Elderly male with shoulder injury

By Husain Bawany, MD
Edited by Hani I. Kuttab, MD and Matthew VandeHei, MD

Clinical Case

An elderly male is brought to the emergency department (ED) after tripping over his walker and falling to the ground. His past medical history is significant for hypertension, diabetes, chronic kidney disease, and heart failure. Vital signs are reassuring. Physical examination is significant for shoulder asymmetry. An X-ray is obtained, demonstrating an anterior dislocation of the right shoulder. The treating team is planning for a closed reduction.

To Sedate or Not to Sedate? Enter the Interscalene Nerve Block

Procedural sedation has downsides, including requiring a period of constant observation for airway monitoring and signs of hemodynamic compromise, especially in those with comorbidities. Additionally, procedural sedation has been associated with adverse outcomes such as respiratory depression, vomiting, and longer ED length of stay when compared with nerve blocks (an average of 228-343 minutes, compared to 60-150 minutes in patients who have received a nerve block).^1-2 Similarly, high doses of opioids are associated with significant risks, especially in an elderly population. The brachial plexus block can provide analgesia from the shoulder to the fingertips depending on the technique, and can thus be utilized for a variety of upper extremity procedures. Common techniques include the interscalene approach and supraclavicular approach.

The interscalene nerve block provides an alternative to procedural sedation and high dose opioids when managing injuries of the upper extremity. In addition to shoulder dislocations, indications for this block include humeral head fractures as well as very proximal arm abscess I&D. The advantage of the interscalene approach is that it provides complete coverage of the shoulder girdle and upper arm and has a lower risk of pneumothorax when compared to the supraclavicular approach.² Furthermore, not only does it offer the potential to decrease ED length of stay, but it can offer pain control comparable to procedural sedation.³ 

An Anatomy Refresher

When performing the interscalene brachial plexus block, the goal is to place anesthetic at the level of the C5 and C6 nerve roots; the inferior portions of the brachial plexus are usually spared, leaving sensation to part of the distal arm, forearm, and hand unaffected. Using larger volume blocks (15-20 mL) can cause anesthetic to spread and affect the inferior roots of the brachial plexus (C7-T1), completely anesthetizing the brachial plexus and providing more complete anesthesia to the distal arm (Figure 1).

Performing the Block: Supplies Needed 

In addition to an ultrasound machine with a high frequency (>10 MHz) linear probe and standard monitoring equipment, Figure 2 highlights the additional supplies needed to perform the interscalene nerve block, which should be opened under sterile precautions (dropped onto a sterile towel), including:

1. Chlorhexidine 2% or povidone-iodine skin disinfectant solution
2. Local anesthetic
3. 10 mL to 20 mL syringe with extension tubing
4. Short bevel block needle (10 cm, 18-22 gauge)
5. Sterile towels to drape the patient
6. Sterile ultrasound gel
7. Sterile ultrasound probe cover
8. Sterile gloves

Tip: for shoulder dislocations, we recommend 1-2% lidocaine, since this is relatively short procedure.

Performing the Block: Patient Positioning and Target Anatomy

The patient should be placed at a 45 degree incline with the head and neck rotated slightly towards the contralateral side. A towel roll may be used under the ipsilateral shoulder if needed to allow more room for needle manipulation. The operating user should stand behind the patient (or laterally positioned, if preferred), with the ultrasound machine positioned on the contralateral side, viewable to the operator. (Figure 3)

The neck and relevant anatomy should always be pre-scanned before beginning the block. Place the probe in the transverse position on the neck, and identify the internal jugular vein and carotid artery near the level of the cricoid cartilage (similar to central lines). Slide the probe laterally, away from the vasculature. Notice the tapering of the sternocleidomastoid as the anterior and middle scalene come into view. Between them, you will visualize the C5 and C6 nerve roots.

• Tip: Nerves have a typical ‘honeycomb’ appearance when visualized under ultrasound. At this level, the brachial plexus appears as multiple anechoic circular structures on top of one another (the characteristics ‘stoplight appearance’) Typically, the topmost structure is C5, while the middle and lower structures are both C6 as it divides. Use of color doppler may also confirm the absence of any vascular structures which may be in the needle path.

