title: Motor evoked potential monitoring during cryoablation of musculoskeletal tumors.
abstract: OBJECTIVE
  To describe the use of intraprocedural motor evoked potential (MEP) monitoring to minimize risk of neural injury during percutaneous cryoablation of perineural musculoskeletal tumors.
  
  
  METHODS
  A single-institution retrospective review of cryoablation procedures performed to treat perineural musculoskeletal tumors with the use of MEP monitoring between May 2011 and March 2013 yielded 59 procedures to treat 64 tumors in 52 patients (26 male). Median age was 61 years (range, 4-82 y). Tumors were located in the spine (n = 27), sacrum (n = 3), retroperitoneum (n = 4), pelvis (n = 22), and extremities (n = 8), and 21 different tumor histologies were represented. Median tumor size was 4.0 cm (range, 0.8-15.0 cm). Total intravenous general anesthesia, computed tomographic guidance, and transcranial MEP monitoring were employed. Patient demographics, tumor characteristics, MEP findings, and clinical outcomes were assessed.
  
  
  RESULTS
  Nineteen of 59 procedures (32%) resulted in decreases in intraprocedural MEPs, including 15 (25%) with transient decreases and four (7%) with persistent decreases. Two of the four patients with persistent MEP decreases (50%) had motor deficits following ablation. No functional motor deficit developed in a patient with transient MEP decreases or no MEP change. The risk of major motor injury with persistent MEP changes was significantly increased versus transient or no MEP change (P = .0045; relative risk, 69.8; 95% confidence interval, 5.9 to > 100). MEP decreases were 100% sensitive and 70% specific for the detection of motor deficits.
  
  
  CONCLUSIONS
  Persistent MEP decreases correlate with postprocedural sustained motor deficits. Intraprocedural MEP monitoring helps predict neural injury and may improve patient safety during cryoablation of perineural musculoskeletal tumors.
authors.affiliation: Department of Radiology , Mayo Clinic, 200 First St. SW, Rochester, MN 55905. Electronic address: kurup.anil@mayo.edu.
authors.forename: Anil Nicholas
authors.initials: AN
authors.lastname: Kurup
authors.affiliation: Department of Radiology , Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Morris
authors.affiliation: Departments of Neurology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905; Department of Physical Medicine and Rehabilitation, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Boon
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Strommen
authors.affiliation: Department of Radiology , Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Grant D
authors.initials: GD
authors.lastname: Schmit
authors.affiliation: Department of Radiology , Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Atwell
authors.affiliation: Department of Biomedical Statistics and Informatics, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Rickey E
authors.initials: RE
authors.lastname: Carter
authors.affiliation: Department of Anesthesiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Brown
authors.affiliation: Department of Anesthesiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: C Thomas
authors.initials: CT
authors.lastname: Wass
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Rose
authors.affiliation: Department of Radiology , Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Callstrom
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D003452:Cryosurgery / Q000379:methods*; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D019042:Muscle Neoplasms / Q000601:surgery*; D009417:Nerve Tissue / Q000601:surgery; D059348:Peripheral Nerve Injuries / Q000175:diagnosis / Q000517:prevention & control*; D010525:Peripheral Nerves; D012189:Retrospective Studies; D055815:Young Adult