title: Efficacy of biphasic transcranial electric stimulation in intraoperative motor evoked potential monitoring for cervical compression myelopathy.
abstract: METHODS
  Retrospective analysis of prospectively collected data from consecutive patients undergoing 2 methods of transcranial electrical motor evoked potential (TCE-MEP) monitoring during cervical spine surgery.
  
  
  OBJECTIVE
  To investigate the efficacy of biphasic transcranial electric stimulation, the deviation rate, amplitude of TCE-MEPs, complications, and sensitivity and specificity of TCE-MEP monitoring were compared between the biphasic and conventional monophasic stimulation methods.
  
  
  BACKGROUND
  With biphasic stimulation, unlike monophasic stimulation, measurement time can be reduced considerably because a single stimulation elicits bilateral responses almost simultaneously. However, no study has yet reported a detailed comparison of the 2 methods.
  
  
  METHODS
  Examination 1: Amplitude and derivation rate of TCE-MEPs was compared for monophasic and biphasic stimulation in the same 31 patients with cervical compression myelopathy. Examination 2: Sensitivity, specificity, and complications of TCE-MEP monitoring were compared in 200 patients with cervical compression myelopathy who received monophasic or biphasic stimulation (100 patients each) during intraoperative monitoring.
  
  
  RESULTS
  Examination 1: Derivation rates of biphasic stimulation in the deltoid, biceps brachii, abductor digiti minimi, and flexor hallucis brevis muscles were the same or higher than for monophasic stimulation. TCE-MEP amplitudes elicited by biphasic stimulation compared with monophasic stimulation were significantly larger in the biceps (paired t, P < 0.0001), but similar in the other 3 muscles. Examination 2: In the biphasic and monophasic stimulation groups, warnings were issued to surgeons in 10 and 11 cases, for a sensitivity of 100% for both groups and specificity of 97.8% and 96.7%, respectively. No complications related to stimulation were observed in any of the 200 patients.
  
  
  CONCLUSIONS
  Biphasic stimulation had similar or higher derivation rates and equivalent sensitivity and specificity than monophasic stimulation. No complications were observed for either stimulation method. Biphasic stimulation is an effective TCE-MEP monitoring method for cervical spine surgery that may also reduce measurement time.
  
  
  METHODS
  4.
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Ukegawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kawabata
authors.forename: Kyohei
authors.initials: K
authors.lastname: Sakaki
authors.forename: Senichi
authors.initials: S
authors.lastname: Ishii
authors.forename: Shoji
authors.initials: S
authors.lastname: Tomizawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inose
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Yoshii
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kato
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Enomoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D046690:Deep Brain Stimulation / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011446:Prospective Studies; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome