughout the exposure period, remaining two days after the last dose. More complex sensory-motor behaviors were affected earliest; hindlimb functions were affected before forelimb functions, characteristic of dying-back axonopathy. These results demonstrate that acrylamide alters common measures of autonomic-cardiovascular functioning in addition to simple sensory-motor behaviors.

Acrylamides↗