Intraoperative nerve stimulation for lesion localization in pediatric traumatic facial paralysis: A Case Report

Authors

Abstract

IntroductionThis study aimed to evaluate the effectiveness of intraoperative nerve stimulation as a novel diagnostic technique for accurately localizing the site of nerve injury in acute peripheral facial paralysis (PFP).
Case PresentationThis study included two patients presenting with acute-onset complete PFP. Intraoperative facial nerve stimulation was performed sequentially along the nerve’s course. Localization of the injured segment was based on the absence of proximal stimulation response in the affected area, while responses remained intact distal to the lesion. In both cases, the site of neural injury was accurately identified using intraoperative stimulation. The findings enabled targeted and limited decompression of the facial nerve.
ConclusionThis is the first study to demonstrate the potential of intraoperative nerve stimulation as a reliable technique for lesion localization in traumatic complete PFP. Accurate identification of the affected segment can optimize surgical outcomes by enabling precise, minimally invasive decompression.

Keywords

Introduction

Traumatic facial nerve paralysis (FNP) requires accurate diagnosis and management.^1,2 It occurs in 7-10% of patients with temporal bone fractures.³ However, surgical indications and timing remain controversial.⁴ Traumatic FNP is classified as early or late based on the onset of paralysis after injury; paralysis developing within 24 to 72 hours is considered the acute form.^1,3 There is no consensus regarding treatment when a displaced fracture line in the facial nerve canal is not observed. In this situation, the physician’s clinical experience and the patient’s or their parents’ choices (once they are informed about the process) are generally significant.
Facial nerve integrity monitoring is routinely employed by many surgeons during otologic procedures to ensure intraoperative nerve preservation. There are no PubMed data on the use of intraoperative nerve stimulation for lesion localization in acute peripheral facial paralysis. We present two pediatric cases in which this novel technique (Ulusoy Technique) was utilized to localize the site of nerve injury in acute peripheral facial paralysis, highlighting its potential diagnostic value and clinical outcomes.

Case Presentation

Case 1A 9-year-old boy presented with left-sided acute complete peripheral FNP (House-Brackmann (HB) grade VI) following blunt trauma to his head while he was playing football with his friends (Figure 1A).
Otoscopic examination revealed marginal perforation of the tympanic membrane in the anterosuperior quadrant. High-resolution CT (HRCT) of the temporal bone identified a nondisplaced fracture extending to the geniculate ganglion (GG) (Figure 2). Surgical decompression was elected without waiting for electroneuronography (ENoG), based on the acute onset and severity of paralysis.
Intraoperatively, after canal wall up tympanomastoidectomy and posterior tympanotomy, each facial nerve segment was stimulated, starting from the GG level and proceeding distally, with 0.8 mA using a monopolar stimulator probe (NIM- Response® 3.0 Medtronic Xomed Inc., Jacksonville, FL 32216- 0980 USA). The presence of visible facial muscle contraction and/or electromyography (EMG) waveform was accepted as an indicator of functional nerve conduction. Nerve stimulation was not seen in the GG and tympanic segments, while nerve stimulation was seen in the second genu and the proximal part of the mastoid segment. After decompression of the fallopian canal at the geniculate ganglion and tympanic segments, the intraoperative nerve integrity monitor (NIM) findings were once again confirmed. The perineurium was edematous in the tympanic and GG segments. As a result, decompression was completed by making an incision in the perineurium only in these two segments. This approach reduced operative time and morbidity.
The patient was followed up with monthly EMG in the postoperative period, and complete functional recovery (HB grade I) was achieved in the fifth month (Figure 1B).
Case 2A 3-year-old male patient presented with right-sided acute complete peripheral facial paralysis (HB grade VI) after striking his head on a stove while running. HRCT revealed no apparent fractures involving the facial nerve canal (Figure 3).
Due to the acute complete peripheral facial paralysis following trauma and the patient’s presentation within the first six hours, a decision was made to perform facial nerve decompression without awaiting ENoG. Intraoperatively, a longitudinal fracture line was observed along the epitympanum, perpendicular to the GG, and a second fracture line was noted parallel to the tympanic segment of the fallopian canal. Using the same stimulation protocol as in Case 1, no evoked response was detected in the first three segments, while a positive response was recorded distal to the second genu.
Facial nerve decompression was performed from the GG to the 2 mm area distal to the second genu. At this stage, the NIM findings were reconfirmed by reapplying stimulation and verifying the absence of a response. This technique enabled precise lesion localization and avoided unnecessary decompression of the mastoid segment. After identifying the lesion site, an incision was performed on the perineurium. The patient was followed up with monthly EMG testing, and complete functional recovery (HB grade I) was achieved in the 6th month.
Ethical ApprovalEthical approval was obtained from the Ethics Committee of Selçuk University (Date: 25.02.2025, Decision No: 2025/125).
This case report was prepared in accordance with the CARE (Case Report) guidelines.

