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Topographic Facial Nerve Transplantation

International Microsurgery Journal. 2021;5(1):1
DOI: 10.24983/scitemed.imj.2021.00139
Article Type: Idea and Innovation

Abstract

This case report describes our successfully attempt to perform a topographically correct sural nerve transplantation in the extracranial facial nerve stem using the intraneural facial nerve stem topography proposed by Meissl in 1979. This is the first reported case of successful fascicular nerve grafting of the facial nerve stem following extensive laceration. The surgery was performed on a young male patient who had suffered total left facial paralysis after a traumatic car accident with laceration of the facial nerve. During a second look surgery, proximal and distal facial nerve stumps with significant nerve gaps were identified. Using Meissl’s approach, the nerve gaps were bridged with five sural nerve grafts. Follow-up after 48 months showed satisfactory results with only minimal synkinesis, thus avoiding additional procedures. No additional corrective interventions were therefore required.

Keywords

  • Facial nerve; facial paralysis; nerve grafting; nerve repair; sural nerve

Clinicle Report

Presentation
This is a clinical report describing the case of performing a topographically correct sural nerve transplantation in the extracranial facial nerve stem using the intraneural facial nerve stem topography. Proposed by Meissl in 1979, this is the first case of successful fascicular nerve grafting of the facial nerve stem following extensive laceration. It was performed on a young male patient who had suffered a deep traumatic soft tissue laceration to the left preauricular area because of a high velocity car accident. In the surgery performed immediately upon presentation, the facial nerve stump could not be identified at the stylomastoid foramen and was therefore not reconstructed. Subsequently, he suffered complete total left facial nerve paralysis.

Three days after the initial presentation, when the swelling of the trauma area had subsided, a high resolution ultrasound was conducted and the transected facial nerve stump was located at the stylomastoid foramen, confirming the indication of secondary facial nerve reconstruction. Surgical exploration identified the distal facial nerve stumps within the parotid gland. There was a significant gap between the nerve stumps due to trauma mechanism. A tension-free direct nerve repair could not be deduced since the gap extended from the extracranial nerve stem to the pes anserinus of the facial nerve within the parotid gland.

Management
Attempting to reconstruct the facial nerve after more than 72 hours post trauma requires the knowledge of the facial nerve's intraneural topography. The senior author referred to an article by Meissl published in 1979 in an Austrian publication in which the intraneural topography of the extracranial facial nerve stem had been examined [1]. Meissl had paired the electrophysiological examination of the facial nerve stem of cats in vivo with sequential microscopic analyses of human cadaveric nerves. He had found three areas within the horizontal cross-section of the proximal facial nerve stem: (i) the ventro-medial portion innervating the muscles of the forehead and upper eyelid, (ii) the lateral portion innervating the lower eyelid and cheek, and upper lip, and (iii) the dorsal fascicles supplying the muscles of the neck and lower lip (Figure 1). We expected to identify the nerve stumps in a second-look surgery which would allow ipsilateral repair instead of a cross-face nerve graft, which would be the alternate option in case of failure to repair the transected facial nerve.

We performed a fascicular repair of the proximal facial nerve stump at the stylomastoid foramen using five autologous grafts from the sural nerve of approximately 6 cm length (Figure 2). They were arranged according to the topography proposed by Meissl for the restoration of distal continuity of the facial nerve.

Outcome
Follow-ups were conducted after eight months and four years post trauma. Both showed excellent clinical outcomes with good symmetric mimic muscle contractions and minimalsynkinesias (Figure 3, Figure 4, Video 1: https://youtu.be/doppARxcr5k). The Sunnybrook Facial Grading System [2] scores at the initial presentation and at the time of follow-up after eight and 48 months are summarized in Table 1. The patient was satisfied with the result and there was no need for further corrective interventions. In this way, additional procedures like nerve or muscle grafting, as well as myectomy or botulinum toxin injection were avoided.
 

Figure 1. Schematic illustration of the fascicular topography of the facial nerve at the stylomastoid foramen and the corresponding innervation of facial muscles as described in the 1979 paper by Meissl.

 

Figure 2. Intraoperative view of the fascicular left facial nerve reconstruction using five sural nerve grafts.

