Bilateral impairment of intracortical inhibition in delayed-onset posthemiplegic dystonia: pathophysiological implications.
OBJECTIVE
To study short interval intracortical inhibition (SICI) in a rare patient with segmental dystonia of the left upper limb due to a vascular lesion in the contralateral putamen without corticospinal tract involvement.


METHODS
Paired-pulse transcranial magnetic stimulation (TMS) was applied to both hemispheres in a conditioning-test paradigm. Six interstimulus intervals (ISIs) and 4 conditioning stimulation intensities were investigated in two separate sessions.


RESULTS
Motor evoked potentials upon single-pulse TMS were within the normal range, whereas paired-pulse TMS revealed major changes in cortical excitability, proving that SICI was bilaterally absent.


CONCLUSIONS
The bilateral impairment of SICI cannot be considered the cause of dystonic contractions, but just a predisposing factor.


CONCLUSIONS
The absence of SICI might be regarded as a condition able to promote maladaptive plastic changes triggered by focal lesions in the putamen.
Trompetto
Carlo
C
Department of Neurosciences, Ophthalmology and Genetics, University of Genoa, Via de Toni, 5, 16132 Genova, Italy.
Buccolieri
Alessandro
A
Bove
Marco
M
Brichetto
Gianpaolo
G
Avanzino
Laura
L
Marinelli
Lucio
L
Abbruzzese
Giovanni
G