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Approximately 5-8 million people in Germany suffer from chronic pain. Some patients can obtain relief from specific interventional techniques. In detail these are blocks of the sympathetic chain and peripheral nerve blocks, regional anesthetic techniques close to the spinal cord and neuromodulation. Part 1 of this article presents peripheral nerve blocks using the example of intercostal blocks and blocks of the sympathetic chain. Peripheral nerve blocks are important for postoperative pain treatment. Only a few methods are used for chronic pain and this applies primarily to the intercostal block which is used for the treatment of pain occurring after thoracotomy, intercostal neuralgia and pain associated with infiltration of cancer. Blocks of the vegetative nervous system are accomplished on the ganglions of the head and the sympathetic chain and are therefore most commonly applied to treat headache, neuropathic and sympathetic pain in the area of abdomen and the extremities.

Objective: Cervicothoracic sympathetic blocks (stellate ganglion blocks) not only influence pain, but also lead to regional sympathetic denervation of part of the left ventricular wall, while other ventricular regions stay under the control of the unblocked side. What is the influence of these imbalances of sympathetic innervation on ventricular function?, Methods: Thirteen anaesthetised dogs were instrumented for measurement of left ventricular pressure (tip-manometer), cardiac output (ultrasonic flow probe) and regional myocardial function (sonomicrometry) in two left ventricular regions, innervated by the left or right sympathetic system, respectively. Electrical stimulations of the left and right stellate ganglia, and left and right sided stellate ganglion blocks were performed. In eight patients with no cardiac disease, the effects of left stellate ganglion blocks on echocardiographic variables of ventricular function were investigated., Results: In dogs, the unilateral ganglion stimulations led to an increase in regional and global contractility. However, left ventricular wall motion became asynchronous and, despite an increase in contractility, relaxation was impaired. After the ganglion blocks, there was a decrease in regional contractility within the denervated area, also leading to an asynchronous wall motion. As a consequence, relaxation was impaired, but cardiac output was maintained. In the patients, there was an increase in isovolumic relaxation time. This change was also within the compensatory range and cardiac output increased slightly as a consequence of a simultaneous afterload reduction by the ganglion block., Conclusion: The studies show a disturbance of diastolic function after stellate ganglion blocks, resulting from an asynchronous wall motion pattern after the regional denervation. However, the changes were within the compensatory range of a healthy ventricle and cardiac output was not reduced.

Repetitive nerve blocks as a monotherapeutic treatment are loosing importance in the therapy of chronic pain. Such invasive methods for pain reduction are just one strategy in the interdisciplinary and multimodal planning of pain therapy. They are mostly used in special indications, e.g. reflex sympathetic dystrophy neurolysis in S3-S5 localized cancer pain. Premises for an invasive pain therapy are the patient's knowledge and agreement concerning this method. Furthermore, it is necessary for the physician to know the typical complications of the invasive treatment and to be able to manage them. It is recommended to document the pain course.

Stellate ganglion blockade (SGB) is an established method in the therapy of chronic pain syndromes. Complications are rare but can be life-threatening (inadvertant subarachnoid or intra-arterial injection). Since no data are currently available as to the incidence of complications, we sent questionnaires to 76 departments of anaesthesiology in West Germany to evaluate this issue. RESULTS. Thirty-nine questionnaires (51%) were returned, representing approximately 45,000 SGBs; 82% of the departments prefer bupivacaine for SGB. The incidence of severe complications was 1.7 in 1000 blockades. Most of these were CNS complications (i.e., convulsions). A high subarachnoid block was reported in 6 cases, high epidural blockade in 3, pneumothorax in 9, and allergic reactions in 2. All departments conduct aspiration tests before injection; 94% take precautionary measures in case of respiratory failure (oxygen, ventilating devices); 73% do not perform SGB without an assistant and an anticonvulsant drug at hand; 72% place an intravenous line before SGB; 28% use ECG monitoring routinely; and 53% administer a test dose of 0.5-2 ml local anaesthetic. DISCUSSION. Severe complications following SGB are rare. Potentially life-threatening complications usually arise from inadvertant subarachnoid or intra-arterial injection. Aspiration tests and test doses obviously do not guarantee proper administration. Placement of an intravenous line, ECG monitoring, and the presence of an assistant are strongly recommended. Anticonvulsant drugs as well as drugs and equipment for intubation and resuscitation should be immediately available. The administration of very low doses of opioids to the stellate ganglion has been shown to have similar therapeutic results to local anaesthetic blocks, whereas the incidence of side effects and complications is lower. Therefore, the administration of opioids to sympathetic ganglia could provide an alternative therapeutic regimen for the future.

Brachial plexus paralysis is a serious complication of stellate blockade (n = 2) and plexus anaesthesia (n = 6) as was observed in 8 patients. It is frequently characterised by localised motor and sensory defects in the affected arm and sometimes accompanied by a causalgia-like pain. Pathogenetically mechanical factors--needle trauma, injection pressure, volume, and velocity--are of decisive importance. Prophylactically intraneural injections must be avoided. The electrifying pain during insertion of the needle and (or) immediate anaesthetic effect require correction of needle position.

Coeliac plexus nerve block by alcohol through a percutaneously introduced, ultrasonically guided, small needle was performed in 36 patients with severe chronic upper-abdominal pains, 32 of them with malignant and four with benign disease. In 11 patients there was lasting, in eight transitory freedom from the pain, while in five other patients there was a definite diminution of pain, and the use of analgesics and especially opiates was discontinued or at least markedly reduced. Body-weight increased in 14 patients. In a woman with chronic pancreatic pain who had several previous operations alcohol injection triggered off an acute attack of pancreatitis which ended fatally.