Peripheral nerve injuries are a significant concern during surgical procedures, especially when compounded by factors like positioning, the use of certain surgical tools, and underlying patient vulnerabilities. Nerves are prone to injury from compression, stretching, or direct trauma.
Ulnar Neuropathy
Ulnar neuropathy is the most common peripheral nerve injury in the operative setting, often occurring at the superficial condylar groove of the elbow. Its superficial location makes the ulnar nerve particularly vulnerable to compression or trauma, especially during prolonged periods of immobility. In a study of 6538 patients, the incidence of ulnar neuropathy was found to be 1 in 3503, with the majority of injuries developing more than one day postoperatively. This delayed onset suggests that many injuries occur while the patient is resting in bed, likely due to improper arm positioning or external compression.
Men are more frequently affected than women (3:1 ratio), potentially because males have a narrower cubital tunnel, making the ulnar nerve more susceptible to compression. Risk factors for ulnar nerve injury include extremes of body weight (either underweight or obese) and prolonged hospital stays. The majority of these injuries occur after general anesthesia, where the ulnar nerve may be compressed against the operating table, especially with the arm extended and pronounced. Extreme elbow flexion, such as positioning the arm across the chest, can also lead to stretching of the ulnar nerve. Preventive measures include careful positioning to avoid excessive elbow extension or flexion during surgery. Padding at the elbow and maintaining the forearm in a supinated position are essential to minimize the risk of injury. Persistent ulnar neuropathy (lasting more than 3 months) is rare but can have severe consequences, including incomplete recovery.
Brachial Plexus Neuropathy
Brachial plexus neuropathy is another common nerve injury, typically resulting from stretching, compression, or direct trauma during surgery. The brachial plexus is particularly vulnerable to stretch injuries caused by excessive abduction, external rotation of the arms, or posterior displacement of the shoulder. A common mechanism involves positioning a patient supine with the neck flexed laterally and the arms abducted and externally rotated. This stretch can lead to damage, particularly to the upper roots of the plexus.
Compression injuries can occur during procedures like sternotomy in cardiac surgery, where sternal retraction places pressure on the brachial plexus. In the lateral decubitus position, compression between the thorax and humeral head can further damage the plexus. Injuries to the long thoracic nerve, a branch of the brachial plexus, can result in scapular winging, characterized by dysfunction of the serratus anterior muscle. Preventing brachial plexus injuries involves minimizing arm abduction to less than 90 degrees, avoiding external rotation, and maintaining the head in a neutral position. Shoulder braces should not be used excessively, especially in the Trendelenburg position, as they can cause direct compression on the plexus.
Lumbosacral Nerve Root Neuropathy
Lumbosacral nerve root neuropathy is less common but still significant, particularly in procedures involving regional anesthesia. The risk of permanent injury is approximately 1 in 5000 cases, and over 90% of these injuries are associated with central neuraxial anesthesia techniques. Patients often report pain or paresthesia during injection, a warning sign of potential nerve damage. The risk increases with multiple needle insertion attempts in the neuraxial space. The most common symptom of lumbosacral neuropathy is persistent paresthesia. Preventive measures include careful technique during neuraxial anesthesia, limiting needle passes, and monitoring for symptoms during the procedure.
Common Peroneal Nerve Injury
The common peroneal nerve is the most frequently injured nerve in the lower limb during surgery. This nerve is particularly vulnerable in the lithotomy position, where it can be compressed against the head of the fibula. It is also at risk in the lateral decubitus position, where pressure between the fibula and the operating table can lead to compression injuries. Common peroneal nerve damage can result in foot drop, characterized by weakness in ankle dorsiflexion and sensory deficits in the dorsal foot. Preventing common peroneal nerve injury involves proper padding of the lateral aspect of the upper fibula and limiting time spent in the lithotomy position, ideally no longer than 2 hours without repositioning. Position respites, where the legs are placed in a neutral position, are recommended to reduce the risk of injury.
Radial Nerve Injury
Radial nerve injuries most commonly occur due to compression of the nerve against the humerus, particularly when a patient’s arm is positioned laterally with excessive abduction. The radial nerve can also be compressed when the patient is in the lateral position and the upper arm is suspended from a support. Compression injuries may lead to wrist drop, where the patient is unable to extend the wrist, along with sensory deficits in the hand. Preventive measures include careful positioning of the arms to avoid excessive abduction and ensuring that the lateral humerus is not compressed by the operating table or supports.
Sciatic Nerve Injury
Sciatic nerve injuries are more common in thin patients, during prolonged surgical procedures, or when hard operating surfaces are used. The sciatic nerve can be stretched excessively in the lithotomy position, particularly with extreme external rotation of the thigh. Sciatic nerve injury has also been reported following coronary artery bypass grafting, likely due to prolonged compression and reduced perfusion to the nerve. Proper positioning, avoiding extreme external rotation of the hip, and using soft operating surfaces can help prevent sciatic nerve injuries. Repositioning the patient periodically during long procedures is also essential.
