A 38-year-old man was diagnosed with pancreatic cancer and was scheduled to undergo pancreaticoduodenectomy. He had an unremarkable medical history. A combination of general anesthesia and epidural anesthesia was considered. Epidural tubing was performed at T8/9, and general anesthesia was induced with 100 μg fentanyl, 100 mg propofol, and 50 mg rocuronium. They were administered intravenously through a peripheral venous catheter inserted in his left cephalic vein near the wrist.
Radial artery catheterization was planned for measuring continuous arterial pressure during surgery. A left radial arterial line was successfully placed on the first try. A wrist split was used to obtain a good arterial pulse waveform.
The surgery was completed on schedule. The total operation time was 7 h 55 min. After the surgery, he was transferred to an intensive care unit (ICU) where he stayed for 4 days and had a wrist-extension split placed.
The radial artery catheter was removed when he was transferred to a general ward. He experienced numbness and a tingling sensation in his left palm during his ICU stay that he considered transient and insignificant and did not report it to the ICU staff. This continued after ICU discharge. On the 10th postoperative day, he complained about his numbness to the physician in charge. The physician consulted a pain specialist, and the medical examination revealed that numbness and paresthesia were present in the left thumb, the second and third fingers, and the lateral half of the fourth finger. His left hand had a weak grip. The patient doubted that these symptoms resulted from an incident during placement of the indwelling radial artery catheter because he recalled irritable lightning and burning pain in his left wrist during the induction of general anesthesia.
Ultrasound examination revealed no hematomas and a normal appearance of the radial artery and radial nerve, but an enlargement of the left median nerve compared with the right median nerve at the pisiform bone level was observed (cross section areas of the left and right median nerves were 12 and 9 mm2, respectively) (Fig. 1). The physical examination showed a positive Tinel’s sign, positive Phalen’s sign (20 s), and positive Flick sign. Considering the present findings, carpal tunnel syndrome was strongly suspected.
Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) were performed. There were no hematomas and no abnormality or deformation of the radial artery and carpal bones on contrast-enhanced CT. There was an enlargement of the median nerve at the pisiform bone level on fat suppression T2-weighted MRI (Fig. 2). There was no thickening of the flexor tendon, but there was fluid stagnation in the deep part of the bursa and intense signals around the flexor tendon; these are typical findings in carpal tunnel syndrome even though the patient has no past medical history of carpal tunnel syndrome. During interviews, some ICU nurses recalled that his wrist-extension split had been fixed in a relatively hyperextended position for 4 days to obtain a good arterial pulse waveform.
Neurological diagnosis revealed iatrogenic carpal tunnel syndrome due to hyperextension of the wrist. The patient’s recollection of burning pain in his left wrist during induction of general anesthesia was considered a side effect of propofol. We started to administer 75 mg pregabalin daily and injected 4 mg of dexamethasone steroid into the carpal canal. He was discharged on the 12th postoperative day. The numbness in his palm interfered with his ability to type and impacted his quality of life. However, it gradually subsided. He was medicated and followed up at the outpatient pain clinic for 6 months before he made a complete recovery.