Comparison of Lexical-Semantic Disorders of Right Hemisphere Damaged Adult Persian-Speaking Patients Based on the Montreal Protocol for the Evaluation of Communication (M.E.C.)

The previous prevailing view in neurolinguistics was that the left hemisphere plays a central role in different linguistic levels. In various forms, damage to this hemisphere causes impairments in individuals' linguistic abilities to varying degrees. But, today, it has become clear that the right hemisphere is involved in processing various linguistic aspects. The current study aimed to evaluate lexical-semantic disorders of right hemisphere damaged adult Persian-speaking patients based on the Montreal Protocol for the Evaluation of Communication (M.E.C)

The research was a case study and descriptive. The statistical population included five right hemisphere damaged patients who had a stroke. Patients’ brain lesions were determined using C.T.Scan and M.R.I. Subjects aged from a minimum of 54 up to a maximum of 76 years (mean age 62 years and eight months), all were righthanded and literate. Screening tests were administered, including Coren Handedness Inventory, Mini-Mental State Examination (MMSE), and Persian Diagnostic Aphasia Battery (Bedside Version-AQ1). Then, the Montreal Protocol for the Evaluation of Communication (M.E.C.) was performed to evaluate lexical-semantic skills. M. E. C protocol was designed by Joanette, Esca, and Cote (2004) in Canada and the French language. This protocol consists of 16 subtests that measure prosodic, lexical-semantic, discourse, and pragmatic skills. Four subtests related to lexical-semantic skills have been used in the present study. Standards scores and patient performance percentages in each subtest were used for analysis.

The data's general analysis of the data based on the patient scores and performances in 4 sub-tests of lexical-semantic processing of M.E.C protocol compared with standard scores showed that patient No. 5, with the wide lesion in the temporal lobe and the posterior lobe, had the weakest function in all four subtests. On the other hand, patient number 4, who suffered an insula lesion, had the best performance. Based on these findings, it seems that the insula region does not play a significant role in lexical-semantic processing. Patients 1, 2, and 3 performed similarly poorly with damages to the frontal-temporal lobe, the inner capsule of the basal ganglia, and the middle temporal lobe, respectively. Study data showed that all five patients performed homogeneously in the sub-test of speech fluency without limitation.

Based on the data obtained from five subjects of the present study, it was observed that the location of brain lesions affects the degree of impairment in lexical-semantic processing. In addition, damage to the right hemisphere, especially the temporal lobe and the inner capsule of the basal ganglia, can lead to impairment of lexical-semantic processing.