Ml. Corradini et al., EARLY RECOGNITION OF POSTURAL DISORDERS IN MULTIPLE-SCLEROSIS THROUGHMOVEMENT ANALYSIS - A MODELING STUDY, IEEE transactions on biomedical engineering, 44(11), 1997, pp. 1029-1038
In the present study, spontaneous postural behavior has been analyzed
in freely standing multiple sclerosis (MS) patients, exhibiting no cli
nically assessable abnormalities of postural control. This population
has been compared with two other groups, healthy people and hemipareti
c patients. This latter group represents a situation where the central
nervous system (CNS) lesion is precisely localized in one anatomical
site and no signal-conduction disorders are present; i.e., it has an o
pposite anatomical character with respect to the MS at a preclinical s
tage. The hypothesis underlying the modeling study is the presence of
a controller block working in a feedback posture control system. This
controller block receives the body sway as input, and produces the cor
responding ankle torque stabilizing the body, the latter being modeled
as an inverted pendulum. The CNS damage, caused by MS, is supposed to
be reflected in some detectable change in the structure of the contro
ller of the posture control system. The identification of the controll
er has been performed by means of a parametric estimation procedure wh
ich employed as input sequences, data recorded by means of a movement-
analysis (MA) system. Reported findings show a structural change of th
e model of the controller block in the posture control system. This re
sult may suggest the presence of an MS-specific reorganization of the
posture control system. Some speculation is finally made on the black-
box approach in comparison with traditional posturography, to arrive a
t hypothesizing a progression path for postural disorders.