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作者：Allison Gandey  
出處：WebMD醫學新聞

　　October 2, 2009 — 一篇新研究認為，巴金森氏症且有動作僵硬問題的患者，真正的問題可能是感覺-知覺議題。這些發現也質疑現在將僵硬視為動作功能不佳的想法，而是將它視為與空間認知有關。此研究發表於神經學、神經外科學與精神醫學期刊。
　　
　　因為僵硬情形經常發生於密閉空間時，研究者提出感覺-知覺問題是否有關的疑問。他們研究了15名巴金森氏症且發生僵硬的患者，其他16名沒有僵硬的巴金森氏症患者，以及16名健康、年齡相仿的對照組。
　　
　　研究者研究出入口的大小對行為的影響。他們評估走過三種不同大小（窄、正常、寬）的出入口時，步態時空方位的改變。
　　
　　他們發現，發生僵硬的巴金森氏症病患，多數受到窄門的影響。當靠近窄門時，這些病患步伐較小，有較多的步態變化，傾向加寬他們的支撐地。研究者發現，在試驗中，有僵硬的病患，其步伐長度和走步時間有較多的變化，且此一情形隨著出入口大小減少而加強[F(4,88) = 2.99；P < .023]。
　　
　　沒有發生僵硬的巴金森氏症病患，也會受到窄門影響而傾向加寬他們的支撐地。
　　
　　第一作者、加拿大Wilfrid Laurier大學的Quincy Almeida博士向Medscape Neurology表示，或許醫師的最重要考量是，有時候跳出框架來思考是重要的。在目前研究發現的案例中，當我們偵測臨床動作不佳時，重點在於質疑是否有潛在的機轉造成這些問題。
　　
　　【步伐縮短、步態多變、加寬支撐地】
　　Almeida博士認為，因為他的研究團隊在門前可以確認正常行走模式的變化，可能有感覺-知覺機轉造成或甚至是引起臨床上可辨識的僵硬發作。
　　
　　Almeida博士表示，或許最令人驚訝的發現是，即便是沒有僵硬問題的巴金森氏症患者，也深受對於即將面臨窄門的認知而影響。
　　
　　他表示，另外，在正常大小的出入口中，典型的巴金森氏症病患行為比較像沒有在門口前改變行走型態的健康年長者。但是在窄門前，行為有所改變，沒有僵硬者的行為很像有僵硬者。
　　
　　其他研究團隊，例如以色列特拉維夫大學的Jeffrey Hausdorff博士領導的團隊，也觀察到有僵硬情形的巴金森氏症患者在跨步調控上有問題(Exp Brain Res. 2003;149:187–194)。
　　
　　相對的，荷蘭阿姆斯特丹VU大學醫學中心的Erwin Van Wegen博士發現，真正的走廊的小空間對於巴金森氏症患者的步態沒有影響(Parkinsonism Relat Disord. 2006;12:21–27)。
　　
　　【需要更多研究】
　　Almeida博士表示，我們現在聚焦於試圖確認出入口大小對於行走型態改變的影響為何。如果這點可以加以確認，那麼，治療發生僵硬者的可能性或改變出入口設計的機會將增加。
　　
　　Almeida博士指出，依舊有許多問題，例如這是否是一個感覺問題：眼睛未能適當分析出入口的特徵，或者是否是認知問題：無法認知出入口的深度或寬度。
　　
　　研究者指出，巴金森氏症病患無法準確評估面對即將來臨的阻礙時的相關自我動作。這在考量其他狀況，如進入一個電梯或任何密閉或狹窄的空間時，可能是一個重要的知覺因素。
　　
　　研究者認為，在未來的研究中，某種眼睛追蹤裝置將有助於監測研究對象在接近時的凝視狀況。
　　
　　加拿大自然科學與工程研究委員會支持本研究。研究者皆宣告沒有相關財務關係。
　　
　　J Neurol Neurosurg Psychiatry. 。線上發表於2009年9月15日。


Freezing in Parkinson's May Be Linked to Perception of Space
By Allison Gandey
Medscape Medical News
October 2, 2009 — Patients with Parkinson's disease and problems with motor freezing may actually be struggling with sensory–perceptual issues, a new study suggests. The findings call into question current thinking that freezing is a motor impairment and propose instead that it is linked to problems with perception of space. The work is published in the Journal of Neurology, Neurosurgery and Psychiatry.
Because freezing frequently occurs in confined spaces, investigators questioned whether sensory–perceptual issues could be at play. They studied 15 patients with Parkinson's disease and freezing episodes, another 16 Parkinson's patients without freezing, and 16 healthy, age-matched control patients.
Researchers studied how doorway size influenced behavior. They evaluated changes in spatiotemporal aspects of gait while walking through 3 different-sized doorways. One was narrow, another normal, and a third wide.
They found that Parkinson's patients experiencing freezing were most affected by the narrow doorway. While approaching the door, these patients took shorter steps, had more gait variability, and tended to widen their base of support. Investigators found that patients with freezing demonstrated increased within-trial variability of step length and step time, which was exaggerated as doorway size decreased [F(4,88) = 2.99; P < .023].
Parkinson's patients with no freezing episodes were also affected by the narrow doorway and tended to widen their base of support.
"Perhaps the most important consideration for clinicians is that sometimes it is important to think outside the box," lead investigator Quincy Almeida, PhD, from Wilfrid Laurier University in Waterloo, Ontario, Canada, told Medscape Neurology. "In the case of the current study's findings, it suggests that when we detect clinical motor impairments, it is important to question what the underlying mechanism for these impairments might be."
  
Dr. Quincy Almeida  
Shorter Steps, Gait Variability, and Wider Base of Support
Dr. Almeida suggests that because his team could identify changes to the normal walking pattern before the door, it is likely that there is a sensory-perceptual mechanism that contributes to — and potentially even causes — the observable freezing episodes identified clinically.
"Probably the most surprising finding is that even Parkinson's patients who do not have issues with freezing can be profoundly influenced by the perception of an upcoming narrow doorway," Dr. Almeida said.
"In other, normal-sized doorways, the typical Parkinson's patient behaves much more like a healthy older adult with no hint of a change in walking pattern prior to the doorway. Yet in the narrow doorway, there is a shift in behavior and the nonfreezer behaves more like a freezer," he said.
Other research teams such as the one led by Jeffrey Hausdorff, PhD, from Tel-Aviv University in Israel, have also observed impaired regulation of stride in Parkinson's patients with freezing (Exp Brain Res. 2003;149:187–194).
In contrast, Erwin Van Wegen, PhD, from the VU University Medical Center in Amsterdam, the Netherlands, found that small spaces in the form of a virtual corridor had no effect on gait in Parkinson's (Parkinsonism Relat Disord. 2006;12:21–27).
More Study Needed
"We are now focusing on trying to identify what it is about the doorway that influences the change in walking pattern," Dr. Alemeida said. "If this can be determined, then the potential to treat or even change doorway designs for freezers would be high."
Dr. Almeida points out that many questions remain as to whether this is a sensory problem in which the eyes inappropriately analyze characteristics of the doorway or whether it is perhaps a cognitive issue and a failure to perceive depth or doorway width.
The researchers point out that patients with Parkinson's appear to be unable to accurately evaluate self-motion in relation to upcoming obstacles. This may be an important perceptual factor to consider for other situations such as entering an elevator or any confined or crowded space.
The investigators suggest that an eye-tracking device might be useful in future research to monitor participant gaze on approach.
This study was supported by the Natural Sciences and Engineering Research Council of Canada. The researchers have disclosed no relevant financial relationships.
J Neurol Neurosurg Psychiatry. Published online September 15, 2009.