title: Preparatory brain activity and anticipatory postural adjustments accompanied by externally cued weighted-rapid arm rise task in non-specific chronic low back pain patients and healthy subjects.
abstract: OBJECTIVE
  Cortical reorganization is one of the most plausible mechanisms underlying impairment of anticipatory postural adjustments (APAs) in low back pain (LBP) patients. In order to clarify changes in corticomotor neurophysiology, APAs were assessed by using electromyography (EMG) and electroencephalography (EEG).
  
  
  METHODS
  An equal number (29) of nonspecific LBP patients and healthy subjects performed unilateral rapid arm movements in response to auditory imperative stimulus preceded by warning stimulus within 2 s interstimulus interval. Burst onset activity was calculated in relation to the activity of anterior deltoid for bilateral transverse abdominis/internal oblique (TrA/IO), and also postural muscles on left side, including rectus abdominis, external oblique (E.O), erector spinae and medial head of gastrocnemius (Gc.M). Contingent negative variation (CNV) potentials were recorded by scalp EEG, and the area under receiver operating characteristic curve (AUC) was analyzed.
  
  
  RESULTS
  In LBP patients, there was a significant onset delay for E.O and bilateral TrA/IO, but a significant earlier activity for Gc.M (for both P < 0.05). The CNV parameters were considerably greater in LBP patients (P < 0.01). The AUC was significant just for left TrA/IO and E.O muscles (P < 0.05).
  
  
  CONCLUSIONS
  The CNV amplitudes were increased, and APA onset times re-organized to be delayed at the trunk and early at the distal limb in LBP cases. These findings support the hypothesis about reorganized activity of cerebral cortex in LBP patients.
authors.affiliation: Department of Physical Therapy, School of Rehabilitation, Tehran University of Medical Sciences, P. O. Box 113635-1683, Tehran, 1148965141 Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Sadeghi
authors.affiliation: Department of Physical Therapy, School of Rehabilitation, Tehran University of Medical Sciences, P. O. Box 113635-1683, Tehran, 1148965141 Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Talebian
authors.affiliation: Department of Physical Therapy, School of Rehabilitation, Tehran University of Medical Sciences, P. O. Box 113635-1683, Tehran, 1148965141 Iran.
authors.forename: Gholam Reza
authors.initials: GR
authors.lastname: Olyaei
authors.affiliation: Department of Physical Therapy, School of Rehabilitation, Tehran University of Medical Sciences, P. O. Box 113635-1683, Tehran, 1148965141 Iran.
authors.forename: Behrouz
authors.initials: B
authors.lastname: Attarbashi Moghadam
keywords: Anticipatory postural adjustments; Cerebral cortex; Contingent negative variation; Electromyography; Low back pain; Preparatory brain activity