Intralimb and Interlimb Incoordination: Comparative Study between Patients with Parkinsonism and with Cerebellar Ataxia

Abstract

Dysfunction of limb coordination may be divided into two categories; intra and inter-limb incoordination. To make clear differential character in these two limb incoordination, we measured 13 patients mainly with cerebellar ataxia and 27 patients mainly with parkinsonism during pedaling of an ergometer with left and right pedals that can be rotated independently. As a result, interlimb incoordination was predominantly observed in patients with parkinsonism, while patients with cerebellar ataxia showed relatively preserved interlimb coordination but intralimb incoordination. We concluded that impairment of intralimb coordination was a character in patients with cerebellar ataxia, while impairment of interlimb coordination was a character in patients with parkinsonism.

Keywords: ataxia; cluster analysis; interlimb coordination; intralimb coordination; parkinsonism; strength ergometer.

Fig. 1.

Definition of the amplitude: Solid and dashed curves represent time profiles of the rotational velocities of the right and left pedals, respectively. A_i is the time interval between the i-th and (i+1)-th peaks of the velocity profile of the right pedal. B_i is the time interval between the i-th peak of the right pedal's velocity and the peak of the left pedal's velocity located between the i-th and (i+1)-th peaks of the right pedal's velocity profile. A peak rotational velocity of each of the left and right pedals for one pedaling cycle was referred to as the amplitude of that cycle. A time series data for single 6 min pedaling exercise gives rise to two sets of the amplitude time series (i.e., for the left and right pedals) as the functions of the pedaling cycle. Definition of the relative phase: The relative phase between the left and right sides during the pedaling exercise was defined as follows. The relative phase of the ith pedaling cycle φ_i was defined by the relative location of a peak of the velocity profile of the left pedal that falls between the i-th and (i+1)-th peaks of the rotational velocity of the right pedal. This gives rise to another time series, the relative phase time series. In equation form, the relative phase was defined as; φ_i = B_i / A_i × 360 degree. (1) where A_i is the time interval between the i-th and (i+1)-th peaks of the velocity profile of the right pedal and B_i is the time interval between the i-th peak of the right pedal's velocity and the peak of the left pedal located between the i-th and (i+1)-th peaks of the right pedal's velocity profile. Non-oscillatory rotational velocity profiles were observed for some periods during the exercise. It was happened more frequently for the affected side than for the less affected side. When the peak of the left pedal's velocity between the i-th and (i+1)-th peaks of the right pedal's velocity profile could not be detected, the relative phase φ_i was not defined for the cycle.

Fig. 2.

The velocity waveforms exhibited different characteristics among patients with parkinsonism. In cluster 1, the amplitude on each side was constant and the relative phase was locked at 180°. The pattern was the same as seen in normal subjects. In cluster 2, the amplitude on each side was constant, but the relative phase was locked at 90°. In cluster 3, the amplitude on each side was modulated, and the relative phase drifted monotonously from 0° to 360° (=0°) during pedaling cycles. In cluster 4, the amplitude on each side was synchronously and irregularly modulated, and the relative phase fluctuated with intermittent spike-like decrement.

Fig. 3.

The scatter-plot for 26 values from 13 patients with ataxia for cluster analysis. The indexed values of these values were superposed on the four clusters obtained from analyses of 111 values of patients with parkinsonism. Clusters are derived from patients with parkinsonism in a previously published study⁴⁾. Every data set, for single 6 min exercise, was analyzed and characterized by values of the five indices (vam, mrp, vrp, mrl and vrl). A set of the five indices for each data set was considered as a point located in the five-dimensional index space. To test exercise results for patients with parkinsonism and ataxic patients for similarities and dissimilarities, we located all the values for ataxic patients in the five dimensional indices space generated from the values for patients with parkinsonism. The mean (coordinates of the centroid) and its standard deviation in the five dimensional index space of the obtained four clusters:

1. Cluster 1: (1.9 ± 1.8, 30 ± 16, 362 ± 509, −0.80 ± 0.15, 0.04 ± 0.07)

2. Cluster 2: (3.3 ± 1.9, 104 ± 23, 449 ± 345, 0.09 ± 0.33, 0.07 ± 0.05)

3. Cluster 3: (8.5 ± 1.2, 80 ± 24, 1743 ± 405, −0.18 ± 0.24, 0.26 ± 0.07)

4. Cluster 4: (5.6 ± 1.7, 85 ± 15, 2753 ± 469, −0.17 ± 0.23, 0.57 ± 0.07)

where the coordinate are (vam, mrp, vrp, mrl, vrl). Twenty-two data sets in ataxic patients were classified into cluster 1 to which all controls belonged. Two data sets were classified into cluster 2. *; cluster 1, ○; cluster 2.

Fig. 4.

Five figures indicate five indices between ataxia, parkinsonism and control. *; significant difference (p<0.0001), **; significant difference (p<0.01), #; significant difference (p<0.05)