Case presentation
The patient was a male truck driver in his fifties, who had his left annular finger amputated in an accident in 2 years previously, and since that time, he had been experiencing pain at the distal end of the amputated finger. Seven months after the accident, the patient underwent VY flap surgery at his previous clinic. He was referred to the Department of Plastic Surgery at our hospital because of stump neuroma 4 months previously, and neuroma resection was performed. (Figure) Because the patient continued to have pain at the left annular transection after surgery, tramadol hydrochloride/acetaminophen combination tablets were prescribed. However, the patient was unable to take this orally at his own discretion owing to concerns about drowsiness and other adverse drug reactions while driving. Owing to poor pain control at the stump of his finger, he was referred to our department. At the time of the initial examination, his pain was localized to the left proximal phalanx, and allodynia was also present over the phalanx. The Numerical Rating Scale (NRS) was 4/10 at rest and 6/10 with movement, with a tendency for the pain to worsen. He had numbness at the site of pain, and also recognized a decrease in sensation. His Self-Rating Depression Scale was 35/80, the Kessler 6 Psychological Distress Scale for mood anxiety disorder questionnaire was 2/24, and the EuroQol 5 Dimension for quality-of-life rating was 0.794. Hematologic laboratory tests revealed mild renal impairment with a blood urea nitrogen level of 13.0 mg/dL, creatinine level of 1.26 mg/dL, and estimated glomerular filtration rate of 47.7 mL/min/1.73 m2, but no other abnormalities were observed in liver function or coagulability.
Considering his occupation as a truck driver, we decided not to prescribe any medications that could cause drowsiness, and prescribed duloxetine 20 mg/day (at bedtime) and acetaminophen 1,200 mg/day. At the time of his visit 7 days after the start of oral therapy, his NRS was about 3 to 4/10 without much change, and the pain during driving continued. Therefore, we concluded that interventional treatment was necessary, and attempted ulnar and median nerve blocks through the left forearm approach. The needle was advanced under ultrasound guidance, and a mixture of 0.75% ropivacaine and 0.5% lidocaine (5 mL each) was administered to the ulnar and median nerves. For oral medication, the same amount of acetaminophen was continued, and the dose of duloxetine was increased to 40 mg (at bedtime). At the time of his visit 7 days after the nerve block was performed, his pain had improved to NRS 1 to 2/10, and the pain while driving had almost disappeared. The same nerve block was repeated, and 4 units of extract from inflammatory rabbit skin inoculated by vaccinia virus was added to the oral medication. After 21 days from the first visit to our hospital, the pain had improved to NRS 1/10, and the medication alone was continued without any additional nerve blocks. The subsequent 21 days passed with his pain at NRS 0 to 1/10, and he was continued on the same dose of oral medication. He had virtually no pain while driving and no problems with his work. However, this was only a short-term follow-up, and there is the possibility that the pain will recur in the future.