title: A methodological reappraisal of non invasive high voltage electrical stimulation of lumbosacral nerve roots.
abstract: OBJECTIVE
  To describe a neurophysiological method to locate the optimal stimulation site (OSS) over the vertebral column, customized to the individual subject, to achieve maximal activation of lumbosacral roots by means of non-invasive high voltage electrical stimulation (HVES).
  
  
  METHODS
  OSS was located in 30 volunteers by testing different stimulation points of a surface multi-electrode array placed over the dorso-lumbar junction of the vertebral column. The dorso-ventral stimulating montage was used (Troni et al., 1996). Motor responses to root stimulation (rCMAPs) were bilaterally recorded from Vastus Medialis (VM), Tibialis Anterior (TA), Soleus (SL) and Flexor Hallucis Brevis (FHB) muscles. The direct nature of rCMAPs was tested by delivering two maximal stimuli 50 ms apart.
  
  
  RESULTS
  Except for a few subjects with large girth, maximal rCMAPs could be obtained from all muscles with a stimulating current intensity up to 550 V (1050 mA). Maximal double HVES excluded any reflex component in the recorded rCMAPs. The procedure was well tolerated and no side effects were observed.
  
  
  CONCLUSIONS
  A single maximal electric shock delivered at the proper vertebral level by means of the dorso-ventral montage is able to safely achieve synchronous, bilateral maximal activation of several roots, from L3 to S1.
  
  
  CONCLUSIONS
  Maximal activation of lumbosacral roots at their origin, unattainable with magnetic stimulation, is the essential requirement for direct detection of proximal nerve conduction slowing and block in lower limbs.
authors: II Neurological Department and Multiple Sclerosis Center, San Luigi Hospital, Orbassano, Turin, Italy. wtroni@yahoo.com
authors: Walter
authors: W
authors: Troni
authors: Alessia
authors: A
authors: Di Sapio
authors: Eliana
authors: E
authors: Berra
authors: Sergio
authors: S
authors: Duca
authors: Aristide
authors: A
authors: Merola
authors: Francesca
authors: F
authors: Sperli
authors: Antonio
authors: A
authors: Bertolotto
mesh_terms: D000368:Aged; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008161:Lumbosacral Region / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000502:physiology*; D055815:Young Adult