Background: White matter nerve fiber injury plays an important role in aphasia. As brain imaging technique have developed, marvelous DTI enables to evaluate white matter nerve fibers in vivo. In patients with hemorrhagic stroke, the hemorrhage mainly occurred in deep white matter structure, which could be suitable to evaluate nerve fiber injury. Since aphasia is serious common problem in patients with stroke, the present study aimed to explore the features of language dysfunction across the various aphasia types based on nerve fiber injury using DTI in patients with acute hemorrhagic stroke.
Method: One normal adult male (control) and five adults with acute hemorrhagic stroke (patient group) within 30 days from symptom onset participated in this study. Brain CT, MRI, DTI images and PK-WAB-R were tested within 1 month after brain damage. In this study, two dorsal nerve fibers [superior longitudinal fasciculus (SLF), arcuate fasciculus (AF)] and two ventral nerve fibers [inferior longitudinal fasciculus (ILF), uncinate fasciculus (UF)] were investigated for DTI analysis. The location and size of hematoma were detected by CT and MRI while the location of nerve fiber injury and severity of nerve fiber injury based on the disconnection, loss of leftward asymmetry of nerve fibers were observed from DTI. In addition, spontaneous speech, auditory comprehension, repetition, naming, word retrieval, reading, and writing scores were measured in PK-WAB-R test and finally, Aphasia Quotient (AQ) score and Language Quotient (LQ) score were obtained.
Result: Hematoma volumes were relatively larger and AQ scores were lower in P1, P3, and P5. In particular, the highest AQ was found in P2 who demonstrated the nerve fiber tract with no disconnection and reconstruction failure except mild loss of leftward asymmetry. Interestingly, the location of lesion on CT and MRI was same with P1, P5, but the aphasia type by PK-WAB-R was different from each other. This finding showed that there was no absolute relationship between the lesion site and aphasia type but the relationship between the nerve fiber injury site on DTI and aphasia type. Non-fluent patients (P1, P3, P5) showed SLF, AF damage whereas relatively good comprehensive patients (P2, P4, P5) showed relative preservation of ventral nerve tract except in P5 who showed UF damage.
Conclusion: DTI provided the sensitive detection of nerve fiber damage in patients with cerebral hemorrhage and useful tool in predicting aphasia type and language dysfunction. The aphasia type and severity by PK-WAB-R had some relationship with the white matter lesion site and severity on DTI. It will be expected that the reliability of PK-WAB-R and the comprehensive knowledge about the white matter nerve injury in aphasia patients would be raised up by using DTI.
Key Word: Aphasia, PK-WAB-R, DTI, Hemorrhagic stroke, White matter nerve tract
Abbreviation: PK-WAB-R=Paradise Korean-Western Aphasia Battery-Revised, CT=computerized tomography, MRI=magnetic resonance imaging, DTI=Diffusion Tensor Imaging, P= Patient