A ganglionic intestinointestinal reflex activated by acute noxious challenge

To investigate noxious stimulation-responsive neural circuits that could influence the gut, we recorded from intestinally directed (efferent) nerve filaments dissected from mesenteric nerves close to the small intestine in anesthetized rats. These exhibited baseline multiunit activity that was almost unaffected by vagotomy (VagX) and reduced only slightly by cutting the splanchnic nerves. The activity was halved by hexamethonium (Hex) treatment. When an adjacent gut segment received an intraluminal stimulus 2,4,6-trinitrobenzenesulfonate (TNBS) in 30% ethanol, mesenteric efferent nerve activity increased for more than 1 h. The increased activity was almost unaffected by bilateral vagotomy or splanchnic nerve section, indicating a lack of central nervous involvement, but it was 60% reduced by hexamethonium. Spike sorting discriminated efferent single and predominantly single-unit spike trains that responded to TNBS, were unaffected by splachnectomy but were silenced by hexamethonium. After noxious stimulation of one segment, the adjacent segment showed no evidence of suppression of gut motility or vasoconstriction. We conclude that luminal application of a noxious stimulus to the small intestine activates an entirely peripheral, intestinointestinal reflex pathway. This pathway involves enteric intestinofugal neurons that excite postganglionic sympathetic neurons via a nicotinic synapse. We suggest that the final sympathetic efferent neurons that respond to a tissue damaging stimulus are distinct from vasoconstrictor, secretomotor, and motility inhibiting neurons.NEW & NOTEWORTHY An intraluminal noxious chemical stimulus applied to one segment of small intestine increased mesenteric efferent nerve activity to an adjacent segment. This was identified as a peripheral ganglionic reflex that did not require vagal or spinal connections. Hexamethonium blocked most, but not all, ongoing and reflex mesenteric efferent activity. The prevertebral sympathetic efferent neurons that are activated likely affect inflammatory and immune functions of other gut segments.

Splanchnic Nerve Block: An Emerging Treatment for Heart Failure

Heart failure (HF) is a disease syndrome whose management is increasingly challenging given the aging population and efficacious management of acute cardiac events. The current treatment options within our armamentarium incompletely address the unmet needs of HF. Splanchnic nerve block (SNB) is a novel technique that targets the greater splanchnic nerve, a potential therapeutic target in HF. However, the technique confers potential adverse side effects and complications that warrant further investigations. In this review paper, we aim to discuss the inextricable role of splanchnic nerve in HF by highlighting their physiological interplay, clinical studies that have exhibited favorable hemodynamic parameters in the context of acute and chronic HF, and common side effects and possible complications from SNB.

Dexmedetomidine in Fluoroscopic Guided Splanchnic Nerve Neurolysis for Pain Control: A Randomized, Controlled Trial

BACKGROUND

Splanchnic nerve neurolysis (SNN) shows beneficial effects in reducing malignancy-associated refractory abdominal pain. Using adjuvants, such as dexmedetomidine to improve the pain was studied.

OBJECTIVE

To detect any role of dexmedetomidine as an additive to local anesthetics with an alcohol injection in the chemical SNN process to improve pain in patients having upper-abdominal cancer.

STUDY DESIGN

Double-blinded, prospective randomized study.

SETTING

Department of Anesthesia and Intensive Care, faculty of medicine, Minia University,Egypt.

METHODS

Forty patients with upper-abdominal malignancy-associated refractory abdominal pain underwent fluoroscopic guided SNN were divided into 2 groups. The SNN was performed by using 1.5 mL lidocaine 1%, dexmedetomidine 2 μg/kg, and then an injection of 4.5 mL of ethanol 96% on each side in group D and without dexmedetomidine in group C is done. Patients gave the score of abdominal pain expressed by the Visual Analog Scale (VAS), which measures the pain intensity. Scors were recorded prior to injection, during injection, after injection by 5 min, and after 2, 6, 12, 24, 72 hours, one week (W), 2 W, one month (M), and 2 M. Also, we recorded the amount of morphine required to relieve the residual pain after injection, the effect of procedure on quality of life (QOL), and any complication after injection.

RESULTS

VAS scores showed a significant increase in group C in comparison to group D during injection, after injection by 5 min, 2, 6, 12, 24 hours, one and 2 months (P < 0.0001, 0.0001, 0.029, 0.031, 0.025, 0.040, 0.020, 0.015), respectively. The morphine requirement was significantly increased at one W, one M, and 2 M in group C in comparison to Group D (P < 0.044, 0.017, 0.033) with no significant change in the QOL observed between groups.

LIMITATIONS

The limitations of this study were a relatively small sample size and short period of follow-up.

CONCLUSIONS

This study revealed that using dexmedetomidine in the chemical SNN process improves the pain results from injection of alcohol and refractory cancer related pain with reduction in the consumption of morphine in patients with upper-abdominal malignancy.

