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Li M-H1, Chan S-T1, Lee Y-Y1
1National Taiwan University, Physical Therapy, Taipei, Taiwan
Background: Transcranial magnetic stimulation (TMS) is a neuroimaging tool that has been widely used to evaluate neurophysiological changes in corticospinal and intracortical excitability. Using TMS, people with Parkinson's disease (PD), known to have striatal dysfunction, were found to present a reduced intracortical inhibition compared with age-matched non-disabled adults. However, previous studies have not further sub-categorized the PD patients into those who have freezing of gait (FoG) or not. Individuals with FoG often feel the feet being glued to the floor despite the intention to walk. While some neuroimaging studies have demonstrated that the brain activated differently between the patients with FoG and those without, no study to date has used TMS to evaluate the neurophysiological changes associated with FoG.
Purpose: This study aimed to use TMS to determine the changes in corticomotor excitability of PD participants with FoG compared with those without FoG and age-matched non-disabled adults.
Methods: This was a cross-sectional study. The PD participants were categorized into those who had FoG and those without FoG according to the New Freezing of Gait Questionnaire. We recruited 18 PD participants with FoG (PD+FoG), 15 PD participants without FoG (PD-FoG) and 14 age-matched non-disabled adults (Control). People with PD were evaluated during ON-phase of medication. TMS stimuli were applied over the cortical representation area of the tibialis anterior muscle of the more-affected side in participants with PD, and of the dominant leg in the control participants. Resting motor threshold (RMT), resting motor evoked potential (MEP) amplitude, active MEP amplitude and cortical silent period (CSP) were determined using single-pulse paradigm. Short interval intracortical inhibition with 2 ms interstimulus interval (SICI-2) and intracortical facilitation with 12 ms interstimulus interval (ICF-12) were evaluated with paired-pulse paradigm. One-way analysis of variance or Kruskal-Wallis test were used to compare the differences among the 3 groups. The α level was set at 0.05.
Results: Participants with PD+FoG were found to have significantly lower RMT than the control participants (p = 0.016). Additionally, SICI-2 was significantly reduced in PD+FoG than Control group (p = 0.014). No statistical significant differences were found on resting MEP, active MEP, CSP, and ICF-12 among the 3 groups.
Conclusion(s): Compared with age-matched non-disabled adults, people with PD and FoG revealed lower RMT and a reduced intracortical inhibition, suggesting that PD individuals with FoG presented an overall hyper-excitability of the corticospinal tract and an abnormal intra-cortical inhibitory mechanism.
Implications: The findings of this research are important for researchers to further understand the neurophysiological changes associated with FoG and may facilitate clinicians design appropriate training strategies for those patients experiencing FoG.
Keywords: Transcranial magnetic stimulation, Parkinson's disease, Freezing of gait
Funding acknowledgements: This study was supported by the Ministry of Science and Technology (MOST 105-2314-B-002 -202 and 106-2314-B-002 -044 -MY3).
Purpose: This study aimed to use TMS to determine the changes in corticomotor excitability of PD participants with FoG compared with those without FoG and age-matched non-disabled adults.
Methods: This was a cross-sectional study. The PD participants were categorized into those who had FoG and those without FoG according to the New Freezing of Gait Questionnaire. We recruited 18 PD participants with FoG (PD+FoG), 15 PD participants without FoG (PD-FoG) and 14 age-matched non-disabled adults (Control). People with PD were evaluated during ON-phase of medication. TMS stimuli were applied over the cortical representation area of the tibialis anterior muscle of the more-affected side in participants with PD, and of the dominant leg in the control participants. Resting motor threshold (RMT), resting motor evoked potential (MEP) amplitude, active MEP amplitude and cortical silent period (CSP) were determined using single-pulse paradigm. Short interval intracortical inhibition with 2 ms interstimulus interval (SICI-2) and intracortical facilitation with 12 ms interstimulus interval (ICF-12) were evaluated with paired-pulse paradigm. One-way analysis of variance or Kruskal-Wallis test were used to compare the differences among the 3 groups. The α level was set at 0.05.
Results: Participants with PD+FoG were found to have significantly lower RMT than the control participants (p = 0.016). Additionally, SICI-2 was significantly reduced in PD+FoG than Control group (p = 0.014). No statistical significant differences were found on resting MEP, active MEP, CSP, and ICF-12 among the 3 groups.
Conclusion(s): Compared with age-matched non-disabled adults, people with PD and FoG revealed lower RMT and a reduced intracortical inhibition, suggesting that PD individuals with FoG presented an overall hyper-excitability of the corticospinal tract and an abnormal intra-cortical inhibitory mechanism.
Implications: The findings of this research are important for researchers to further understand the neurophysiological changes associated with FoG and may facilitate clinicians design appropriate training strategies for those patients experiencing FoG.
Keywords: Transcranial magnetic stimulation, Parkinson's disease, Freezing of gait
Funding acknowledgements: This study was supported by the Ministry of Science and Technology (MOST 105-2314-B-002 -202 and 106-2314-B-002 -044 -MY3).
Topic: Neurology; Neurology
Ethics approval required: Yes
Institution: National Taiwan University Hospital
Ethics committee: Research Ethics Committee of the National Taiwan University Hospital
Ethics number: 201606057RINA
All authors, affiliations and abstracts have been published as submitted.
