Inflammation in dorsal root ganglia after peripheral nerve injury: Effects of the sympathetic innervation

Following a peripheral nerve injury, a sterile inflammation develops in sympathetic and dorsal root ganglia (DRGs) with axons that project in the damaged nerve trunk. Macrophages and T-lymphocytes invade these gan- glia where they are believed to release cytokines that lead to hyperexcitability and ectopic discharge, possibly contributing to neuropathic pain. Here, we examined the role of the sympathetic innervation in the inflammation of L5 DRGs of Wistar rats following transection of the sciatic nerve, comparing the effects of specific surgical in- terventions 10–14 days prior to the nerve lesion with those of chronic administration of adrenoceptor antago- nists. Immunohistochemistry was used to define the invading immune cell populations 7 days after sciatic transection. Removal of sympathetic activity in the hind limb by transecting the preganglionic input to the rele- vant lumbar sympathetic ganglia (ipsi- or bilateral decentralization) or by ipsilateral removal of these ganglia with degeneration of postganglionic axons (denervation), caused less DRG inflammation than occurred after a sham sympathectomy. By contrast, denervation of the lymph node draining the lesion site potentiated T-cell in- flux. Systemic treatment with antagonists of α1-adrenoceptors (prazosin) or β-adrenoceptors (propranolol) led to opposite but unexpected effects on infiltration of DRGs after sciatic transection. Prazosin potentiated the influx of macrophages and CD4+ T-lymphocytes whereas propranolol tended to reduce immune cell invasion. These data are hard to reconcile with many in vitro studies in which catecholamines acting mainly via β2-adrenoceptors have inhibited the activation and proliferation of immune cells following an inflamma- tory challenge. 

Autonomic Neuroscience: Basic and Clinical 182 (2014) 108–117 

Neuroscience Research Australia, Randwick, NSW 2031, and the University of New South Wales, Sydney, NSW 2052, Australia

Functional and organic vascular wall changes after sympathectomy and partial nerve damage

Langenbecks  

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1959;;291:217-31. 

"patient information must include the long-term substantial risk for severe CS and regret of the procedure"

http://www.ncbi.nlm.nih.gov/pubmed/22191130

"lowering of heart rate and blood pressure, decreased responsiveness of the cardiocirculatory system to emotional stimuli

"lowering of heart rate and blood pressure, decreased responsiveness of the cardiocirculatory system to emotional stimuli: it is an effect that is especially noticeable in patients operated on for erythrophobia and less evident in those operated for hyperhidrosis. It is almost always a welcome phenomenon, which contributes considerably to the feeling of tranquility and serenity that generally supersedes anxiety. Excessive reduction in blood pressure or heart rate may lead to a state of weakness and fatigue that may require removal of the clips in approx. 2%. This rare state of asthenia contrasts with the increased energy and vigor that most patients experience when they feel freed from overwhelming anxiety."    

"The neurovegetative nervous system is, however, very dynamic and tends to adapt continuously during lifetime to all environmental or organic changes and conditions. Therefore, it reacts very individually when a reflex circuit has been blocked. The resulting side effects cannot be predicted in detail, and though they in most patients are relatively mild or even absent, there is a small group of patients developing heavy side effects. Therefore, surgery should only be considered in carefully selected cases in whom non-invasive treatment has failed and in whom the detrimental consequences of erythrophobia regarding the psychosocial situation and the quality of life is such to justify more adverse side effects. It should also always be kept in mind that therapy can be ineffective and that, in the long term, 10-15% of patients do not consider themselves satisfied with the result of surgery. In any case, the author prefers the use of a potentially reversible surgical technique (ESB), instead of destructive techniques (cutting, coagulation, removal of ganglia)."  

http://www.chir.it/en_erythrophobia.php

significant associations between heart rate and regional cerebral blood flow

Neurosci Biobehav Rev. 2012 Feb;36(2):747-56. doi: 10.1016/j.neubiorev.2011.11.009. Epub 2011 Dec 8.

A meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health.