Discussion

The main finding was accurate lesion localization of the injured site in both pediatric patients with acute traumatic peripheral facial paralysis using the novel technique we describe. This technique may enable minimally invasive management of acute traumatic facial paralysis.
Emergency surgical intervention is generally recommended for cases of acute complete FNP secondary to trauma, whereas delayed-onset cases are usually managed conservatively.³ Hato et al. reported a 92.9% recovery rate to HB grade I or II following decompression within two weeks in patients with severe acute traumatic FNP.³ The standard criteria for surgical intervention include onset of paralysis within 14 days, greater than 90% degeneration on ENoG, and absent activity on EMG.^2,3
Trauma may lead to perineural edema, vascular congestion, partial or complete rupture, and degeneration of the facial nerve.² In such cases, surgical decisions regarding the extent of decompression and the need for nerve repair depended on subjective microscopic evaluations of the facial nerve during exploration, which do not entirely reflect the physiological status of the nerve fibers.⁴ Therefore, more specific criteria are needed to guide clinical decision-making.⁴ Furthermore, the success of surgical decompression depends on accurately identifying the injured nerve segment.⁵
HRCT and electrophysiological tests are used to plan treatment.⁴ Electrophysiological tests play an essential role in demonstrating the degree of nerve damage and the stages of nerve degeneration and regeneration.¹ ENoG, nerve excitability test (NET), and maximal stimulation test (MST) may be used to evaluate acute complete paralysis when the nerve is in the degenerative phase. These tests provide accurate information during the first 3 weeks and are not used during the first 3 days because Wallerian degeneration has not yet reached the stylomastoid foramen.¹ EMG plays a supportive role within the first 14 days following the onset of acute paralysis and is particularly valuable for assessing chronic paralysis after the third week.¹
Because electrophysiological tests such as ENoG cannot be performed within the first 72 hours, deferring intervention during this period may miss the crucial therapeutic window in cases of actual nerve injury. In such cases, many clinicians make decisions based on HRCT findings of the temporal bone and carry out decompression if a displaced fracture is identified along the course of the facial nerve.
Facial nerve monitoring is routinely used in otologic procedures; intraoperative facial nerve monitoring is routinely employed. However, the use of a nerve integrity monitor is not routine in patients with facial nerve paralysis. We routinely use facial nerve monitoring in patients undergoing facial nerve decompression. In a case of acute traumatic complete peripheral FNP, we decided to perform decompression following the family’s informed consent. Intraoperative findings during this case prompted the development of a novel method for determining lesion localization. Given that Wallerian degeneration takes approximately 72 hours to reach the stylomastoid foramen, we hypothesized that early intraoperative nerve stimulation could enable real-time identification of the damaged segment.
Using a monopolar stimulator probe, we sequentially stimulated the facial nerve from the GG distally. In the first patient, no evoked response was detected in the GG and tympanic segments, whereas positive responses were obtained in the second genu and proximal mastoid segments (Case 1). The same method was successfully applied in a second case, confirming its potential diagnostic value in the early period of complete traumatic FNP (Case 2).
Although intraoperative facial nerve stimulation is commonly used in neurotologic surgeries (e.g., for cerebellopontine angle tumors or tympanomastoidectomy), there is a deficiency of literature on its use in traumatic facial palsy surgery. Notably, Gantz et al. briefly discussed a method for Bell’s palsy in the 1980s, suggesting that it may outperform the Schirmer test for lesion localization.^5,6 To date, no clinical applications of this technique have been reported in traumatic cases. This report appears to be the first clinical application of intraoperative nerve stimulation for accurately identifying lesion sites in acute traumatic peripheral facial paralysis.

