Exploring the use of transcranial direct current stimulation in upper-limb rehabilitation

Alabdulaali, Luluh Abdulaziz (2023). Exploring the use of transcranial direct current stimulation in upper-limb rehabilitation. University of Birmingham. Ph.D.

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Abstract

Upper limb motor function is an important factor in many activities of daily living. Stroke patients and older people suffer from limitation in upper limb function that reduces their independence and quality of life. Transcranial direct current stimulation (tDCS) is a promising intervention to enhance upper limb motor function. Its safety, tolerability and cost- effectiveness make it an easily applicable instrument to be employed in clinical and research settings. This thesis, therefore, sought to investigate the motor behaviour of the upper limb and in what way the tDCS could enhance it. We shed light on the difference in the recovery between distal and proximal segments of the upper limb by testing our hypothesis that stimulating the Primary Motor Cortex (PMC) using tDCS could improve the movement of the distal segment more than proximal segment.

Three studies were undertaken: secondary research, systematic review and meta-analysis and behavioural experimental study. The finding of the secondary research demonstrated the possibility of the superior effect of anodal tDCS stimulating the PMC on improving the tasks that require primarily fine hand movement more than tasks that require primarily arm movement in chronic stroke patients. The systematic review and meta-analysis indicated a moderate quality of evidence that tDCS stimulating the PMC enhances fine dexterity and has no significant effect on gross dexterity. The fine dexterity improved in chronic stroke patients more than in subacute and acute stroke patients. Furthermore, the bilateral tDCS montage showed the highest beneficial effect of tDCS. Finally, the findings of the behavioural study highlighted the significant deterioration in fine and gross dexterity in healthy active lifestyle older people compared to healthy young participants. The older participants showed strong pinch grip which was similar to that of young participants. We suggested that the age-related cortical changes are the underlying cause of dexterity deterioration, also, the hand strength is not indicator for hand function because loss of dexterity in older people could be present with or without muscle weakness. The plan was to follow the behavioural study by an experiment examining the effect of the tDCS stimulation of the PMC and cerebellum on improving the movement of the distal versus proximal segments of the upper limb using fine and gross dexterity measures in healthy young and older people. The experiment was discontinued due to the COVID-19 pandemic.

Overall, tDCS is a promising intervention has an additional value to motor rehabilitation for improving upper limb motor function. The targeted stimulation is the key to getting the highest benefit of tDCS. tDCS stimulating the primary motor cortex showed beneficial effect on fine dexterity. The targeted area for improving gross dexterity needs to be explored. We hope this thesis will add to the enhancement of the application of the tDCS.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):