Hemifacial Spasm Caused by Vascular Compression in the Cisternal Portion of the Facial Nerve: Report of Two Cases with Review of the Literature

Hemifacial Spasm Caused by Vascular Compression of the Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Common Trunk Anomaly at the Cisternal Portion of the Facial Nerve: A Case Report

W report the first case of hemifacial spasm (HFS) caused by vascular compression of the anterior inferior cerebellar artery (AICA)-posterior inferior cerebellar artery (PICA) common trunk anomaly at the cisternal portion of cranial nerve VII (CN VII). A 71-year-old female with a typical right HFS was admitted to our hospital. As per her magnetic resonance (MR) imaging results, no offending arteries were noted around the CN VII root exit zone (REZ). Computed tomography angiography revealed an AICA-PICA common trunk anomaly with a dominant PICA, with the rostral branch of the AICA-PICA common trunk anomaly compressing the CN VII at the cisternal portion. The patient underwent microvascular decompression (MVD), and the HFS disappeared after surgery. The amplitude of the abnormal muscle responses (AMR) disappeared immediately after complete transposition of the offending artery. However, the patient experienced mild transient facial palsy 3 days after MVD which was eventually resolved with the administration of vitamin B12. No HFS recurrence was observed during the 1-year follow-up period. The AICA-PICA common trunk anomaly has been found to cause HFS as it compressed the CN VII at the cisternal portion, and not at the REZ. AMR monitoring might be helpful for cases where the unusual vessel particularly compresses the CN VII.

Facial Spasm Caused by Compression of the Distal Portion of the Facial Nerve by the Anterior Inferior Cerebellar Artery, Resulting in Delayed Peripheral Facial Nerve Palsy: A Case Report

Delayed onset of facial spasm following surgery for unilateral facial spasm after microvascular decompression (MVD) of the distal facial nerve is rare. We report a case of unilateral facial spasm caused by compression of the distal facial nerve successfully treated with MVD resulting in delayed peripheral facial nerve palsy. A 51-year-old male patient with a left facial spasm showed a gradual worsening of symptoms. Head imaging revealed that the left anterior inferior cerebellar artery (AICA) was in contact with the distal portion of the left facial nerve; hence, MVD was performed. The AICA was pressing on the distal facial nerve, so the AICA was transpositioned. Postoperatively, the facial spasm improved. On the eighth postoperative day, the patient showed left peripheral facial nerve palsy and was given conservative treatment. The patient was discharged home on the sixteenth postoperative day. One month after discharge, the facial palsy was in complete remission. Distal facial nerve compression may cause unilateral facial spasms. Although delayed facial nerve palsy may occur, the prognosis is good.

[Interposition and transposition techniques of vascular decompression for hemifacial spasm]

OBJECTIVE

To analyze the vessels compressing facial nerve root exit zone and efficacy of interposition and transposition techniques of vascular decompression for hemifacial spasm.

MATERIAL AND METHODS

Vascular compression was evaluated in 110 patients. Implant interposition between vessels and nerve was performed in 52 cases, transposition of arteries without contact between implants and nerve - in 58 patients.

RESULTS

Compressing vessels were anterior (44), posterior (61) inferior cerebellar, vertebral (28) arteries and veins (4). Multiple compressing vessels were found in 27 cases. Premeatal meningioma and jugular schwannoma were accompanied by vascular compression in 2 cases. Immediate regression of symptoms was observed in 104 patients, partial regression - in 6 patients. Transient facial paresis (4) and impaired hearing (5) were noted after implant interposition. Redo vascular decompression was performed in one case.

CONCLUSION

The most common compressing vessels were cerebellar arteries, vertebral artery and veins. Transposition of arteries is highly effective technique with low incidence of VII-VII nerve dysfunction but relatively slow regression of symptoms.

Bibliometric analysis of studies on the treatment of hemifacial spasm

Objective

Hemifacial spasm (HFS) is a common neurological disorder of the brain, which is difficult to treat. Most patients are distracted by it and are unable to work or study normally, which seriously affects their physical and mental health. However, there are a few bibliometric studies on it. This paper searched the articles on HFS using a bibliometric approach.

Method

Articles about HFS were retrieved from the Web of Science (WoS) Core Collection database. We employed the Visualization of Similarities (VOS)viewer to analyze these publications.

