MRI Findings in Patients with a History of Failed Prior Microvascular Decompression for Hemifacial Spasm: How to Image and Where to Look

Hughes, Marion A.; Branstetter, Barton F.; Taylor, Caren; Fakhran, Saeed; Delfyett, William; Frederickson, Andrew M.; Sekula, Raymond F.

doi:10.3174/ajnr.a4174

Cited by 50 publications

(37 citation statements)

References 22 publications

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“…[26][27][28] In contrast, MVD of the facial nerve generally requires less Teflon by virtue of its shorter REZ, as well as more proximal pledget placement that may minimize risk of articulation between Teflon and dura. 10,26,27,29 Of note, all three reported cases involved the nonroutine placement of Teflon at the porus acusticus, providing substrate for a Teflon-dura interface and lending further support to Chen's theory of dural contact.…”

Section: Discussionmentioning

confidence: 65%

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression

et al. 2016

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Section: Discussionmentioning

confidence: 65%

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression

et al. 2016

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“…This is in contrast to the patients with HFS who more commonly demonstrate compression in the proximal segments, from the RExP at the pontomedullary sulcus medially to the end of the TZ, which is roughly 3.5 to 4 mm distal to the RDP. 6,8 Recent research on patients with a history of failed prior microvascular decompression for HFS have identified persistent neurovascular contact along the more proximal portion of the facial nerve in most patients. 8,25 Their findings highlight the importance of addressing the proximal vascular compression of the facial nerve where compression of the nerve is more likely to cause symptoms as compared with the more resistant, peripherally myelinated segment of the nerve located more distally.…”

Section: Discussionmentioning

confidence: 99%

“…6,7 Vascular contact in this area from the RExP to the end of the TZ has been found to be associated with HFS and inadequate decompression of this proximal segment has been associated with persistent symptoms following surgery. 6,8 Although investigators have studied the accuracy of different types of magnetic resonance imaging (MRI) sequences for identifying vascular loop compression preoperatively as compared with the gold standard of intraoperative findings during microvascular decompression for HFS, there is much less data to address the frequency with which a vessel is contacting or compressing the facial nerve as an incidental finding in the absence of a history of HFS. [9][10][11][12][13][14][15] The purpose of this study was to determine the prevalence of facial nerve vascular contact on MRI in patients without HFS.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Resonance Imaging Assessment of Vascular Contact of the Facial Nerve in the Asymptomatic Patient

et al. 2016

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Objective?The objective of this study was to determine the prevalence of facial nerve vascular contact on magnetic resonance imaging (MRI) in patients without hemifacial spasm (HFS). Study Design?Our radiology database was queried to identify consecutive adult patients without a history of HFS, intracranial tumor, brain radiation therapy, intracranial surgery, traumatic brain injury, or trigeminal nerve vascular compression. One hundred high-resolution MRIs of the posterior fossa were independently reviewed by two neuroradiologists for facial nerve vascular contact (200 sides). Main Outcome Measures?The prevalence of vascular nerve contact in the non-HFS patient, the location of contact along the facial nerve, the culprit vessel, and severity of compression was recorded. Results?The presence of vascular contact in the non-HFS patient may be as high as 53%. It is typically mild to moderate in severity, most commonly involves the cisternal portion, and usually caused by the anterior inferior cerebellar artery. Conclusion?Vascular contact of the facial nerve is frequently identified in asymptomatic individuals but tends to be more peripheral and mild compared with previous descriptions of neurovascular contact in HFS patients. These results should be considered in assessing the candidacy of HFS patients for microvascular decompression.

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“…MVD was conducted as previously described. 14,15 General anesthesia utilizing inhalational and/or intravenous medications was used during MVD. Short-acting neuromuscular blockade was utilized during induction of anesthesia with no additional neuromuscular blocking agents administered during the surgical procedures to avoid false-negative t-EMG interpretation.…”

Section: Methodsmentioning

confidence: 99%

Estimation of Intraoperative Stimulation Threshold of the Facial Nerve in Patients Undergoing Microvascular Decompression

et al. 2019

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Introduction Facial weakness can result from surgical manipulation of the facial nerve. Intraoperative neuromonitoring reduces functional impairment but no clear guidelines exist regarding interpretation of intraoperative electrophysiological results. Most studies describe subjects with facial nerves encumbered by tumors or those with various grades of facial nerve weakness. We sought to obtain the neurophysiological parameters and stimulation threshold following intraoperative facial nerve triggered electromyography (t-EMG) stimulation during microvascular decompression for trigeminal neuralgia to characterize the response of normal facial nerves via t-EMG. Methods Facial nerve t-EMG stimulation was performed in seven patients undergoing microvascular decompression for trigeminal neuralgia. Using constant current stimulation, single stimulation pulses of 0.025 to 0.2 mA intensity were applied to the proximal facial nerve. Compound muscle action potentials, duration to onset, and termination of t-EMG responses were recorded for the orbicularis oculi and mentalis muscles. Patients were evaluated for facial weakness following the surgical procedure. Results Quantifiable t-EMG responses were generated in response to all tested stimulation currents of 0.025, 0.05, 0.1, and 0.2 mA in both muscles, indicating effective nerve conduction. No patients developed facial weakness postoperatively. Conclusions The presence of t-EMG amplitudes in response to 0.025 mA suggests that facial nerve conduction can take place at lower stimulation intensities than previously reported in patients with tumor burden. Proximal facial nerve stimulation that yields responses with thresholds less than 0.05 mA may be a preferred reference baseline for surgical procedures within the cerebellopontine angle to prevent iatrogenic injury.

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MRI Findings in Patients with a History of Failed Prior Microvascular Decompression for Hemifacial Spasm: How to Image and Where to Look

Cited by 50 publications

References 22 publications

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression

Magnetic Resonance Imaging Assessment of Vascular Contact of the Facial Nerve in the Asymptomatic Patient

Estimation of Intraoperative Stimulation Threshold of the Facial Nerve in Patients Undergoing Microvascular Decompression

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