 

Figure 3. Closing of the eyelids 48 months after reconstructive surgery. Note the marked reduction in lagophthalmos of the left eye and resting asymmetry of the mid- and lower face.

 

Figure 4. Reconstruction of the patient’s smile after reconstructive surgery with symmetric elevation of the corners of the mouth, nasolabial fold creasing and mild synkinesis of the left orbicularis oculi muscle.

 

Discussion

Direct tension-free nerve coaptation is generally preferred in nerve repair surgery [3,4]. In this case, nerve coaptation was not a viable option because of the extent of the nerve gap created by the laceration and the initially unlocated proximal nerve stump. The typical reconstructive approach in this case would have been a cross-facial nerve grafting to provide innervation from the contralateral facial nerve or the ipsilateral extra-facial nerve transfer to a free muscle graft [5-7]. In contrast to these methods, we restored the physiological muscle innervation by direct fascicular nerve repair of the proximal and distal facial nerve stumps [8-10]. Although other authors have reported on the fascicular structure of the facial nerve [11,12], Meissl’s contribution is unique as it describes the method of correlating the fascicles of the nerve stem with target muscles. However, his description of the facial nerve intraneural topography is only a rough outline of the mimic muscle innervation pattern. Hence the procedure of topographic facial nerve transplantation carries the risk of mass movements, aberrant innervations and synkineses. Although these risks may be manageable with additional corrective interventions, further preclinical studies are necessary to refine and improve the knowledge of intraneural topography of the facial nerve. 

Conclusion

This is the first clinical report that describes the application of Meissl’s findings on the intraneural topography of the extracranial facial nerve. We were able to successfully reconstruct a facial nerve stump at the stylomastoid foramen according to the topographic pattern as proposed by him. The clinical outcomes were excellent as was evident in the follow-up examination after four years of surgery. However, current knowledge on the topography of the facial nerve is still coarse and its clinical use restricted to seldom events. Therefore, we plan further preclinical research to reinforce Meissl´s findings and refine the topography of the fascicular architecture of the facial nerve.

References

  1. G Meissl. Die intraneurale topographie des extrakraniellen nervus facialis. Acta Chir Austr 1979, Suppl 28:1-17.
  2. BG Ross, G Fradet, JM Nedzelski. Development of a sensitive clinical facial grading system. Otolaryngol Head Neck Surg 1996;114(3):380-386. [View Article]
  3. H Millesi. Factors affecting the outcome of peripheral nerve surgery. Microsurgery 2006;26(4):295-302. [View Article]
  4. Brushart TM. Nerve Repair. New York, NY: Oxford University Press, Inc; 2011
  5. M Frey, M Michaelidou, C-H Tzou, A Hold, I Pona, E Placheta. Proven and innovative operative techniques for reanimation of the paralyzed face, Handchir Mikrochir Plast Chir 2010;42(2):81-89. [View Article]
  6. S M Rozen, Facial reanimation: basic surgical tools and creation of an effective toolbox for treating patients with facial paralysis: part B. nerve transfer combined with cross-facial nerve grafting in the acute facial palsy patient. Plast Reconstr Surg 2017;139(3):725-727. [View Article]
  7. Ritvik P Mehta. Surgical treatment of facial paralysis. Clin Exp Otorhinolaryngol 2009;2(1): 1-5. [View Article]
  8. Natalie A Brill, Dustin J Tyler. Quantification of human upper extremity nerves and fascicular anatomy. Muscle Nerve 2017;56(3):463-471. [View Article]
  9. H Millesi, G Meissl, A Berger. The interfascicular nerve-grafting of the median and ulnar nerves. J Bone Joint Surg Am 1972;54(4):727-750. [View Article]
  10. S Sunderland. The intraneural topography of the radial, median and ulnar nerves. Brain 1945;68:243-299. [View Article]
  11. Jorge O Güerrissi, Maximiliano F Gil Miranda. Intraneural topography of the extratemporal facial nerve: microsurgical nerve reconstruction. J Craniofac Surg 2007;18(3):578-585. [View Article]
  12. Guillaume Captier, François Canovas, François Bonnel, François Seignarbieux. Organization and microscopic anatomy of the adult human facial nerve: anatomical and histological basis for surgery. Plast Reconstr Surg 2005;115(6):1457-1465. [View Article]

Editorial Information

Publication History

Received date: September 03, 2020
Accepted date: November 20, 2020
Published date: January 23, 2021

Ethics Approval and Consent to Participate

The study is in accordance with the ethical standards of the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from the patient for publication of this Case report and any accompanying images.

