Role of Right Cerebral Hemisphere in Language Processing in Dysphasic Patients

Abstract

Dysphasia, a condition defined as the partial or complete loss of language function after brain damage, is one of the most devastating cognitive deficits produced by stroke lesions. Over the past decades, there have been great advances in the diagnosis and treatment of post-stroke language and communication deficits. In particular, the advent of functional brain imaging and other brain mapping methods has advanced our understanding of how the intact and lesioned brain takes over the activity of irretrievably damaged networks in dysphasic patients. Right hemisphere (RH) regions contralateral to the dysphasiainducing lesion may be recruited to support recovery of language. Several variables affect language recovery–related neuroplastic processes, including patient variables. Patients vary with regard to lesion characteristics and the language deficits that they present. Lesions may extend beyond their structural boundaries, and we therefore recommend using perfusion imaging as well as structural imaging to determine the dimensions of the lesion and, in turn, to determine candidate tissue for recovery. Because it is possible that damage to white matter connections may play a role in dysphasia recovery, we recommend that future studies of language recovery use diffusion tensor imaging to evaluate the integrity of these pathways. Dysphasia following a right hemisphere lesion (crossed dysphasia) in right-handed individuals is rare, most studies shows a prevalence of less than 3%. Two studies reported an increased incidence of about 20% to 25% for language deficits in left- or non-right-handers after right hemispheric stroke. Another study found no such increase and suggested a negligible role of the right hemisphere in speech function in most leftSummary and Conclusions 128