Transvenous Right Greater Splanchnic Nerve Ablation in Heart Failure and Preserved Ejection Fraction: First-in-Human Study

BACKGROUND

Ablation of the right-sided greater splanchnic nerve (GSN) can reduce excessive splanchnic vasoconstriction, potentially improving the handling of volume shifts in patients with heart failure with preserved ejection fraction (HFpEF).

OBJECTIVES

The purpose of this study was to assess a novel catheter procedure of right-sided GSN ablation to treat HFpEF: splanchnic ablation for volume management.

METHODS

This trial included 11 HFpEF patients (8 women, age 70 ± 8 years) with New York Heart Association functional class II or III symptoms, ejection fraction ≥50%, and elevated pulmonary capillary wedge pressure at rest or with exercise. After splanchnic ablation for volume management, follow-up at 1, 3, 6, and 12 months included 6-minute walk test, Kansas City Cardiomyopathy Questionnaire (KCCQ), and echocardiography.

RESULTS

There were no device-related adverse cardiac events or clinical sequelae following right GSN ablation through 12 months. Patients experienced clinical improvements by 1 month that were sustained through 12 months. KCCQ score improved from baseline median 48 (IQR: 35-52) to 65 (IQR: 58-77) at 1 month and 80 (IQR: 77-88) at 12 months (P &lt; 0.05). The 6-minute walk test distance increased from baseline 292 ± 82 m to 341 ± 88 m at 1 month and 359 ± 75 m at 12 months (P &lt; 0.05). The NT-proBNP decreased from a baseline mean of 1,292 ± 1,186 pg/mL to 1,202 ± 797 pg/mL (P = 0.585) at 1 month, to 472 ± 226 pg/mL (P = 0.028) at 6 months, and to 379 ± 165 pg/mL (P = 0.039) at 12 months.

CONCLUSIONS

In this open-label, single-arm feasibility study, right-sided GSN ablation was safe and improved mostly subjective clinical metrics in patients with HFpEF over 12 months. (Endovascular GSN Ablation in Subjects With HFpEF; NCT04287946).

Splanchnic nerve modulation in heart failure: mechanistic overview, initial clinical experience, and safety considerations

Volume recruitment from the splanchnic compartment is an important physiological response to stressors such as physical activity and blood loss. In the setting of heart failure (HF), excess fluid redistribution from this compartment leads to increased cardiac filling pressures with limitation in exercise capacity. Recent evidence suggests that blocking neural activity of the greater splanchnic nerve (GSN) could have significant benefits in some patients with HF by reducing cardiac filling pressures and improving exercise capacity. However, to date the long-term safety of splanchnic nerve modulation (SNM) in the setting of HF is unknown. SNM is currently used in clinical practice to alleviate some forms of chronic abdominal pain. A systematic review of the series where permanent SNM was used as a treatment for chronic abdominal pain indicates that permanent SNM is well tolerated, with side-effects limited to transient diarrhoea or abdominal colic and transient hypotension. The pathophysiological role of the GSN in volume redistribution, the encouraging findings of acute and chronic pilot SNM studies and the safety profile from permanent SNM for pain provides a strong basis for continued efforts to study this therapeutic target in HF.

A Technical Report on the Performance of Percutaneous Cryoneurolysis of Splanchnic Nerves for the Treatment of Refractory Abdominal Pain in Patients with Pancreatic Cancer: Initial Experience

PURPOSE

To report our preliminary results upon feasibility, efficacy and safety of percutaneous splanchnic nerves cryoneurolysis for the treatment of abdominal pain refractory to conservative medication in patients with pancreatic cancer MATERIALS METHODS: Institutional database research (retrospective review of prospectively collected data from April 2019 till August 2020) identified 5 patients with pancreatic cancer and pain refractory to conservative medication who underwent percutaneous cryoneurolysis of splanchnic nerves. In all patients, percutaneous cryoneurolysis was performed with posterolateral paravertebral approach using a 17 Gauge cryoprobe under computed tomography guidance and local anesthesia. Self-reported pain scores were assessed before and at the last follow-up using a pain inventory with visual analog scale (VAS) units.

RESULTS

Mean patient age was 63.81 years (male-female: 3-2). Mean pain score prior to cryoanalgesia of splanchnic nerves was 9.4 VAS units. This score was reduced to a mean value of 2.6, 2.6 and 3 VAS units at 1, 3 and 6 months of follow-up, respectively. All patients reported significantly reduced analgesic usage. No complication was reported according to the CIRSE classification system. The mean procedure time was 44.4 min (range 39-50 min), including local anesthesia, cryoprobe(s) placement, ablation and post-procedural CT evaluation.

CONCLUSION

Percutaneous cryoanalgesia of the splanchnic nerves is a minimally invasive, safe and effective procedure for pancreatic cancer pain relief. A larger, randomized trial is justified to substantiate these findings.

