Screening for Early Stages of Nigrostriatal Alteration (II): Gait Pattern in Healthy Subjects with Increased Echogenicity of the Substantia Nigra

Background: The majority of patients with Parkinson's disease (PD) show an increased echogenicity of the substantia nigra (SN) [1]. In healthy subjects, these abnormalities could be found in 9%. 60% of them had a malfunction of the nigrostriatal system as demonstrated by reduced putaminal ¹⁸F-Dopa uptake values [2, 3]. These findings have been suggested to represent a risk factor for PD. Objective: We have studied the gait pattern in healthy subjects with increased SN echogenicity. Methods: 31 healthy male subjects were studied. 16 had an increased SN echogenicity (mean age 58±5.4 years, range: 51–67 years), 15 subjects had a normal echogenicity (57±5.6 years; 51–69 years). UPDRS (part III) was normal in all subjects. Gait was analyzed during walking on a treadmill using two different velocities: 1) the normal gait velocity and 2) the maximal possible gait velocity. The following parameters were measured: the maximal elbow extension, the total range of elbow angle movements, the maximal knee extension, and the total range of knee angle movements of left and right side, respectively; upper body inclination, and stride length and length of arm swing. Results: The combination of parameters which distinguished best between both groups using discriminant analysis (p=0.0016) were: range of angle movements of knee and elbow of both sides and with both gait velocities, and the gait velocities itself. Stride length, length of arm swing, and maximal angles of knee and elbow could not be proven to be useful for the differentiation between both groups. Conclusion: We could demonstrate that an increased echogenicity of the substantia nigra is associated with an altered gait pattern in healthy subjects. References: [1] Becker G, Berg D Mov Disord 2001; 16: 23–32. [2] Berg D, Becker G, Zeiler B et al. Neurology 1999; 53: 1026–1031. [3] Becker G et al. Neurology 1995; 45: 182–184.

This study is dedicated to our former head of the department Prof. G. Becker, who died at the age of 42 years in a sports accident.