[IDENTIFYING BRAIN STRUCTURES THAT CONTRIBUTE TO UPPER-LIMB RECOVERY POST STROKE USING THREE DIFFERENT METHODS OF LESION-SYMPTOM MAPPING].

Abstract

Aims: The identification of brain structures that are critical for upper limb residual motor function following stroke is an essential step towards the development of advanced treatment modalities for improving rehabilitation outcomes among brain-injured patients, such as non-invasive brain stimulation techniques, which aim to induce neuroplasticity in motor-critical brain regions. In the current study we attempted to identify the critical brain regions for upper limb motor function among stroke patients, using three different methods of lesion-symptom mapping (LSM).

Methods: Brain imaging data and Fugl-Meyer Assessment for upper-limb (FMA) scores for 107 patients admitted to the neurological rehabilitation department at Loewenstein Rehabilitation Medical Center, were analyzed using 3 LSM methods: Voxel-based Lesion-Symptom Mapping (VLSM), Region-based Lesion-Symptom Mapping (RLSM), and Multi-perturbation Shapley-value Analysis (MSA).

Results: In left-hemispheric damaged (LHD) patients only a relatively small number of brain regions were found, in comparison with right-hemispheric damaged (RHD) patients. For LHD, two regions important for movement planning were found to be critical - the supplementary motor area and the premotor area. For RHD, parts of the temporal, frontal and insular cortices, as well as the cingulate gyrus were exclusively detected as critical. Sub-cortical brain structures (basal ganglia, corona radiata, internal capsule and superior longitudinal fasciculus) were detected in both hemispheres.

Conclusions: Despite the variability between different LSM methods, all methods have consistently shown a difference between the critical brain-regions for upper-limb function following LHD vs. RHD. These findings support previous works suggesting that the left (motor-dominant) hemisphere is more inter-connected, thus it has higher redundancy and decreased vulnerability to focal damage.