Importance of bilateral sympathetic innervation on cerebral blood flow autoregulation in the thalamus

Brain Res. 1987 Jun 16;413(2):297-301.

Effects of bilateral sympathetic innervation on the regulation of cerebral blood flow to the thalamus were examined in spontaneously hypertensive rats (SHR). The superior cervical ganglion was removed on one side or bilaterally, and blood flow in the thalamus was repeatedly measured with a hydrogen clearance technique during a stepwise increase in arterial pressure. Sympathectomy on one side neither had effects on the pressure-flow relationship nor on the blood pressure levels of upper limits of autoregulation in the ipsilateral thalamus. In contrast, bilateral sympathetic denervation impaired the autoregulatory function in the thalamus and the upper limits were significantly lower than those in intact rats: 206 +/- 8 vs 226 +/- 10 mm Hg, respectively (P less than 0.02).
PMID: 3607478 [PubMed - indexed for MEDLINE]

effect of electric stimulation of the sympathetic cord in the upper thoracic level on the middle cerebral artery blood flow

Source: CEREBROVASCULAR DISEASES Volume: 2 Issue: 6 Pages: 359-364 Published: NOV-DEC
1992
Times Cited: 20 References: 41
Abstract: The effect of electric stimulation of the sympathetic cord in the upper thoracic level on the middle cerebral artery blood flow veloCitY (V(MCA)) in humans was examined using transcranial Doppler sonography monitoring during surgery for palmar hyperhidrosis.
Sympathetic stimulation resulted in marked and rapid increases Of V(MCA). The responses were preceded by prompt increases of mean arterial blood pressure (MABP) and heart rate (HR).
Division of the sympathetic cord cranially or caudally to the stimulation site partially reduced the V(MCA), MABP and HR responses. Both these operations reduced sympathetic pathways to the heart as reflected by a decrease in HR and MABP. The integrity of the sympathetic pathway from the stimulation site through the superior cervical ganglion and the carotid plexus was not a prerequisite for a V(MCA) response. Our data suggest that the V(MCA) increase mainly results from stimulation of the heart and the cardiovascular system, resulting in marked increases of blood
pressure and heart rate.

Obviously, it is not simply a compensatory hyperhidrosis transposition from postoperative reduction

In contrast, it is of particular interest to find that patients with cerebroischemic syndrome who received thoracic sympathectomy rarely developed substantial postsympathectomy compensatory hyperhidrosis (PCH). The etiology of PCH is still unclear. Obviously, it is not simply a compensatory hyperhidrosis transposition from postoperative reduction of palmar sweating. Based on our observations, we postulated two possible mechanisms. The first of these mechanisms is denervation hypersensitivity of the surgically injured distal sympathetic stump. This could explain why CH may appear soon after sympathectomy, but is not found in patients who undergo local excision of axillary sweat glands or undergo local treatment. Another mechanism is regeneration of preganglionic fibers or collateral sprouting of sympathetic fibers from the proximal stump of the sympathetic trunk. This could explain the long-term existence of PCH.
Ann Thorac Surg 2001;72:667-668

Receptor hypersensitivity is a common problem after significant sympathetic injury, including clammy hands, erythema, and allodynia. When sympathetic nerves regenerate, they may establish aberrant connections to sensory receptors, muscles, or other sympathetics receptors; this may lead to an over-response or abnormal response.
http://wiki.cns.org/wiki/index.php/Injury,_Sympathetic_Nerve

Cervical sympathectomy and cerebral microvascular and blood flow responses to hypocapnic hypoxia

The number of perfused arterioles and capillaries was significantly higher under hypoxic conditions than under normoxic conditions in sham and ganglionectomized animals. During hypoxia, the percent of arterioles per squared millimeter perfused increased to 63 +/- 5% in sham-lesioned rats and to a significantly greater extent, 80 +/- 6%, in ganglionectomized rats. The percentage of capillaries per squared millimeter perfused changed similarly. The peripheral sympathetic nervous system appeared to play an important role in the control of cerebral microvascular response to hypoxia.
Am J Physiol Heart Circ Physiol 256: H460-H467, 1989;

http://ajpheart.physiology.org/cgi/content/abstract/256/2/H460

In patients with sympathetic failure, the orthostatic reduction in cerebral blood velocity and oxygenation is larger.

In patients with sympathetic failure, the orthostatic reduction in cerebral blood velocity and oxygenation is larger. Patients who become symptomatic within 5 minutes of standing are characterized by a pronounced orthostatic fall in blood pressure, cerebral blood velocity, and oxygenation manifest within the first 10 seconds of standing.
Stroke. 2000;31:1608-1614

Increased cerebral vasoconstriction or reduced vasomotion also may attenuate CBFV variability

Altered cerebral hemodynamics in early Alzheimer disease: a pilot study using transcranial Doppler.

J Alzheimers Dis. 2009 Jul;17(3):621-9.

