PMID- 8624691
OWN - NLM
STAT- MEDLINE
DCOM- 19960625
LR  - 20190512
IS  - 0006-8950 (Print)
IS  - 0006-8950 (Linking)
VI  - 119 ( Pt 1)
DP  - 1996 Feb
TI  - Abnormalities of the balance between inhibition and excitation in the motor 
      cortex of patients with cortical myoclonus.
PG  - 309-317
AB  - Patients with cortical myoclonus may have purely focal or multifocal jerks, or 
      they may have additional bilateral or generalized jerks, suggesting the spread of 
      excitatory myoclonic activity between the cerebral hemispheres and across the 
      sensorimotor cortex. The factors contributing to this spread of activity were 
      investigated in 10 patients with multifocal cortical myoclonus and eight patients 
      with multifocal and bilateral or generalized cortical myoclonus. The two groups 
      were termed 'non- spreaders' and 'spreaders' respectively. Eight of the patients 
      were also epileptic. Motor thresholds to single transcranial magnetic shocks at 
      rest were higher in 'non- spreaders' (median 88%, range 45-100% of stimulator 
      output) than either 'spreaders' (50%, range 26-90%, P=0.023) or health controls 
      (38%, range 28-53%, P<0.001). This pathological elevation in motor threshold was 
      not simply an effect of treatment with antiepileptic drugs. Paired transcranial 
      magnetic stimuli were used to investigate ipsilateral cortico-cortical and 
      transcallosal inhibition, There was less (MANOVA, P<0.05) ipsilateral inhibition 
      at interstimulus intervals (ISIs) of 1-6 ms in 'spreaders' (mean 107+/-SEM 23% of 
      control) compared with 'non- spreaders' (75+/-15%) or healthy subjects 
      (59+/-10%). There was also less (P<0.05) transcallosal inhibition across 
      inhibitory timings (10, 12 and 14 ms) in the 'spreaders' (98+/-6% of control) 
      compared with the 'non-spreaders' (64+/-8%) or healthy subjects (59+/-6%). There 
      was no relationship between ipsilateral cortico-cortical and transcallosal 
      inhibition and the presence or absence of epilepsy, although non-epileptic 
      patients did have higher motor thresholds (median 85%, range 32-100% of 
      stimulator output) than either epileptic patients (50%, range 26-90%, P<0.001) or 
      healthy controls (38%, range 28-53%, P=0.002). Abnormalities in ipsilateral and 
      transcallosal inhibition appear to facilitate the spread of the cortical 
      myoclonic activity responsible for bilateral and generalized jerks. However, 
      these abnormalities in inhibition do not play a major role in the development of 
      generalized seizures in patients with cortical myoclonus.
FAU - Brown, P
AU  - Brown P
AD  - National Hospital for Neurology and Neurosurgery, London, UK.
FAU - Ridding, M C
AU  - Ridding MC
FAU - Werhahn, K J
AU  - Werhahn KJ
FAU - Rothwell, J C
AU  - Rothwell JC
FAU - Marsden, C D
AU  - Marsden CD
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Brain
JT  - Brain : a journal of neurology
JID - 0372537
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Aged
MH  - Corpus Callosum/physiopathology
MH  - Electric Stimulation/methods
MH  - Electromyography
MH  - Epilepsy/physiopathology
MH  - Evoked Potentials, Somatosensory
MH  - Female
MH  - Humans
MH  - Magnetics
MH  - Male
MH  - Middle Aged
MH  - Motor Cortex/*physiopathology
MH  - Myoclonus/*physiopathology
MH  - *Neural Inhibition
MH  - Reference Values
MH  - Time Factors
EDAT- 1996/02/01 00:00
MHDA- 1996/02/01 00:01
CRDT- 1996/02/01 00:00
PHST- 1996/02/01 00:00 [pubmed]
PHST- 1996/02/01 00:01 [medline]
PHST- 1996/02/01 00:00 [entrez]
AID - 10.1093/brain/119.1.309 [doi]
PST - ppublish
SO  - Brain. 1996 Feb;119 ( Pt 1):309-317. doi: 10.1093/brain/119.1.309.