Increasing Blood Pressure by Greater Splanchnic Nerve Stimulation: a Feasibility Study

The splanchnic vascular compartment is the major reservoir for intravascular blood volume, and dysregulation of the compartment was implicated in a series of cardiovascular conditions. We explored feasibility and effectiveness of an implantable cuff system on the greater splanchnic nerve (GSN) in healthy canines for short- and long-term neuromodulation to affect the circulation. Five mongrel hounds underwent minimally invasive right-sided unilateral GSN cuff placement. All animals underwent same day GSN stimulation and repeat stimulation at 9-30 days. Stimulation parameter optimization was conducted both acutely and chronically. Parameters ranged from 1-250 Hz, 0.25 mA-35 mA, 0.1-0.5 ms, and 30-s pulse duration. Two animals were survived for 9 days and 3 animals for 30 days. Stimulation of the right GSN increased mean arterial blood pressure by 36.9 mmHg ± 13.4 (p < 0.0001), central venous pressure by 6.9 mmHg ± 1.7 (p < 0.0001), and mean pulmonary arterial pressure by 6.3 mmHg ± 2.0 (p < 0.0001). Peak effects were observed within 30 s, and magnitude of effects was comparable between stimulation cycles (p = 0.4). Stimulation-induced changes in hemodynamics were independent of afferent nerve fibers (pain response) or the adrenal gland. Necropsy showed no evidence of nerve damage on histologic studies up to 30 days after implantation. GSN stimulation via an implanted nerve cuff provided a reproducible and rapid method to increase arterial, central venous, and pulmonary arterial pressures. The neuromodulation cuff was well tolerated and elicited a response up to 30 days after implantation. The clinical application of GSN stimulation as a tool to change central and peripheral cardiovascular hemodynamics needs to be explored.

Effectiveness of Splanchnic Nerve Neurolysis for Targeting Location of Cancer Pain: Using the Pain Drawing as an Outcome Variable

The effectiveness of splanchnic nerve neurolysis (SNN) for cancer-related abdominal pain has been investigated using numeric pain intensity rating as an outcome variable. The outcome variable in this study used the grid method for obtaining a targeted pain drawing score on 60 patients with pain from pancreatic or gastro-intestinal primary cancers or metastatic disease to the abdominal region. Results demonstrate excellent inter-rater agreement (intra-class correlation [ICC] coefficient at pre-SNN = 0.97 and ICC at within one month post-SNN = 0.98) for the grid method of scoring the pain drawing and demonstrate psychometric generalizability among patients with cancer-related pain. Using the Wilcoxon signed rank test and associated effect sizes, results show significant improvement in dispersion of pain following SNN. Effect sizes for the difference in pre-SNN to 2 post-SNN time points were higher for the pain drawing than for pain intensity rating. Specifically, the effect size difference from pre- to within one month post-SNN was r = 0.42 for pain drawing versus r = 0.23 for pain intensity rating. Based on a smaller subset of patients who were seen within 1 - 6 months following SNN, the effect size difference from pre-SNN was r = 0.46 for pain drawing versus r = 0.00 for pain intensity rating. Collectively, these data support the use of the pain drawing as a reliable outcome measure among patients with cancer pain for procedures such as SNN that target specific location and dispersion of pain.

Surgical preparation of mice for recording cardiorespiratory parameters in vivo

BACKGROUND

The explosion in the use of genetically modified mouse strains to investigate function in biology has an enormous potential to expand on pharmacological studies traditionally conducted in rats. A key limitation to date is the inability to record from multiple nerves in an anaesthetised mouse for long periods.

NEW METHOD

Here we describe an in vivo preparation that maintains mice in a suitable physiological state, under anaesthesia, for at least 6 hr and also enables multiple cardiorespiratory recordings over that time.

RESULTS

Using the method described, blood pressure, heart rate, phrenic nerve activity, splanchnic nerve activity and heart rate were able to be recorded for hours in an anaesthetised, paralysed and mechanically ventilated mouse.

COMPARISON WITH EXISTING METHOD

Existing anaesthetised mouse preparations are limited by difficulties in maintaining mice under anaesthesia for long periods. This time constraint therefore limits the surgical time and number of cardiorespiratory variables recorded. It also limits the type of stimuli that can be administered and the length of recorded responses. The method described here optimises these variables to overcome these challenges.

CONCLUSIONS

In summary, we report an approach that enables physiological and pharmacological studies previously undertaken in larger animals or 'reduced' preparations, to be conducted in vivo in mice. We anticipate that the use of this preparation will enable a deeper understanding of genetic variation, and allow a much greater level of phenotypic characterisation in genetically modified mice.

[Efficacy of CT-guided splanchnic nerve block for persistent pain after fluoroscopy-guided nerve block in a patient with advanced pancreatic cancer]

We report a successful case of CT-guided splanchnic nerve block in a patient with advanced pancreatic cancer. A 76-year-old woman with epigastric distress was diagnosed with pancreatic cancer with multiple metastases. She underwent chemotherapy, but decided on best supportive care when her performance status worsened. Computed tomography revealed a 6 x 8 cm tumor mass in the pancreatic head. Oral oxycodone 20 mg x day(1) was ineffective and her Numerical Rating Scale (NRS) score was 9. Fluoroscopy-guided splanchnic nerve block with alcohol from L1-2 significantly reduced her pain, but she still required a fentanyl patch 2.1 mg x 3 days(-1) and loxoprofen (NRS 3). Four days later, we performed CT-guided splanchnic nerve block with alcohol 10 ml from T11-12. This significantly alleviated her pain and she was discharged uneventfully. She died 3 weeks after discharge. CT-guided splanchnic nerve block may be useful in cases of insufficient pain relief after fluoroscopy-guided splanchnic nerve block.

