Cerebellum (in blue) of the human brain
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Spinocerebellar ataxia

Spinocerebellar ataxia (SCA) is a genetic disease with multiple types, each of which could be considered a disease in its own right. As with other forms of ataxia, SCA results in unsteady and clumsy motion of the body due to a failure of the fine coordination of muscle movements, along with other symptoms. more...

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It can be easily misdiagnosed as another neurological condition, such as multiple sclerosis (MS). There is no known cure for this degenerative condition, which lasts for the remainder of the sufferer's life. Treatments are generally limited to softening symptoms, not the disease itself. The condition is irreversible. A person with this disease will usually end up needing to use a wheelchair, and eventually they will need assistance to perform daily tasks. The symptoms of the condition vary with the specific type (there are several), and with the individual patient. Generally, a sufferer retains full mental capacity while they progressively lose physical control over their body until their death.

One means of identifying the disease is with an MRI to view the brain. Once the disease has progressed sufficiently, the cerebellum (a part of the brain) can be seen to have visibly shrunk. The most precise means of identifying SCA, including the specific type, is through DNA analysis. Some, but far from all, types of SCA may be inherited, so a DNA test may be done on the children of a sufferer, to see if they are at risk of developing the condition.

SCA is related to olivopontocerebellar atrophy (OPCA); SCA types 1, 2, and 7 are also types of OPCA. However, not all types of OPCA are types of SCA, and vice versa. This overlapping classification system is both confusing and controversial to some in this field.


The following is a list of some, not all, types of Spinocerebellar ataxia. The first ataxia gene was identified in 1993 for a dominantly inherited type. It was called “Spinocerebellar ataxia type 1" (SCA1). Subsequently, as additional dominant genes were found they were called SCA2, SCA3, etc. Usually, the "type" number of "SCA" refers to the order in which the gene was found. At this time, there are at least 22 different gene mutations which have been found (not all listed).

Identifying the different types of SCA now requires knowledge of the normal genetic code, and faults in this code, which are contained in a person's DNA (Deoxyribonucleic acid). The "CAG" mentioned below is one of many three-letter sequences that makes up the genetic code, this specific one coding the aminoacid glutamine. Thus, those ataxias with poly CAG expansions, along with several other neurodegenerative diseases resulting from a poly CAG expansion, are referred to as polyglutamine diseases.


Both onset of initial symptoms and duration of disease can be subject to variation. If the disease is caused by a polyglutamine trinucleotide repeat CAG expansion, a longer expansion will lead to an earlier onset and a more radical progression of clinical symptoms, resulting in earlier death.

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Fractal dimension analysis of static stabilometry in Parkinson's disease and spinocerebellar ataxia
From Neurological Research, 6/1/01 by Manabe, Yasuhiro

The static stabilometry patterns associated with Parkinson's disease (PD, n = 15) and spinocerebellar ataxia (SCA, n = 15) were compared with those of normal control (n = 15) by measuring the fractal dimensions. Fractal dimensions were estimated using the modified pixel dilation (mPD) method. The fractal dimensions with closed eyes showed a significant correlation with Environmental area for SCA group (p

Keywords: Fractal dimension; static stabilometry; Parkinson's disease; spinocerebellar ataxia


Parkinson's disease (PD) and spinocerebellar ataxia (SCA) are neurodegenerative diseases of later life. A clinical hallmark of advanced PD and SCA is postural instability, which results in significant morbidity due to falls, associated injury and functional impairment1. To evaluate the postural dyscontrol, we measured fractal dimension of stabilometry pattern. Fractal dimension is a geometry advocated by Mandelbrot2, which was established as a method expressing an image of self-similarity. The value of the fractal dimension reflects the complexity of the image, the higher being the more complex. The usefulness of the fractal dimension has been reported in analysis of the sulcus in the brain 3, electroencephalograms4, bacterial colonies5, neurons 6,7, and heart rate8-10.

In this study, we utilized fractal dimension analysis to yield useful parameter to evaluate the postural dyscontrol associated with PD and SCA.



The PD group consisted of 15 patients (7 males and 8 females) with a mean age of 65.0 +/- 10.0 (mean +/- SD) years. The disease duration was 2.9 +/- 2.4 years. PD patients were divided into three groups according to Hoehn-Yahr stage (Table 1). The SCA group consisted of 15 patients (8 males and 7 females) with a mean age of 59.5 +/- 11.9 years. The disease duration was 4.5 +/- 3.2 years. SCA patients could be divided into three groups according to the SCA disability grade of Japan national research group of ataxic disorders11 (Table 2).

