2011 年 70 巻 2 号 p. 67-76
Appearance of the dominant peak-frequency in body sways during standing was retrospectively investigated in patients with spinocerebellar degeneration (SCD). Subjects tested were 25 patients with SCD (16 men and 9 women, ranging in age from 25 to 80; mean 55.8±15.4 yr). The disease types comprised SCA3 (n=5), SCA 6 (n=3), MSA-C (n=12), and an unknown type (n=5). Stabilometry was performed in each patient, who was asked to stand upright with a closed stance, with eyes open and eyes closed, using Anima's stabilometer G6100. The sampling time was 50 ms (20Hz) and the correcting time was 60 s. The peak-frequency was measured based on the power spectrum using the maximum entropy method (MEM). Total locus length, envelope area and velocity-vector of movement of the center of foot-pressure were also measured.
The first or main peak appeared in a low frequency range between 0.10 and 0.59Hz in most of the cases with eyes open and eyes closed. It was detected in the lateral direction in 24 patients of the total number (96.0%) and in the anterior-posterior direction in 22 patients of the total (88.0%).
The body sway of a frequency of 3Hz was detected in 4 patients (16.0%). Among them, the peak in the lateral direction was observed in 2 (8.0%) with eyes open or closed (one with SCA 6 and one with an unknown disease type). The peak in the anterior-posterior direction was detected in 3 (12.0%) with eyes open or closed (one each with SCA 6, MSA-C and an unknown disease type); in these subjects, the values of the total locus length divided by envelope area were more than 40.
The dominant peak-frequency of 3Hz in body sways during standing did not frequently appear in patients with SCD, but it is suggested to be one of characteristic balance disorders in the disease.