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Randomized prospective crossover study of interstim lead wire placement with curved versus straight stylet

Authors

  • Stephanie A. Jacobs,

    Corresponding author
    1. Division of Urogynecology, Department of Obstetrics and Gynecology, University of California-Irvine, Orange, California
    • Correspondence to: Stephanie Jacobs, M.D., Division of Urogynecology, University of California, Irvine, 101 The City Drive South, Bldg 56, Orange, CA 92868. E-mail: jacobssa@uci.edu

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  • Felicia L. Lane,

    1. Division of Urogynecology, Department of Obstetrics and Gynecology, University of California-Irvine, Orange, California
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  • Kathryn E. Osann,

    1. Department of Medicine, University of California-Irvine, Orange, California
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  • Karen L. Noblett

    1. Division of Urogynecology, Department of Obstetrics and Gynecology, University of California-Irvine, Orange, California
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  • Eric Rovner led the peer-review process as the Associate Editor responsible for the paper.
  • Conflict of interest: Grant support was received through AUGS Foundation Thomas Benson Award in Neuromodulation; Karen Noblett, MD is a Proctor and Consultant for Medtronic; Stephanie Jacobs, MD received a Fellows Travel Grant for Presentation from Medtronic.
  • This research was accepted for full oral presentation at the American Urogynecologic Society (AUGS) October 2012 meeting in Chicago, Illinois.

Abstract

Aims

To assess whether InterStim lead wire placement with the curved stylet achieves motor response at lower amplitudes compared to straight stylet use.

Methods

This was a prospective, randomized, crossover study of patients scheduled for InterStim lead wire placement. All patients underwent lead wire testing with both the curved and straight stylets. Patients were randomized to determine stylet order, and then crossed-over to the alternate. Intra-operatively, the amplitude achieving motor response at each electrode was recorded. The stylet with lowest overall amplitudes was used for final placement. Primary outcome measure was amplitude requirement in the two deepest (0 and 1) electrodes. Secondary outcomes included amplitudes at the number 2 and 3 electrodes, combined amplitudes, stylet order, and adverse outcomes.

Results

Forty-two patients were enrolled, 40 of whom were included in the final analysis. Mean age was 69 years (SD = 12.8) and mean BMI 27 (SD = 5.6). Indications for placement included: urge urinary incontinence (N = 26), urge/frequency (N = 25), non-obstructive urinary retention (N = 5), and fecal incontinence (N = 10). There were no significant differences between randomized groups. Regardless of order, the curved stylet achieved a motor response at lower amplitudes in the deepest electrodes (P < 0.001). Combined amplitudes of all electrodes were also significantly lower with the curved stylet (P < 0.001). Subsequently, 88% underwent final “optimal” placement with curved stylet (N = 35).

Conclusions

The curved stylet for InterStim lead wire placement consistently achieved motor response at lower amplitudes. A brief intra-operative exchange of stylets represents a minor procedural alteration that could maximize Implantable Pulse Generator battery life and facilitate programming. Neurourol. Urodynam. 33:488–492, 2014. © 2013 Wiley Periodicals, Inc.

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