Interscalene Block: Uses and Consideration

In 1970, the interscalene or brachial plexus block was devised as a technique for administering regional anesthesia of the shoulder. This technique has evolved over time, accessing the brachial plexus first through a nerve stimulator and more recently through an ultrasound guided block¹.  

Administration of local anesthesia in shoulder surgery is made difficult by the emergence of the brachial plexus between the anterior scalene and middle scalene, and its subsequent, complicated descent and innervation of the shoulder and upper limb¹. Because of this, general anesthesia is often preferred during shoulder surgery¹. Interscalene block provides an option for regional anesthesia during surgery and, more commonly, is also used for preventing and managing postoperative pain¹. The interscalene block is the most common postoperative analgesic for shoulder arthroplasty, and the PROSPECT guidelines have named interscalene block as the first line treatment for pain after rotator cuff surgery⁵. It can be used successfully with adjuvant therapies as well; one study showed that dexmedetomidine, an alpha-2 receptor agonist, works synergistically with an interscalene block to reduce postoperative pain after arthroscopic rotator cuff repair³. Because this combination of therapies significantly decreases postoperative pain in shoulder surgery patients, it offers an alternative to opioids in pain management³.  

However, there are some important complications of this technique that should be considered. The local anesthetic could be spread to the phrenic nerve, the sympathetic ganglia or other tissues, causing hemi diaphragmatic paresis, Horner syndrome and hoarseness². Other acute reported complications include peripheral neuropathy caused by nerve injury and postoperative paresthesias, and while these were originally thought to be due to the block itself, researchers are investigating the possibility that they are caused by the interactions between the peripheral block and patient risk factors². Rarely, an interscalene block can cause spontaneous pneumothorax and seizures, although it is not generally considered to be a risk factor for these complications². Furthermore, the interscalene block has reportedly caused chronic complications in rare cases, such as carpal tunnel, prolonged paresthesia and loss of sensory function in the hand, and in one puzzling case, idiopathic neuropathy². The patient in question had an uncomplicated interscalene block combined with general anesthesia, and their symptoms spontaneously resolved in nine months².  

While this technique does not seem to cause long-term or unresolvable complications, the complications noted above have caused researchers to consider the use of other access techniques, such as the interscalene perineural catheter or the supraclavicular plexus block^2,4. One study in the European Journal of Anesthesiology performed a systematic review and meta-analysis on the efficacy of the supraclavicular plexus block in preventing postoperative pain compared to the interscalene block⁴. This study found that the two analgesics resulted in comparable pain scores, but that the supraclavicular block was associated with fewer adverse events⁴.  

Interscalene block has provided an avenue for managing pain in patients that have undergone shoulder surgery. Clinicians should investigate the use of interscalene block on a case by case basis and evaluate risk prediction based on individual patient health profiles.  

References 

1. Banerjee S, Acharya R, and Sriramka B. Ultrasound-Guided Inter-scalene Brachial Plexus Block with Superficial Cervical Plexus Block Compared with General Anesthesia in Patients Undergoing Clavicular Surgery: A Comparative Analysis. Anesthesia Essays and Researches, 2019; 13(1): 149-154. doi: 10.4103/aer.AER_185_18 

2. Borgeat A, Ekatodramis G, Kalberer F, Benz C. Acute and Nonacute Complications Associated with Interscalene Block and Shoulder Surgery: A Prospective Study. Anesthesiology, 2001; 95: 875-880. doi: 10.1097/00000542-200110000-00015 

3. Hwang JT, Jang JS, Lee, JJ et al. Dexmedetomidine combined with interscalene brachial plexus block has a synergistic effect on relieving postoperative pain after arthroscopic rotator cuff repair. Knee Surgery, Sports Traumatology, Arthroscopy, 2020; 28: 2343–2353. doi: 10.1007/s00167-019-05799-3 

4. Schubert AK, Dinges HC, Wulf H, Wiesmann T. Interscalene versus supraclavicular plexus block for the prevention of postoperative pain after shoulder surgery. European Journal of Anaesthesiology, 2019; 36: 427-435 doi: 10.1097/EJA.0000000000000988. 

5. Toma O, Persoons B, Pogatzki-Zahn, E, Van de Helde M, Joshi GP. PROSPECT guideline for rotator cuff repair surgery: systematic review and procedure specific postoperative pain management recommendations. Anaesthesia, 2019; 74(10): 1320-1331. doi: 10.1111/anae.14796