Value of Intraoperative Monitoring of the Trigeminal Nerve in Detection of a Superiorly Displaced Facial Nerve During Surgery for Large Vestibular Schwannomas

Abstract ObjectiveTo investigate the role of trigeminal and facial nerve monitoring in the early identification of a superiorly displaced facial nerve.Patients and MethodsThis prospective study included 24 patients operated for removal of large vestibular schwannomas (VS). Electromyographic (EMG) events recorded after mapping the superior surface of the tumor were evaluated by analyzing the latencies of the responses from the masseter and facial nerve innervated muscles.ResultsThe latency of the recorded compound muscle action potential (CMAP) from the masseter muscle was 3.6 ±0.5 msec, and of the simultaneously recorded volume conducted responses from the frontalis, o.oculi, nasalis, o.oris and mentalis muscles were 4.6 ±0.9, 4.1 ±0.7, 3.9 ±0.4, 4.3 ±0.8 and 4.5 ±0.6 msec respectively after trigeminal nerve stimulation in 24 (100%) patients. In 6 (25%) patients, the mean latency of CMAP on the masseter was 3.6 ±0.5 msec, and the latencies of the CMAP from the frontalis, nasalis, o.oris and mentalis muscles were longer than those of the volume conduced responses (p=0.002; p=0.001; p< 0.001; and p=0.015 respectively) indicating stimulation of both nerves (trigemino-facial EMG response). All patients with this response were later confirmed anatomically to have an AS displaced facial nerve. ConclusionUnderstanding the trigemino-facial EMG response is of value in identifying an AS displaced facial nerve; in preventing electrophysiological confusion between the trigeminal and the facial nerves; and in detecting the presence of volume conducted contributions in the measured facial nerve CMAP at the end of surgery.

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Improved preservation of function during acoustic neuroma surgery

Journal of Neurosurgery ◽

10.3171/2014.8.jns132525 ◽

2015 ◽

Vol 122 (1) ◽

pp. 24-33 ◽

Cited By ~ 17

Author(s):

Hirofumi Nakatomi ◽

Hidemi Miyazaki ◽

Minoru Tanaka ◽

Taichi Kin ◽

Masanori Yoshino ◽

...

Keyword(s):

Action Potential ◽

Facial Nerve ◽

Acoustic Neuroma ◽

Compound Muscle Action Potential ◽

Dorsal Cochlear Nucleus ◽

Factors Affecting ◽

Root Exit Zone ◽

Muscle Action Potential ◽

Monitoring Response ◽

Potential Monitoring

OBJECT Restoration of cranial nerve functions during acoustic neuroma (AN) surgery is crucial for good outcome. The effects of minimizing the injury period and maximizing the recuperation period were investigated in 89 patients who consecutively underwent retrosigmoid unilateral AN surgery. METHODS Cochlear nerve and facial nerve functions were evaluated during AN surgery by use of continuous auditory evoked dorsal cochlear nucleus action potential monitoring and facial nerve root exit zone–elicited compound muscle action potential monitoring, respectively. Factors affecting preservation of function at the same (preoperative) grade were analyzed. RESULTS A total of 23 patients underwent standard treatment and investigation of the monitoring threshold for preservation of function; another 66 patients underwent extended recuperation treatment and assessment of its effect on recovery of nerve function. Both types of final action potential monitoring response and extended recuperation treatment were associated with preservation of function at the same grade. CONCLUSIONS Preservation of function was significantly better for patients who received extended recuperation treatment.

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Prognostic Value of Evoked and Standard Electromyography in Acute Facial Paralysis

Otolaryngology ◽

10.1177/019459989210700306 ◽

1992 ◽

Vol 107 (3) ◽

pp. 377-381 ◽

Cited By ~ 55

Author(s):

Jonathon S. Sillman ◽

John K. Niparko ◽

Sharon S. Lee ◽

Paul R. Kileny

Keyword(s):

Facial Nerve ◽

Facial Paralysis ◽

Prognostic Value ◽

Compound Muscle Action Potential ◽

Surgical Decompression ◽

Muscle Action ◽

Clinical Recovery ◽

Muscle Action Potential ◽

Evoked Electromyography ◽

Nerve Recovery

Ninety-one patients with idiopathic (n = 62) and traumatic (n = 29) facial paralyses were available for evaluation at least 1 year after the onset of paralysis. In nine cases of idiopathic paralysis and in 12 cases of traumatic paralysis, total intratemporal nerve decompression was performed. The remaining patients were treated with steroids alone. All patients underwent evoked electromyography (EEMG) testing within 2 weeks of the onset of paralysis. Facial nerve recovery was graded using the House-Brackmann facial nerve recovery scale. Subjects were grouped according to maximal decline of compound muscle action potential (CAP), as determined by EEMG, and by level of recovery 1 year after onset of paralysis. Among patients who did not undergo surgical decompression of the facial nerve, incomplete clinical recovery (grade III or higher) was significantly associated with CAP decline of >90% (p < 0.05) for idiopathic paralysis. In contrast, there was no significant association between CAP decline of >90% and clinical outcome in traumatic paralysis. These findings support previous reports of the prognostic value of EEMG in idiopathic facial paralysis, but suggest that this test may have less predictive value in the evaluation of facial paralysis as a result of trauma.

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Anatomical study of the trigeminal and facial cranial nerves with the aid of 3.0-tesla magnetic resonance imaging

Journal of Neurosurgery ◽

10.3171/jns/2008/108/3/0483 ◽

2008 ◽

Vol 108 (3) ◽

pp. 483-490 ◽

Cited By ~ 49

Author(s):

Yukinari Kakizawa ◽

Tatsuya Seguchi ◽

Kunihiko Kodama ◽

Toshihiro Ogiwara ◽

Tetsuo Sasaki ◽

...

Keyword(s):

Magnetic Resonance ◽

Facial Nerve ◽

Trigeminal Nerve ◽

Cranial Nerves ◽

Older Individuals ◽

Normal Anatomy ◽

Contact Points ◽

Facial Nerves ◽

The Mean ◽

Trigeminal Nerves

Object Neuroimages often reveal that the trigeminal or facial nerve comes in contact with vessels but does not produce symptoms of trigeminal neuralgia (TN) or hemifacial spasm (HFS). The authors conducted this study to determine how often the trigeminal and facial nerves came in contact with vessels in individuals not suffering from TN or HFS. They also investigated the correlation between aging and the anatomical measurements of the trigeminal and facial nerves. Methods Between November 2005 and August 2006, 220 nerves in 110 individuals (60 women and 50 men; mean age 55.1 years, range 19–85 years) who had undergone brain magnetic resonance (MR) imaging for other reasons were studied. The lengths, angles, ratio, and contact points were measured in each individual. A correlation between each parameter and age was statistically analyzed. Results The mean (± standard deviation) length of the trigeminal nerve was 9.66 ± 1.71 mm, the mean distance between the bilateral trigeminal nerves was 31.97 ± 1.82 mm, and the mean angle between the trigeminal nerve and the midline was 9.71 ± 5.83°. The trigeminal nerve was significantly longer in older patients. Of 220 trigeminal nerves, 108 (49.0%; 51 women and 57 men) came in contact with vasculature. There was 1 contact point in 99 nerves (45%) and 2 contact points in 9 nerves (4.1%). Contact without deviation of the nerve was seen in 91 individuals (43 women and 48 men), and mild deviation was noted in 17 individuals (8 women and 9 men). There was no moderate or severe deviation in any individual in this series. The mean length of the facial nerve was 29.78 ± 2.31 mm, the mean distance between the bilateral facial nerves was 28.65 ± 2.22 mm, the angle between the nerve and midline was 69.68 ± 5.84°, and the vertical ratio at the porus acusticus was 0.467 ± 0.169. Of all facial nerves, 173 (78.6%; 101 in women and 72 in men) came in contact with some vasculature. Contact without deviation was seen on 64 sides (in 37 women and 27 men), mild deviation on 98 sides (in 57 women and 41 men), and moderate deviation on 11 sides (in 7 women and 4 men). There was no severe deviation of the facial nerve in this series. The proximal length of the facial nerve, interval, angle, and ratio against the age were significantly shorter or smaller in the older individuals. Conclusions The findings in asymptomatic individuals in this study will help in deciding which findings observed on MR images may cause symptoms. In addition, the authors describe the variations of normal anatomy in older individuals. Knowledge of the normal anatomy helps to hone the diagnostic practices for microvascular decompression, which may increase the feasible results on such surgery.

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Facial Nerve Function and Quality of Resection in Large and Giant Vestibular Schwannomas Surgery Operated By Retrosigmoid Transmeatal Approach in Semi-sitting Position with Intraoperative Facial Nerve Monitoring

World Neurosurgery ◽

10.1016/j.wneu.2017.02.053 ◽

2017 ◽

Vol 103 ◽

pp. 231-240 ◽

Cited By ~ 9

Author(s):

Lotfi Boublata ◽

Mohamad Belahreche ◽

Rafik Ouchtati ◽

Zarina Shabhay ◽

Leila Boutiah ◽

...

