title: Pallidotomy does not ameliorate abnormal intracortical inhibition in Parkinson's disease.
abstract: Motor cortex excitability was assessed in 12 patients with Parkinson's disease (PD) using transcranial magnetic stimulation. Patients were studied when mobile and medicated ("ON") and when immobile after medication withdrawal ("OFF"). Results were compared to eight age-matched and 11 young controls. Cortical excitability was assessed by measurement of resting motor threshold (RMT), intracortical inhibition and cortical silent period duration. In five patients, the studies included assessments following pallidotomy. Cortical excitability was abnormal in patients with PD with reduced RMT in "ON" and "OFF" states, and less effective intracortical inhibition. Pallidotomy did not affect cortical excitability in either "ON" or "OFF" states, indicating that enhanced motor cortex excitability in patients with PD is unaffected by pallidotomy despite clinical improvement in motor scores.
authors.affiliation: Discipline of Physiology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia. martin.sale@adelaide.edu.au
authors.forename: M V
authors.initials: MV
authors.lastname: Sale
authors.forename: M A
authors.initials: MA
authors.lastname: Nordstrom
authors.forename: B P
authors.initials: BP
authors.lastname: Brophy
authors.forename: P D
authors.initials: PD
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D007839:Functional Laterality; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology*; D053860:Pallidotomy / Q000379:methods*; D010300:Parkinson Disease / Q000473:pathology / Q000601:surgery*; D011930:Reaction Time; D012684:Sensory Thresholds / Q000502:physiology; D018709:Statistics, Nonparametric; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult