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Brachial Plexus Entrapment of Interscalene Nerve Catheter after Uncomplicated Ultrasound-Guided Placement

Clifford Bowens Jr MD, Eric R. Briggs MD, Randall J. Malchow MD
DOI: http://dx.doi.org/10.1111/j.1526-4637.2011.01177.x 1117-1120 First published online: 1 July 2011


We report on the case of an entrapped interscalene nerve catheter in a 46-year-old male undergoing left shoulder arthroscopic lysis of adhesions for a frozen shoulder. The catheter was placed under ultrasound guidance without any apparent complications. The continuous interscalene nerve block was successfully used as the primary anesthetic and for postoperative pain management. Upon attempted catheter removal, the patient experienced severe pain and paresthesias. Fluoroscopy revealed possible brachial plexus involvement, and surgery was performed to extract the catheter, which had become hooked and entrapped around the C5 nerve root and sheath.

  • Acute Pain
  • Nerve Block
  • Pain Management
  • Ultrasound
  • Neuromuscular Electrical Stimulation
  • X-Rays/Radiographic


Continuous interscalene nerve blocks have been shown to provide superior postoperative analgesia, decrease opioid consumption, and improve patient satisfaction compared with a single-injection interscalene block for shoulder surgery [1–3]. Patients can be discharged home with portable, disposable infusion pumps that provide prolonged postoperative analgesia and facilitate physical therapy [4,5]. Furthermore, interscalene catheter complications are uncommon [5–7]. We report on a unique complication of a continuous interscalene nerve block. After the catheter was successfully utilized for the primary anesthetic and postoperative pain management, it required surgical extraction due to being hooked around the C5 nerve root. The authors obtained written permission from the patient to report the case.

Case Description

A 46-year-old male patient, American Society of Anesthesiologists (ASA) 4, with left shoulder adhesive capsulitis (frozen shoulder), presented for left shoulder arthroscopic lysis of adhesions and manipulation under anesthesia. The patient's history was significant for ischemic cardiomyopathy with an ejection fraction of 30%. Six months prior, a left anterior descending artery bare metal stent had been placed following a myocardial infarction. The patient also received experimental stem cell transplant to his myocardium and prophylactic automatic implantable cardioverter-defibrillator (AICD) placement. Left shoulder stiffness and pain occurred following the AICD procedure. As a result of the above medical conditions, the patient was taking clopidogrel, aspirin, and hydrocodone preoperatively. Ideally, the antiplatelet therapy would have been discontinued for at least 7 days [8], but it was continued at the request of the patient's cardiologist. Ultrasound was planned for catheter placement to minimize bleeding risk.

After informed consent was obtained, standard monitors and a peripheral IV were placed. Oxygen was administered via nasal cannula and light sedation was achieved with midazolam and fentanyl. The patient was positioned supine and an anterolateral approach was used for catheter placement. Using both ultrasound guidance in short axis and nerve stimulation, an 18-gauge, 50-mm Tuohy needle (Contiplex, B. Braun, Bethlehem, PA) was advanced in-plane between the C5 and C6 nerve roots. No nerve stimulation was detected at 0.5 mA, and the patient reported no paresthesias during the procedure. Twenty milliliters of 0.5% ropivacaine was injected in 5 mL increments with good hydrodissection noted around the C5–C6 roots. A 20-gauge multi-orifice, non-stimulating, polyamide (clear nylon) closed-tip catheter (B. Braun) was advanced 5 cm past the tip of the needle and secured 9 cm at the skin with a LockIt Plus device (Smiths Medical, Keene, NH). An additional 20 mL of 0.5% ropivacaine was incrementally injected through the catheter. Continuous ultrasound imaging during the injections verified local anesthetic spread within the interscalene groove. There was no evidence of any complications. Intra-operatively, the case was uneventful with monitored anesthesia care and light sedation with midazolam and fentanyl.

Postoperative, the interscalene catheter was maintained with a programmable, electronic pump infusing 0.125% bupivacaine at 10 mL/h with a patient controlled bolus option of 5 mL every 30 minutes. The patient reported adequate pain control throughout his uncomplicated hospital course with an average pain score of 2/10 pain at rest and 4/10 during physical therapy (0–10 point verbal scale). He was discharged home on postoperative day 2 with a disposable infusion pump (On-Q, I-Flow, Lake Forest, CA), administering 0.125% bupivacaine at 6 mL/h (adjustable between 2–14 mL/h). The patient was contacted daily by phone and reported good pain control with minimal adjustments of the infusion rate.

On postoperative day 4, the patient's wife tried to remove the catheter as described in our catheter care instructions. However, withdrawal of the catheter was met with significant resistance and painful paresthesias of the ipsilateral deltoid, and the patient reported to the Acute Pain Service for further evaluation. Steady traction revealed an entrapped catheter, and efforts to remove the catheter again elicited pain and paresthesias. Twenty milliliters of sterile saline was injected through the catheter to aid in removal, yet this technique proved unsuccessful as well. Fluoroscopy was then performed with Omnipaque dye, which revealed lateral movement of a contrasted structure as traction was applied to the catheter (Figure 1). Although it was unclear to what structure the catheter was adherent, possibilities included scalene musculature vs the roots of the brachial plexus.

