Peripheral nerve injury (PNI) is a recognized complication that can occur during the operative period. A variety of predisposing factors contribute to the likelihood of PNI, and these factors can be categorized into surgical factors and anesthetic/positioning-related factors. Each of these categories influences the risk of nerve damage in different ways, and understanding these predisposing elements is crucial for minimizing the risk of injury.
Surgical Factors
The type of surgery being performed is often the most significant determinant of PNI risk. Neurosurgery, cardiac surgery, general surgery, and orthopedic surgery carry the highest risks for nerve damage. In these procedures, nerves can be damaged by the use of surgical instruments such as needles, sutures, retractors, diathermy, and scalpels. Direct trauma to nerves during surgery is a common cause of injury, and nerves can also be damaged indirectly through prolonged compression or stretching. Certain procedures, such as those involving the use of tourniquets or tight-fitting plaster casts, further increase the likelihood of PNI due to prolonged compression of nerves.
For example, ulnar nerve injuries are particularly associated with cardiac surgery, where the use of rib retractors may stretch the brachial plexus, resulting in nerve damage. In surgeries such as pneumonectomy or axillary lymph node dissection, there is a risk of injury to specific nerves. Stretching of the long thoracic nerve can result in motor deficits, including weakness of the serratus anterior muscle, which affects scapular movement and causes “winged scapula.” Longer hospital stays, particularly those exceeding 14 days, are associated with an increased risk of PNI. This may be due to prolonged immobility, increased pressure on certain nerves, or the cumulative effects of multiple procedures.
Anesthetic and Positioning Factors
Anesthetic techniques and positioning during surgery also play a critical role in predisposing patients to PNI. Regional anesthesia, particularly when administered through needle injection, can directly damage nerves if the needle is incorrectly positioned or manipulated. While regional anesthesia is generally safe and effective, improper technique can lead to mechanical trauma, resulting in nerve injury. Inadequate padding during surgery can lead to prolonged pressure on nerves, particularly in areas where the nerve is close to the surface or in contact with hard surfaces, such as the elbows, knees, or shoulders. This prolonged pressure can lead to compression neuropathies, which are a common cause of operative PNI.
Poor positioning during surgery is another major factor. Surgical positions such as the lithotomy or prone position can place specific nerves at risk. For example, the ulnar nerve is vulnerable when the arm is abducted for prolonged periods during surgery, while the sciatic nerve can be compressed during procedures that require patients to be in the lithotomy position. Proper positioning, along with the use of supportive devices and adequate padding, is essential to minimize the risk of PNI during surgery. Anesthesia providers and surgical teams must carefully monitor patients’ positioning throughout the procedure, adjusting as needed to prevent excessive nerve stretch or compression.
| Factor | How it puts the nerve at risk |
|---|---|
| Type of surgery | Neurosurgery, cardiac, general, and orthopedic surgery carry the highest risk. |
| Surgical instruments | Needles, sutures, retractors, diathermy, and scalpels can cause direct trauma. |
| Rib retractors in cardiac surgery | Stretch the brachial plexus; ulnar nerve injury is particularly associated with cardiac surgery. |
| Tourniquets and tight plaster casts | Prolonged compression of nerves. |
| Hospital stay beyond 14 days | Associated with increased risk, possibly from prolonged immobility, sustained pressure, or cumulative procedures. |
| Regional anesthesia | Incorrect needle position or manipulation can mechanically traumatize the nerve. |
| Inadequate padding | Prolonged pressure where nerves are superficial or against hard surfaces — elbows, knees, shoulders. |
| Prolonged arm abduction | Leaves the ulnar nerve vulnerable. |
| Lithotomy or prone position | Lithotomy can compress the sciatic nerve; both positions place specific nerves at risk. |
