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  • The application of ferromagnetic dissection in neurosurgery: A preliminary study

    Final Number:

    Aaron Mohanty MD; David Paul Paulson MD; Sohum K Desai MD; Achal Patel MD; Joel T. Patterson MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2013 Annual Meeting

    Introduction: We report our initial experience with the FM wand, a new tissue dissection technique using ferromagnetic energy. It differs from electrosurgery in that radio frequency (RF) current never passes into tissue. Instead, it couples to a 10 micron thick layer of ferromagnetic alloy coating on the instrument tip, achieving a pure thermal surface effect. As a result, there is no electrostimulation and a very shallow tissue injury.

    Methods: We used the FM wand as the principle energy modality for tissue dissection in 12 patients with a variety of cranial and spinal neurosurgical procedures.

    Results: : The age varied between 2 – 65 years with 3 in the pediatric age group. Of the 12, 6 were reoperations; 9 underwent spinal and 3 cranial procedures. Of the 12, 3 had Chiari malformation with syrinx (2 reoperations), 2 had tethered cord with intraspinal tumors (both reoperations), 2 had recurrent lumbar disc prolapse (both reoperations), 2 had intraspinal tumor, 2 had intracranial meningioma and one had a recurrent glioblastoma. 9 underwent simultaneous intraoperative evoked potential monitoring. The FM wand was effective in dissecting the scar tissue in close proximity to neural structures and dural tube especially during the reoperations. In patients with meningioma it was predominantly used as a cutting loop and was able to dissect the tumor safely out of its close proximity to intracranial vessels. While slower than monopolar, there was no interference with evoked potential monitoring during continuous dissection with the FM wand. There was no spark. Tissue desiccation or char effects were comparatively minimal. There was no muscle stimulation.

    Conclusions: Though the FM wand can be used as an alternative to conventional monopolar dissection, the authors believe that its greatest use lies in dissecting critical neurovascular planes or intradural scarring in close proximity due to its much shallower thermal margins of injury compared to RF.

    Patient Care: The present communication is directed to create an awareness of ferromagnetic dissection and its effective utilization in various neurosurgical procedures.

    Learning Objectives: 1By the conclusion of this session, participants should be able to able to: 1.Describe the importance of ferromagnetic dissection 2.Discuss in small groups the differences between ferromagnetic dissection and electrocautery 3. Identify an effective indication for usage of ferromagnetic dissection in neurosurgerical procedures


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