PMID- 9339689
OWN - NLM
STAT- MEDLINE
DCOM- 19971114
LR  - 20220311
IS  - 0028-3878 (Print)
IS  - 0028-3878 (Linking)
VI  - 49
IP  - 4
DP  - 1997 Oct
TI  - Impaired inhibition in writer's cramp during voluntary muscle activation.
PG  - 1054-9
AB  - We used paired transcranial magnetic stimulation (TMS) to evaluate inhibitory 
      mechanisms in eight patients with writer's cramp during rest and isometric wrist 
      extension. Both stimuli were 110% of the motor threshold; the interstimulus 
      intervals (ISIs) were 20 to 200 ms in increments of 10 ms. Surface EMG was 
      recorded from wrist extensors. In the symptomatic hemisphere, there was no 
      significant difference in the amplitude of the test (second) motor 
      evoked-potential (MEP) between patients and age-matched controls at rest. 
      However, with voluntary muscle activation, inhibition of the test MEP by the 
      conditioning MEP was significantly less in writer's cramp patients than in 
      controls (p = 0.02). The difference was most prominent at ISIs of 60 to 80 ms in 
      which inhibition is maximum. In the asymptomatic hemisphere, there was no 
      significant difference between patients and controls in both rest and active 
      conditions. The silent period was shorter in patients than controls on the 
      symptomatic side (p = 0.003) but not on the asymptomatic side. We conclude that 
      the inhibitory effects induced by magnetic stimulation are reduced in patients 
      with writer's cramp, but only on the symptomatic side during muscle activation. 
      This may relate to the overflow of muscle activity that characterizes this 
      condition.
FAU - Chen, R
AU  - Chen R
AD  - Medical Neurology Branch, National Institute of Neurological Disorders and 
      Stroke, National Institutes of Health, Bethesda, MD, USA.
FAU - Wassermann, E M
AU  - Wassermann EM
FAU - Canos, M
AU  - Canos M
FAU - Hallett, M
AU  - Hallett M
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Neurology
JT  - Neurology
JID - 0401060
SB  - IM
MH  - Adult
MH  - Aged
MH  - Brain/physiopathology
MH  - Electromyography
MH  - Evoked Potentials, Motor
MH  - Functional Laterality/physiology
MH  - *Handwriting
MH  - Humans
MH  - Isometric Contraction
MH  - Magnetics
MH  - Middle Aged
MH  - Muscle, Skeletal/*physiology
MH  - Neural Inhibition/*physiology
MH  - Physical Stimulation
MH  - Reference Values
MH  - Rest
MH  - Volition
MH  - Wrist/physiopathology
EDAT- 1997/10/27 00:00
MHDA- 1997/10/27 00:01
CRDT- 1997/10/27 00:00
PHST- 1997/10/27 00:00 [pubmed]
PHST- 1997/10/27 00:01 [medline]
PHST- 1997/10/27 00:00 [entrez]
AID - 10.1212/wnl.49.4.1054 [doi]
PST - ppublish
SO  - Neurology. 1997 Oct;49(4):1054-9. doi: 10.1212/wnl.49.4.1054.