Correlation of injury of arcuate fasciculus with aphasia in patients of mild tbi using diffusion tensor imaging

Background: The Arcuate fasciculus (AF) is an important neural tract for language function. Various language deficits including conduction aphasia can be caused by injury of the AF. Little is known about injury of the arcuate fasciculus (AF) in patients with mild traumatic brain injury (TBI). Objective: To investigate the injury of the AF in the dominant hemisphere in patients with mild TBI presenting with aphasia, using diffusion tensor tractography (DTT) and to find a correlation between them. Materials and Methods: Study design was observational retrospective cross sectional study. We recruited 20 patients with injury of the left AF with mild TBI and evaluated the DTTs of the left AF ; decline in FA values of left AF compared to right AF using age matched controls using previous study data was used as an index of dominant AF injury. On WAB evaluation, aphasia quotient was calculated and correlated with the degree of aphasia and the severity of AF injury. Results: Based on the aphasia quotient patients were classified into mild, moderate and severe and this was correlated well with the level of arcuate fasciculus injury. A positive linear correlation between the decline of FA values in the language dominant hemisphere to the degree of aphasia in that patient was established. Hence it can be postulated that severity of injury to arcuate fasciculus is directly proportional to the degree of severity of aphasia. However, no such correlation could be established between the FA values to the specific type of aphasia. Conclusion: DTT could provide useful information in detecting injury of the AF and evaluation of the AF using DTT would be necessary even in the case of a patient with mild TBI who complains of mild language deficit.