Duplicated Vagus Nerve in Adolescence: Case Report and Review of Literature

Duplicate Left-Sided Vagus Nerve: Intraoperative Imaging, Management, and Placement

Introduction  Duplicate cranial nerves are fundamentally rare anatomical variants. Few case reports have documented cranial nerve duplication. One previous case report has reported a vagus nerve with a smaller secondary accessory nerve component. We present the first reported case of duplicate vagus nerves identical in size and thickness with otolaryngological diagnostic confirmation. Case Description  A 25-year-old woman with seizures refractory to medical management decided to undergo placement of a vagus nerve stimulator. During carotid sheath microdissection, two parallel nerve tracts were identified. The two nerves were identical in size and width. Proximal dissection confirmed that the two nerves were independent of one another and neither was a branching segment. To confirm duplicate vagus nerves, otolaryngology was consulted intraoperatively and the duplicate nerves were verified. The vagus nerve stimulator was placed in typical fashion around the medial nerve. Conclusion  This is the first reported case of duplicate vagus nerves identical in size and with confirmation by otolaryngology. The authors would like to highlight the operative management of the vagus nerve stimulator placement as well as integrity of the diagnostic conclusions based on size, further dissection, and specialist consultation.

Intra-operative monitoring as an adjuvant to standard vagus nerve stimulation implantation

PURPOSE

The treatment of refractory epilepsy by vagus nerve stimulation (VNS) is a well-established therapy. Complications following VNS insertion may be procedure-related or stimulation-related. Herein, we describe our technique of intra-operative neuro-monitoring (IONM) in an attempt to diminish these adverse events.

METHODS

This retrospective study describes 66 consecutive patients between the ages of 3 and 12 years who had undergone primary VNS implantation. The study population consisted of two cohorts, one in which the VNS device was implanted according to the standard described technique and a second group in which IONM was used as an adjuvant during the VNS device placement. Prior to VNS insertion, a Pediatric Voice Handicap Index (PVHI) was performed to assess voice-related quality of life, and this was repeated at 3 months following VNS insertion.

RESULTS

Sixty-six patients underwent the VNS implantation. Forty-three patients had a "standard" VNS insertion technique performed, whereas 23 had IONM performed during the VNS implantation. There were significant changes in the PVHI scores across both cohorts at 3-month follow-up. There were no statistically significant differences in PVHI scores between the monitored group and non-monitored group at 3-month follow up.

CONCLUSIONS

IONM can be used during VNS insertions to ensure correct placement of the leads on CNX. IONM may minimise vocal cord stimulation by placing the lead coils on the area of nerve eliciting the least amount of vocal cord EMG response. IONM however does not appear to improve voice outcomes at early follow up.