gms | German Medical Science

57th Annual Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN)

German Society for Neuropathology and Neuroanatomy

12. - 15.09.2012, Erlangen

57th Annual Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN)

Anatomic study of the auricular branch of the vagus nerve (ABNV) in man

Meeting Abstract

Search Medline for

  • presenting/speaker Sami Alexander Safi - Anatomy Institute I, Faculty of Medicine, FAU, Erlangen, Germany
  • Winfried Neuhuber - Anatomy Institute I, Faculty of Medicine, FAU, Erlangen, Germany

Deutsche Gesellschaft fr Neuropathologie und Neuroanatomie. 57th Annual Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN). Erlangen, 12.-15.09.2012. Dsseldorf: German Medical Science GMS Publishing House; 2012. Doc12dgnnPP6.7

DOI: 10.3205/12dgnn118, URN: urn:nbn:de:0183-12dgnn1184

Published: September 11, 2012

© 2012 Safi et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Introduction: Changes in cerebral activities have occurred during transcutaneous vagus nerve stimulation with deactivation patterns in limbic and temporal brain structures. (Kraus et al.) These findings are similar to previous invasive (i)-VNS studies. (Chae) Presumably, both i-VNS and t-VNS stimulated myelinated afferent axons in the A range (diameter ≥ 7m) There is no knowledge about the nerve fibre (NF) spectrum of the ABNV, and how it relates to the cervical vagus nerve (CV). Thus, we counted the numbers of all myelinated axons in the ABNV, and compared them with the numbers of presumed afferent axons with diameters ≥7 m in the CV of the same individual.

Materials and methods: 17 bodies donated to the Anatomy Institute I of the University of Erlangen-Nuremberg conventionally embalmed with formaldeyde were used. The ABNV, CV, recurrent laryngeal nerve (RLN) and thoracic vagus nerve (TV) were dissected, postfixed in 2.5% glutaraldehyde in 0.1M phosphate puffer, osmicated and embedded in Epon according to standard protocols. A Leica Aristoplan microscope equipped with an oil-immersion objective (100X, num. aperture 1.32) and a digital camera was used. An average axon diameter was calculated from the long and short axis, including the myelin sheath.

Results: We counted an average of 324 NFs ≥7 m in the TV, 760 in the CV, and 485 in the RLN. Subtraction of 485 (presumed motor axons) from 760 (motor axons and A afferent axons) NFs resulted in an average of 275 A afferent axons in the CV, that roughly corresponded to a direct count of 324 A axons in the TV (containing no motor axons). We counted on average 372 axons in the ABNV (range 180 to 548 ). The largest group of axons was thinly myelinated with diameters between 2 and 5 m. An average of 272 (73% of total, range 139 to 430) of these presumed Aδ fibres were counted. Presumed A fibres measuring ≥7m were much fewer. An average of these 60 axons (22% of all, range 16 to 133) was counted. The group of axons with diameters between 5-7m were not allocated to a defined category but included in the total count. We tentatively considered them as small A axons.

Conclusion: On average, there are five times less A axons in the ABNV which is stimulated in t-VNS than in the CV, the usual site of i-VNS. It remains to be determined if this discrepancy renders t-VNS less effective than i-VNS for treatment.