Autonomic neural control of cerebral hemodynamics

it has been found that in humans CBFV in the middle cerebral artery decreased substantially during
lower body negative pressure (LBNP) and head-up tilt in the absence of systemic hypotension, which suggests the presence of cerebral vasoconstriction associated with augmented sympathetic nerve activity during orthostatic stress.
IEEE Eng Med Biol Mag. 2009 Nov-Dec;28(6):54-62.

SYMPATHETIC-NERVE STIMULATION IN HUMANS INCREASES MIDDLE CEREBRAL-ARTERY BLOOD-FLOW VELOCITY

The effect of electric stimulation of the sympathetic cord in the upper thoracic level on the middle cerebral artery blood flow veloCitY (V(MCA)) in humans was examined using transcranial Doppler sonography monitoring during surgery for palmar hyperhidrosis. Sympathetic stimulation resulted in marked and rapid increases Of V(MCA). The responses were preceded by prompt increases of mean arterial blood pressure (MABP) and heart rate (HR). Division of the sympathetic cord cranially or caudally to the stimulation site partially reduced the V(MCA), MABP and HR responses. Both these operations reduced sympathetic pathways to the heart as reflected by a decrease in HR and MABP. The integrity of the sympathetic pathway from the stimulation site through the superior cervical ganglion and the carotid plexus was not a prerequisite for a V(MCA) response. Our data suggest that the V(MCA) increase mainly results from stimulation of the heart and the cardiovascular system, resulting in marked increases of blood pressure and heart rate. CEREBROVASCULAR DISEASES Volume: 2 Issue: 6 Pages: 359-364 Published: NOV-DEC 1992

ETS suppresses the activation of the sympathetic nervous system slightly, similar to beta-blocker therapy

On the 123I-MIBG imaging studies, the early H/M ratio before EUTS was 2.35 ± 0.26 and postoperatively it was 2.29 ± 0.23. The delayed H/M ratio before EUTS was 2.59 ± 0.3 and after the procedure it was 2.66 ± 0.27. There was no significant difference between the H/M ratio before and after EUTS. The washout rate after EUTS (14.27 ± 4.71%) was significantly lower than that measured before EUTS (18.36 ± 5.13%; p < 0.01).

Endoscopic upper thoracic sympathectomy is a minimally invasive procedure; no local denervation was found after EUTS. Findings on 123I-MIBG imaging studies indicate that EUTS suppresses the activation of the sympathetic nervous system slightly, similar to beta-blocker therapy.

Journal of Neurosurgery March 2004 Volume 100, Number 3

a significant decrease in heart rate and ejection fraction, a significant decrease of ‘rest’ and ‘peak’ heart rate

In pulmonary function tests, we found a statistically significant decrease forced expiratory flow in small airways and an increase of residual volume, a significant decrease in heart rate and ejection fraction, a significant decrease of ‘rest’ and ‘peak’ heart rate, and a significant increase of oxygen pulse (O2 pulse) and oxygen peak uptake ( peak) after ETS (p < 0.05).

Eur J Cardiothorac Surg 2009;36:491-496. doi:10.1016/j.ejcts.2009.03.059

Significant reductions in maximal heart rate (HR) and oxygen and carbon dioxide uptakes were observed

The maximal midexpiratory flow was the only variable that showed significant changes, from 101% (SD, 26%) to 92% (SD, 27%) [p < 0.05]. Ten patients had positive bronchial challenge test results that remained positive 3 months after surgery, and 2 patients whose challenge test results were negative before surgery became positive after sympathectomy. Significant reductions in maximal heart rate (HR) and oxygen and carbon dioxide uptakes were observed during the maximal exercise test.
Chest. 2005 Oct;128(4):2702-5.

Changes in hemodynamics of the carotid and middle cerebral arteries before and after endoscopic sympathectomy in patients with palmar hyperhidrosis

Patients who underwent T-2 sympathectomy demonstrated a significant increase in blood flow volume and flow velocities of the CAs and MCA, especially on the left side. Asymmetry of sympathetic influence on the hemodynamics of the CAs and MCA was noted. The usefulness of sympathectomy for the treatment of ischemic cardiovascular and cerebrovascular disease deserves further investigation.
Journal on Neurosurgery March 1999 Volume 90, Number 3

http://thejns.org/doi/abs/10.3171/jns.1999.90.3.0463

Clinical significance of chemosensitivity in chronic heart failure

Increased chemosensitivity has been observed in HF (heart failure) and, in order to clarify its pathophysiological and clinical relevance, the aim of the present study was to investigate its impact on neurohormonal balance, breathing pattern, response to exercise and arrhythmic profile.

Those with enhanced chemosensitivity to both hypoxia and hypercapnia (i.e. HVR and HCVR), compared with those with normal chemosensitivity, had significantly (all P<0.01) higher noradrenaline (norepinephrine) and BNP (B-type natriuretic peptide) levels, higher prevalence of daytime and night-time CSR, worse NYHA (New York Heart Association) class and ventilatory efficiency [higher VE (minute ventilation)/VCO(2) (carbon dioxide output) slope], and a higher incidence of chronic atrial fibrillation and paroxysmal non-sustained ventricular tachycardia, but no difference in left ventricular volumes or LVEF. A direct correlation was found between HVR or HCVR and noradrenaline.

