Spinal and cortical inhibition in Huntington's chorea

Alberto Priori, Luigi Polidori, Sabine Rona, Mario Manfredi, Alfredo Berardelli

Research output: Contribution to journalArticlepeer-review

Abstract

In this article we studied spinal and cornical inhibitory mechanisms in patients with Huntington's disease. To evaluate spinal cord inhibitory circuitries, we assessed reciprocal inhibition between antagonist forearm muscles and the recovery cycle of the H reflex in the flexor carpi radialis. Patients showed a significant decrease in the presynaptic phase of reciprocal inhibition reaching a minimum at the conditioning-test interval of 20 msec and an abnormal facilitation of the test H reflex at the conditioning test interval of 40 to 60 msec. Throughout its time course (10-200 msec), the H reflex recovery cycle showed a more prominent facilitation in patients than in control subjects. To assess whether the observed pathophysiological abnormalities might have arisen from an abnormal motor cortical excitability, we examined the recovery cycle of the motor potentials evoked by paired transcranial magnetic stimuli. We found that the inhibitory mechanisms controlling motor cortical excitability were normal. An interpretation of the spinal cord abnormalities is that the intrinsically normal but deafferentated motor cortex in Huntington's disease partly loses its inhibitory control, thus disinhibiting spinal cord circuitry. Our findings from paired transcranial magnetic stimulation suggest that cortical motor areas are not hyperexcitable in Huntington's disease. Hence, the postulated thalamocortical overactivity in experimental models of Huntington's disease needs to be reappraised.

Original languageEnglish
Pages (from-to)938-946
Number of pages9
JournalMovement Disorders
Volume15
Issue number5
DOIs
Publication statusPublished - 2000

Keywords

  • Cortical stimulation
  • Hyperkinesia
  • Reciprocal inhibition

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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