Is facial nerve integrity monitoring of value in chronic ear surgery?

Heman‐Ackah, Selena E.; Gupta, Sachin; Lalwani, Anil K.

doi:10.1002/lary.23363

Cited by 28 publications

(25 citation statements)

References 3 publications

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“…Therefore, it is proposed that the described system be used in conjunction with other reported methods of drilling error detection such as the use of intraoperative imaging or redundant instrument tracking algorithms (29). Finally, although stimulation intensity values found in the sheep model proved similar to those obtained on patients (21), translation of the proposed system and protocols to human subjects requires further verification.…”

Section: Discussionmentioning

confidence: 93%

“…The approach results in the drilling tool passing within close proximity (0.1-1.2 mm [6,12]) of the facial nerve (FN), placing this vital structure at risk from either excessive drilling temperature or mechanical destruction by collision with the drill bit. Although electromyogram (EMG)-based neuromonitoring has become a standard safety mechanism for identification and preservation of the FN in middle ear surgeries, such as revision cases and cochlear implantations (13)(14)(15)(16)(17)(18)(19)(20)(21), it has yet to achieve the sensitivity and specificity required to become a reliable safety mechanism when operating in close vicinity of the FN (<0.3 mm), without line of sight to the surrounding anatomy.…”

mentioning

confidence: 99%

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A Neuromonitoring Approach to Facial Nerve Preservation During Image-guided Robotic Cochlear Implantation

Ansó

Dür

Gavaghan

et al. 2016

Otology &Amp; Neurotology

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Hypothesis: A multielectrode probe in combination with an optimized stimulation protocol could provide sufficient sensitivity and specificity to act as an effective safety mechanism for preservation of the facial nerve in case of an unsafe drill distance during image-guided cochlear implantation. Background: A minimally invasive cochlear implantation is enabled by image-guided and robotic-assisted drilling of an access tunnel to the middle ear cavity. The approach requires the drill to pass at distances below 1 mm from the facial nerve and thus safety mechanisms for protecting this critical structure are required. Neuromonitoring is currently used to determine facial nerve proximity in mastoidectomy but lacks sensitivity and specificity necessaries to effectively distinguish the close distance ranges experienced in the minimally invasive approach, possibly because of current shunting of uninsulated stimulating drilling tools in the drill tunnel and because of nonoptimized stimulation parameters. To this end, we propose an advanced neuromonitoring approach using varying levels of stimulation parameters together with an integrated bipolar and monopolar stimulating probe. Materials and Methods: An in vivo study (sheep model) was conducted in which measurements at specifically planned and navigated lateral distances from the facial nerve were performed to determine if specific sets of stimulation parameters in combination with the proposed neuromonitoring system could reliably detect an imminent collision with the facial nerve. For the accurate positioning of the neuromonitoring probe, a dedicated robotic system for image-guided cochlear implantation was used and drilling accuracy was corrected on postoperative microcomputed tomographic images. Results: From 29 trajectories analyzed in five different subjects, a correlation between stimulus threshold and drillto-facial nerve distance was found in trajectories colliding with the facial nerve (distance <0.1 mm). The shortest pulse duration that provided the highest linear correlation between stimulation intensity and drill-to-facial nerve distance was 250 ms. Only at low stimulus intensity values ( 0.3 mA) and with the bipolar configurations of the probe did the neuromonitoring system enable sufficient lateral specificity (>95%) at distances to the facial nerve below 0.5 mm. However, reduction in stimulus threshold to 0.3 mA or lower resulted in a decrease of facial nerve distance detection range below 0.1 mm (>95% sensitivity). Subsequent histopathology follow-up of three representative cases where the neuromonitoring system could reliably detect a collision with the facial nerve (distance <0.1 mm) revealed either mild or inexistent damage to the nerve fascicles. Conclusion: Our findings suggest that although no general correlation between facial nerve distance and stimulation threshold existed, possibly because of variances in patient-specific anatomy, correlations at very close distances to the facial nerve and high levels of specificity would enable a binary respo...

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Section: Discussionmentioning

confidence: 93%

mentioning

confidence: 99%

A Neuromonitoring Approach to Facial Nerve Preservation During Image-guided Robotic Cochlear Implantation

Ansó

Dür

Gavaghan

et al. 2016

Otology &Amp; Neurotology

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“…Facial nerve monitoring has been shown to bolster the confidence of surgeons (particularly those with less experience), regarding their ability to identify facial nerves, perform dissection and drilling with sufficient precision, and ensure nerve integrity while preserving neural function [11] . Measures aimed at reducing the risk of iatrogenic facial nerve injury can also be justified as cost-effective [12] , despite the fact that not all hospitals possess such equipment and that facial nerve monitoring can not be considered 100% accurate [13] . Nonetheless, surgeons must consider the risks and benefits of specific surgical techniques in the treatment of each case they encounter and must not be guided by dogma.…”

Section: Discussionmentioning

confidence: 99%

Deceptive Facial Nerve Variant May Cloud Otologists’ Judgment: A Dilemma in Middle Ear Surgery

Kuo

Liao

et al. 2015

Int Adv Otol

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Tympanomastoid surgery constitutes the vast majority of procedures performed by otologists. Intra-operatively, identifying the facial nerve is always a challenge. We present an unusual case of fibrous connective tissue mimicking a facial nerve variant during cholesteatoma surgery. The variant was inadvertently damaged during surgery, and we feared devastating complications; however, the pathology revealed that it was not the actual facial nerve. This case is important, in that it serves as a reminder for otologists to be aware of the many possible presentations of the facial nerve in otologic surgery.

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“…Although facial nerve monitoring is not legally the standard of care (as shown in one of our cases), its routine use should be adopted to reduce the risk of facial nerve injury during middle ear and mastoid surgery (15,16). The senior author (P. D. L.) uses it for all ear surgery other than tympanoplasty and primary stapedotomy and will even use it in tympanoplasty if planning to drill on the posteriorinferior ear canal.…”

Section: Facial Nerve Injurymentioning

confidence: 97%

“…As stated in the highly regarded legal treaties by Goldsmith (17), intraoperative facial nerve monitoring may only serve to increase the time and cost of surgeries. That said, studies also show that facial nerve monitoring is cost effective (15,16).…”

Section: Facial Nerve Injurymentioning

confidence: 99%