Figure 1

Fluoroscopic image of interscalene nerve catheter, applied traction caused lateral displacement of the contrasted structure (white arrowheads outline catheter).

The following day, the patient underwent a neck exploration under general endotracheal anesthesia by an orthopedic surgeon specializing in peripheral nerve surgery. Prior to skin incision, the catheter entered the skin at approximately the 3.5-cm mark. A 6-cm transverse incision was made at the base of the left neck. The catheter was identified as it coursed between the anterior and middle scalene muscles, penetrating the sheath of the brachial plexus (Figure 2). Careful dissection through the sheath revealed the catheter hooked around the C5 nerve root and sheath. The catheter was extracted without difficulty, revealing an area of focal buckling or kinking (Figure 3). This deformity of the catheter caused it to behave functionally as a hook. When traction was applied during attempted withdrawal, the C5 nerve root was pulled, resulting in resistance, pain, and paresthesias.

Figure 2

Interscalene nerve catheter entrapped by C5 nerve root and sheath (black arrowheads outline catheter; large, black arrow points to the blue catheter tip).

Figure 3

Rigid, hook-shaped deformity at the distal end of interscalene nerve catheter necessitated surgical removal.

The patient was seen in orthopedic clinic for follow-up 2 weeks after the second surgery. Motor testing revealed 5/5 strength throughout the left upper extremity. The patient was noted to have an area of decreased sensation between the incision and the acromioclavicular joint, which was consistent with postsurgical changes.


Complications with perineural catheters are relatively rare, but they include infection, nerve injury, leaking, migration, kinking, shearing, and knotting [7,9]. With the increasing use of perineural catheters, especially in the ambulatory setting, providers may encounter these complications more frequently. In our case, the catheter did not appear to be defective when it was inserted. Upon postoperative examination, the hook in the catheter was extremely rigid. Ates examined the mechanical properties of epidural catheters designed for 18-gauge Tuohy needles: polyurethane, clear nylon, and radiopaque nylon catheters. Polyurethane and clear nylon catheters were found to have a greater ability to deform without breaking, i.e., toughness [10]. However, the mechanical properties that make these catheters tough may predispose them to kinking or permanent deformation changes when contacting dense tissues. In addition, the catheter in our case was inserted 5 cm past the tip of the needle, which is an accepted distance [11]. However, the greater the distance that a catheter is advanced, the greater the risk of contacting undesired structures, looping, and knotting. More recently, a maximum catheter distance of 2–3 cm past the needle tip has been advocated [12]. With shallow catheter placement, one could tunnel the catheter to prevent accidental dislodgement.

There are a number of cases in which perineural catheters have been difficult to extract. Burgher reported an incidence of knotting eight of 5,964 catheters (0.13%), although no interscalene catheter became knotted during the study period [9]. Ilfeld described a stimulating infraclavicular catheter that was removed surgically because attempted manual removal caused severe pain; it appeared that the metallic tip had caught on either the median nerve or the surrounding fascia [13]. Brenier reported the need for surgical extraction of a stimulating interscalene catheter that caused radicular pain on attempted removal, but was not looped or knotted [14]. Boezaart described an unpublished case of a patient that avulsed the superior trunk of his brachial plexus after the patient was advised to remove a catheter even though he had radiating pain, resulting in permanent loss of superior trunk function [15].

Effective management of perineural catheters is imperative for patient safety and outcome, patient satisfaction, and cost containment. Patients should be properly educated and given information to care for perineural catheters. Patients discharged from our institution with portable infusion pumps receive verbal instructions, a pamphlet of written instructions, and a health care provider contact number. The instructions outline how to manage the infusion pump including infusion rate adjustments, potential problems, and catheter removal. Patients are instructed to call the acute pain service for any difficulty with catheter removal or other questions or concerns. While the catheter is in place, the patient is contacted daily by a health care provider to coordinate the management of the infusion system and answer any questions.

In order to avoid catheter entrapment, excessive force should be avoided during catheter insertion, and the catheter distance past the needle tip should be limited [16,17]. Furthermore, several recommendations have been made to manage entrapped perineural catheters. Patients should be positioned to minimize pressure and tension on the perineural soft tissues, which may facilitate catheter removal [18]. Burgher applied a minimally invasive, fluoroscopically guided method used by radiologists to remove kinked or knotted peripheral nerve catheters [9]. Boezaart recommended that catheters should be removed only after resolution of the nerve blockade to ensure that there are no painful paresthesias during extraction. He also recommended fluoroscopy to evaluate entrapped catheters and surgical removal if necessary [15].

In summary, this report describes the case of a perineural catheter that developed a rigid, hook-shaped deformity after uneventful ultrasound-guided and nerve stimulation placement. Fluoroscopy aided in the diagnosis of an entrapped catheter that hooked the C5 nerve root and sheath, eliciting pain and paresthesias with attempted removal. Surgery was required to extract the catheter. Patient education is essential in perineural catheter management, especially in ambulatory surgery. Recommendations to prevent catheters from becoming entrapped include avoiding excessive force when placing catheters and limiting the distance of catheter advancement. Entrapped catheters should be evaluated by radiographic methods and may be removed by optimizing patient position before applying traction, utilizing minimally invasive fluoroscopic techniques or surgery.


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