[Progressive limb-kinetic apraxia with myoclonus focal atrophy in the postcentral gyrus and the supplementary motor area].
We report a 70-year-old right handed man with a 5-year history of slowly progressive clumsiness of his left hand. A neurological examination disclosed mild rigidity and myoclonus in his left hand. He showed limb-kinetic apraxia, but neither ideational apraxia nor ideomotor apraxia was present. Aphasia and agnosia were also absent. He was thought to have the primary progressive limb-kinetic apraxia clinically. Brain CT and MRI revealed focal atrophy in the right postcentral gyrus and the supplementary motor area. A positron emission tomography (PET) study showed diffuse decrement of cerebral blood flow, predominantly in the right hemisphere. The decrease in the uptake of [18F]-Fluoro-deoxyglucose also revealed glucose hypo-metabolism, especially in the right frontal and parietal lobe. Striatal [11C]NMSP and [18F]FDOPA uptake were also reduced in an asymmetric pattern. These findings suggest that our patient is likely to have corticobasal degeneration. Transcranial magnetic stimulation using double pulse paradigm revealed a decrease in the level of cortico-cortical inhibition in the motor cortex on the affected side. Our results indicate increase in the excitability of motor cortical neurons in primary progressive limb-kinetic apraxia, likely due to a decreased excitability of cortico-cortical inhibitory mechanism as a result of focal degeneration of cortical neurons.
Ishiwata
T
T
Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
Suzuki
A
A
Mochizuki
H
H
Okuma
Y
Y
Mitani
K
K
Mizuno
Y
Y
D000368:Aged; D001072:Apraxias / Q000503:physiopathology*; D001284:Atrophy; D001921:Brain / Q000473:pathology*; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory; D005121:Extremities / Q000502:physiology; D006801:Humans; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D009207:Myoclonus / Q000150:complications*; D009410:Nerve Degeneration