Now it’s Time to Perform the Block!

After the above steps, it is now finally time to perform the block!

1. Prep the skin and don your sterile glove. Drape the patient’s neck with sterile towels.
2. With assistance, draw up 5-10 mL of your anesthetic. Prime extension tubing with small amount of anesthetic.
3. Insert the block needle in an in-plane approach (parallel to the foot of the probe), aim towards the interscalene groove (in a posterior-to-anterior, then lateral-to-medial motion). Be cautious not to advance the needle in between any of the nerve roots.
   • Do NOT advance your needle forward unless it is directly visualized (hyperechoic structure). If you are having difficulty locating the needle, ‘rock’ the probe backwards to bring it into view. Do not ‘bounce’ your needle as this can cause tissue and/or inadvertent nerve injury.
4. Once your needle tip is in the groove, confirm it is not intravascular by negative aspiration.
5. Have a second user (whom is holding the syringe with anesthetic), inject approximately 5-10mL of anesthetic into the groove, until you see ‘spread’ around the nerve roots laterally. The brachial plexus sheath is not a diffusion barrier, so do not attempt to get ‘inside’ the sheath (e.g., placing the local anesthetic placed near/outside of the sheath easily diffuses across to give you an effective block.)
6. Remove your needle. Wait a few minutes, then test sensation to light touch in the shoulder.
7. If analgesia is achieved, attempt your closed shoulder reduction.

Understanding the Risks

All blocks may cause nerve injury due to inadvertent intraneural injection, local anesthetic neurotoxic properties, and physical damage from the block needle. Local anesthetic systemic toxicity (LAST) can also occur in the setting of inadvertent intravascular injection, though is very rare.⁴

Additional complications to this block may include:

• Ipsilateral phrenic nerve palsy, resulting in hemidiaphragmatic paralysis (the phrenic nerve runs on the surface of the anterior scalene and can be inadvertently anesthetized). As a result, this can cause up to a 25% reduction in forced vital capacity. Thus this block should not be performed on those who cannot tolerate a temporary, moderate impairment of their respiratory mechanics.⁵
• Damage to the long thoracic nerve, which pass through middle scalene muscle. To avoid this, needle trajectory should be kept superficial in the muscle until reaching the brachial plexus in order to avoid damaging these nerves. 
• Vascular injury including vertebral artery puncture, Horner syndrome, or injury to brachial plexus itself.

Outcome

This patient received an ultrasound-guided interscalene brachial plexus block and had total shoulder and upper arm analgesia. A closed shoulder reduction was successfully performed and confirmed by repeat X-ray. The patient was placed in a sling and discharged with a plan to follow up with Orthopedic Surgery the following week.

References

1. Stone MB, Wang R, Price DD. Ultrasound-guided supraclavicular brachial plexus nerve block vs procedural sedation for the treatment of upper extremity emergencies. Am J Emerg Med. 2008;26(6):706-710. doi:10.1016/j.ajem.2007.09.011
2. Kakazu C, Tokhner V, Li J, Ou R, Simmons E. In the new era of ultrasound guidance: is pneumothorax from supraclavicular block a rare complication of the past? Br J Anaesth. 2014;113(1):190-191. doi:10.1093/bja/aeu214
3. Blaivas M, Adhikari S, Lander L. A prospective comparison of procedural sedation and ultrasound-guided interscalene nerve block for shoulder reduction in the emergency department. Acad Emerg Med Off J Soc Acad Emerg Med. 2011;18(9):922-927. doi:10.1111/j.1553-2712.2011.01140.x
4. Hussain N, Goldar G, Ragina N, Banfield L, Laffey JG, Abdallah FW. Suprascapular and Interscalene Nerve Block for Shoulder Surgery: A Systematic Review and Meta-analysis. Anesthesiology. 2017;127(6):998-1013. doi:10.1097/ALN.0000000000001894
5. Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anesth Analg. 1992;74(3):352-357. doi:10.1213/00000539-199203000-00006