title: Surface electromyography activity in the upper limbs of patients following surgery for compressive cervical myelopathy.
abstract: BACKGROUND
  Surface electromyography (EMG) is a noninvasive, accurate method to measure electrical activity produced in muscles.
  
  
  OBJECTIVE
  To assess the improvement of spasticity after decompressive surgery for compressive myelopathy using surface EMG.
  
  
  METHODS
  Neurophysiology laboratory of a tertiary care center. Before-after trial. Both EMG and Modified Modified Ashworth Scale (MMAS) were utilized.
  
  
  METHODS
  Thirty-one nonconsecutive patients (28 males; age 25-72 years) with compressive cervical myelopathy and spasticity (MMAS score ≥1) were recruited. Patients with lower motor neuron findings, Nurick grade 5, and those with joint deformities, contractures, or thrombophlebitis of the upper limbs were excluded. EMG activity was measured from the pronator teres and biceps brachii for 31 age-related controls (25 males) as well as for the patients both pre- and post-operatively.
  
  
  METHODS
  Student's t-test for comparison of continuous variables and Pearson correlation co-efficient for assessing the significance of associations.
  
  
  RESULTS
  EMG recording done 1-week postoperatively showed a reduction in baseline activity in the pronators and supinators by 21% and 36%, respectively. There was a decrease in co-activation of the pronators during active supination by almost 62% and of the supinators during active pronation by around 33% (P < 0.05). On passive movement, there was a decrease in co-activation of the pronators during supination by approximately 23%, and the supinators during pronation by 35% (P < 0.05). EMG activity was significantly reduced in the pronators during supination in all patients, including those in whom the MMAS scores remained the same postoperatively.
  
  
  CONCLUSIONS
  Surface EMG is an objective tool to detect improvement in spasticity following decompressive surgery for compressive cervical myelopathy even in those patients who showed no improvement on the MMAS.
authors.forename: Ananth P
authors.initials: AP
authors.lastname: Abraham
authors.forename: S Balaji
authors.initials: SB
authors.lastname: Srinivas
authors.forename: Muthukumar
authors.initials: M
authors.lastname: Murthy
authors.forename: K Srinivasa
authors.initials: KS
authors.lastname: Babu
authors.affiliation: Divisions of Neurosurgery, Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Ari G
authors.initials: AG
authors.lastname: Chacko