Abstract
Objective: We focused our attention on the localization of the laryngeal phonatory area in a somatotopic context. This study investigates brain modification consequent to partial or complete removal of the larynx.
Methods: From 2009 to 2011 we enrolled 18 patients, divided into 3 groups: 6 healthy volunteers, 6 subtotal laryngectomy patients, and 6 total laryngectomy patients. During fMRI recording, all subjects were trained to carry out 5 motor tasks.
Results: Analyzing group 1, we obtained: bilateral activation in prefrontal gyrus and in cerebellar lobule VI during the phonation of the vowel E; activation of the same areas in addition to basal ganglia, cerebellar lobule VI and VIII, insular lobe, 42 Brodmann area and basal gyrus bilaterally, Rolandic operculum, and the supplementary motor area intonating vowel E. Glottal adduction during forced expiration and phonatory task activated the same areas. Phonatory tasks determined the same activation in all groups, with an extension of these areas proportional to surgical damage. In lip and tongue tasks we observed the same results in all groups.
Conclusion: This study permitted the mapping of the human motor cortical areas that control intrinsic laryngeal muscles, differentiating them from those referable to the articulatory process. Studying subtotal and total laryngectomies, we identified an expansion of the laryngeal area activation, proportional to the degree of the laryngeal injury. We observed the functional recovery of brain regions considered evolutionarily ancient that are normally virtually quiescent.
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