Supraclavicular brachial plexus anatomical variation leading to rare left recurrent laryngeal nerve block along with block failure: A case report : Bali Journal of Anesthesiology

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Supraclavicular brachial plexus anatomical variation leading to rare left recurrent laryngeal nerve block along with block failure: A case report

Jain, Mamta1,; Bansal, Teena1; Singh, Anish Kumar1; Mittal, Kiran2

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Bali Journal of Anesthesiology 7(2):p 121-123, April-June 2023. | DOI: 10.4103/bjoa.bjoa_23_23
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Hoarseness of voice resulting from recurrent laryngeal nerve block is occasionally seen after interscalene brachial plexus block, but chances are remote in the case of supraclavicular approach with a reported incidence of 1.3% and rarer on left compared with the right side. Anatomical variations not only increase the chances of block failure but also increase the risk of side effects or complications. We report a case of hoarseness of voice after left-sided supraclavicular brachial plexus block in a variant anatomy that completely resolved after 10–12 h postoperatively. Hence, whenever anatomical variation is found in sonography, extreme caution should be taken while administering block.


Incidence of success rate has increased and complications have markedly decreased by using ultrasound guidance for brachial plexus block (BPB).[1] But the same is not true in the presence of anatomical variations.[2,3] Blockade of recurrent laryngeal nerve (RLN) is relatively common and well-documented after interscalene block compared with supraclavicular BPB due to its close proximity to plexus at this location.[4] However, its chances are remote in the case of supraclavicular BPB (1.3%) and rarer on the left side compared with the right side.[5] We report a case of hoarseness of voice after left-sided supraclavicular BPB in a variant anatomy that completely resolved after 10–12 h postoperatively.

Case Report

A 50-year-old male weighing 68 kg and 170 cm in height was scheduled for fixation of fracture humerus. Regional anesthesia of limb was planned by giving ultrasound-guided supraclavicular BPB. Standard monitoring including electrocardiograph, pulse oximetry (SpO2), and noninvasive blood pressure was started and light sedation in the form of midazolam 2 mg was administered. Block was given in supine position with soft roll between the shoulders. Under all aseptic precautions, scanning of the supraclavicular area was done using linear probe of high frequency (6–13 MHz) of SonoSite M-Turbo machine at the midpoint of clavicle. A variant anatomy, as shown in Figure 1, was observed.

Figure 1::
Ultrasound image showing variant anatomy of left supraclavicular area before block (red arrows indicate vessels and green arrow indicates brachial plexus)

The needle was inserted in plane from lateral to medial side. After visualization of needle tip at the specific locations and carefully observing for hydrodissection, drug was deposited at two points: first between the first rib and lower end of the plexus and second at the upper end of the plexus [Figure 2]. A total of 25 mL of local anesthetic (LA) (10 mL of 0.5% bupivacaine and 10 mL of 2% lignocaine with adrenaline 1:2,00,000, and 5 mL of normal saline) was administered, 12.5 mL at each point. On evaluating after 15–20 min, no sensory or motor effect was observed. Only sympathetic blockade as evaluated by change in local skin temperature and veins engorgement was recorded. After 20 min of block administration, patient started complaining of difficulty in speech, and hoarseness of voice was noted. No difficulty in breathing or fall in saturation was seen. Vitals remained stable except slight tachycardia that too could be due to anxiety of voice change. Pneumothorax was ruled out by careful auscultation and also doing bedside lung ultrasound. Patient was reassured by explaining the transient nature of this complication. Surgery was done under general anesthesia with supraglottic airway device. Surgery lasted for two and a half hours. At the end of surgery, patient was reassessed for hoarseness of voice that was still present. After 10–12 h, hoarseness of voice resolved completely, and the rest of the postoperative period was uneventful.

