STUDY DESIGN: This study analyzed the parameters needed for electrical stimulation of vertebral pedicle drill bits and screws. OBJECTIVES: The feasibility of using electrically evoked electromyography was studied. SUMMARY OF BACKGROUND DATA: Considerable potential for damage of adjacent nerve roots with incorrectly placed bits and screws exists with pedicular fixation of the lumbar spine. METHODS: Ninety-five drill bits, one hundred forty-four screws, and thirty-four exposed nerve roots were electrically stimulated in thirty-six patients. Simultaneous evoked electromyographic activity was recorded from four muscle groups in each lower extremity during partial neuromuscular blockade. RESULTS: A constant current threshold of 6 mA or less correlated with misplaced drill bits and screws that broached the cortex. Evoked electromyography was 93% sensitive whereas radiography was only 63% sensitive to detecting bits and screws that had broached the cortex. CONCLUSIONS: Evoked electromyography is a valuable sensitive adjunct to radiographic examination of pedicle drill bit and screw placement.
STUDY DESIGN: This study analyzed the parameters needed for electrical stimulation of vertebral pedicle drill bits and screws. OBJECTIVES: The feasibility of using electrically evoked electromyography was studied. SUMMARY OF BACKGROUND DATA: Considerable potential for damage of adjacent nerve roots with incorrectly placed bits and screws exists with pedicular fixation of the lumbar spine. METHODS: Ninety-five drill bits, one hundred forty-four screws, and thirty-four exposed nerve roots were electrically stimulated in thirty-six patients. Simultaneous evoked electromyographic activity was recorded from four muscle groups in each lower extremity during partial neuromuscular blockade. RESULTS: A constant current threshold of 6 mA or less correlated with misplaced drill bits and screws that broached the cortex. Evoked electromyography was 93% sensitive whereas radiography was only 63% sensitive to detecting bits and screws that had broached the cortex. CONCLUSIONS: Evoked electromyography is a valuable sensitive adjunct to radiographic examination of pedicle drill bit and screw placement.
Authors: Amer F Samdani; Mark Tantorski; Patrick J Cahill; Ashish Ranade; Stephen Koch; David H Clements; Randal R Betz; Jahangir Asghar Journal: Eur Spine J Date: 2010-12-18 Impact factor: 3.134