decreased conditioning-related activity in insula and amygdala in patients with autonomic denervation

The degree to which perceptual awareness of threat stimuli and bodily states of arousal modulates neural activity associated with fear conditioning is unknown. We used functional magnetic neuroimaging (fMRI) to study healthy subjects and patients with peripheral autonomic denervation to examine how the expression of conditioning-related activity is modulated by stimulus awareness and autonomic arousal. In controls, enhanced amygdala activity was evident during conditioning to both "seen" (unmasked) and "unseen" (backward masked) stimuli, whereas insula activity was modulated by perceptual awareness of a threat stimulus. Absent peripheral autonomic arousal, in patients with autonomic denervation, was associated with decreased conditioning-related activity in insula and amygdala. The findings indicate that the expression of conditioning-related neural activity is modulated by both awareness and representations of bodily states of autonomic arousal.

http://www.ncbi.nlm.nih.gov/pubmed/11856537

Effect of sympathectomy on mechanical properties of common carotid and femoral arteries

Compared with the intact animals, sympathectomized rats showed a marked increase in arterial distensibility over the entire systolic-diastolic pressure range. When quantified by the area under the distensibility-pressure curve, the increase was 59% and 62% for the common carotid and femoral arteries, respectively (P<.01 for both). In the femoral but not in the common carotid artery, sympathectomy was accompanied also by an increase in arterial diameter (+18%, P<.05 versus intact). Therefore, in the anesthetized normotensive rat, sympathetic activity exerts a tonic restraint on large-artery distensibility. This restraint is pronounced in elastic vessels and even more pronounced in muscle-type vessels.

http://www.ncbi.nlm.nih.gov/pubmed/9369260

endoscopic sympathicotomy in carotid and vertebral arteries in the surgical treatment of primary hyperhidrosis

Analyze, in patients with primary hyperhidrosis (PH) who was undergone to videothoracoscopic sympathicotomy, the degree of vascular denervation after surgical transection of the thoracic sympathetic chain by measuring ultrasonografic parameters in carotid and vertebral arteries.

METHODS:

Twenty-four patients with PH underwent forty-eight endoscopic thoracic sympathicotomy and were evaluated by duplex eco-Doppler measuring systolic peak velocity (SPV), diastolic peak velocity (DPV), pulsatility index (PI) and resistivity index (RI) in bilateral common, internal and external carotids, besides bilateral vertebral arteries. The exams were performed before operations and a month later. Wilcoxon test was used to analyse the differences between the variables before and after the sympatholisis.

RESULTS:

T3 sympathicotomy segment was the most frequent transection done (95.83%), as only ablation (25%) or in association with T4 (62.50%) or with T2 (8.33%). It was observed increase in RI and PI of the common carotid artery (p < 0.05). The DPV of internal carotid artery decreased in both sides (p < 0.05). The SPV and the DPV of the right and left vertebral arteries also increased (p < 0.05). Asymmetric findings were observed so that, arteries of the right side were the most frequently affected.

CONCLUSIONS:

Hemodynamic changes in vertebral and carotid arteries were observed after sympathicotomy for PH. SPV was the most often altered parameter, mostly in the right side arteries, meaning significant asymmetric changes in carotid and vertebral vessels. Therefore, the research findings deserve further investigations to observe if they have clinical inferences.

http://www.ncbi.nlm.nih.gov/pubmed/16186983

sweating from these areas could be under cortical control, separate from the hypothalamic centers involved in thermoregulation

Compensatory hyperhidrosis is excessive sweating of the abdomen, chest, back, thighs, and face,[6,72] usually in response to increased temperature.[46] This is the most common complication following ETS, reported to occur at an average rate of about 60%, with a range of 3% to 98%.[46] Higher rates have been reported from countries with warmer climates, such as in Asia and the Middle East.[46,82] The sweating can be severe for 10% to 40% of patients.[10] Although it has been written that compensatory sweating diminishes with time, several series have documented continued symptoms with longer-term follow-up.[46] In one series of 270 patients followed for a mean of 15 years postsympathectomy, 67% still complained of compensatory sweating, and overall satisfaction fell from an initial level of 96% to 67%.[55] It is possible that patients begin to notice compensatory sweating some time after ETS, as they are initially more aware of the marked reduction of their primary hyperhidrosis.[46] The mechanism for compensatory sweating is unclear; the most likely explanation is that sweating in the trunk increases to compensate for the lack of sweating from the denervated areas in order to maintain thermoregulation.[82] The occurrence of decreased sweating in other areas not innervated by the ganglia treated by ETS suggests that the response to ETS is more complex. The soles are the most common area with decreased sweating post-ETS, and, along with the axillae and palms, sweating from these areas could be under cortical control, separate from the hypothalamic centers involved in thermoregulation.[72] It has also been proposed that ganglion destruction affects axons of neurons in the interomediolateral spinal cord, which could lead to cell death or re-organization, changing the control of the sympathetic system by the spinal cord and higher, leading to increased sympathetic tone in the other body areas not treated by ETS.[10]  http://www.sweathelp.org/English/HCP_Treatment_ETS_Surgery_Complications.asp?printfriendly=true

the decrease in CBF induced by chronic sympathectomy cannot be attributed to the development of hypersensitivity

