A 76-year-old female patient (weight, 56 kg; height, 158 cm) was referred from the Department of Neurosurgery to the Pain Clinic with worsened lower back and bilateral leg pain that had started 3 months before presentation. In the Department of Neurosurgery, she received medications, including gabapentin, celecoxib, tramadol, and limaprost for 4 weeks. Despite medications, the patient complained of persistent severe pain. Upon visiting our Pain Clinic, the patient presented with lower back and bilateral leg pain. Radiating pain was present along the L5 and S1 dermatomes. Her pain score was eight on an 11-point Numeric Rating Scale (0 = no pain, 10 = worst pain imaginable), and no abnormal signs were observed on physical examination. The patient had a history of hypertension and had received PEN using a Racz catheter, epidural steroid injection, and medial branch block 6 months ago. Lumbar spine magnetic resonance imaging revealed severe degenerative spinal stenosis at L4–L5 and intervertebral disc space narrowing at L5–S1 (Fig. 1). The patient was diagnosed with degenerative lumbar spinal stenosis and intermittent neurogenic claudication. Initially, we performed an L5 transforaminal nerve root block twice at 2-week intervals; however, her symptoms did not improve. We decided to perform a percutaneous epidural balloon neuroplasty using an inflatable balloon catheter to reduce pain and improve symptoms.

Preoperative laboratory tests were normal: hemoglobin, 12.7 g/dl; platelet count, 190,000/µl; prothrombin time (international normalized ratio), 1.04; and activated partial thromboplastin time, 23.3 s. In the operating room, the patient was placed in a prone position with a pillow under the abdomen. The entire procedure was performed under fluoroscopy. After sterile preparation, a 16-gauge guide needle was inserted into the epidural space through the sacral hiatus. A caudal epidurogram showed a filling defect in the central epidural space at the L4 level and both L4–L5 and L5–S1 intervertebral foramina (Fig. 2). We performed neuroplasty with an inflatable balloon neuroplasty catheter (Expedio balloon catheter, Innosys Co., Ltd.) in both the foraminal and central portions of the L5 vertebra. Adhesiolysis and decompression were performed using gentle side-to-side movement of the catheter with ballooning. The balloon was filled with 0.1 ml of contrast agent, and each ballooning process was limited to 5 s. The catheter was moved only in the deflated state. After adhesiolysis and decompression, the contrast agent in the anterior epidural space spread upward above the level of L5–S1, suggesting that successful adhesiolysis had been achieved. Before catheter removal, 10 ml of a mixture of 0.5% preservative-free lidocaine, 5 mg of dexamethasone, and 1,500 IU of hyaluronidase was injected via the catheter. After injection, the catheter was pulled out into the epidural space. The practitioner withdrew both the catheter and the needle simultaneously, encountering resistance during removal. The catheter could not be removed under fluoroscopic guidance because it was trapped in the sacral and coccyx regions. Upon withdrawing the epidural catheter, its inner wire became deformed and irremovable. Subsequently, the catheter itself broke. Despite persistent attempts over several minutes, we were unable to remove the broken fragment from the coccyx. Computed tomography (CT) of the lumbar spine revealed an acute epidural fluid along the spinal cord, but it did not show the remaining catheter (Fig. 3). Subsequently, she experienced severe radiating pain in her left leg. We explained the issue and possible complications to our patient.

The day after the procedure, the pain intensity decreased; however, the symptoms persisted. We decided to surgically remove the broken catheter after obtaining the patient’s consent. Seven days after the procedure, the foreign body was removed by a neurosurgeon. Under general anesthesia, the patient was placed in the prone position with an Allen bed. A vertical skin incision of 2 cm was made in the sacral area, and gentle dissection was performed around the foreign body. The foreign body was removed. The retained catheter measured 13 cm (Fig. 4). The patient tolerated the procedure well. The patient’s symptoms subsided postoperatively. No definite motor weakness was observed. At 1-month follow-up, the patient experienced no symptoms or neurological deficits.

Although several cases of Racz catheter shearing in the lumbar epidural space during PEN have been reported, there are no documented instances of broken balloon catheters during this procedure. Previous reports suggest that catheter shearing in the epidural space is often caused by a bend in the needle tip and torsion of the catheter [3-7]. Factors like partial tearing of spinal ligaments, catheter kinking or knotting during placement or removal, and design imperfections are frequently associated with epidural catheter breakage [3,4,8]. Furthermore, patients with lumbar spinal stenosis, ligament, and facet hypertrophy may be more susceptible to such incidents [6,8,9].

