Clinical Efficacy and Mechanism of tDCS for Dysphagia in PD

Rosenbek Penetration-Aspiration Scale (PAS):

Scored 1-8, with higher scores indicating poorer swallowing safety. 1. Level 1: The bolus does not enter the airway; it remains entirely within the oral cavity or pharynx and is propelled normally. 2. Level 2: The bolus enters the supraglottic area (e.g., vallecula) but does not touch the vocal cords, and is completely cleared (e.g., via swallowing or coughing). 3. Level 3: The bolus enters the supraglottic area without touching the vocal cords, but residue remains (not fully cleared). 4. Level 4: The bolus touches the vocal cords but does not enter the subglottic airway, and is completely cleared. 5. Level 5: The bolus touches the vocal cords without entering the subglottic airway, but residue remains. 6. Level 6: The bolus enters the subglottic airway (into the trachea) but is completely cleared by the patient (e.g., via coughing). 7. Level 7: The bolus enters the subglottic airway; the patient exhibits protective responses (e.g., coughing) but cannot fully clear it, leaving

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

Videofluoroscopic Dysphagia Scale (VDS)

14 items in total, including 7 items for oral-phase swallowing function and 7 for pharyngeal-phase function, used to assess overall swallowing function;

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

oral residue

Post-swallow residue was scored 0-3, with higher scores indicating more food residue and lower swallowing efficiency

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

Amplitude of Low Frequency Fluctuation (ALFF)

ALFF focuses on the low-frequency components of these HbO/HbR time series. It is defined as the average amplitude of hemodynamic signal fluctuations within a specific low-frequency range (typically 0.01-0.1 Hz, though the exact band may vary by study). This range is chosen because it captures slow, spontaneous oscillations in cerebral blood flow and oxygenation, which are hypothesized to reflect synchronized neural activity across brain regions (e.g., default mode network, sensorimotor networks). Mathematically, ALFF quantifies the "strength" of these low-frequency oscillations: a higher ALFF value indicates more prominent or intense fluctuations in the target frequency band, suggesting greater spontaneous hemodynamic (and thus neural) activity in that brain region.

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

Functional Connectivity (FC)

Functional Connectivity (FC) refers to the statistical association or synchronization between spontaneous hemodynamic signals from different cortical regions, reflecting the coordinated activity of spatially distinct brain areas. It quantifies how closely the neural activity (inferred from blood oxygenation changes) in one brain region correlates with that in another, providing insights into the integration of brain networks.

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

vellaculae residue

The residue amount was rated on a scale from 0 to 3: 0 indicates that no residue was visible, 1 indicates mild residue(the level of contrasted material constituted less than 25% of the height of the structure), 2 indicates moderate residue (the level of contrasted material constituted between 25 and 50%of the height of the structure), and 3 indicates severe residue(the level was higher than 50% of the height of the structure).

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up

pyriform sinuses residue

The residue amount was rated on a scale from 0 to 3: 0 indicates that no residue was visible, 1 indicates mild residue(the level of contrasted material constituted less than 25% of the height of the structure), 2 indicates moderate residue (the level of contrasted material constituted between 25 and 50%of the height of the structure), and 3 indicates severe residue(the level was higher than 50% of the height of the structure).

Time frame: at baseline, after the completion of 10 days of intervention, at the 3-month follow-up