2008 Annual Meeting Abstracts

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PURPOSE: Functional imaging is a new method by which changes in neurophysiology following reconstructive procedures may be assessed. Only recently have we been able to utilize such advanced techniques as functional MRI (fMRI) to study the adaptation of the nervous system following autologous tissue transfers. A requirement for such adaptation, known as cortical neuroplasticity, has been suspected in the successful treatment of facial paralysis with dynamic muscle transfer. An understanding of the process by which the brain becomes plastic following muscle transfers will lead to improved procedural design on the part of the surgeon, as well as functional treatments for multiple forms of paralysis. Similarly, functional imaging of identifiable perceptual regions may be used to better understand patient satisfaction following autologous breast reconstruction. Such studies will allow the plastic surgeon to give valuable advice regarding reconstructive options. METHODS: We studied eight patients both before and after free autologous tissue transfer with fMRI. Patients were selected for a unilateral deficit of form (mastectomy) or function (facial nerve palsy), allowing for comparison to a normal side of the body. Functional imaging paradigms were designed and cued visually, taking into consideration both the original deficit and characteristics of the reconstructive procedure. Regions of neural activity exhibiting change over time could be compared and averaged across similar patients using normalized spatial coordinates. General linear models examining patterns of neural activity were applied to patient data before and after reconstruction for statistical analysis. In addition, structural MRI imaging of patients undergoing dynamic muscle transfer was analyzed for changes in thickness over time, and compared to a database of over 100 normal individuals matched for age and gender.
RESULTS: Patients undergoing muscle transfer for a gain of movement exhibited both functional and structural changes in the primary motor regions of the brain following operation (p<0.01, corrected). This pattern of neural plasticity concurred with previous maps of the motor cortex, but is newly demonstrated following dynamic tissue transfer. Perceptual function was altered following deep inferior epigastric perforator flap transfer for delayed reconstruction of the breast. Self-association of the reconstructed breast was significantly increased in the post-operative as compared to pre-operative state (p<0.05, corrected).
CONCLUSION: Functional imaging has been successfully used in identifying the neural plasticity induced by dynamic tissue transfer for facial animation. With this technique we are able to report the first human studies of induced motor plasticity in the brain. The ability of the brain to adapt to motor groups introduced artificially has further implications for the surgical treatment of paralysis. Similarly, fMRI has identified cognitive outcomes following reconstruction of the breast with autologous tissue. An understanding of these outcomes may allow us to optimize patient satisfaction following reconstructive free tissue transfer. Functional imaging techniques provide a new paradigm in the recommendation and planning of surgical procedures, and have created a new path for research in the field of plastic surgery.

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