Frequency analyses of posturography using logarithmic translation

Abstract

Background: Power-spectral analysis of the centre of pressure (CoP) frequencies of posturography provides exponentially approximated distributions, whereas logarithmic translation enables linear approximation.

Objectives: Frequency analyses were adopted for posturography of healthy subjects and patients with spinocerebellar degeneration (SCD) using logarithmic translation to determine its clinical usefulness for managing the elderly and patients with disequilibrium.

Material and methods: We included 172 healthy subjects and 47 SCD patients. Posturography was performed with the eyes fixated and closed, with and without foam rubber. The power-spectral data of the CoP were obtained with the maximum entropy method. Power-spectral data were logarithmically translated for quantitative evaluation.

Results: For teenagers, high-frequency fluctuations were dominant and attributable to proprioceptive compensation due to immature postural control. In elderly populations, the increased frequency in the lateral direction was characterised by three peaks indicating postural disturbances attributed to three sensory inputs. The disappearance of one peak in the anteroposterior fluctuation indicates a decrease in vestibular contribution. The foam rubber and the closed-eye condition enhanced fluctuations in two peaks. There were differences in power-spectral distributions of two peaks between the healthy subjects and SCD patients.

Conclusions: Logarithmic power-spectral data distribution could provide an age- and disease-specific novel and visually-comprehensible parameter.

Chinese abstract

背景：体位图的压力中心（CoP）频率的功率谱分析提供了指数级近似分布, 而对数转换可产生线性近似值。

目的：采用对数转换法对健康人和脊髓小脑退化（SCD）患者的体位图进行频率分析, 以确定其对老年人和失去平衡的患者的临床应用价值。

材料与方法：纳入172例健康人和47例SCD患者。在定睛和闭上眼睛的情况下, 使用和不使用泡沫橡胶进行体位描记。利用最大无序状态测量法获得了CoP的功率谱数据。功率谱数据经对数转换后用于定量评估。

结果：对于青少年, 高频波动占主导地位, 归因于体位控制不成熟引起的本体感觉代偿。在老年人群中, 侧向增加的频率的特征是三个峰值, 表明由于三种感觉输入引起的体位障碍。前后波动的一个峰值消失表明前庭影响减少。泡沫橡胶和闭眼条件增强了两个峰值的波动。正常人和SCD患者两个峰的功率谱分布存在差异。

结论：对数功率谱数据分布可以提供一个年龄特定性和疾病特定性的可直观理解的新参数。

Keywords:

• Posturography
• power-spectral
• ageing
• spinocerebellar degeneration
• logarithmic

Disclosure statement

The authors have no conflict of interest to report regarding this manuscript.

Additional information

Funding

This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI (grant no. JP17K11314), the Terumo Foundation for the Life Sciences and Arts (grant no. 18-III-124)