MRI-Guided Stereotactic System for Delivery of Intraspinal Microstimulation

Peter J. Grahn, Stephan J. Goerss, Jose Lujan, Grant W. Mallory, Bruce A. Kall, Aldo A. Mendez, James K. Trevathan, Joel P. Felmlee, Kevin E. Bennet, Kendall H Lee

Research output: Contribution to journalArticle

5 Scopus citations


STUDY DESIGN.: Laboratory/animal based proof of principle study OBJECTIVE.: To validate the accuracy of a magnetic resonance image (MRI)-guided stereotactic system for intraspinal electrode targeting and demonstrate the feasibility of such system for controlling implantation of intraspinal electrodes. SUMMARY OF BACKGROUND DATA.: Intraspinal microstimulation (ISMS) is an emerging preclinical therapy, which has shown promise for the restoration of motor function following spinal cord injury (SCI). However, targeting inaccuracy associated with existing electrode implantation techniques remains a major barrier preventing clinical translation of ISMS. METHODS.: System accuracy was evaluated using a test phantom comprised of nine target locations. Targeting accuracy was determined by calculating the root mean squared (RMS) error between MRI-generated coordinates and actual frame coordinates required to reach the target positions. System performance was further validated in an anesthetized pig model by performing MRI-guided intraspinal electrode implantation and stimulation followed by computed tomography of electrode location. Finally, system compatibility with a commercially available microelectrode array was demonstrated by implanting the array and applying a selection of stimulation amplitudes that evoked hind limb responses. RESULTS.: The RMS error between actual frame coordinates and software-coordinates, both acquired using the test phantom, was 1.09?±?0.20?mm. Post-operative CT in the anesthetized pig confirmed spatially accurate electrode placement relative to preoperative MRI. Additionally, MRI-guided delivery of a microwire electrode followed by intraspinal microstimulation evoked repeatable electromyography responses in the biceps femoris muscle. Finally, delivery of a microelectrode array produced repeatable and graded hind limb evoked movements. CONCLUSIONS.: We present a novel frame-based stereotactic system for targeting and delivery of intraspinal instrumentation. This system utilizes magnetic resonance imaging (MRI) guidance to account for variations in anatomy between subjects, thereby improving upon existing ISMS electrode implantation techniques.Level of Evidence: N/A

Original languageEnglish (US)
StateAccepted/In press - Dec 14 2015

ASJC Scopus subject areas

  • Clinical Neurology
  • Orthopedics and Sports Medicine

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    Grahn, P. J., Goerss, S. J., Lujan, J., Mallory, G. W., Kall, B. A., Mendez, A. A., Trevathan, J. K., Felmlee, J. P., Bennet, K. E., & Lee, K. H. (Accepted/In press). MRI-Guided Stereotactic System for Delivery of Intraspinal Microstimulation. Spine.