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Accuracy of Lumbar Pedicle Screw Placement Assisted With Continuous Pulse-train Stimulation

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified April 2011 by American British Cowdray Medical Center.
Recruitment status was:  Recruiting
Information provided by:
American British Cowdray Medical Center Identifier:
First received: April 20, 2011
Last updated: April 26, 2011
Last verified: April 2011
The purpose of this study is to establish the accuracy of pedicle positioning using continuous electrical pulse during screwing. Additionally, the investigators evaluate if this maneuver can prevent neurological injury during track creation and screwing in lumbar and thoracic spine instrumentation surgery

Condition Intervention
Spine Pedicle Screw Placement
Procedure: Electric pulse train stimulation

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Supportive Care
Official Title: Accuracy of Lumbar Pedicle Screw Placement Assisted With Continuous Pulse-train Stimulation During Track Creation and Screw Insertion

Further study details as provided by American British Cowdray Medical Center:

Primary Outcome Measures:
  • Intra operative neurophysiological monitoring (IONM) alert [ Time Frame: Participants will be followed for the duration of surgical procedure, an expected average of 3-4 hours ]
    - Continuous electrical stimulation delivered by a wire connected to the surgical instruments only during pedicle track creation and screw placement combined with neurophysiological monitoring will let us identify any IONM alert, defined as nerve irritation or a decrease in voltage and/or amplitude response. This is a single and immediate measurement obtained at surgery during spinal screw placement.

Secondary Outcome Measures:
  • Pedicle screw accuracy [ Time Frame: On day 2 after surgery before patient discharge, a CT scan will be performed ]
    On day 2 post surgery, a CT scan with sagittal, coronal and axial reconstructions will be obtained . The same day of the study, two independent observers will assess the accuracy of screws inside lumbar pedicles, recording in millimeters, any pedicle wall violation on sagittal, axial and coronal views for each screw placed. In that way we could have the accuracy of pedicle screws placed with the proposed technique, before patient discharge.

Estimated Enrollment: 60
Study Start Date: January 2011
Estimated Study Completion Date: May 2012
Estimated Primary Completion Date: April 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Electrical stimulation
Only arm of the study, the experimental
Procedure: Electric pulse train stimulation
Electric pulse train stimulation of regular probes and screw drivers used in track creation and screw placement Using a standard neurophysiological work station, a series of square wave pulses will be delivered through standard probes and screw drivers using an alligator clip during pedicle probing and screw insertion (4 Hz for 50-200 μsec at 10-30 μAmp)

Detailed Description:

Pedicle screw instrumentation as part of spine surgery is a recurrent technique used for most of spine surgeons. Since its description by Boucher in 1959 and its popularization later by Roy-Camille, has been considered a technique that demands great anatomy knowledge and some grade of expertise. Even in experienced hands the misplacement of pedicle screws could have an incidence of 10-40% (average of 20%). Medially misplacements during track creation and screw insertion are the most feared complications, because the anatomic relationship between medial pedicle wall and neural structures. The first attempt to use continuous electrical stimulation during pedicle track creation and screw insertion was communicated in 1997 by Welch WC, et al. In that study they used the bone impedance as a direct measurement of pedicle wall integrity; unfortunately they used inhaled anesthetics and assessed the final screw position with plain X-rays. They reported a sensibility and specificity of 98% and 99% respectively. The great limitation for this study is its assessment of screw accuracy performed by plain X-rays, now a days the best way to do it is with computed tomography (CT).

After the Welch report, a couple of studies more have used similar techniques in the thoracic spine trying to avoid neurological injuries during pedicle screw insertion, but none described the use of continuous train pulses during screwing.

The present study pretends to evaluate the final accuracy and trans-operative usefulness of the pulse train stimulation during track creation and screw insertion using intra venous anesthetic agents and CT scans to assess the integrity of pedicle walls


Ages Eligible for Study:   18 Years to 70 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Any patient who needs pedicle screw placement for any spine condition

Exclusion Criteria:

  • Previous spine surgery
  • Pedicle fracture documented before or during surgery.
  • Preoperative identified neurological deficit of the nerve roots close to the instrumented levels
  Contacts and Locations
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Please refer to this study by its identifier: NCT01342588

Contact: Ernesto E Galvan Hernandez, MD, MsC 52 (55) 16647205 ext 4155

American British Cowdray Medical Center Recruiting
Mexico City, Mexico DF, Mexico, 05300
Contact: Ernesto E Galvan Hernandez, MD, MsC    16647205 ext 4155   
Principal Investigator: Ernesto E Galvan Hernandez, MD, MsC         
Sub-Investigator: Roberto De Leo, MD         
Sub-Investigator: Miguel Angel Collado Corona, MD         
Sub-Investigator: Angel Romero, MD         
Sub-Investigator: Maximino Tellez Gutierrez, MD         
Sub-Investigator: Ildelfonso Muñoz Romero, MD         
Sponsors and Collaborators
American British Cowdray Medical Center
Principal Investigator: Ernesto E Galvan Hernandez, MD, MsC American British Cowdray Medical Center, Neurological Center