| Variable | Risk Factors |
|---|---|
| Patient | Body habitus |
| Pre-existing neurologic disorder (diabetes mellitus, past chemotherapy) | |
| Male gender | |
| Advanced age | |
| Surgical | Direct surgical trauma or stretch |
| Prolonged tourniquet time | |
| Hematoma | |
| Infection | |
| Tightly applied casts or surgical dressings | |
| Patient positioning | |
| Regional anesthesia | Mechanical injury from the needle or catheter Chemical neurotoxicity from the local anesthetic Ischemic injury to the nerve |