Keyword(s):

Facial Nerve ◽

Vestibular Schwannomas ◽

Sitting Position ◽

Nerve Function ◽

Facial Nerve Function ◽

Nerve Monitoring ◽

Facial Nerve Monitoring

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Dosimetric Analysis of Neural and Vascular Structures in Skull Base Tumors Treated with Stereotactic Radiosurgery

Otolaryngology ◽

10.1177/0194599817691452 ◽

2017 ◽

Vol 156 (5) ◽

pp. 857-862

Author(s):

Yarah M. Haidar ◽

Jay M. Bhatt ◽

Yaser Ghavami ◽

Omid Moshtaghi ◽

Amanda Schwer ◽

...

Keyword(s):

Carotid Artery ◽

Facial Nerve ◽

Stereotactic Radiosurgery ◽

Trigeminal Nerve ◽

Tumor Volume ◽

Case Series ◽

Vestibular Schwannomas ◽

Anterior Inferior Cerebellar Artery ◽

Cerebellar Artery ◽

Neurovascular Structures

Objective To examine the relationship between the prescribed target dose and the dose to healthy neurovascular structures in patients with vestibular schwannomas treated with stereotactic radiosurgery (SRS). Study Design Case series with chart review. Setting SRS center from 2011 to 2013. Subjects Twenty patients with vestibular schwannomas treated at the center from 2011 to 2013. Methods Twenty patients with vestibular schwannomas were included. The average radiation dose delivered to healthy neurovascular structures (eg, carotid artery, basilar artery, facial nerve, trigeminal nerve, and cochlea) was analyzed. Results Twenty patients with vestibular schwannomas who were treated with fused computed tomography/magnetic resonance imaging–guided SRS were included in the study. The prescribed dose ranged from 10.58 to 17.40 Gy over 1 to 3 hypofractions to cover 95% of the target tumor volume. The mean dose to the carotid artery was 5.66 Gy (95% confidence interval [CI], 4.53-6.80 Gy), anterior inferior cerebellar artery was 8.70 Gy (95% CI, 4.54-12.86 Gy), intratemporal facial nerve was 3.76 Gy (95% CI, 3.04-4.08 Gy), trigeminal nerve was 5.21 Gy (95% CI, 3.31-7.11 Gy), and the cochlea was 8.70 Gy (95% CI, 7.81-9.59 Gy). Conclusions SRS for certain vestibular schwannomas can expose the anterior inferior cerebellar artery (AICA) and carotid artery to radiation doses that can potentially initiate atherosclerotic processes. The higher doses to the AICA and carotid artery correlated with increasing tumor volume. The dose delivered to other structures such as the cochlea and intratemporal facial nerve appears to be lower and much less likely to cause immediate complications when shielded.

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Resection of large vestibular schwannomas: facial nerve preservation in the context of surgical approach and patient-assessed outcome

Journal of Neurosurgery ◽

10.3171/jns.2005.102.4.0643 ◽

2005 ◽

Vol 102 (4) ◽

pp. 643-649 ◽

Cited By ~ 77

Author(s):

Douglas E. Anderson ◽

John Leonetti ◽

Joshua J. Wind ◽

Denise Cribari ◽

Karen Fahey

Keyword(s):

Facial Nerve ◽

Vestibular Schwannomas ◽

Facial Nerve Paralysis ◽

Nerve Paralysis ◽

Nerve Monitoring ◽

Content Type ◽

Nerve Preservation ◽

Facial Nerve Monitoring ◽

Facial Function ◽

Fine Print

Object. Vestibular schwannoma surgery has evolved as new therapeutic options have emerged, patients' expectations have risen, and the psychological effect of facial nerve paralysis has been studied. For large vestibular schwannomas for which extirpation is the primary therapy, the goals remain complete tumor resection and maintenance of normal neurological function. Improved microsurgical techniques and intraoperative facial nerve monitoring have decreased the complication rate and increased the likelihood of normal to near-normal postoperative facial function. Nevertheless, the impairment most frequently reported by patients as an adverse effect of surgery continues to be facial nerve paralysis. In addition, patient assessment has provided a different, less optimistic view of outcome. The authors evaluated the extent of facial function, timing of facial nerve recovery, patients' perceptions of this recovery and function, and the prognostic value of intraoperative facial nerve monitoring following resection of large vestibular schwannomas; they then analyzed these results with respect to different surgical approaches. Methods. The authors retrospectively reviewed a database of 67 patients with 71 vestibular schwannomas measuring 3 cm or larger in diameter. The patients had undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were analyzed with respect to intraoperative facial nerve activity, responses to intraoperative stimulation, and time course of recovery. Eighty percent of patients obtained normal to near-normal facial function (House—Brackmann Grades I and II). Patients' perceptions of facial nerve function and recovery correlated well with the clinical observations. Conclusions. Trends in the data lead the authors to suggest that a retrosigmoid exposure, alone or in combination with a translabyrinthine approach, offers the best chance of facial nerve preservation in patients with large vestibular schwannomas.

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