Brachial plexus block

A conduction block is a type of regional anesthesia produced by injection of a local anesthetic drug into or near a nerve trunk. Examples of a conduction block include an epidural block (injection of a local anesthetic into the space surrounding the dura of the spinal cord) a trails sacral (caudal) block (injection of a local anesthetic into the epidural space at the level of the sacrococcygeal notch) and brachial plexus block (injection of a local anesdietic into the brachial plexus). Epidural, especially, and trailssacral blocks are often used in obstetrics. A brachial plexus block may be used for surgery of the arm or hand. 

Regional block, a form of anesthesia that includes spinal and epidural anesthesia, involves injection near a nerve or nerve plexus proximal to the surgical site. It provides excellent anesthesia for a variety of procedures. Brachial plexus block is commonly used for the upper extremity. Individual blocks of the sciatic, femoral, and obturator nerves can be used for the lower extremity. An amount that is close to the maximally tolerated dose is required to produce blockade of a major extremity. 

Intra-arterial injection of thiopentone is a serious complication as crystals of the thiobarbiturate can form in the arterioles and capillaries, causing intense pain, vasoconstriction, thrombosis, and even tissue necrosis. Accidental intra-arterial injections should be treated promptly with intra-arterial administration of a vasodilator (papaverine 20 mg) and lignocaine (lidocaine) Note leave the needle/cannula in the artery), as well as a regional anaesthesia-induced sympathectomy (stellate ganglion block, brachial plexus block) and anticoagulation with intravenous heparin. The risk of ischaemic damage is much higher with a 5% solution and the use of this concentration is not recommended. 

The variability can be accounted for largely by the diffusion barriers of the different fibre types and by Na+ channel density. For example, the presence of a Schwann cell and myelin sheath poses a considerable barrier to the diffusion of local anaesthetic to the interior of the cell. There is in vitro evidence to indicate that all desheathed nerves require a similar minimum concentration of local anaesthetic to induce block irrespective of fibre type. A consequence of the physical architecture of a mixed nerve is that access of the drug to the outer fibres is easier than access to fibres at the core. It is for this reason that the onset of proximal analgesia of the limb precedes distal analgesia with a brachial plexus block. 

Crews JC, Rothman TE. Seizure after levobupivacaine for interscalene brachial plexus block. Anesth Analg. 2003 96 1188-1190. 

Liisanantti O, Luukkonen J, Rosenberg PH. High-dose bupivacaine, levobupivacaine and ropivacaine in axillary brachial plexus block. Acta Anaesthesiol Scand. 2004 48 601-606. 

Singelyn FJ, Lhotel L, Fabre B. Pain relief after arthroscopic shoulder surgery a comparison of intraar-ticular analgesia, suprascapular nerve block, and inter-scalene brachial plexus block. Anesth Analg. 2004 99 589-592. 

A healthy 17-year-old man received an interscalene brachial plexus block using mepivacaine 600 mg and bupivacaine 150 mg. He became disorientated and showed signs of local anesthetic toxicity, for which he was given midazolam 5 mg. Flumazenil 0.5 mg was given 23 minutes after the end of the procedure, causing opisthotonos. 

Karakaya D, Buyukgoz F, Baris S, Guldogus F, Tur A. Addition of fentanyl to bupivacaine prolongs anesthesia and analgesia in axUlaiy brachial plexus block. Reg Anesth Pain Med 2001 26(5) 434-8. 

A 60-year-old 70 kg woman with a fractured radius had an axillary brachial plexus block for postoperative analgesia after uneventful general anesthesia (5). A 50 mm insulated regional block needle attached to a nerve stimulator was used to locate the brachial plexus, and after negative aspiration, levobupivacaine 125 mg was injected with intermittent aspiration. Within 30 seconds the patient had a generalized tonic-clonic seizure which lasted about 30 seconds and self-terminated. She remained car-diovascularly stable and made an uneventful recovery. 

The adverse effects of ropivacaine and bupivacaine have been compared in 104 patients who received 30 ml of either 0.75% ropivacaine or 0.5% bupivacaine for subclavian perivascular brachial plexus block (48). There were similar incidences of nausea (33 and 28%), vomiting (8 and 14%), and Horner s syndrome (8 and 6%), and one patient who received bupivacaine developed a tonic-clonic generalized seizure 8 minutes after injection, suggestive of systemic toxicity. 

Pulmonary embolism has been attributed to brachial plexus block. 

An 84-year-old woman weighing 74 kg had a past history of hypertension, emphysema, and ischemic heart disease. She had an infraclavicular brachial plexus block with 40 ml (400 mg) of prilocaine 1% and 10 ml (75 mg) of ropivacaine 0.75%, and 20 minutes later developed difficulty in breathing and became desaturated. She had received midazolam 2 mg before the block. 

A 47-year-old woman with a history of hypertension, gastric reflux, and obesity was premedicated with oxazepam 10 mg and had an infraclavicular brachial plexus block with the same doses of ropivacaine and prilocaine as in the first case 10 minutes later she developed dyspnea and became desaturated. 

A 47-year-old woman received an axillary brachial plexus block with 3 ml of 1% lidocaine after negative aspiration. She became dysphoric 30 seconds later, with muscle twitching in the face and distal arms, became unresponsive, and required ventilation. 

Horner s syndrome is a well-recognized complication of interscalene brachial plexus block, stellate ganglion block, and occasionally epidural blockade. It occurs when the local anesthetic reaches the cervical sympathetic trunk and is usually transient. However, persistent Horner s syndrome is a rare complication, and may represent traumatic interruption of the cervical sympathetic chain. Cases of prolonged Horner s syndrome related to prevertebral hematoma formation at the site of continuous interscalene blockade have been described (66). 