Funding

The study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of Interest

The authors report no financial or other conflict of interest relevant to this article, which is the intellectual property of the authors.

Copyright

© 2021 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY).

Department of Cardiac Surgery, München Klinik Bogenhausen, Munich, Germany
Plastic and Reconstructive Surgery, Department of Surgery, Hospital of Divine Savior, Vienna, Austria
Plastic and Reconstructive Surgery, Department of Surgery, Hospital of Divine Savior, Vienna, Austria
Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Austria
Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Austria
  1. Plastic and Reconstructive Surgery, Department of Surgery, Hospital of Divine Savior, Vienna, Austria
  2. Faculty of Medicine, Sigmund Freud University, Vienna, Austria
  3. Tzou Medical. Vienna, Austria
  1. Plastic and Reconstructive Surgery, Department of Surgery, Hospital of Divine Savior, Vienna, Austria
  2. Faculty of Medicine, Sigmund Freud University, Vienna, Austria
  3. Tzou Medical. Vienna, Austria

    Address: Gumpendorfer Strasse 10-12/ Top 14, 1060 Vienna, Austria
Table 1.JPGScores of facial symmetry and movement according to the Sunnybrook Facial Grading System [2] at the initial presentation and at follow-ups after 8 and 48 months.

Figure 1.jpg
Figure 1. Schematic illustration of the fascicular topography of the facial nerve at the stylomastoid foramen and the corresponding innervation of facial muscles as described in the 1979 paper by Meissl.
Figure 2.jpg
Figure 2. Intraoperative view of the fascicular left facial nerve reconstruction using five sural nerve grafts.
Figure 3.jpg
Figure 3. Closing of the eyelids 48 months after reconstructive surgery. Note the marked reduction in lagophthalmos of the left eye and resting asymmetry of the mid- and lower face.
Figure 4.jpg
Figure 4. Reconstruction of the patient’s smile after reconstructive surgery with symmetric elevation of the corners of the mouth, nasolabial fold creasing and mild synkinesis of the left orbicularis oculi muscle.

Reviewer 1 Comments

  1. Examination of the nerve trunk of the facial nerve by degeneration techniques in animal studies showed that there is no representation of the peripheral branches in the nerve trunk. In this human case, however, the authors successfully reconstructed a facial nerve stump at the stylomastoid foramen according to the proposed topographic pattern. A further research to reinforce Meissl´s findings and refine the topography of the fascicular architecture of the facial nerve is indeed required. This is a well written case report that contributes to the existing literature.
    ResponseThank you for your kind comment. We see it as our duty to disseminate the knowledge and information of medical therapies to improve QoL of Facial Palsy Patients.
     
  2. The only issue I would raise is that how a surgeon meticulously repairs the severed trunk to avoid neuroma formation during the surgery.
    ResponseThank you for your kind question. We recommend atraumatic handling of the nerve stumps and nerve grafts and meticulous sutures. Editor in Chief, Professor Chuang, always told me: “Treat the nerve like your girlfriend. No touch!”.

Reviewer 2 Comments

  1. Could you show more preoperative and intraoperative photos?
    ResponseWe have more photos, due to limited space and photo allowance of a case report /innovation idea paper, we could not add more photos. Sorry!
     
  2. Have you done electromyography before and after surgery?
    ResponseThe Patient had total complete facial palsy when he was admitted into the hospital. At the initial operation, directly after admission, the operator did not find any proximal nerve stump for coaptation. The resected facial nerve stump was intraoperatively verified. In this way no EMG was done before re-exploration and nerve graft.
     