Clin Sci (Lond). 2008 Apr;114(7):489-97.

Impaired autonomic function results in impaired cerebral regulation

The absence of an increase in the power of 0.1 Hz blood pressure and cerebral blood flow velocity oscillations confirmed autonomic neuropathy in the diabetic patients. Gain analysis did not show altered cerebral regulation. The decrease in phase shift in the patients indicates a more passive transmission of neck suction-induced blood pressure fluctuations onto the cerebrovascular circulation, i.e. altered cerebral regulation, in the patients, and is therefore suited to identifying subtle impairment of cerebral regulation in these patients.
http://www.springerlink.com/content/14m7g478j7ux11hv/

Superior cervical ganglionectomy caused a marked decrease in noradrenaline concentrations in major cerebral arteries

Superior cervical ganglionectomy caused a marked decrease in noradrenaline concentrations in major cerebral arteries (−77%), although the reduction was less pronounced (−34%) in small pial vessels. Sympathectomy decreased by 33% 5-HT concentrations in the major cerebral arteries but was without effect on 5-HT levels in the small pial vessels.

Journal of Neurochemistry

Volume 56 Issue 2, Pages 681 - 689

Published Online: 5 Oct 2006

Received March 28, 1990 revised manuscript received July 12, 1990; accepted August 14, 1990.

Experimental study of progressive facial hemiatrophy: effects of cervical sympathectomy in animals

Progressive facial hemiatrophy (Romberg's syndrome) is of unknown cause and uncertain pathogenesis. The main pathogenetic hypotheses are: sympathetic system alterations, localized scleroderma, trigeminal changes, possibly of genetic origin. To test the hypothesis of sympathetic system alterations, we designed an experimental model with ablation of the superior cervical sympathetic ganglion in rabbits, cats and dogs. All the animals were operated upon when 30 days old and were examined monthly for 1 year. During this period localized alopecia, corneal ulceration, keratitis, strabismus, enophthalmos, ocular atrophy, hemifacial atrophy and slight bone atrophy on the side of the sympathectomy were observed. Thus, cervical sympathectomy reproduces in animals the principal clinical alterations of Romberg's syndrome. Our data suggest that the sympathetic system is involved in the pathogenesis of this syndrome.

Rev Neurol (Paris). 1991;147(8-9):609-11.

sympathectomy causes qualitative alterations in bone modeling and remodeling

The results further support that a regional sympathectomy causes qualitative alterations in bone modeling and remodeling, leading to bone resorption.
J Auton Nerv Syst. 2000 Jan 14;78(2-3):113-6.

noradrenaline loss in the sympathetic nervous system of the heart

Symptoms or signs of abnormal autonomic nervous system function occur commonly in several neurological disorders.
Clinical evaluations have depended on physiological, pharmacological, and neurochemical approaches. Recently, imaging of sympathetic noradrenergic innervation has been introduced and applied especially in the heart. Most studies have used the radiolabeled sympathomimetic amine, (123)I-metaiodobenzylguanidine. Decreased uptake or increased "washout" of (123)I-metaiodobenzylguanidine-derived radioactivity is associated with worse prognosis or more severe disease in hypertension, congestive heart failure, arrhythmias, and diabetes mellitus. This pattern may reflect a high rate of postganglionic sympathetic nerve traffic to the heart. Many recent studies have agreed on the remarkable finding that all patients with Parkinson's disease and orthostatic hypotension have a loss of cardiac sympathetic innervation, whereas all patients with multiple system atrophy, often difficult to distinguish clinically from Parkinson's disease, have intact cardiac sympathetic innervation. Because Parkinson's disease entails a postganglionic sympathetic noradrenergic lesion, the disease appears to be not only a movement disorder, with dopamine loss in the nigrostriatal system of the brain, but also a dysautonomia, with noradrenaline loss in the sympathetic nervous system of the heart. As new ligands are developed, one may predict further discoveries of involvement of components of the autonomic nervous system in neurological diseases.
Semin Neurol. 2003 Dec;23(4):423-33.

Psychoneurological applications of endoscopic sympathetic blocks

In addition to more widely and longer known indications of ETS, various neurological disorders and psychologically stressful situations in their worst expressions might be alleviated by the reversible ESB procedure. The patients with social phobia, especially those who have also blushing and/or stage fright type of heart racing, benefit from the ESB. The disturbances of the sympathetic nervous system, e. g. in Parkinson's disease and multiple system atrophy might be alleviated with sympathetic block, especially the extrapyramidal symptoms in these diseases. In migraine, sympathetic surgery has been noted to give some help. The unilateral left-sided block has been effective in long QT-syndrome type arrhythmias. In schizophrenia, the phobic, paranoic or confusional reactions have been tentatively treated by the sympathetic block.
Clin Auton Res. 2003 Dec;13 Suppl 1:I20-1; discussion I21.