Letter to the Editor: Failed microvascular decompression surgery

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TO THE EDITOR: I read the article by Bigder and Kaufmann2 with great interest (Bigder MG, Kaufmann AM: Failed microvascular decompression surgery for hemifacial spasm due to persistent neurovascular compression: an analysis of reoperations. J Neurosurg 124:90–95, January 2016). I would like to address several comments to the authors. In the article, the authors mentioned that microvascular decompression (MVD) is no guarantee of a hemifacial spasm (HFS) cure, presumably given a failure rate of nearly 10%. Despite all our efforts, we do know that there is a discrepancy between technical and clinical success in the operation; that is, the surgeons are quite sure of decompression during the surgery, but the clinical results do not always correspond. In this respect I agree with the authors. However, I do wonder what rate of failure would fulfill the authors' guarantee of success because I believe that our mission continues to be improvement of the surgery as long as MVD is the only curative treatment for HFS.

Previously, in a report on patients with trigeminal neuralgia in whom treatment had failed, Jannetta and Bissonette described, “a ‘failed’ patient is a signal that we are not perfect and that the forces of nature have again outwitted us. We cannot hide these failures, avoid them, or ignore them. Rather, we can learn from them and, frequently, can make the patients feel better or even cure them.”4 The article by Bigder and Kaufmann illustrates 3 important points that can help us achieve better outcomes. Firstly, exposure of the sigmoid sinus and inferior floor of the cerebellum should never be skipped. Secondly, the vertebral artery should be properly transposed but not interposed. Thirdly, we should try our best to mobilize the responsible artery in the presence of perforating arteries. I fully agree with their conclusion that caudal side exposure is very important for observation of the entire facial nerve as well as the protection of hearing function.1 In addition, I mobilize the arterial loops close to the facial root exit zone (fREZ) that represent potential causes of HFS in the future to avoid new neurovascular compression, if this maneuver can be achieved safely. I believe that correct application of all these procedures in the initial surgery will increase the rate of success.

Finally, I would like to discuss the importance of preoperative imaging, which the authors did not mention in their article. The techniques of preoperative MRI are well advanced and established.3 However, I am afraid that neurosurgeons may depend on MRI too much. Vascular components can be located nearby or even conflict with the seventh and eighth cranial nerve complex in the absence of symptoms and can represent the cisternal part that is not responsible for the symptoms in patients with HFS. Consequently, the proximal part of the fREZ may be overlooked.

References

  • 1

    Amagasaki KWatanabe SNaemura KNakaguchi H: Microvascular decompression for hemifacial spasm: how can we protect auditory function?. Br J Neurosurg 29:3473522015

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  • 2

    Bigder MGKaufmann AM: Failed microvascular decompression surgery for hemifacial spasm due to persistent neurovascular compression: an analysis of reoperations. J Neurosurg 124:90952016

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  • 3

    Du ZYGao XZhang XLWang ZQTang WJ: Preoperative evaluation of neurovascular relationships for microvascular decompression in the cerebellopontine angle in a virtual reality environment. J Neurosurg 113:4794852010

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  • 4

    Jannetta PJBissonette DJ: Management of the failed patient with trigeminal neuralgia. Clin Neurosurg 32:3343471985

Disclosures

The author reports no conflict of interest.

Response

We thank Dr. Amagasaki for his thoughtful comments regarding MVD for HFS. The objective of our paper was to highlight what we perceived to be a frequent source of failed surgery: incomplete exposure, exploration, and decompression of the fREZ. The successful alleviation of the compression caused by culprit vessels is associated with a high rate of disease cure. We also agree that vessels “that represent potential causes of HFS in the future” should be similarly mobilized or transposed when it can be safely achieved during surgery.

