CHAPTER 65 Sympathetic System
STELLATE GANGLION BLOCK
Clinical syndrome
‘Sympathetically maintained pain’ is defined as ‘pain that is maintained by sympathetic efferent innervation or by circulating catecholamines (especially norepinephrine).’1 This presents an assumed pain mechanism, not a clinical syndrome, and therefore it can be present in different pain syndromes. The most common places where it occurs are the extremities and the face. Disturbances in the mechanism of the sympathetic system of the face and the upper extremity can give the following symptoms: swelling, hyperhidrosis, disturbances in the temperature regulation of the skin, and changes in skin coloring. There are several diseases and syndromes that can show disturbances in the sympathetic innervation. One example is the complex regional pain syndrome type 1 (CRPS-1) that is characterized by continuing pain after an initiating noxious event or after an immobilization, allodynia, or hyperalgesia with which the pain is disproportionate to any inciting event.2 There is a growing controversy on the value of sympathetic blocks in CRPS-1 and 2. A recent review raises questions on the efficacy of local anesthetic sympathetic blockade as a treatment of CRPS. In this review it was concluded that less than one-third of patients involved in trials obtained full pain relief.3 Further studies are needed to clarify this indication.
Indications and contraindications
Side effects and complications
One of the most serious complications can occur if there is an unintentional injection involving the vertebral and/or the carotid artery,7 as seizures that are difficult to treat will result. Accidental injection intrathecally will lead to respiratory failure and the requirement of mechanical ventilation.8–11 In anticipation of these potential complications, it is advised that an intravenous line be in place prior to the blockade. A less serious but quite disconcerting side effect results from inadvertent diffusion of local anesthetics into nearby nerve structures. In particular, blockade of the recurrent laryngeal nerve typically results in hoarseness, the sensation of a mass in the throat, and sometimes a subjective shortness of breath. Of course, this complication can be dangerous when the blockade has been performed bilaterally in patients with preprocedural respiratory impairment.12 In other instances, a partial blockade of the brachial plexus with temporary paralysis of arm musculature can result.13 If the phrenic nerve is blocked, a temporary unilateral paralysis of the diaphragm transpires with resultant respiratory impairment.14
Outcomes
There are only a handful of published studies regarding the efficacy of a stellate ganglion block. In 1983, Bonelli et al. performed a randomized, controlled trial in patients with reflex sympathetic dystrophy (RSD) of the upper extremity in which they compared the efficacy of stellate ganglion block using 15 ml bupivacaine 0.5%, up to a total of eight blocks, with treatment by a regional intravenous sympathetic block using 20 mg guanethidine every 4 days up to a total of four blocks.15 They concluded that there was a significant improvement in the visual analogue scale (VAS), skin temperature, and skin plethysmography as compared to baseline. There were no significant baseline differences between the two groups. Malmqvist et al. published a randomized controlled trial in 1992 which assessed the efficacy of stellate ganglion blocks using different concentrations and volumes of local anesthetic and different sites of injection.16 They called the sympathetic block ‘complete’ if the following five criteria were met: the presence of a change in skin temperature, skin blood flow, resistance response and skin resistance level, and the symptoms of Horner’s syndrome. They concluded that it is difficult to perform a block that meets all the five criteria since only six of the 54 blocks met all five criteria. They claimed that injection toward C7 (instead of injection toward C6) and a high concentration were more likely to achieve a successful block. The volume seemed of less importance.
There has been only one study performed addressing RF lesioning of the stellate ganglion for the treatment of pain in the upper extremity caused by RSD.17 It was a poorly designed retrospective study.
In 1998, Price et al. published a study with a small number of participants in which they compared the efficacy of a sympathetic ganglion block using 1% lidocaine/bupivacaine and a block with normal saline in patients with CRPS-1 using a double-blinded, cross-over paradigm.18