Figure 2::
Ultrasound image of left supraclavicular brachial plexus with anatomical variation after block (red arrows indicate vessels and green arrow indicates brachial plexus)


Hoarseness of voice resulting from unintended RLN block has been reported after interscalene BPB due to the close proximity of neurovascular bundle at this location.[4] However, it is reasonable to carefully exclude the other causes of hoarseness of voice (e.g., pneumothorax, severe bronchospasm) that require urgent management by careful auscultation, vital monitoring, and appropriate radiology or other bedside tests.

RLN blockade leading to hoarseness of voice during BPB at supraclavicular area is rarer but has been reported by a few authors that too commonly on the right side.[5] This side effect results from the unintended distal spread of LA along subclavian artery (SCA) to the position where the right RLN loops under the artery.[6,7] Whereas on the left side, as the nerve lies more medial to SCA and loops around the aortic arch more distally, so chances of its blockade are rare.[6,7] In a rare case report of left RLN block by Naaz et al.,[7] they explained this could be due to the blockade of RLN fibers present in vagus nerve that lies medial to SCA instead of direct spread to left RLN, as medial spread of LA was noted in their case.

It is advised to use lower volumes of LA under ultrasound guidance to prevent the unintended medial spread of LA and to decrease these side effects. Classically, the brachial plexus lies superior and posteriolateral to SCA over the first rib in the supraclavicular area. However, in our case, due to anatomical variation, brachial plexus seems to lie between two vessels resting on the first rib [Figure 1]. We deposited LA in brachia plexus between these two vessels, possibly the lateral vessel could be SCA and drug being deposited medial to it. As the RLN lies medial to SCA, so this may be the cause of relatively rarer left RLN blockade in our case. In the presence of anatomical variations, chances of block failure and side effects or complication increase even under ultrasound guidance.[2,3]

It has been observed that the effective spread of LA to the complete plexus may be limited by the abnormal vessels mostly the dorsal scapular artery and the transverse cervical artery passing through the plexus.[2,3] So in cases of anatomical variations, it is advisable to either use nerve stimulator in addition to ultrasound to improve the chances of success or to administer block at a different location along the nerve course, or to abandon the procedure and go for general anesthesia.


Ultrasound guidance does help in identifying the anatomical variations but performing block in a variant anatomy, and increases the chances of block failure as well as side effects or complication. So, it is prudent to avoid giving block at the location with variable anatomy.

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Conflicts of interest

There are no conflicts of interest.


1. Lewis SR, Price A, Walker KJ, McGrattan K, Smith AF. Ultrasound guidance for upper and lower limb blocks. Cochrane Database Syst Rev 2015;2015:CD006459
2. Kinjo S, Frankel A. Failure of supraclavicular block under ultrasound guidance: Clinical relevance of anatomical variation of cervical vessels. J Anesth 2012;26:100-2
3. Sites BD, Macfarlane AJ, Sites VR, Naraghi AM, Chan VWS, Antonakakis JG, et al. Clinical sonopathology for the regional anesthesiologist: Part 1: Vascular and neural. Reg Anesth Pain Med 2010;35:272-80
4. Guo CW, Ma JX, Ma XL, Lu B, Wang Y, Tian AX, et al. Supraclavicular block versus interscalene brachial plexus block for shoulder surgery: A meta-analysis of clinical control trials. Int J Surg 2017;45: 85-91
5. Neal JM, Gerancher JC, Hebl JR, Ilfeld BM, McCartney CJ, Franco CD, et al. Upper extremity regional anesthesia: Essentials of our current understanding, 2008. Reg Anesth Pain Med 2009;34:134-70. Review. Erratum in: Reg Anesth Pain Med. 2010;35:407
6. Sahu SK, Badole U. A rare complication in ultrasound-guided supraclavicular brachial plexus block. Res Innov Anesth 2016;1: 30-1
7. Naaz S, Asghar A, Jha NK, Ozair E. A unique case of hoarseness of voice following left supraclavicular brachial plexus block. Saudi J Anaesth 2020;14:109-11

Anatomical variation; brachial plexus block; hoarseness of voice; recurrent laryngeal nerve

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