title: Painful paresthesiae are infrequent during brachial plexus localization using low-current peripheral nerve stimulation.
abstract: BACKGROUND
  Considerable controversy exists over the relationship of paresthesia to nerve stimulation. The purpose of this study was to determine the frequency with which patients report paresthesia at the point that an acceptable motor response is obtained to low-intensity current electrical stimulation.
  
  
  METHODS
  Low-intensity current nerve stimulation (0.6 mA, 200 microseconds, 2 Hz) was used to identify the brachial plexus in 64 consecutive patients having shoulder or arm surgery with an interscalene block. During nerve localization and while maintaining a motor response (0.20 mA-0.40 mA), the patients were queried regarding any radiating sensation or pain (paresthesia) in the shoulder or extremity on the side of the blockade. Sensory distribution of the block, motor strength of the arm muscles, and adequacy of anesthesia were used to assess the extent of blockade.
  
  
  RESULTS
  Ninety-five percent of patients had satisfactory surgical anesthesia. None of the patients spontaneously reported having a paresthesia during nerve stimulation. However, on careful questioning, half of the patients (55%) reported electrical paresthesia, defined as dull tingling sensation traveling down to their hands and coinciding with the motor response. In addition, most patients (71%) spontaneously reported having a mild, radiating paresthesia on initial injection of local anesthetic.
  
  
  CONCLUSIONS
  Painful paresthesiae should be infrequent when a low-stimulating current is used to identify the neural components of the brachial plexus and when the block needle is advanced slowly. Low-current intensity nerve stimulation can be used to achieve successful interscalene block with minimal discomfort to the patient.
authors.affiliation: College of Physicians and Surgeons of Columbia University, New York, NY, USA.
authors.forename: Pelin
authors.initials: P
authors.lastname: Karaca
authors.forename: Admir
authors.initials: A
authors.lastname: Hadzic
authors.forename: Marina
authors.initials: M
authors.lastname: Yufa
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Vloka
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Brown
authors.forename: Alex
authors.initials: A
authors.lastname: Visan
authors.forename: Kevin
authors.initials: K
authors.lastname: Sanborn
authors.forename: Alan C
authors.initials: AC
authors.lastname: Santos
mesh_terms: D000328:Adult; D001132:Arm / Q000601:surgery; D001917:Brachial Plexus; D004558:Electric Stimulation; D006801:Humans; D009046:Motor Neurons / Q000502:physiology; D009407:Nerve Block / Q000379:methods; D010292:Paresthesia / Q000209:etiology*; D010525:Peripheral Nerves / Q000502:physiology*; D012782:Shoulder / Q000601:surgery