Effect of tourniquet time and nerve diameter change on nerve damage in upper extremity surgery interventions

Peripheral nerve damage is the most common and most frightening complication after a peripheral nerve block procedure. The purpose of this study was to evaluate the effects of different tourniquet durations on the sensory, motor, and sympathetic functions of peripheral nerves in patients undergoing upper extremity surgery by measuring nerve diameters under ultrasound guidance and performing nerve conduction studies to evaluate the effects on nerve damage in distal forearm.

This study was conducted on ASA I-III patients between the ages of18 and70 who were scheduled to undergo surgery on the mid and distal forearm. All patients underwent brachial plexus block via an axillary approach using USG and a nerve stimulator Prior to the application of the block, the diameters of the median, radial, ulnar, and musculocutaneous nerves were measured under USG guidance.The same assistant personnel injected 7 ml of bupivacaine and lidocaine mixture into each nerve (median, radial, ulnar). Local anesthetic(LA) to spread along the nerve sheath, the diameters of each nerve sheath were measured and recorded again by USG. Nerve conduction studies using EMG were performed by the same researcher before surgery and 1month after surgery to evaluate for nerve damage.

The study consisted of 61 patients. Of the patients, 42.6 % were aged 40-60 years, and 54.1 % were women. One patient was switched to general anesthesia due to block failure, and the patient was excluded from the study. Three patients experienced complications (prolonged sensory block of 15 h in two patients, and sensory paralysis of one month in one patient. The tourniquet times of the patients were almost equal.There was a statistically significant difference between the first and final measurements of patients' Median Nerve Diameter, Radial Nerve Diameter, Ulnar Nerve Diameter, Median Nerve Sensory Amplitude, Ulnar Nerve Sensory Amplitude, Radial Nerve Sensory Amplitude, Ulnar Nerve Motor Amplitude, Median Sensory Latency, Ulnar Sensory Latency, and Radial Sensory Latency(p < 0.05).). In both patients with and without DM, the difference between the first and last measurements of Median Nerve Diameter, Radial Nerve Diameter, Ulnar Nerve Diameter, Median Sensory Latency, and Radial Sensory Latency was statistically significant (p < 0, 05).

Involuntary intraneural injections can occur with peripheral nerve blocks. When the effect of the increase in nerve diameter due to local anesthesia and appropriate tourniquet duration on nerve damage is evaluated by nerve conduction studies, although it causes partial impairment of nerve function (slowing of nerve conduction, decrease in amplitude), it generally does not cause permanent nerve damage.