The intimate connection between the brain and the heart was enunciated by Claude Bernard over 150 years ago. In our neurovisceral integration model we have tried to build on this pioneering work. In the present paper we further elaborate our model and update it with recent results. Specifically, we performed a meta-analysis of recent neuroimaging studies on the relationship between heart rate variability and regional cerebral blood flow. We identified a number of regions, including the amygdala and ventromedial prefrontal cortex, in which significant associations across studies were found. We further propose that the default response to uncertainty is the threat response and may be related to the well known negativity bias. Heart rate variability may provide an index of how strongly 'top-down' appraisals, mediated by cortical-subcortical pathways, shape brainstem activity and autonomic responses in the body. If the default response to uncertainty is the threat response, as we propose here, contextual information represented in 'appraisal' systems may be necessary to overcome this bias during daily life. Thus, HRV may serve as a proxy for 'vertical integration' of the brain mechanisms that guide flexible control over behavior with peripheral physiology, and as such provides an important window into understanding stress and health.

http://www.ncbi.nlm.nih.gov/pubmed/22178086

important relationship among cognitive performance, HRV, and prefrontal neural function

"These findings in total suggest an important relationship among cognitive performance, HRV, and prefrontal neural function that has important implications for both physical and mental health. Future studies are needed to determine exactly which executive functions are associated with individual differences in HRV in a wider range of situations and populations."

http://www.ncbi.nlm.nih.gov/pubmed/19424767

Many injuries to the nervous system are followed by incomplete recovery or even increasing disability over time

Many injuries to the nervous system are followed by incomplete recovery or even increasing disability over time. Some of these long term effects are due to the loss of access to growth factors called neurotrophins that provide essential support for adult nerve cells. We recently discovered that immune responses can be triggered by injury leading to inflammation around the damaged nerve cells. Control of inflammation may therefore allow the remaining nerve cells to survive until treatments that enable them to regenerate can be developed.
http://www.neura.edu.au/health/nerve-and-spinal-cord-injury

the pain is the result of the sympathectomy itself rather than the technique used

Post"sympathectomy neuralgia is a syndrome of pain in the thigh, often of a burning nature, 
which can occur after sympathectomy and typically lasts 2– 3 months. The incidence has 
been variously quoted as 12–35% after both open sympathectomy47 49 and percutaneous 
phenol sympathectomy.13 50 The fact that the incidence is so similar after open and 
percutaneous sympathectomy suggests that the problem is a result of the sympathectomy 
itself rather than the technique used to achieve it. In the past, some authors have blamed 
the spread of phenol from the sympathetic chain posteriorly to the spinal nerve roots for 
this pain syndrome. There has never been any evidence to support this claim, and the fact 
that open sympathectomy has the same incidence of post"sympathectomy neuralgia 
suggests that spread of phenol is not the cause. 
http://bja.oxfordjournals.org/content/87/1/88.full

"Sympathectomy can enhance or suppress antibody production"

Neuropsychiatry - Google Books: Neuropsychiatry
 edited by Randolph B. Schiffer, Stephen M. Rao, Barry S. Fogel

The mechanisms by which sympathectomy leads to increased local bone loss is unknown

In vivo effects of surgical sympathectomy on intra... [Am J Otol. 1996] - PubMed - NCBI: "Am J Otol. 1996 Mar;17(2):343-6.
In vivo effects of surgical sympathectomy on intramembranous bone resorption.
Sherman BE1, Chole RA.
Author information
1Department of Otolaryngology--Head and Neck Surgery, School of Medicine, University of California, Davis, USA.
Abstract
Bone modeling and remodeling are highly regulated processes in the mammalian skeleton. The exact mechanism by which bone can be modeled at a local site with little or no effect at adjacent anatomic sites is unknown. Disruption of the control of modeling within the temporal bone may lead to various bone disease such as otosclerosis, osteogenesis imperfecta, Paget's disease of bone, fibrous dysplasia, or the erosion of bone associated with chronic otitis media. One possible mechanism for such delicate control may be related to the ubiquitous and rich sympathetic innervation of all periosteal surfaces. Previous studies have indicated that regional sympathectomy leads to qualitative alterations in localized bone modeling and remodeling. In this study, unilateral cervical sympathectomy resulted in significant increases in osteoclast surface and osteoclast number within the ipsilateral bulla of experimental animals. The mechanisms by which sympathectomy leads to increased local bone loss is unknown. Potential mechanisms include disinhibition of resorption, secondary to the elimination of periosteal sympathetics, as well as indirect vascular effects."



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