Anatomic identification and functional outcomes of the nerve sparing Okabayashi radical hysterectomy

OBJECTIVES

To clarify the anatomy necessary for the nerve sparing Okabayashi's radical hysterectomy, we meticulously separated the blood vessels and connective tissues to preserve the pelvic splanchnic nerve, the hypogastric nerve, and the bladder branch of the inferior hypogastric plexus under magnification (x2.5) during the Okabayashi radical hysterectomy.

METHODS

Twenty-four patients (FIGO stage IB, n=22, and stage IIA, n=2) underwent meticulous nerve sparing radical hysterectomy during 2004 to 2006. Postoperative assessment of bladder function consisted of the time to (a) achieve a postvoid residual urine volume (PVR) less than 50 ml, (b) obtain a sensation of bladder fullness, and (c) obtain satisfaction of micturition.

RESULTS

Isolation of the deep uterine vein could preserve one of the branches of the pelvic splanchnic nerve. The hypogastric nerve in the lateral rectal wall was isolated to the inferior hypogastric plexus. During the division of the posterior leaf of the vesicouterine ligament (VUL), isolation of the inferior vesical vein could reveal the bladder branch from the inferior hypogastric plexus. Only the uterine branch from the inferior hypogastric plexus was isolated and divided. Then, the T-shaped nerve plane consisting of the hypogastric nerve, the pelvic splanchnic nerve and the bladder branch from the inferior hypogastric plexus is preserved. Urinary functions: (a) 11 out of 24 patients had measured PVR of less than 50 ml by postoperative day (POD) 14 and all patients had achieved this by day 21 (mean POD: 14.64+/-2.04). (b) Twenty-two out of 24 patients reported a sensation of bladder fullness by POD 14 and all by POD 21 (mean POD: 11.25+/-1.78). (c) Seventeen out of 24 patients reported satisfaction of micturition by POD 14 and all by POD 21 (mean POD: 12.34+/-2.32).

CONCLUSION

In order to accomplish the nerve sparing Okabayashi's radical hysterectomy, it is necessary to meticulously divide the posterior leaf of the vesicouterine ligament. By the separation of the inferior vesical vein in the posterior leaf of the vesicouterine ligament, the bladder branch from the inferior hypogastric plexus can be identified and preserved. All patients recovered their urinary function completely by POD 21.

Abdominal pain related to mitochondrial neurogastrointestinal encephalomyopathy syndrome may benefit from splanchnic nerve blockade

Patients diagnosed with abdominal pain related to mitochondrial neurogastrointestinal encephalopathy (MNGIE) may benefit from splanchnic nerve blockade. MNGIE, varying in age of onset and rate of progression, is caused by loss of function mutation in thymidine phosphorylase gene. Gastrointestinal dysmotility, pseudo-obstruction and demyelinating sensorimotor peripheral neuropathy (stocking-glove sensory loss, absent tendon reflexes, distal limb weakness, and wasting) are the most prominent manifestations. Patients usually die in early adulthood (mean 37.6 years; range 26-58 years). We report a case of an 18-year-old patient with MNGIE. Our patient's abdominal pain was relieved after splanchnic nerve blockade.

"A girdle-like tightening sensation" misapprehended as abdominal splanchnopathy in a sarcoidosis patient

We describe a 53-year-old man with the isolated manifestation of girdle-like tightening sensation of the trunk due to polyradiculopathy at the beginning of sarcoidosis which was first misapprehended as abdominal splanchnopathy. Late development of other neurological and systemic symptoms led to the final diagnosis of sarcoidosis. Segmental dysesthesia at the trunk in neurosarcoidosis is unique and may mimic a splanchnic pain. Such a dysesthesia may be solely manifested at the beginning of sarcoidosis and may continue for days without other symptoms. When patients complain of a girdle-like tightening with unknown etiology, sarcoidosis should be suspected as the possible cause.

