Epidural catheterization with a subcutaneous injection port for the long-term administration of opioids and local anesthetics to treat zoster-associated pain -a report of two cases-
72-year-old man (height 163 cm, weight 72 kg) with a 10-year history of diabetes mellitus presented with intermittent intolerable sharp and lancinating pain over the left anterior chest wall and the back for 1 month. He received 300 mg/day of carbamazepine, 300 mg/day of gabapentin, and 1500 mg/day of valacyclovir orally for 7 days following diagnosis with acute herpes zoster at a local private clinic. He reported severe pain in the affected area (a score of 8 or 9 on a visual analog scale where 0 indicated "no pain" and 10 indicated "the strongest pain imaginable") despite a healed skin rash. A physical examination revealed allodynia and hyperalgesia over the left T2 and T3 dermatomes. The pain relief was maintained for only 3 days through the use of a thoracic epidural block with 10 ml of 0.1% bupivacaine and 10 mg of triamcinolone at the intervertebral space between the T1 and T2 (a visual analog scale pain score of 2 or 3). Simultaneously, the gabapentin and carbamazepine dosages were increased to 900 mg/day and 400 mg/day, respectively, and the antiviral therapy was completed. The patient received 6 subsequent blocks, but each block relieved the pain for only 3 days. He complained about the short-lasting effect of the blocks and the frequent follow up. After reviewing the benefit-risk ratio of the various available forms of therapy, the decision was made to implant a subcutaneous port connected to an epidural catheter for the continuous infusion of opioids and local anesthetics.\nOn arrival in the operating room, the arterial pressure, electrocardiogram, and peripheral oxygen saturation (SpO2) of the patient were monitored, and venous access was secured. The patient was positioned on an operating table in the lateral decubitus position with the patient's side for the port pocket nondependent. His arms were extended at the shoulders and secured in position away from the surgical field. The skin was prepared, and sterile drapes were applied. The radiographic C-arm was then positioned across the thoracic region to provide a cross-table anteroposterior view of the thoracic spine. Using fluoroscopy, the T7-8 interspace, which was thought to be the most appropriate interspace, was identified for the subcutaneous tunneling of an epidural catheter connected to an injection port placed in the right upper quadrant of the abdomen. An epidural catheter was then inserted through an 18-gauge Tuohy needle using a loss of resistance technique until the tip was at the intervertebral space between the T1 and T2 (). The needle was then withdrawn. An 8 cm transverse incision was made in the right upper quadrant of the abdomen, and a subcutaneous pocket was created caudad to the incision using a blunt dissection. A tunneling device was then extended within the subcutaneous tissue between the needle insertion site and the pocket. The catheter was then advanced through the tunnel and trimmed to a length that allowed a small loop of catheter to remain deep to the port (Celsite®, B. Braun, Boulogne-Billancourt, France). The port was connected to the epidural catheter and sutured to the abdominal fascia. Finally, the skin incision was closed. A port needle (Hubsite®, B. Braun, Ecouen, Germany) with a length appropriate for the thickness of the subcutaneous needle was used to deliver epidural medications: 25 mg of morphine, 200 mg of bupivacaine, and 185 ml of normal saline (a total volume of 250 ml) (). The background infusion rate was 2 ml/hr (no bolus).\nAfter the completion of the procedure, the patient was delivered to the general ward and was observed closely for morphine-induced respiratory depression using pulse oximetry. The other side effects related to the use of epidural morphine and bupivacaine (pruritus, nausea, vomiting, urinary retention, constipation, systemic toxicity, motor weakness, etc.) were also monitored. Oral bisacodyl (5 mg) and docusate (16.75 mg) were administered daily for constipation prophylaxis. Because no side effects or complications associated with the epidural catheterization, implanted injection port and epidural medications were reported during the 11 days of admission, the patient was discharged and followed up every 10 days to exchange the port needle and epidural infusion pump (Accufuser®, WooYoung Medical, Seoul, Korea). The epidural infusion and concurrent administration of 900 mg/day gabapentin and 10 mg/day amitriptyline were maintained for 66 days. During treatment, the patient's pain intensity was successfully reduced from 10 (using the visual analog scale) and maintained between 2 and 3. The patient was very satisfied with the treatment. He reported slight hypoesthesia over the left anterior chest and back in the early treatment period. There were no complications associated with the epidural catheters or the medications used. Sixty-six days after the procedure, the subcutaneous port and epidural catheter were removed due to the obstruction of the catheter. He did not complain of pain thereafter but reported a slight numb sensation that remained over the lesion site for 3 months, during which oral gabapentin and amitriptyline were tapered off uneventfully. The patient was thereafter lost to follow up.