Left parietal cortex transcranial direct current stimulation enhances gesture processing in corticobasal syndrome

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Corticobasal syndrome (CBS) presents with higher cortical dysfunction and asymmetric parkinsonism.
• Limb apraxia is a common and debilitating symptom in CBS, impacting daily activities.
• Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique with potential for neurorehabilitation.

Purpose of the Study:

• To investigate the efficacy of anodal tDCS applied to the parietal cortex (PARC) in improving ideomotor upper limb apraxia in CBS patients.
• To determine if stimulation of the left or right PARC yields better outcomes for apraxia.
• To assess tDCS as a potential therapeutic tool for CBS-related apraxia.

Main Methods:

• Fourteen patients diagnosed with possible CBS and upper limb apraxia participated.
• Each patient received two active anodal tDCS sessions (left and right PARC) and one placebo session.
• Ideomotor apraxia was evaluated using the De Renzi ideomotor apraxia test, focusing on imitation tasks.

Main Results:

• Significant improvement in De Renzi ideomotor apraxia test scores was observed after active anodal stimulation over the left PARC compared to pre-stimulation.
• No significant improvement was noted after active stimulation over the right PARC.
• Post hoc analysis confirmed selective improvement in apraxia scores for both right and left upper limbs following left PARC stimulation compared to placebo.

Conclusions:

• Anodal tDCS applied to the left parietal cortex effectively enhances performance on ideomotor apraxia tests in CBS patients.
• These findings suggest tDCS is a promising non-invasive approach for the neurorehabilitation of limb apraxia in corticobasal syndrome.
• Further research into tDCS protocols for CBS rehabilitation is warranted.