Efficacy of coeliac plexus and splanchnic nerve blockades in body and tail located pancreatic cancer pain

Palliative treatment, pain therapy and quality of life (QOL) are very important in pancreatic cancer patients. We evaluated the pain relieving efficacy, side effects and effects on QOL of neurolytic coeliac plexus blockade (NCPB) and splanchnic nerves neurolytic blockade (SNB) in body and tail located pancreatic cancer. The study protocol was approved by the local ethics committee. Patients were randomly divided into two groups. Coeliac group; GC, N = 19 were treated with coeliac plexus blockade, whereas the patients in splanchnic group; GS, N = 20 were treated with bilateral splanchnic nerve blockade. The VAS values, opioid consumption and QOL (Patient satisfaction scale=PSS, performance status scale=PS) were evaluated prior to the procedure and at 2 weeks intervals after the procedure with the survival rates. The demographic features were found to be similar. The VAS differences (difference of every control's value with baseline value) in GS were significantly higher than the VAS differences in GC on every control meaning that VAS values in GS decreased more than the VAS values in GC. GS patients were found to decrease the opioid consumption significantly more than GC till the 6th control. GS patients had significant improvement in PS values at the first control. The mean survival rate was found to be significantly lower in GC. Two patients had severe pain during injection in GC and 5 patients had intractable diarrhoea in GC. Comparing the ease, pain relieving efficacy, QOL-effects of the methods, splanchnic nerve blocks may be an alternative to coeliac plexus blockade in patients with advanced body and tail located pancreatic cancer.

Celiac ganglion block

The percutaneus blockade of the celiac plexus is being performed nearly for a century. The aim of performing celiac plexus and splancnic nerve blocks was surgical anesthesia at the beginning. But because of the technical demands and variable results of celiac plexus and splanchnic nerve blocks as a surgical anesthetic, over time, these techniques were supplanted by spinal anesthesia and segmental blockade of the somatic paravertebral nerves. As celiac plexus and splanchnic nerve blocks were falling into disuse for surgical anesthesia, the clinical utility of these techniques was becoming apparent in the new specialty of pain management. Celiac plexus and splancnic nerve blocks are effective in relieving chronic abdominal pain, especially originating from the malignancies of the pancreas, liver, gallbladder, omentum, mesentery, and alimentary tract from the stomach to the transverse portion of the large colon. The relevant anatomy, indications, cotraindications, different application techniques and results of celiac blockade is reviewed in this paper.

[Transdiscal percutaneous approach of splanchnic nerves]

Neurolytic celiac plexus block is an established, well-developed procedure and the most accepted and applied in visceral pain; recognized by the WHO and the IASP, it is very good in palliative management of cancer pain in visceral of superior hemiabdomen. However, conventional techniques in celiac plexus have not been successful in patients with organomegaly and/or anatomic abnormalities, except when splanchnic nerve neurolytic blockade is used. On the other hand, conventional techniques in splanchnic nerves are highly associated with complications such as paraplegia, pneumothorax and liver or renal punction. For these reasons an alternative option has ben designed, termed transdiscal percutaneous approach of splanchnic nerves under tomographic control; this technique affords the option of improving accuracy and performance with minimum risks, particularly lung puncture and its consequences. Under this technique, 64 superior hemi-abdomen cancer patients initiated such a study (four without morphine treatment quit the study), 55% females and 45% males, visceral pain syndrome 65%, and mixed, 35%. Side effects were dyspnea 5%, hypotension 26.7%, nausea 31.7%, diarrhea 83.3% in which diarrhea means increased peristalsis showing adequate sympathetic inhibition via splanchnic nerves), vomiting 28.3%, punction-site pain 46.7%, aorta punction 6.7%, anal pleural punction 5%. All these incidents were dealt with by conservative treatment. Student t test showed that pain intensity in all measurements after procedure was different in comparison to basal pain intensity prior to procedure (p<0.05), emphasizing that at the 12th, 18th and 24th months, there was noticeable reduction in participants number with eight, five and four participants, respectively. Morphine intake at week 1, and 1, 2, 3, 6 and 12 months after procedure was different from basal intake prior to procedure (p<0.05) with same noticeable reduction in participant numbers at last stages. Butylhioscine intake at week 1, 1, 2, 3 and 6 months after procedure was different from basal intake prior to procedure (p<0.05). NSAIDs consumption was likely during 2 months after procedure (p<0.05). Linear regression showed that butylhioscine and morphine explained low percentage of pain intensity variance, controlling statistically that effect over pain. There were no differences in pain pathophysiology with regard to cancer type. Transdiscal percutaneous approach of splanchnic nerves guided by CAT is an alternative with minimal risks, as with lung punction, confirming that inhibiting splanchnic nerves has advantages in pain release, reducing and/or eliminating morphine consumption.

Effects of protoveratrine, serotonin and ATP on afferent and splanchnic nerve activity

Splanchnic outflow was studied along with carotid and aortic presso- and chemoreceptor inflow in cats under a variety of conditions. Splanchnic activity was increased by a decrease in presso- or increase in chemoreceptor activity and vice-versa. Blood pressure rose following splanchnic activation. Protoveratrine and serotonin, reported to activate the "coronary chemoreflex," depressed completely splanchnic outflow, without enhancing pressoreceptor activity. Prolonged hypotension from protoveratrine coincided with partial return of splanchnic activity and tonic discharge of pressoreceptors. ATP increased splanchnic activity simultaneously with the hypotension and it is suggested that it be excluded from the list of drugs eliciting the "coronary chemoreflex."

