Background
Resection of large retroperitoneal neoplasms may injure the femoral nerve, thereby causing a permanent neurological deficit. We used electrical neurophysiological monitoring to identify, map, and preserve
the femoral nerve during surgical resection to reduce the risk of neurological deficit.
Methods
Seven patients with retroperitoneal neoplasms underwent eight resections.
Compound muscle action potentials (CMAPs) were recorded from needle electrodes placed in the iliacus, quadriceps, and sartorius
muscles. Spontaneous electromyography (EMG) was contnuously monitored from the same muscle groups. A handheld monopolar stimulator
was used to elicit evoked EMG responses to identify and map the course of the femoral nerve. A stimulating strength of 10 mA
was used to map the nerve. The stimulation threshold was tested after neoplasm resection to predict postoperative femoral
nerve function.
Results
Electrical stimulation with CMAP recording and a stimulating strength of 10 mA successfully localized the femoral nerve in
six cases. Monitoring with a stimulating threshold between 0.6 and 1.6 mA predicted postoperative femoral nerve preservation
after tumor resection in four of the six cases.
Conclusion
Neurophysiological monitoring using CMAP and spontaneous EMG can protect the femoral nerve during resection of large retroperitoneal
neoplasms.
Keywords Retroperitoneal sarcoma - Intraoperative neurophysiological monitoring - Femoral nerve - Electrical stimulation - Electromyography