Institute for Ageing and Health, Newcastle University, Wolfson Research Centre, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
Br J Psychiatry. 2011 Dec;199(6):492-500. doi: 10.1192/bjp.bp.110.090373. Epub 2011 Oct 20.
The aetiology of visual hallucinations is poorly understood in dementia with Lewy bodies. Pathological alterations in visual cortical excitability may be one contributory mechanism.
To determine visual cortical excitability in people with dementia with Lewy bodies compared with aged-matched controls and also the relationship between visual cortical excitability and visual hallucinations in dementia with Lewy bodies.
Visual cortical excitability was determined by using transcranial magnetic stimulation (TMS) applied to the occiput to elicit phosphenes (transient subjective visual responses) in 21 patients with dementia with Lewy bodies and 19 age-matched controls.
Phosphene parameters were similar between both groups. However, in the patients with dementia with Lewy bodies, TMS measures of visual cortical excitability correlated strongly with the severity of visual hallucinations (P = 0.005). Six patients with dementia with Lewy bodies experienced visual hallucination-like phosphenes (for example, seeing people or figures on stimulation) compared with none of the controls (P = 0.02).
Increased visual cortical excitability in dementia with Lewy bodies does not appear to explain visual hallucinations but it may be a marker for their severity.
路易体痴呆的视觉幻觉病因尚不清楚。视觉皮层兴奋性的病理性改变可能是一个促成机制。
与年龄匹配的对照组相比，确定路易体痴呆患者的视觉皮层兴奋性，并确定路易体痴呆患者的视觉皮层兴奋性与视觉幻觉之间的关系。
通过经颅磁刺激（TMS）施加于枕部来诱发视幻（短暂的主观视觉反应），以确定 21 例路易体痴呆患者和 19 例年龄匹配的对照组的视觉皮层兴奋性。
两组的视幻参数相似。然而，在路易体痴呆患者中，TMS 测量的视觉皮层兴奋性与视觉幻觉的严重程度密切相关（P=0.005）。6 例路易体痴呆患者出现类似视觉幻觉的视幻（例如，在刺激时看到人或图像），而对照组无一例（P=0.02）。
路易体痴呆患者的视觉皮层兴奋性增加似乎不能解释视觉幻觉，但它可能是其严重程度的标志物。
