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DTI Prediction of Treatment Response to cerebellar tDCS plus language therapy

Poster B59 in Poster Session B, Tuesday, October 24, 3:30 - 5:15 pm CEST, Espace Vieux-Port

Rajani Sebastian1, Zafer Keser2, Ji Hyun Kim1, Sarah Cust1, Becky Lammers1, Myra Sydnor1, Donna Tippett1, Argye Hillis1; 1Johns Hopkins University School of Medicine, 2Mayo Clinic

Introduction Neuromodulation techniques especially transcranial direct current stimulation (tDCS) have provided tools to augment language rehabilitation effects in poststroke aphasia. Studies including our work have shown that cerebellar tDCS in conjunction with language therapy, improves language outcomes in aphasia (DeMarco et al., 2021; Marangolo et al., 2018; Sebastian et al., 2017, 2020). However, the results of our study indicate marked individual variability in cerebellar tDCS response. Therefore, it is critical to address the question of who may benefit from neuromodulation. This can inform our knowledge base regarding optimal benefit from adjuvant tDCS. We have shown that aphasia severity and lesion characteristics influence outcome of cerebellar neuromodulation in chronic aphasia (Sebastian et al., 2020). In the present study, we aimed to determine whether cerebello-cerebral white matter integrity is associated with cerebellar tDCS effects in participants with aphasia. Methods Nineteen, right-handed participants with chronic aphasia due to left hemisphere stroke were included in the study (67 ± 9.18 years of age, 3 females). Pre-treatment magnetic resonance & diffusion tensor imaging (MR-DTI) were acquired on a Philips 3T scanner. All participants received language assessments before and after 15 sessions of computerized aphasia therapy (Fridriksson et al., 2018) combined with cerebellar tDCS and sham tDCS in a randomized, cross-over trial study design. The primary variable of interest was post-treatment functional communication scores assessed via the American Speech-Language-Hearing Association Functional Assessment of Communication Skills for Adults (ASHA-FACS, Frattali et al., 1995). The ASHA FACS has two dimensions: Communication Independence (CI) scale and Qualitative Dimension of Communication (QDC) scale. MR-DTI analysis included lesion load and cerebellar lobules segmentation and semi-automated brute force and multiple regions-of-interest (ROI) deterministic tractography of bilateral cerebellar segments and cerebello-cerebral white matter connections (Keser et al., 2023). White matter integrity was measured by mean diffusivity (MD) and fractional anisotropy (FA). Recursive feature elimination and Spearman correlation analyses were performed to evaluate the relationship between baseline bilateral cerebellar segments and cerebello-cerebral white matter integrity and post-treatment functional communication scores (CI and QDC) for tDCS and sham interventions. The analysis was adjusted for age and lesion load. Results The results revealed that lower baseline MD values of the right cerebellar segments (VIIb: R=-0.57, p=0.026; VIIIa:R=-0.48, p=0.039) and left cortico-ponto-cerebellar tracts connecting the left cerebrum to the right cerebellum (fronto-ponto-cerebellar tract: R=-0.57,p=0.01; parieto-ponto-cerebellar tract: R=-0.6,p=0.006; temporo-ponto-cerebellar tract: R=-0.59, p=0.007; occipito-ponto-cerebellar tract : R=-0.51, p=0.026) were associated with greater improvement on the QDC scores for tDCS intervention. Lower baseline MD values of the right cerebellar segments (VIIb: R=-0.52, p=0.03; VIIIa:R=-0.51, p=0.038) were also associated with greater improvement on the QDC scores for sham intervention. Conclusion: Our preliminary analysis showed that the integrity of the left cortico-ponto-cerebellar tracts (as measured by MD) predicted tDCS effects for functional communication skills, whereas white matter integrity of right cerebellar segments predicted effects of tDCS and sham interventions. These findings hold promise that baseline cerebello-cerebral white matter integrity could be used as a biomarker for treatment response to cerebellar tDCS in aphasia, but larger studies are needed.

Topic Areas: Disorders: Acquired,

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