Long-term Effect of Low Frequency Stimulation on Aspiration and Freezing of Gait in PD With STN DBS

A speech pathologist used the Penetration-Aspiration Scale (PAS) to rate swallows captured by a radiologist during VFSS recording. PAS is an 8-point interval scale: a score of 0 indicates no penetration or aspiration & a score of 6-8 indicates aspiration of increasing severity. For the purpose of this study, aspiration was dichotomized to "0" if PAS score was under 6 or "1" if PAS score was between 6-8. Frequency of aspiration events was calculated by adding number of aspiration events in VFSS under various liquid & food textures. The maximum aspiration frequency was 12 if aspiration occurred on every texture after 2 trials. Lower aspiration frequency means better swallowing function.

The Swallowing Disturbance Questionnaire contains 15 items. Each item has 4-points ranging from 0 (absence of symptoms) to 3 (severe or very frequent). Total score ranges from 0-45, with higher scores corresponding to more severe swallowing disturbance.

The Freezing of Gait (FOG) Questionnaire contains 6 items to evaluate the severity of FOG in patients with Parkinson's disease. Each item has 5 points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-24, with higher scores corresponding to more severe FOG.

The Stand-Walk-Sit (SWS) Test assesses freezing of gait (FOG) spells observed when standing up, walking 7 meters, and returning to a seated position. The greater the number of FOG spells counted, the worse the FOG symptoms.

Stand-Walk-Sit (SWS) Time measures the total time taken to complete the SWS test of standing up, walking 7 meters, and returning to a sitting position. The longer time (in seconds) it took to complete the SWS test, the worse the FOG symptoms.

A speech pathologist used the Penetration-Aspiration Scale (PAS) to rate swallows captured by a radiologist during VFSS recording. PAS is an 8-point interval scale: a score of 0 indicates no penetration or aspiration & a score of 6-8 indicates aspiration of increasing severity. For the purpose of this study, aspiration was dichotomized to "0" if PAS score was under 6 or "1" if PAS score was between 6-8. Frequency of aspiration events was calculated by adding number of aspiration events in VFSS under various liquid & food textures. The maximum aspiration frequency was 12 if aspiration occurred on every texture after 2 trials. Lower aspiration frequency means better swallowing function.

The Swallowing Disturbance Questionnaire contains 15 items. Each item has 4-points ranging from 0 (absence of symptoms) to 3 (severe or very frequent). Total score ranges from 0-45, with higher scores corresponding to more severe swallowing disturbance.

The Freezing of Gait (FOG) Questionnaire contains 6 items to evaluate the severity of FOG in patients with Parkinson's disease. Each item has 5 points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-24, with higher scores corresponding to more severe FOG.

The Stand-Walk-Sit (SWS) Test assesses freezing of gait (FOG) spells observed when standing up, walking 7 meters, and returning to a seated position. The greater the number of FOG spells counted, the worse the FOG symptoms.

Stand-Walk-Sit (SWS) Time measures the total time taken to complete the SWS test of standing up, walking 7 meters, and returning to a sitting position. The longer time (in seconds) it took to complete the SWS test, the worse the FOG symptoms.

Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 33 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-132, with higher scores corresponding to more severe parkinsonism.

The axial subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 7 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-28, with higher scores corresponding to more severe axial symptoms. Specifically, axial symptoms include: speech, facial expression, arising from chair, gait, freezing of gait, postural stability, posture.

The bradykinesia subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 11 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-44, with higher scores corresponding to more severe bradykinesia. Specifically, bradykinesia symptoms include: finger tapping right hand, finger tapping left hand, hand movements right hand, hand movements left hand, pronation-supination movements right hand, pronation- supination movements left hand, toe tapping right foot, toe tapping left foot, leg agility right leg, leg agility left leg, global spontaneity of movement.

The rigidity subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 5 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-20. with higher scores corresponding to more severe rigidity. Specifically, rigidity symptoms include: rigidity neck, rigidity right upper extremity, rigidity left upper extremity, rigidity right lower extremity, rigidity left lower extremity.

The tremor subscore of Unified Parkinson's Disease Rating Scale (UPDRS-III) contains 10 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-40, with higher scores corresponding to more severe tremor. Specifically, tremor symptoms include: postural tremor right hand, postural tremor left hand, kinetic tremor right hand, kinetic tremor left hand, rest tremor amplitude right upper extremity, rest tremor amplitude left upper extremity, rest tremor amplitude right lower extremity, rest tremor amplitude left lower extremity, rest tremor amplitude lip/jaw, constancy of rest tremor.

Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 33 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-132, with higher scores corresponding to more severe parkinsonism.

The axial subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 7 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-28, with higher scores corresponding to more severe axial symptoms. Specifically, axial symptoms include: speech, facial expression, arising from chair, gait, freezing of gait, postural stability, posture.

The bradykinesia subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 11 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-44, with higher scores corresponding to more severe bradykinesia. Specifically, bradykinesia symptoms include: finger tapping right hand, finger tapping left hand, hand movements right hand, hand movements left hand, pronation-supination movements right hand, pronation- supination movements left hand, toe tapping right foot, toe tapping left foot, leg agility right leg, leg agility left leg, global spontaneity of movement.

The rigidity subscore of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) contains 5 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-20. with higher scores corresponding to more severe rigidity. Specifically, rigidity symptoms include: rigidity neck, rigidity right upper extremity, rigidity left upper extremity, rigidity right lower extremity, rigidity left lower extremity.

The tremor subscore of Unified Parkinson's Disease Rating Scale (UPDRS-III) contains 10 items. Each item has 5-points ranging from 0 (absence of symptoms) to 4 (severe). Total score ranges from 0-40, with higher scores corresponding to more severe tremor. Specifically, tremor symptoms include: postural tremor right hand, postural tremor left hand, kinetic tremor right hand, kinetic tremor left hand, rest tremor amplitude right upper extremity, rest tremor amplitude left upper extremity, rest tremor amplitude right lower extremity, rest tremor amplitude left lower extremity, rest tremor amplitude lip/jaw, constancy of rest tremor.