Limitations

This study has several limitations that should be acknowledged. The small number of patients is the most important limitation. Larger, prospective, multicenter studies are needed to validate the reliability, reproducibility, and clinical utility of this novel approach.

Conclusion

This preliminary study suggests that this technique may be an important diagnostic tool in determining the area of nerve damage in acute complete PFP following trauma. Accurate identification of the damaged segment will allow decompression to be performed at the correct location and to a minimal extent, thereby enabling personalized treatment. In addition, it may help us define this region in cases where nerve integrity is preserved despite axonal damage. In some cases of traumatic peripheral facial paralysis, although the perineurium appears intact, a reduction in nerve diameter compared to adjacent segments may become evident upon perineurial incision. In such cases, precise identification of the damaged segment can significantly reduce operative time and surgical morbidity. Although the preliminary findings of this study are promising, multicenter studies are needed to elucidate issues such as the technique's diagnostic reliability and reproducibility.

Declarations

Abbreviations

CT: Computed tomography
EMG: Electromyography
ENoG: Electroneuronography
FNP: Facial nerve paralysis
GG: Geniculate ganglion
HB: House-Brackmann
HRCT: High-resolution computed tomography
NIM: Nerve integrity monitor
PFP: Peripheral facial paralysis

References

1. Ziai K, Daher GS, Henry CR, Lighthall JG. Evaluation and surgical decision making in facial paralysis. Oper Tech Otolaryngol Head Neck Surg. 2021;32(4):205-212. doi:10.1016/j.otot.2021.10.011
   Article PubMed Google Scholar
2. Andresen NS, Sun DQ, Hansen MR. Facial nerve decompression. Curr Opin Otolaryngol Head Neck Surg. 2018;26(5):280-285. doi:10.1097/moo.0000000000000478
   Article PubMed Google Scholar
3. Hato N, Nota J, Hakuba N, Gyo K, Yanagihara N. Facial nerve decompression surgery in patients with temporal bone trauma: analysis of 66 cases. J Trauma. 2011;71(6):1789-1792. doi:10.1097/ta.0b013e318236b21f
   Article PubMed Google Scholar
4. Ashram YA, Badr-El-Dine MM. Surgery for traumatic facial nerve paralysis: does intraoperative monitoring have a role? Eur Arch Otorhinolaryngol. 2014;271(9):2365-2374. doi:10.1007/s00405-013-2712-9
   Article PubMed Google Scholar
5. Gantz BJ. Intraoperative facial nerve monitoring. Am J Otol. 1985;Suppl:58-61.
   PubMed Google Scholar
6. Gantz BJ, Gmur A, Fisch U. Intraoperative evoked electromyography in Bell’s palsy. Am J Otolaryngol. 1982;3(4):273-278. doi:10.1016/s0196-0709(82)80066-5
   Article PubMed Google Scholar

Additional Information

Publisher’s Note
Bayrakol MP remains neutral with regard to jurisdictional and institutional claims.

Rights and Permissions

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). To view a copy of the license, visit https://creativecommons.org/licenses/by-nc/4.0/

View full license details →

About This Article

Received:

July 31, 2025

Accepted:

August 31, 2025

Published Online:

September 7, 2025