Hypophonia in Parkinson disease: Neural correlates of voice treatment with LSVT revealed by PET

This study investigated the neural correlates of hypophonia in individuals with Idiopathic Parkinson's disease (IPD) before and after the Lee Silverman Voice Treatment (LSVT), using 15O-H2O Positron Emission Tomography (PET). Regional cerebral blood flow (rCBF) changes associated with overt speech-motor tasks relative to the resting state were measured in the IPD subjects before and after therapy, and in a group of healthy controls. Before LSVT, patients had strong speechrelated activations in motor and premotor cortex, supplementary motor cortex and inferior lateral premotor cortex which were significantly reduced post-LSVT. In addition, significant right-sided activations were present in anterior insular cortex, caudate head, putamen, and dorsolateral prefrontal cortex following LSVT. Finally, the LSVT-induced neural changes were not present with transient experimentercued increases of loudness in LSVT-untreated patients. This treatment-dependant functional reorganization suggests a shift from an abnormally effortful to a more automatic implementation of speech-motor actions.