title: Usefulness of Transcranial Magnetic Stimulation to Assess Motor Function in Patients With Parkinsonism.
abstract: OBJECTIVE
  To investigate the clinical significance of upper and lower extremity transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) in patients with parkinsonism.
  
  
  METHODS
  Twenty patients (14 men, 6 women; mean age 70.5±9.1 years) suffering from parkinsonism were included in this study. All participants underwent single-pulse TMS session to assess the corticospinal excitability of the upper and lower extremity motor cortex. The resting motor threshold (RMT) was defined as the lowest stimulus intensity able to evoke MEPs of an at least 50 µV peak-to-peak amplitude in 5 of 10 consecutive trials. Five sweeps of MEPs at 120% of the RMT were performed, and the mean amplitude and latency of the MEPs were calculated. Patients were also assessed using the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) and the 5-meter Timed Up and Go (5m-TUG) test.
  
  
  RESULTS
  There was a significant positive correlation between the RMTs of MEPs in the upper and lower extremities (r=0.612, p=0.004) and between the amplitude of MEPs in the upper and lower extremities (r=0.579, p=0.007). The RMT of upper extremity MEPs showed a significant negative relationship with the UPDRS-III score (r=-0.516, p=0.020). In addition, RMTs of lower extremity MEPs exhibited a negative relationship with the UPDRS-III score, but the association was not statistically significant (r=-406, p=0.075).
  
  
  CONCLUSIONS
  These results indicated that the RMT of MEPs reflect the severity of motor dysfunction in patients with parkinsonism. MEP is a potential quantitative, electrodiagnostic method to assess motor function in patients with parkinsonism.
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jaechan
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Won Hyuk
authors.initials: WH
authors.lastname: Chang
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jin Whan
authors.initials: JW
authors.lastname: Cho
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jinyoung
authors.initials: J
authors.lastname: Youn
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yun Kwan
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sun Woong
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.; Department of Health Science and Technology, SAIHST, Sungkyunkwan University, Seoul, Korea.; Department of Medical Device Management & Research, SAIHST, Sungkyunkwan University, Seoul, Korea.
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Kim
keywords: Motor disorders; Motor evoked potentials; Parkinsonian disorders; Transcranial magnetic stimulation