A group of normal controls, 8 males and 7 females, mean age 59.5 +/- 10.5 years, without a history of head injury or physical or neurological illness, were also tested. Informed consent was obtained from all patients and control subjects prior to testing.

Stabilometry assessment

Each subject assumed a relaxed standing posture in bare feet, with feet shoulder-width apart and arms folded across the chest, on a force platform. Subjects performed for each 60-sec trial with eyes open and closed. Environment and Longitude/Environmental areas were calculated by this system. Environmental area indicates sway area. Longitude/Environmental area indicates sway path per unit sway area.

Image input

The traced image was input into the image-analyzer through a television camera, and a fractal dimension of the stabilometry pattern was measured by a modified pixel dilation as described below (see Measurement of the fractal dimension section). When the image was input through the television camera, the stage position was fixed so that the magnifying factor was constant.

Image analyzer

Statistical analysis

Statistical analysis was carried out using means and SDs, analysis of variance (ANOVA) and Student's t-test. Statistical significance was defined as p


The fractal dimensions with closed eyes showed no significant correlation with the parameter of Environmental area for normal and PD group (correlation coefficient r=0.055, 0.109, respectively), and significant correlation with that for SCA group (Figure 3A, r=0.730, p

As shown in Figure 3, the fractal dimensions were 1.61 +/- 0.04 (mean +/- SD) and 1.63 +/- 0.04 with open or closed eyes, respectively, for the normal group. Those were 1.63 +/- 0.05 and 1.66 +/- 0.04 for PD group, and 1.63 +/- 0.06 and 1.69 +/- 0.06 for SCA group. The fractal dimension for SCA group was significantly higher with closed eyes than that with open eyes (Figure 4, SCA, p

In contrast, no significant correlation was found between Environmental (Figure 5A,B) and Longitude/ Environmental (Figure 6A,B) areas, and the clinical stages for PD and SCA groups. The fractal dimension with closed eyes was higher when the clinical stage was more severe with PD and SCA group (Figure 7AB). The fractal dimension with closed eyes for Hoehn-Yahr III stage of PD was significantly higher than that for stage I (Figure 7, PD, p


Postural control involves appropriate integration of the visual, vestibular, and somatosensory systems . When this interaction is disrupted, the normal weighing of sensory cues is altered and the remaining cues may alternatively provide adequate information for proper maintenance of balance. These changes can be assessed by static stabilometry 15,16. However, traditional parameters of stabilometer were not well correlated to the severity of diseases, and quantitative analysis of the stabilometry pattern using gravity movements has not been fully investigated. Therefore, we have attempted to estimate the stabilometry pattern more quantitatively by measuring the fractal dimension. A fractal dimension in a two-dimensional picture ranges from 0 to 2, with 0 for the point, 1 for the straight line, and 2 for the plane. This dimension is higher when the picture is more complex (Figure 2). This study examined a possible usefulness of the fractal dimension in an evaluation of postural instability in PD and SCA.

The fractal dimensions with closed eyes showed a significant correlation with parameter of Environmental area for SCA group (Figure 3A, p

The fractal dimension for SCA group was significantly higher with closed eyes than that with open eyes (Figure 4, SCA, p

It is often difficult to determine the clinical stages by means of quantitative scale. In fact, no significant correlation was found between Environmental (Figure SA,B) and Longitude/Environmental (Figure 6A,B) areas, and the clinical stages for PD and SCA groups. However, the fractal dimension with closed eyes showed a good correlation to the clinical stage with PD and SCA (Figure 7A,B). The fractal dimension with closed eyes for Hoehn-Yahr III stage of PD was significantly higher than that for stage I (Figure 7, PD, p


We wish to thank Okayama Kyokuto Hospital for paving the cases.


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Yasuhiro Manabe, Eiichi Honda*, Yoshihiko Shiro, Kenichi Sakai, Ichiro Kohira, Kenichi Kashihara, Toshikiyo Shohmori and Koji Abe

Department of Neurology, Okayama University Medical School, Okayama

*Department of Dental Radiology and Radiation Research, Faculty of Dentistry, Tokyo Medical and Dental University, Tokyo, Japan

Copyright Forefront Publishing Group Jun 2001
Provided by ProQuest Information and Learning Company. All rights Reserved

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