In the present case, several factors likely contributed to the catheter breakage. During needle introduction, bony structures may have been damaged and a bent, sharpened needle tip. This likely caused the catheter to become stuck at the needle's tip, leading to its tearing when forcibly pulled. To prevent epidural catheter breakage, it is crucial to avoid excessive insertion depth, perform careful physical assessments, and use reliable catheters [8]. Talu and Erdine [3] recommended applying force slowly and continuously during removal, discontinuing if resistance or catheter stretching is felt. We further advise practitioners to avoid rough and repeated retrieval attempts if catheter removal is difficult, as repeated attempts may cause nerve injury. Another potential cause of catheter breakage in the present case was spinal canal stenosis or deformity. The patient’s history of PEN with a Racz catheter six months ago may have exacerbated central stenosis or scarring, potentially contributing to the catheter shearing. Scar tissue formation in the epidural space because of previous surgeries or inflammation around nerve roots in patients with back pain or radiculopathy is well-documented [6].

In rare cases, PEN can result in serious complications [3,4]. Catheter shearing and retention within the epidural space are major complications that could occur during PEN. The catheter used for PEN is specifically and strongly designed. However, if the catheter is long, it may become tortuous, bent, or sheared. In a study using a Racz catheter, the reported incidence of catheter shearing was 1.2% and the most common cause was bending of the needle tip [3]. During insertion, the needle tip comes into contact with bony structures, and bending can occur. This can seriously damage the end of the catheter during its insertion and removal. When catheter shearing occurs, it is necessary to determine the positions of the proximal and distal tips. For definite evaluation, CT is the most recommended method and was used in the present case. In the present case, CT revealed an acute epidural fluid, but it did not show the remaining catheter. Therefore, it was difficult to determine the cause of the epidural fluid. However, several factors may have contributed to the epidural fluid being found in the CT. First, the saline and lidocaine injected during the PEN maybe the cause of the epidural fluid. More than 20 ml of the saline and lidocaine was injected during the PEN, and the CT was taken within 6 hours after the PEN. Second, the attempts of the practitioner to withdraw the catheter against resistance may have caused the bleeding. Additionally, the patient's medication (limaprost) may have further aggravated the bleeding. The authors believe that the lidocaine and saline are the more likely to remain in the epidural space after the PEN.

In previous reports using an epidural catheter, surgeons have succeeded in withdrawing the broken piece using a needle, arthroscope, and/or forceps [5-7]. In the present case, we attempted to remove a piece of the catheter using forceps for several minutes but failed to withdraw the piece from the epidural space. Additional attempts were avoided to prevent neurological damage to the patient. The necessity for the surgical removal of a sheared epidural catheter has been controversial for many years. Leaving a fragment within the spinal canal is considered safe if no neurological symptoms or signs exist [9,10]. However, several authors have reported side effects of retained epidural catheters [8,11]. A torn PEN catheter may exacerbate the symptoms of a compressed root. In these cases, the catheters were surgically removed [8,11]. In cases of retained PEN catheters, especially those with balloons, there is a high possibility of neurological sequelae caused by compressed lesions aggravated by the retained catheter. This is because, unlike conventional epidural catheters made of nylon, catheters for PEN are made of polyurethane and thicker, which makes them more likely to cause complications, such as nerve compression, bleeding, and worsened clinical symptoms (including pain or numbness). Therefore, we suggest surgical removal of the broken epidural balloon catheter for PEN if it remains in the spinal canal.

PEN using an inflatable balloon catheter is effective for significant pain relief and functional improvement in patients with lumbar spinal stenosis [2,12]. PEN with intermittent ballooning is effective for mechanical detachment of perineural adhesions and decompression of the epidural space in patients with lumbar spinal stenosis [2,13]. A combination of mechanical balloon decompression and adhesiolysis may reduce venous congestion [13]. In patients with lumbar spinal stenosis, epidural balloon neuroplasty showed better outcomes than those with conventional PEN with Racz-type catheters [2,14]. Moreover, this approach is effective in patients unresponsive to conventional PEN [2]. In the present case, we performed PEN using a balloon catheter because the effect of conventional PEN using Racz-type catheters was insufficient.

Surgical removal is advised because of the potential for an implanted catheter to exacerbate symptoms and lead to neurological deficits. In the current situation, the catheter experienced shearing as a result of forceful removal. The manipulation of a catheter within a damaged needle, particularly if bent, carries a risk of shearing. Consequently, meticulous care should be taken during the introduction of the catheter through the needle to prevent shearing.