Korman B, Riley RH. Convukions induced by ropivacaine during interscalene brachial plexus block. Anesth Analg 1997 85(5) 1128-9. 

Sala-Blanch X, Lazaro JR, Correa J, Gomez-Fernandez M. Phrenic nerve block caused by interscalene brachial plexus block effects of digital pressure and a low volume of local anesthetic. Reg Anesth Pain Med 1999 24(3) 231-5. 

Matthes H, Denhardt B. Erfahrungen bei Blockaden des Plexus brachialis. [Experiences with brachial plexus blocks.] Langenbecks Arch Chir 1977 345 505-10. 

Mak PH, Irwin MG, Ooi CG, Chow BF. Incidence of diaphragmatic paralysis following supraclavicular brachial plexus block and its effect on pulmonary function. Anaesthesia 2001 56(4) 352-6. 

Dominguez E, Garbaccio MC. Reverse arterial blood flow mediated local anesthetic central nervous system toxicity during axillary brachial plexus block. Anesthesiology 1999 91(3) 901-2. 

Raeder JC, Drosdahl S, Klaastad O, Kvalsvik O, Isaksen B, Stromskag KE, Mowinckel P, Bergheim R, Selander D. Axillary brachial plexus block with ropivacaine 7.5 mg/ml. A comparative study with bupivacaine 5 mg/ml Acta Anaesthesiol Scand 1999 43(8) 794-8. 

Rodriguez J, Quintela O, Lopez-Rivadulla M, Barcena M, Diz C, Alvarez J. High doses of mepivacaine for brachial plexus block in patients with end-stage chronic renal failure. A pilot study. Eur J Anaesthesiol 2001 18(3) 171-6. 

Two episodes of central nervous system toxicity without significant cardiovascular toxicity have been described in a patient who had brachial plexus blocks with excessively high doses of ropivacaine 6 weeks apart (6). 

A 56-year-old 70 kg woman with a Colles fracture received a brachial plexus block at the humeral canal with 0.75% ropivacaine 40 ml using a nerve stimulator (11). The local anesthetic was administered slowly with negative intermittent aspiration. However, 15 minutes later she had two generalized convulsions, which were treated with diazepam. The total venous ropivacaine concentration measured 2 hours after the block was 2.3 gg/ml. 

Ala-Kokko TI, Lopponen A, Alahuhta S. Two instances of central nervous system toxicity in the same patient foUow-ing repeated ropivacaine-induced brachial plexus block. Acta Anaesthesiol Scand 2000 44(5) 623-6. 

Injection of a local anesthetic into or around individual peripheral nerves or nerve plexuses produces even greater areas of anesthesia than do the techniques described above. Blockade of mixed peripheral nerves and nerve plexuses also usually anesthetizes somatic motor nerves, producing skeletal muscle relaxation, which is essential for some surgical procedures. The areas of sensory and motor block usually start several centimeters distal to the site of injection. Brachial plexus blocks are particularly useful for procedures on the upper extremity and shoulder. Intercostal nerve blocks are effective for anesthesia and relaxation of the anterior abdominal wall. Cervical plexus block is appropriate for surgery of the neck. Sciatic and femoral nerve blocks are useful for surgery distal to the knee. Other useful nerve blocks prior to surgical procedures include blocks of individual nerves at the wrist and at the ankle, blocks of individual nerves such as the median or ulnar at the elbow, and blocks of sensory cranial nerves. 

Freysz M, Beal JL, D Athis P, Mounie J, Wilkening M, Escousse A, Pharmacokinetics of bupivacaine after axillary brachial plexus block, IntJClin Pharmacol Ther Toxicol (1987) 25,392-5,... 

Nerve injuries have also been reported after combined ultrasound- and electrostimulation-guided supraclavicular brachial plexus block [9" ]. 

Dhir S, Ganapathy S, Lindsay P, Athwal GS. Case report ropivacaine neurotoxicity at clinical doses in interscalene brachial plexus block. Can J Anaesth 2007 54 912-6. 

Reiss W, Kurapati S, Shariat A, Hadzic A. Nerve injury complicating ultrasound/elec-trostimulation-guided supraclavicular brachial plexus block. Reg Anesth Pain Med 2010 35 400-1. 

Fig. 11.1. Pancoast s syndrome with major cervical spine invasion in a patient with excruciating pain in the upper limb. A 22-gauge needle was introduced just lateral to the transverse process of the affected vertebra under CT guidance. The spinal nerve lies in the sulcus of the transverse process. Brachial plexus block was performed at C5 and C6 level. Slight weakness of the limb after alcoholization. Good pain relief was obtained lasting until death of the patient 6 weeks later...

Brachial plexus block with 50% ethanol produces effective pain relief with manageable weakness of the limb. 

Mullin V (1980) Brachial plexus block with phenol for painful arm associated with Pancoast s syndrome. Anesthesiology 53 431... 

One of the first uses of local anesthetics (LA) for anesthesia was in the late nineteenth century with William Halsted reporting a mandibular block and brachial plexus block using cocaine [37,38]. The chemical structure of local anesthetics in clinical use consists of an aromatic (lipophilic) benzene ring linked to an amino group (hydrophflic) via either an ester or an amide intermediate chain. The intermediate link classifies the local anesthetic as either an ester (procaine, chloroprocaine, tetracaine, and cocaine) or an amide (lidocaine, prilocaine, mepivacaine, bupi-vacaine, etidocaine, and ropivacaine). 

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