  3. Why did you use the babysitter nerve in this case?
    ResponseThank you for this question. Due to the experience with and confidence in the cross-face nerve grafting technique at our department, we would have considered a cross-face nerve graft as a second-line option in this case. We inserted a statement regarding this decision in the “Management” section of the revised manuscript.

Reviewer 3 Comments

  1. There should be an Introduction section prior to Clinical Report Section.
    ResponseThank you so much for your commendation, due to limits on word count and this very interesting case, we went in medias res to describe this case and innovation report.
     
  2. Seventy-two hours after acute injuries to the extratemporal facial nerve, the neurotransmitter stores, that are required for motor end plate depolarization, may be irreversibly depleted. Also, the target muscles may no longer respond to stimulation of the distal nerve stump. Therefore, acute injuries to the extratemporal facial nerve should be repaired as soon as possible after injury to facilitate identification of the transected nerve stumps. In this case, how many days did the patient receive a secondary facial nerve reconstruction?
    ResponseThank you for your comment. The nerve transplantation was carried out after 70 hours. First exploration on the day of admission, was carried out from doctor on duty, who could not find nerve stumps to be bridged/repaired.
     
  3. Facial nerve repair is frequently complicated by synkinesis or dyskinesis. In this case, 48 months after reconstructive surgery, mild synkinesis of the left orbicularis oculi muscle was observed. Did the patient have unintended facial muscle contractions 4 years after surgery?
    ResponseIn this case, we did not have any unintended movement so far.
     
  4. The sentences “Therefore, we plan further preclinical research to reinforce Meissl´s findings and refine the topography of the fascicular architecture of the facial nerve” should be placed in the Discussion section.
    ResponseThank you for this comment. In our opinion, the necessity to research the hypothesized topography further and to hopefully replicate the clinical success is the ultimate conclusion of this report. We therefore decided to place this statement in the conclusions section.
     
  5. In the Discussion section, the authors stated that the procedure of topographic facial nerve transplantation carries the risk of mass movements, aberrant innervations and synkinesis; and these risks may be manageable with additional corrective interventions. The authors should clarify the socalled additional corrective interventions.
    ResponseThank you for this proposal. We have included examples of secondary or corrective procedures in the “Outcomes” section: “such as additional nerve or muscle grafting, myectomy or botulinum toxin injection.”

Reviewer 4 Comments

  1. The authors should clarify the reason why they restored the physiological muscle innervation by direct fascicular nerve repair of the proximal and distal facial nerve stumps, rather using other methods. For instance, the modern-day hypoglossal nerve transfer provides reanimation to a House–Brackmann grade II of VI, yielding spontaneous motion with resting facial symmetry.
    ResponseThank you for this comment. To reconstruct alike with alike is the highest priority in reconstructive surgery, with nerve graft we could achieve an emotional smile. If the nerve reconstruction was not successful, other procedures as you mentioned could have been employed.

  2. In the Abstract and Introduction sections, the authors need to explain the rationale for reporting the case, the surgical idea as well as the innovation of their technique.
    ResponseThank you for this proposal. We have inserted a statement that this was the first reported case of successful fascicular nerve grafting of the facial nerve stem following extensive laceration in the Abstract/Summary.

  3. In Figure 1, the dorsal region of nerve should supply innervation of the muscles of the upper face, whereas neurons in the ventral region should innervate muscles of the lower face. The labels of ventral and dorsal are not correct. In addition, the labels of lateral and medial need to be confirmed.
    ResponseThank you for this comment. We understand the ambiguity which caused confusion and adjusted the figure to clarify the anatomical orientation.

  4. Immediate complete paralysis of facial nerve warrants surgical exploration. Delayed paralysis or incomplete paresis should be treated medically with high-dose steroids. In this case, when was the complete total left facial nerve paralysis observed?
    ResponseLeft total complete facial palsy was observed on the day of admission, at the emergency exploration operation. The physical nerve defect was seen, but no nerve stumps were found for surgical repair. In this way, surgical nerve restoration was initiated.

Schwaiger BM, Tinhofer I, Steinbacher J, Rath T, Meissl G, Tzou CHJ. Topographic facial nerve transplantation. Int Microsurg J. 2021;5(1):1. https://doi.org/10.24983/scitemed.imj.2021.00139