Introduction

When the culprit vessel in hemifacial spasm (HFS) is hard to determine, this is a challenge in microvascular decompression (MVD) surgery. In such a situation, small arteries such as perforators to the brainstem might be suspected. But small arteries are omnipresent near the facial nerve root exit/entry zone (fREZ). How to decide whether a given small artery is responsible for HFS is unclear.

Method

We report a case with a previously unreported form of neurovascular impingement, in which the culprit was found to be the recurrent perforating artery (RPA) from the anterior inferior cerebellar artery (AICA). An aberrant anatomic configuration of the RPA was found intraoperatively, which we thought was responsible for generating focal pressure on the facial nerve.

Case report

A 62-year-old woman presented with a 1-year history of paroxysmal but increasingly frequent twitching in her right face. MRI showed tortuosity of the vertebral artery and apparently marked neurovascular impingement on the asymptomatic left side, while only the right AICA could be implicated as the possible culprit. Hemifacial spasm was diagnosed based on the typical clinical manifestation, and MVD was performed. The pre-meatal segment of the AICA was found not to be impinging the facial nerve at any susceptible portion near the fREZ: root exit point, attached segment, or root detachment point. The real culprit was in fact the RPA. This occult culprit vessel was tortuous, forming a coil-shaped twist which was interposed between the facial nerve and the intermediate nerve near the root detachment point. Focal pressure atrophy of the nerve was clearly observed at the compressing site. The patient achieved total spasm relief immediately after surgery, and remained spasm-free at 1-year follow-up, without any postoperative complications.

Conclusion

MVD is the only curative treatment for hemifacial spasm, but with a failure rate of around 10%. Mistaking the real culprit has been reported to be the most likely reason for surgical failure. Therefore, intraoperative identification of atypical occult forms of vascular compression is of importance to improve surgical outcome. In the present case, the RPA formed a coil-shaped twist, which inflicted focal vascular compression causing hemifacial spasm. We recommend careful inspection of the recurrent perforating artery during MVD for HFS, and decompressing any such neurovascular impingement.

中文翻译：

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曲折返支穿支所致面肌痉挛一例

介绍

当面肌痉挛 (HFS) 的罪魁祸首血管难以确定时，这是微血管减压 (MVD) 手术中的一个挑战。在这种情况下，可能会怀疑脑干穿支等小动脉。但是小动脉在面神经根出口/入口区 (fREZ) 附近无处不在。如何确定给定的小动脉是否导致 HFS 尚不清楚。

方法

我们报告了一个以前未报告的神经血管撞击形式的病例，其中发现罪魁祸首是来自小脑前下动脉 (AICA) 的复发性穿支动脉 (RPA)。术中发现 RPA 的异常解剖结构，我们认为这是造成面神经局部压力的原因。

案例报告

一名 62 岁女性因右面部阵发性抽搐病史 1 年，但越来越频繁就诊。MRI 显示椎动脉迂曲，无症状左侧有明显明显的神经血管撞击，而只有右侧 AICA 可能是可能的罪魁祸首。根据典型的临床表现诊断面肌痉挛，并进行MVD。发现 AICA 的前肉骨段没有在 fREZ 附近的任何易感部分撞击面神经：牙根出口点、附着段或牙根脱离点。真正的罪魁祸首实际上是 RPA。这条隐匿的罪魁祸首血管是曲折的，在根部脱离点附近插入面神经和中间神经之间的螺旋状扭曲。在压迫部位清楚地观察到神经的局灶性压力萎缩。患者术后即刻痉挛完全缓解，随访1年无痉挛，无术后并发症。

结论

MVD 是治疗面肌痉挛的唯一方法，但失败率约为 10%。据报道，误认为真正的罪魁祸首是手术失败的最可能原因。因此，术中识别非典型隐匿形式的血管压迫对于改善手术结果非常重要。在本例中，RPA 形成线圈状扭曲，造成局灶性血管压迫，导致面肌痉挛。我们建议在 HFS 的 MVD 期间仔细检查复发性穿支动脉，并对任何此类神经血管撞击进行减压。