Electromyography for Pedicle Screw Placement Assessed
Triggered electromyography may be more useful in children getting lumbar than thoracic screws
THURSDAY, Jan. 28 (HealthDay News) -- The use of triggered electromyography (EMG) may have more of a role in determining proper placement of lumbar than thoracic pedicle screws in pediatric deformity surgeries, according to research published in the Jan. 15 issue of Spine.
Michael F. Duffy, M.D., of the Arnold Palmer Hospital for Children in Orlando, Fla., and colleagues analyzed data from 329 pedicle screws placed in the thoracic or lumbar areas in 30 pediatric scoliosis patients. Pedicle pilot holes were tested with a pedicle sound, and holes and placed screws were tested with triggered EMG. Any readings below 6 mA led to further investigation of placement. Patients underwent postoperative computed tomography scanning.
The researchers found that, if acceptable placement was defined as intrapedicular or a breach of no more than 2 mm, the negative likelihood ratios of an EMG reading of 6 mA or greater were 0.96 and 0.35 for the thoracic and lumbar spine, respectively; positive likelihood ratios were 1.4 and 12.5, respectively.
"The use of mechanically elicited and triggered EMG potentials has an important role in pedicle screw placement; however, the use of this test seems to be more applicable to the lumbar spine," the authors write. "Radiographic parameters of screw position in the thoracic spine and manual probing of the screw tract have a greater role to ensure accurate screw position."