Regarding preoperative diagnostic imaging, it is not uncommon for dictated reports to describe the common association between vessels and the cisternal portion of the facial nerve, which is usually incidental, whereas the culprit neurovascular compression at the fREZ is not noted. We have previously reported on the nature of this compression causing HFS and agree that high-resolution imaging has a very high degree of sensitivity when carefully interpreted.1 Such imaging has also been quite useful in the evaluation of patients with persisting spasms after MVD surgery. In our paper we referenced 2 such cases (Cases 3 and 5) in which previously unidentified neurovascular compression was clearly evident following the first surgery and supported early reoperation.

It also bears emphasizing that HFS cure sometimes follows a latency period of several months, even more than 1 year, after technically effective alleviation in culprit neurovascular compression.2–5 Reoperations in such cases are unnecessary and subject the patient to unnecessary surgical risks. It is our practice to offer reoperation for persisting spasms within the 1st year only if persisting vascular compression on the fREZ is demonstrable on high-resolution MRI. The majority of patients will, however, demonstrate immediate or gradual resolution of HFSs in the first few months following technically thorough MVD surgery.

References

  • 1

    Campos-Benitez MKaufmann AM: Neurovascular compression findings in hemifacial spasm. J Neurosurg 109:4164202008

  • 2

    Dai YNi HXu WLu TLiang W: Clinical analysis of hemifacial spasm patients with delay symptom relief after microvascular decompression of distinct offending vessels. Acta Neurol Belg 116:53562016

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  • 3

    Li CS: Varied patterns of postoperative course of disappearance of hemifacial spasm after microvascular decompression. Acta Neurochir (Wien) 147:6176202005

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    • Export Citation
  • 4

    Oh ETKim EHyun DKYoon SHPark HPark HC: Time course of symptom disappearance after microvascular decompression for hemifacial spasm. J Korean Neurosurg Soc 44:2452482008

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    • Export Citation
  • 5

    Shin JCChung UHKim YCPark CI: Prospective study of microvascular decompression in hemifacial spasm. Neurosurgery 40:7307351997

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    • Export Citation

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Article Information

INCLUDE WHEN CITING Published online April 22, 2016; DOI: 10.3171/2015.12.JNS152925.

© AANS, except where prohibited by US copyright law.

Headings

References

  • 1

    Amagasaki KWatanabe SNaemura KNakaguchi H: Microvascular decompression for hemifacial spasm: how can we protect auditory function?. Br J Neurosurg 29:3473522015

    • Search Google Scholar
    • Export Citation
  • 2

    Bigder MGKaufmann AM: Failed microvascular decompression surgery for hemifacial spasm due to persistent neurovascular compression: an analysis of reoperations. J Neurosurg 124:90952016

    • Search Google Scholar
    • Export Citation
  • 3

    Du ZYGao XZhang XLWang ZQTang WJ: Preoperative evaluation of neurovascular relationships for microvascular decompression in the cerebellopontine angle in a virtual reality environment. J Neurosurg 113:4794852010

    • Search Google Scholar
    • Export Citation
  • 4

    Jannetta PJBissonette DJ: Management of the failed patient with trigeminal neuralgia. Clin Neurosurg 32:3343471985

  • 1

    Campos-Benitez MKaufmann AM: Neurovascular compression findings in hemifacial spasm. J Neurosurg 109:4164202008

  • 2

    Dai YNi HXu WLu TLiang W: Clinical analysis of hemifacial spasm patients with delay symptom relief after microvascular decompression of distinct offending vessels. Acta Neurol Belg 116:53562016

    • Search Google Scholar
    • Export Citation
  • 3

    Li CS: Varied patterns of postoperative course of disappearance of hemifacial spasm after microvascular decompression. Acta Neurochir (Wien) 147:6176202005

    • Search Google Scholar
    • Export Citation
  • 4

    Oh ETKim EHyun DKYoon SHPark HPark HC: Time course of symptom disappearance after microvascular decompression for hemifacial spasm. J Korean Neurosurg Soc 44:2452482008

    • Search Google Scholar
    • Export Citation
  • 5

    Shin JCChung UHKim YCPark CI: Prospective study of microvascular decompression in hemifacial spasm. Neurosurgery 40:7307351997

    • Search Google Scholar
    • Export Citation

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