The effect of anatomical variation of the sural nerve on nerve conduction studies

Objective: To investigate the types of sural nerve formation through cadaver study, and to evaluate the relationship between anatomical variation and nerve conduction study (NCS). Design: We examined the formation of the sural nerve in 26 legs from cadavers. Sural NCS was performed in 60 legs of healthy adults to evaluate the influence of anatomical variation on NCS. Results: The sural nerve was formed by the anastomosis of the MSCN and LSCN in the calf in 20 out of 26 legs (76.9%). The sural nerve was a direct continuation of the MSCN in four (15.4%) cases, and there was no communication between the MSCN and LSCN in two cases (7.7%). The anastomoses were located in the middle and distal third of the leg in 9 and 11 out of 20 legs, respectively. Separate sensory nerve action potentials of the MSCN and LSCN were recorded in 4 out of 60 legs (6.7%) during NCS of the sural nerve, and a double peak was recorded in each of these legs. Conclusions: Because the sural nerve formation is highly variable, the possibility of anatomical variation should be considered when the sural sensory nerve action potential is of low amplitude and disproportionate to the neurologic evaluation.