Asymmetric cortico-cortical inhibition in patients with progressive limb-kinetic apraxia.
OBJECTIVE
To evaluate the activity of cortico-cortical (intracortical) inhibitory circuits within the motor cortex in patients with progressive asymmetric limb-kinetic apraxia.


METHODS
We studied 4 patients with progressive limb-kinetic apraxia whose clinical diagnosis was corticobasal degeneration (CBD) and 7 control subjects. Cortico-cortical inhibition was measured using the technique of double pulse transcranial magnetic stimulation over the motor cortex. The effects of conditioning stimuli on the test responses were examined.


RESULTS
In the normal control subjects, the conditioning magnetic stimulus suppressed motor evoked responses to the test stimulus at interstimulus intervals of 1 to 5 ms. This inhibition was significantly diminished on the affected side of the patients, but it was normal on the less affected side.


CONCLUSIONS
Disruption of intracortical inhibitory circuits in the motor cortex may, at least in part, be related to severe limb clumsiness in the patients with progressive limb-kinetic apraxia.
Okuma
Y
Y
Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
Urabe
T
T
Mochizuki
H
H
Miwa
H
H
Shimo
Y
Y
Mori
H
H
Mizuno
Y
Y
D000368:Aged; D001072:Apraxias / Q000175:diagnosis / Q000503:physiopathology*; D001284:Atrophy / Q000473:pathology; D018450:Disease Progression; D004576:Electromyography; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D014953:Wrist / Q000503:physiopathology