Cryoablation of unresectable pancreatic cancer

BACKGROUND

Most patients with pancreatic cancer are not candidates for curative resection. The goal of this study was to evaluate the safety of an intraoperative ultrasound-guided cryosurgical procedure in a phase I study of unresectable pancreatic cancer.

METHODS

From March 1995 to March 1999, 10 cryosurgeries using intraoperative ultrasound were performed on 9 patients with unresectable cancers at laparotomy. Four patients had a concurrent gastrojejunostomy, 2 had a chemical splanchnicectomy, and 1 underwent a concurrent hepatic cryosurgical procedure.

RESULTS

There was no intraoperative morbidity or mortality. No patients developed postoperative pancreatitis or fistula. All patients had good pain control postoperatively and were tolerating a regular diet at the time of discharge. Pain control at discharge was achieved with an oral formulation (4/9), transdermal patch (3/9), no pain medication (1/9), and intravenous patient controlled analgesia (1/9).

CONCLUSIONS

Ultrasound-guided cryoablation for unresectable pancreatic cancer appears safe and may contribute to improved postoperative pain control. Future studies to determine its therapeutic role in the management of unresectable pancreatic cancer are indicated.

Effects of long-term renal sympathetic denervation on heart failure after myocardial infarction in rats

The purpose of the present study was to investigate the effects of long-term renal denervation (RD) on heart failure due to myocardial infarction (MI). Wistar rats were anesthetized and the bilateral renal nerves were surgically denervated 2 days before MI was induced by coronary artery ligation. Four weeks later, left ventricular (LV) function and sodium excretion were determined. In MI rats, RD improved the reduced sodium excretion. MI + RD rats revealed lower LV end-diastolic pressure and greater maximum dP/dt as compared with those of MI+ innervation (INN) rats. LV end-diastolic and end-systolic dimensions were significantly smaller and LV fractional shortening was greater in MI + RD rats than in MI + INN rats (20.9% +/- 3.2% vs 14.9% +/- 3.0%). In rats without MI, RD did not affect either sodium excretion or LV function and dimensions. The present results suggest that the long-term RD reduces LV filling pressure and improves LV function after MI, probably due to a restoration of impaired natriuresis. Increased renal sympathetic nerve activity might contribute to the progression of heart failure after MI.

The effect of drugs on spontaneous motility and on response to stimulation of the extrinsic nerves of the gut of a teleostean fish

Trout gut shows, in addition to changes in general muscle tone, longitudinal "pendular" rhythms, peristaltic waves, and longitudinal "colic" contractions. Both vagus and splanchnic nerves are motor and there is no evidence of antagonistic "sympathetic" and "parasympathetic" nervous control. A posterior autonomic nerve supplying the rectum stimulated or inhibited according to the duration and frequency of the electrical pulses applied. Acetylcholine increased the tone and amplitude of pendular movements in all regions of the gut, and produced strong contraction of the circular muscles. Both nicotine and hexamethonium antagonized the action of acetylcholine, suggesting that its principal site of action is the neurone. Adrenaline lowered the tone of the longitudinal muscle and abolished pendular activity in the intestine and rectum, but contracted the longitudinal and circular muscles of the stomach. Hexamethonium bromide abolished peristalsis but greatly increased the amplitude of pendular contractions.The reaction of the trout intestine to both histamine and pilocarpine was slight, but nicotine, 5-hydroxytryptamine, eserine, and barium caused strong contractions. The actions of atropine and piperoxan (933F) are discussed. Evidence is presented which suggests that the postganglionic vagus nerve fibres supplying the trout stomach may be adrenergic, while both the splanchnic nerve fibres to the stomach and intestine, and the preganglionic vagal fibres to the stomach, may be cholinergic. It is also suggested that there is a continuous release of acetylcholine by cholinergic neurones in the gut wall.

The release of adrenaline and noradrenaline from the adrenal medulla of the cat during splanchnic stimulation

Cats were anaesthetized with chloralose, eviscerated and the right adrenal gland was removed. The venous outflow from the left adrenal gland was collected during 10 five-minute periods of stimulation of the left splanchnic nerve. The amounts of adrenaline and noradrenaline in the venous outflow and in the stimulated and unstimulated glands were determined by a fluorimetric method. In eight experiments a mean of 50.5 mug. of total catechol amine was recovered from the effluent blood. The mean difference in amine content between the stimulated and unstimulated glands was 50 mug., representing a loss of 29% from the stimulated gland. The proportions of the two amines in the effluent blood were very similar to those found in the gland. The results provide no evidence for an increase in the rate of synthesis of catechol amines during splanchnic stimulation.

