Carvell, PhD, PTUniversity
PD MOTOR DEFICITS: What It Teaches Us
About Movement II
Individuals with Parkinsonís Disease
tend to move slowly
(bradykinesia). The level of force production by PD patients is often comparable to aged-matched controls.
However, force curves show that
movement time is
increased for PD subjects compared to neurologically-intact elderly. Rise and fall times to and from peak torque are
slower than normal (see
fig 18-5). Part of this slowing may
be due to a motor control problem and part may be due to the increased stiffness (rigidity) characteristic of PD.
Reaction times are also
prolonged (not shown here).
18-5 In: C.M. Fredericks and L.K. Saladin, Pathophysiology of the Motor Systems. Philadelphia: F. A. Davis, 1996.
Fig 18-5 p 430
Can individuals with PD move fast?
An experiment by
Hallett and colleagues looked
at EMG from elbow flexors and extensors
while an individual performed rapid
movements. The authors concluded that
PD does not prevent the normal triphasic
EMG pattern characteristic of fast
movements, but a single triphasic burst
is inadequate to achieve the desired ROM. Therefore, the PD subjects repeated the triphasic pattern in an attempt
to reach the final
desired position which they
overshot (see fig 14.11 in Brooks).