Severe Tibial Neuropathy and Myonecrosis After Prolonged Surgery in Lithotomy Position
Osman Ozel1, Sebnem Nash2, Karin Woodman3
1Houston Methodist Hospital, 2M.D. Anderson Cancer Center, 3M. D. Anderson Cancer Center
Objective:
Explore risks and diagnosis of this unusual injury.
Background:
Peripheral neuropathies and myonecrosis are post-operative complications associated with prolonged surgeries in lithotomy position. Peroneal, sciatic, obturator, lateral femoral cutaneous, and femoral nerves are most affected but tibial neuropathy is not reported.
Design/Methods:
A 55-year-old man with rectal cancer underwent robotic surgery in lithotomy position for >12 hours. Post-operatively, his left calf was swollen, with focal painful “knot”. CK was 4,661 improving to 547 within 5 days, consistent with rhabdomyolysis without compartment syndrome, given a compressible calf. His pain became neuropathic with burning in the sole, worse with weightbearing.
Results:
MRI 2 weeks later showed calf myonecrosis. Exam 1 month later revealed altered pinprick sensation with hyperesthesia in left sole, absent left ankle reflex, inability to walk on toes, intact strength. EMG showed severe left tibial nerve injury (nearly absent motor and sensory amplitudes but no denervation/reinnervation, suggestive of demyelinating process) and generalized polyneuropathy. Oxaliplatin was omitted from future chemotherapy plan, to avoid further neurotoxicity.
Conclusions:
This case underscores the importance of EMG in localization, characterizing injury (axonal or demyelinating), prognosis for recovery. The tibial neuropathy may improve due to the possibility of conduction block, rather than axonal injury; this correlates with intact strength on exam. EMG must be strategic; it is less sensitive in the acute period due to the time needed for Wallerian degeneration to be measurable on needle EMG. Despite careful padding and positioning, it is essential to recognize the risk, examine patients carefully, plan EMG for confirmation. The best risk mitigation is that of avoidance of prolonged surgery times.