Bihemispheric stimulation over left and right inferior frontal region enhances recovery from apraxia of speech in chronic aphasia

• Published in: The European journal of neuroscience 2013-11, Vol.38 (9), p.3370-3377
• Main Authors: Marangolo, Paola, Fiori, Valentina, Cipollari, Susanna, Campana, Serena, Razzano, Carmelina, Di Paola, Margherita, Koch, Giacomo, Caltagirone, Carlo
• Format: Article
• Language: English
• Subjects: Adult; Aphasia - physiopathology; Aphasia - therapy; Apraxias - physiopathology; Apraxias - therapy; Biological and medical sciences; brain stimulation; Electric Stimulation; Female; Frontal Lobe - physiopathology; Functional Laterality; Fundamental and applied biological sciences. Psychology; Humans; language articulation; Language Therapy; Male; Middle Aged; Speech Therapy; transcranial stimulation; Vertebrates: nervous system and sense organs
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.12332

Several studies have already shown that transcranial direct current stimulation (tDCS) is a useful tool for enhancing recovery in aphasia. However, all tDCS studies have previously investigated the effects using unihemisperic stimulation. No reports to date have examined the role of bihemispheric tDCS on aphasia recovery. Here, eight aphasic persons with apraxia of speech underwent intensive language therapy in two different conditions: real bihemispheric anodic ipsilesional stimulation over the left Broca's area and cathodic contralesional stimulation over the right homologue of Broca's area, and a sham condition. In both conditions, patients underwent concurrent language therapy for their apraxia of speech. The language treatment lasted 10 days (Monday to Friday, then weekend off, then Monday to Friday). There was a 14‐day intersession interval between the real and the sham conditions. In all patients, language measures were collected before (T0), at the end of (T10) and 1 week after the end of (F/U) treatment. Results showed that after simultaneous excitatory stimulation to the left frontal hemisphere and inhibitory stimulation to the right frontal hemisphere regions, patients exhibited a significant recovery not only in terms of better accuracy and speed in articulating the treated stimuli but also in other language tasks (picture description, noun and verb naming, word repetition, word reading) which persisted in the follow‐up session. Taken together, these data suggest that bihemispheric anodic ipsilesional and cathodic contralesional stimulation in chronic aphasia patients may affect the treated function, resulting in a positive influence on different language tasks. Eight aphasics with apraxia of speech underwent an intensive language therapy with concomitant anodal, ipsilesional stimulation and cathodal, contralesional stimulation over the left and right inferior frontal gyrus. After 2 weeks, a significant improvement in terms of better accuracy and speed in articulating the treated stimuli and in other nontreated language domains was found for real stimulation compared to the sham condition. Bihemispheric stimulation may be considered an useful tool to speed up the recovery process in chronic aphasia.