Results

A total of 645 reviews or articles in English were retrieved from WoS. In this study, we found that the number of publications showed a rising trend and China is the most active in searching the treatment of HFS. About keywords, neurosciences and neurology was searched (422 times) keyword, followed by hemifacial spasm (420 times) and surgery (320 times). By assessing the organizations, Shanghai Jiao Tong University published the most papers (8.68%), followed by Sungkyunkwan University (3.26%) and Baylor College Medicine (2.64%). A total of 247 journals have delivered publications on the treatment of HFS, World Neurosurgery (44 papers) published the largest number of articles.

Conclusion

The annual publications have increased with a fluctuating tendency. More researchers were taking an interest in HFS. This study helped us find out the hotspot and trend in research about facial spasm treatment.

Imaging predictors of successful surgical treatment of hemifacial spasm

Identify preoperative imaging findings in hemifacial spasm patients that predict the post-surgical success following microvascular decompression. This is a retrospective study of patients who were diagnosed with hemifacial spasm, had a dedicated cranial nerve MRI, and underwent microvascular decompression for hemifacial spasm. Bilateral facial nerves were interrogated for neurovascular compression. If neurovascular compression was identified, we recorded whether the offending vessel was an artery, a vein or both. The location of the neurovascular compression (proximal nerve versus distal nerve) was noted. The severity of the neurovascular compression was categorized as contact versus deformity of the nerve. Patients were contacted to determine their post-operative spasm status. The relationships between imaging findings and post-surgical outcome were assessed by Chi-square tests, and odds ratios were calculated to quantify the degree of association. The study included 212 patients. Upon follow up, 192 patients were spasm free (90.57%). Imaging findings on the symptomatic side were as follows: arterial neurovascular compression was seen in 207 patients (97.64%), venous only neurovascular compression in two patients (0.94%), and no neurovascular compression in three patients (1.42%). Arterial neurovascular compression along the proximal, susceptible segment of the nerve was observed in 202 patients (95.28%); deformity was observed more commonly than contact alone. Arterial neurovascular compression along the distal segment only of the nerve was observed in five patients (2.36%). In patients with arterial neurovascular compression of the proximal and distal portions of the nerve, 93.07% and 60.0% of patients were spasm-free respectively. If venous neurovascular compression only was observed on imaging, 0% of patients were spasm-free. Patients with arterial neurovascular compression of the susceptible segment are much more likely to be spasm free than patients without this imaging finding, [odds ratio 20.14 (CI 5.08, 79.81), P-value <0.0001]. When comparing the two groups of arterial neurovascular compression (deformity versus contact), no statistically significant difference in outcomes was observed. In patients with hemifacial spasm undergoing microvascular decompression, imaging findings do predict surgical outcome. Patients with arterial neurovascular compression of the proximal, susceptible portion of the nerve are much more likely to be spasm free after surgery than those without this imaging finding. The imaging findings inform the risk benefit analysis and discussion with patients before they undergo microvascular decompression for hemifacial spasm.

Wide distribution of central myelin segment along the facial nerve might explain hemifacial spasm with distal nerve compression

INTRODUCTION

Many researchers have assumed that neurovascular compression of the facial nerve at the site covered by central myelin sheath causes hemifacial spasm. However, some cases do not correspond to this hypothesis. The aim of this study was to clarify the myelin histology in the facial nerve.

MATERIALS AND METHODS

Histological analyses were conducted on 134 facial nerves from 67 cadavers. Three dimensions were measured in these sections: the length from the upper border of the medullopontine sulcus to the boundary between the central and peripheral myelin sheath along the anterior side; the length from the detachment point of the brain stem to the boundary along the posterior side; and the length of the transitional zone (TZ), known as the Obersteiner-Redlich zone.

RESULTS

Of the 134 facial nerves, 41 were available for study. The length of the central myelin segment ranged from 4.62 to 12.6 mm (mean 8.06 mm; median 7.98 mm) along the anterior side and from 0.00 to 4.58 mm (mean 1.68 mm; median 1.42 mm) along the posterior side of the facial nerve, and the length of the TZ ranged from 0.00 to 2.76 mm (mean 1.51 mm; median 1.42 mm).

CONCLUSIONS

In this study, the length of the central myelin segment in the facial nerve was found to be longer than that previously reported.