巴金森氏症病患於聽覺提示下執行節律性動作之依頻大腦皮質興奮性

Abstract

背景：外在提示 (External cue) 被廣泛運用於巴金森氏症 (Parkinson’s disease) 之動作功能訓練。前驅研究發現，巴金森氏症病患於2赫茲聽覺提示下執行手指敲擊 (Finger tapping) 訓練後，除了動作表現進步外，亦可能調節大腦動作皮質的活性。然而，患者並不侷限於單一的動作頻率，且物理治療師會依病患狀況給予不同頻率的外在提示。根據以往研究，不同頻率的聽覺提示會影響巴金森氏症患者的動作表現，而大腦動作皮質活性是否能顯現不同頻率間的差異，目前仍未清楚。目的：本研究採用同步化的1赫茲或3赫茲的聽覺提示，對照無同步化的聽覺提示，並要求巴金森氏症病患執行節律性手指動作，觀察其動作表現，且利用經顱磁刺激 (Transcranial magnetic stimulation, TMS) 評估訓練前後大腦皮質興奮性改變情況，是否與2赫茲有所差異。以研究巴金森氏症於不同頻率之聽覺提示訓練時神經生理的改變及可能機轉。方法：此為隨機交叉研究 (Cross-over study)，收取25位侯葉分期 (Modified Hoehn & Yahr Stage) 為I至III期原發性巴金森氏症候群患者，其中12位 (年齡為64.2 ± 8.0歲) 分配至1赫茲組，13位 (年齡為61.4 ± 9.4歲) 則分配至3赫茲組。而兩組受試者皆需接受兩次相隔一星期之介入，外在提示為同步化的聽覺提示下進行手指節律動作，而自我導引則於無聽覺提示下進行。結果：外在提示練習後，只有2赫茲組快速手指動作的變異度顯著減少 (p= .032)，三組大腦皮質內的抑制強度 (Short intracortical inhibition, SICI) 顯著增加 (1赫茲：p= .002；2赫茲：p< .001；3赫茲：p< .001)，且與自我引導練習後有顯著差別 (1赫茲：p< .001；2赫茲：p= .005；3赫茲：p= .011)，而大腦皮質內促進強度 (Intracortical facilitation, ICF) 則顯著降低 (1赫茲：p= .006；3赫茲：p= .002)。三組間比較發現，大腦皮質內促進強度於1赫茲與3赫茲相對2赫茲有顯著差異 (1赫茲與2赫茲間：p= .001；2赫茲與3赫茲間：p= .008)。結論：僅2赫茲同步化聽覺提示能顯著增加節律性動作表現，雖然三者頻率皆能調節大腦皮質內興奮性，但並未能完整地解釋運動皮質興奮性之改變與運動表現的相互關係。

Background: External cues are widely applied on training motor functions in movement disorder such as Parkinson’s disease (PD). In our previous study, changes in the motor cortex excitability were shown the 2 Hz finger tapping with auditory cue might modulate the cortical activity in PD patients. However, movements of human subjects are not restricted to a specific rhythm, and physical therapists use external cues across different frequencies depending on patients’ status in rehabilitation. Frequency-dependent movement activities were reported in present studies. It is still unclear whether motor cortex activity reveals a frequency-dependent pattern at different rates in PD. Objective：The performance and motor cortex excitability of frequency-dependent finger movements with auditory cue in patients with PD were investigated in this study. To explore the mechanism underlying the auditory cued training across different frequencies, changes of motor cortex excitability were obtained by using transcranial magnetic stimulation (TMS). Methods: This study was a cross-over study. A total of twenty-five patients (H & Y stage I-III) were randomly assigned to 1 Hz (12 patients, 64.2 ± 8.0 years) or 3 Hz (13 patients, 61.4 ± 9.4 years) group. All participants received two sessions of experiment in random order, one was external-triggered condition which received auditory cue while performed movements, and self-initiated condition which performed movement after listened to required rhythm. Results: After training with auditory cues, CV of fast tapping only significantly decreased in 2 Hz condition (p= .032). There were significant increase of short intracortical inhibition (SICI) (1 Hz: p= .002; 2 Hz: p< .001; 3Hz: p< .001) and significant difference between ET and SI conditions (1 Hz: p< .001; 2 Hz: p= .005; 3Hz: p= .011). Significant post-training decrease of intracortical facilitation (ICF) in 1 Hz and 3 Hz groups (1 Hz: p= .006; 3Hz: p= .002). Additionally, ICF was significantly different between 1 Hz and 2 Hz conditions (p= .001), 2 Hz and 3 Hz conditions (p= .008). Conclusions: Only 2 Hz auditory cues had significant benefit in rhythmic movements. Though 1 Hz, 2 Hz and 3 Hz cues were able to modulate the cortical excitability in the motor cortex, the mechanisms involved in the application of auditory cues still needed more studies.