The actions of bretylium: adrenergic neurone blocking and other effects

Bretylium caused a specific and lasting depression of many excitatory and inhibitory responses evoked by electrical stimulation of the peripheral sympathetic nervous system, probably by impairing conduction of impulses in adrenergic neurones with consequent failure of noradrenaline and adrenaline release. This effect, which will be referred to as the adrenergic neurone blocking action, was preceded by weak sympathomimetic effects. In the presence of bretylium the effects of adrenaline and noradrenaline were increased, as after sympathectomy. Concentrations producing blocking of adrenergic neurones did not prevent the release of adrenaline and noradrenaline from the adrenal medulla by splanchnic nerve stimulation or by the injection of dimethylphenylpiperazinium iodide, nor did they cause antiparasympathetic or parasympathomimetic effects. No action on the central nervous system has been detected. Curare-like neuromuscular block occurred with 10 to 30 times the amount required to block the response to adrenergic nerve stimulation alone and was accompanied by signs of temporary synaptic block in autonomic ganglia. Adrenergic nerve trunks and sensory nerves in the skin were readily blocked for long periods by topical application of bretylium, whereas the phrenic nerve of the rat was not. Bretylium had little effect on gastrointestinal propulsion or on the sensitivity of smooth muscle to acetylcholine, 5-hydroxytryptamine, adrenaline, or noradrenaline, but moderate amounts depressed the peristaltic reflex and the sensitivity of the guinea-pig ileum to histamine. Bretylium caused postural hypotension in the cat in doses which had little effect on the supine blood pressure. Experiments on the nictitating membrane indicated that compensation for the effects of bretylium on low rates of stimulation of postganglionic sympathetic nerves could be attained by a small increase in the rate of stimulation, whereas compensation for its effects on high rates required an increase in the rate of stimulation beyond physiological limits.

The action of guanethidine with particular reference to the sympathetic nervous system

It has been suggested that guanethidine can release and then deplete postganglionic sympathetic nerve endings of noradrenaline. However, no release of noradrenaline from postganglionic nerve endings or from the adrenal medulla by guanethidine was found by direct experiment. Although release of noradrenaline from postganglionic sympathetic nerve endings in response to nerve stimulation was rapidly reduced and finally abolished by guanethidine, the drug did not appear to affect the release of catechol amines from the adrenal medulla in response to splanchnic nerve stimulation. The nature of the action of guanethidine is discussed, and it is concluded that it blocks the effect of postganglionic sympathetic nerve stimulation by interfering with the synthesis of transmitter and that it also has a direct sympathomimetic effect.

Is there a bilateral block of the thoracic sympathetic chain after unilateral intrapleural analgesia?

This study was designed to ascertain, by telethermography and clinical observation, the effect of injecting anesthetic solutions into the intrapleural space on thoracic sympathetic chains and splanchnic nerves. We studied 15 patients with neoplastic (n = 8) or benign (n = 7) pain, divided into three groups of 5 patients each. The first group received 20 mL of bupivacaine 0.25% in the intrapleural space, the second received 20 mL of bupivacaine 0.5%, and the third received 20 mL of isotonic sodium chloride solution. Each patient was examined telethermographically 30, 60, 90, and 120 min after the blockade. Visceral pain intensity was measured in eight patients using a visual analog scale. Patients receiving bupivacaine had a uniform bilateral increase of cutaneous temperature (+2 degrees C). In those with diffuse visceral pain, the mean value of the pain score decreased from 82 +/- 10 mm at the time of injection to 16 +/- 5 at 120 min. We conclude that intrapleural bupivacaine 0.25% and 0.5% results in bilateral blockade of the thoracic sympathetic chain and also of the splanchnic nerves, which pass in front of the spinal column between the two thoracic sympathetic chains. Our data indicate that intrapleural analgesia can be used in the treatment of not only unilateral visceral and somatic pain, but also diffuse abdominal visceral pain. The bilateral increase of the cutaneous temperature of the trunk (measured telethermographically) and the reduction of the diffuse visceral pain suggest a bilateral block of the sympathetic chain and of the splanchnic nerves.

IMPLICATIONS

We subjected 10 patients to monolateral intrapleural analgesia. Five other patients served as controls. The bilateral increase of the cutaneous temperature of the trunk (measured telethermographically) and the reduction of the diffuse visceral pain suggest a bilateral block of the sympathetic chain and of the splanchnic nerves. Our data indicate that intrapleural analgesia can be used in the treatment of not only unilateral visceral and somatic pain, but also diffuse abdominal visceral pain.

[Computerized tomography-guided neurolytic block of the splanchnic nerve]

CT-guided neurolytic splanchnic nerve block is a technique for relieving abdominal cancer pain; the goal is the alcoholic neurolytic interruption of the sensitive structures in retroperitoneal space. CT yields accurate anatomical detailing and the course for needle placement and alcohol spread. January, 1993, to July, 1996, twenty-one bilateral splanchnic nerve blocks were performed through the posterior access. Forty-eight hours after alcoholization, 14 patients (66%) had complete pain regression; 52% of the patients needed no analgesics for 6 to 54 days and only 9 patients (42%) needed another low opioid therapy. Complications included hypotension and diarrhea in all cases. One had a cardiac arrest and died 8 days after the procedure. There were no other complications. The whole procedure usually lasted 60 min (range: 45 to 90 min). Splanchnic nerve neurolysis is a useful treatment in the patients with severe chronic abdominal pain. It is used as a second line treatment when large lesions change celiac anatomy and complicate the percutaneous block of the celiac plexus.