Thus the decrease in CBF induced by chronic sympathectomy cannot be attributed to the development of hypersensitivity to catecholamines. This decrease remained stable whatever the value of resting flow and was maintained under anesthesia. It is concluded that, as in the peripheral circulation, chronic sympathectomy affects the equilibrium of the vascular smooth muscle fibers, but that circulating amines play no compensatory role in the cerebral circulation because of the blood-brain barrier.

http://www.sciencedirect.com/science/article/pii/0006899385902434

Post-sympathectomy pain and changes in sensory neuropeptides

Postsympathectomy limb pain, postsympathectomy parotid pain, and Raeder's paratrigeminal syndrome are pain states associated with the loss of sympathetic fibres and in particular with postganglionic sympathetic lesions. There is a characteristic interval of about 10 days between surgical sympathectomy and onset of pain. It is proposed that this pain in man is correlated with the delayed rise in sensory neuropeptides seen in rodents after sympathectomy. These chemical changes probably reflect the sprouting of sensory fibres and may result from the greater availability of nerve growth factor after sympathectomy. The balance between the sensory and sympathetic innervations of a peripheral organ may be determined by competition for a limited supply of nerve growth factor.
Lancet. 1985 Nov 23;2(8465):1158-60http://www.ncbi.nlm.nih.gov/pubmed/2414615?dopt=Abstract

sensory abnormalities, abnormal body sweating, and pathologic gustatory sweating

The aim of this study is to describe the incidence and characteristics of pain, sensory abnormalities, abnormal body sweating, and pathologic gustatory sweating in pain patients with persistent post-sympathectomy pain.
Results: Seventeen adults (13 females and 4 males) with a mean age of 37 years (range 25-52) at the time of sympathectomy met the inclusion criteria. Five of the 17 patients experienced temporary pain relief for an average of 4 months (range 2-12 months), 3/17 retained the same pain as before the surgery, 1 patient was cured of her original pain but experienced a new debilitating pain, and 8/17 patients continued to have the same or worse pain in addition to a new or expanded pain. Pathologic gustatory sweating was present in 7/11 patients asked, and abnormal sweating (known as compensatory hyperhidrosis) in 11/13 patients asked. Discussion: The present study does not allow for conclusions about the effectiveness of surgical sympathectomy for neuropathic pain. However, our findings indicate that if the pain persists after the procedure, the complications may be quite serious and at times worse than the problem for which the surgery was originally performed.
The Clinical journal of pain
2003, vol. 19, n^o3, pp. 192-199http://cat.inist.fr/?aModele=afficheN&cpsidt=14775091

Recurrent sweating occurred in 17.6% of patients

J Neurosurg Spine. 2005 Feb;2(2):151-4.http://www.ncbi.nlm.nih.gov/pubmed/15739526

Post-sympathectomy neuralgia

Post-sympathectomy neuralgia is proposed here to be a complex neuropathic and central deafferentation/reafferentation syndrome dependent on: (a) the transection, during sympathectomy, of paraspinal somatic and visceral afferent axons within the sympathetic trunk; (b) the subsequent cell death of many of the axotomized afferent neurons, resulting in central deafferentation; and (c) the persistent sensitization of spinal nociceptive neurons by painful conditions present prior to sympathectomy. Viscerosomatic convergence, collateral sprouting of afferents, and mechanisms associated with sympathetically maintained pain are all proposed to be important to the development of the syndrome.

Pain. 1996 Jan;64(1):1-9
http://www.ncbi.nlm.nih.gov/pubmed/8867242?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Neuroma following Sympathectomy

The authors conclude recomemnding the application of clips and if the syndrome nevertheless appears novocaine infiltration of the upper end of the sympathetic chain. The authors are convinced that the theory of Hermann and Cooley about neuroma formation at the ends of the sympathetic chain after resection of a segment is true.
http://www.revangiol.com/sec/resumen.php?or=web&i=e&id=227082.
Traumatic neuroma follows different forms of nerve injury (often as a result of surgery). They occur at the end of injured nerve fibres as a form of ineffective, unregulated nerve regeneration; it occurs most commonly near a scar, either superficially (skin, subcutaneous fat) or deep (e.g., after acholecystectomy). They are often very painful. It is also known as "pseudoneuroma".

A depression in the heart rate and decrease in response to stress is expected to some degree in all patients after sympathectomy

A depression in the heart rate with resultant drop in the heart rate product and decrease in response to stress is expected to some degree in all patients. Some series have described this finding in most patients, whereas others report at least a 10% drop in heart rate in all patients. This is a possible major cause for postoperative dysfunction and should be cautiously sought after. Patients with resting heart rate that is below 50 to 60 beats/min should undergo electrocardiography. It is recommended that if the heart rate is low on a subsequent electrocardiogram as well, that a tilt test should be performed to exclude patients in whom there is an inordinately high risk of postoperative bradycardia.

In conclusion, thoracoscopic sympathectomy can be done as an outpatient procedure safely and efficiently. Debate continues about the correct transection levels, but at this time there is a consensus that division or clipping is equal to resection. Although the procedure has several severe side effects, they are rare. The predominant complication remains compensatory sweating, which may occur regardless of the level transected or the indication. Future clinical trials should compare some of the different techniques to achieve a global consensus of the surgical approach.

http://ats.ctsnetjournals.org/cgi/content/full/85/2/S764