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Canadian Journal of Anesthesia

, Volume 53, Issue 1, pp 67–72 | Cite as

Somatosensory evoked potentials as an objective assessment of the sensory median nerve blockade after infraclavicular block

  • Pierre Pandin
  • Jean Corentin Salengros
  • Alain ďHollander
  • Christiane Tchekap
  • Arlette Vandesteene
Regional Anesthesia and Pain

Abstract

Purpose

Median nerve somatosensory evoked responses (MnSSER) alterations were compared to clinical tests (cold and pinprick) variations, in 20 ASA I adult patients following infraclavicular block obtained with 40 mL ropivacaine 0.5% to assess first, the difference of time course of the respective electrophysiological and clinical signs, and second, the objectivity and the reproducibility of MnSSER changes.

Clinical features

Four MnSSER derivations (Erb’s point; cutaneous projection of peripheral end of brachial plexus; posterior neck at C6 level, frontal and controlateral parietal scalp) were monitored and recorded for retrospective analysis. Continuous data acquisition were started before ropivacaine injection (baseline) and maintained for 30 min thereafter. Every three minutes after ropivacaine injection, cold and pinprick tests were performed in the hand median nerve cutaneous supply zone and were assessed using a sensory visual score (varying from 0–10). Data were compared using analysis of variance. Although MnSSER values were stable during baseline period, after ropivacaine administration, severe progressive amplitude depressions of selected MnSSER were detected in every patient. While clinical cold and pinprick tests became positive (score > 8) only 15.8 ± 1.2 min and 20.1 ± 1.8 min respectively after ropivacaine administration, the mean time to observe the earliest MnSSER 20% amplitude decrease at Erb’s point derivation was reduced to 5.6 ± 1.1 min (P < 0.01).

Conclusion

Selected MnSSER amplitude reduction indicates objectively the onset of median nerve anesthesia following infraclavicular brachial plexus block before the appearance of clinical signs.

Keywords

Median Nerve Brachial Plexus Ropivacaine Brachial Plexus Block Neural Blockade 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Les potentiels évoqués somesthésiques comme évaluation objective du bloc sensitif du nerf médian après un bloc sous-claviculaire

Résumé

Objectif

Les modifications des potentiels évoqués somesthésiques du nerf médian (PESNM) induit par un block infraclaviculaire (40 mL de ropivacaine 0,5 %) on été comparés avec les tests cliniques usuels (tests au froid et à la piqûre) chez 20 patients adultes ASA I afin ďévaluer la différence ďévolution et de survenue des signes électrophysiologiques et cliniques, ľobjectivité et la reproductibilité des modifications des PESNM et finalement le possible intérêt en pratique clinique.

Eléments cliniques

Les PESMN étaient enregistrés en continu au point ďErb (projection cutanée de ľextrémité latérale du plexus brachial) et successivement au niveau cervical en regard de la sixime vertèbre), frontal et pariétal controlatéral pour une comparaison secondaire. Ľenregistrement a commencé avant ľinjection de ropivacaine et jusqu’à 30 min après. Toutes les trois minutes après la réalisation du bloc, les tests cliniques étaient réalisés au niveau de la main ďinnervation du nerf médian en utilisant une échelle visuelle analogique (0–10). Une analyse de variance a été utilisée pour comparer les résultats. Si les PESNM étaient remarquablement stables avant la réalisation du bloc, après leur amplitude diminue précocement et de fa÷on importante, chez tous les sujets. Alors que les tests au froid et à la piqûre peuvent être considérés comme positifs (> 8 sur ľéchelle) seulement après 15,8 ± 1,2 min et 20,1 ± 1,8 min respectivement après ľinjection de ropivacaêne, la diminution la plus précocement détectable de ľamplitude du potentiel (20 %) au point ďErb, survenait en moyenne en 5,6 ± 1,1 min (P < 0,01).

Conclusion

La diminution de ľamplitude des PESNM indique objectivement la survenue du bloc du nerf médian après la réalisation ďun bloc infraclaviculaire avant toute modification clinique.

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Copyright information

© Canadian Anesthesiologists 2006

Authors and Affiliations

  • Pierre Pandin
    • 1
  • Jean Corentin Salengros
    • 1
  • Alain ďHollander
    • 2
  • Christiane Tchekap
    • 1
  • Arlette Vandesteene
    • 1
  1. 1.Department of AnesthesiologyErasmus Hospital, Free University of BrusselsBrusselsBelgium
  2. 2.the Division of AnesthesiologyCantonal University HospitalGenevaSwitzerland

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