Involvement of the adrenal medulla in ejaculatory reactions in the dog

To explore the peripheral signal controlling ejaculatory reactions, contraction of the seminal tract and seminal emission were monitored in the dog during electrical stimulation of the lumbar and greater splanchinc nerves in the presence or absence of sympathetic pathways connecting the lumbar sympathetic trunk to the seminal tract including the vas deferens, prostate and bladder neck. Electrical stimulation of the lumbar splanchnic nerve caused seminal emission, elevation of intraluminal pressure of the vas deferens and bladder neck, and contraction of the prostate without elevation of blood pressure. Transection of all peripheral sympathetic nerve pathways to the seminal tract completely blocked these responses. Electrical stimulation of the greater splanchnic nerve caused a marked elevation of blood pressure as well as the responses described above in both the presence and absence of peripheral sympathetic nerve pathways to the seminal tract. However, clamping the adrenal veins bilaterally blocked all of the above responses and declamping immediately reversed the block. Serum levels of epinephrine, norepinephrine and dopamine were significantly increased by electrical stimulation of the greater splanchnic nerve, while cortisol levels remained unchanged. Furthermore, intravenous administration of epinephrine (5 micrograms/kg) caused responses similar to those elicited by stimulating the greater splanchnic nerve. Dogs in which all sympathetic pathways to the seminal tract had been transected chronically showed retrograde ejaculation during manual penile stimulation. The above results indicate possible involvement of the greater splanchnic nerve and adrenal medulla in ejaculatory reactions in the dog.

Effect and clinical value of splanchnic nerve block of hemodynamics in ACST

The condition of acute cholangitis of severe type (ACST) develops very rapidly and the prognosis is poor. The main clinical feature is that there is an obvious dynamic variation, which is the principal factor for the early occurrence of shock and death. In this study the Japanese long ear rabbits were used and biliary tract pressure increasing and splanchnic nervous plexus blocking experiments were conducted. Our results indicate that 0.6% of lidocaine can be used to block the right celiac plexus. It can avoid the decrease of blood pressure due to the pressure increase of the biliary tract, and the decrease of blood pressure due to the pressure increase of the biliary tract can be corrected by local anesthesia. 8 cases in conformity with the ACST diagnostic standards received the right renal capsule block injection for the purpose of stopping the celiac plexus, 6 cases of whom had a return of blood pressure to various extent, suggesting that the splanchnic nervous activity in the occurrence of ACST is of great significance. The technique may provide a new approach for the clinical treatment of ACST.

THE MECHANISM OF THE PRESSOR RESPONSES TO PHYSOSTIGMINE IN THE RAT AND THEIR MODIFICATION BY MEBUTAMATE AND AMYLOBARBITONE

Pressor responses to intravenous injections both of physostigmine and of pilocarpine were smaller in rats anaesthetized with either mebutamate or amylobarbitone than in rats anaesthetized with urethane. The response to electrical stimulation of the hypogastric nerve in the isolated hypogastric nerve-vas deferens preparation was diminished by mebutamate and by amylobarbitone, but not by urethane. Similar results were obtained with the cat isolated splenic nerve-spleen preparation. In the rat anaesthetized with urethane, pressor responses to physostigmine were only partially antagonized by hexamethonium but were completely abolished during "depolarizing" ganglionic block by nicotine or tetramethylammonium. It is suggested that, in addition to the central mechanism, there is a peripheral component in the pressor action of physostigmine and in the antihypertensive actions of mebutamate and amylobarbitone.

INNERVATION OF THE LARGE INTESTINE OF THE TOAD (BUFO MARINUS)

The morphology, physiology and pharmacology of the innervation of the toad (Bufo marinus) large intestine have been studied. The large intestine can be divided into the regions colon, rectum and cloaca, on morphological grounds, but acts as a unit in response to nerve stimulation. Of the right and left nerves, each appears to supply the entire large intestine. Autonomic innervation of the large intestine of Bufo marinus is as follows: (1) The 9th and 10th spinal nerves (pelvic) contain predominantly excitatory preganglionic cholinergic fibres, but some inhibitory adrenergic fibres are also present in most preparations. (2) The splanchnic nerves contain inhibitory postganglionic adrenergic fibres from the 3rd to 5th sympathetic ganglia, and a small number of excitatory cholinergic fibres. The pathway of adrenergic inhibitory fibres to the large intestine alongside the posterior mesenteric artery as seen in mammals is rarely present in the toad. Several nonspecific actions of autonomic drugs on the large intestine are discussed. The functional organization of the autonomic innervation of the toad large intestine is similar to that in mammals, that is the large intestine is controlled by antagonistic cholinergic and adrenergic nerves. However, the separation of these two types of nerve fibres into anatomically distinct nerves does not appear to be as complete as in mammals. It is suggested that inhibitory autonomic control of the alimentary canal in vertebrates first appears in the hind-gut region.