Elsevier

World Neurosurgery

Volume 113, May 2018, Pages e707-e713
World Neurosurgery

Original Article
Microvascular Decompression for Classical Trigeminal Neuralgia Caused by Venous Compression: Novel Anatomic Classifications and Surgical Strategy

https://doi.org/10.1016/j.wneu.2018.02.130Get rights and content

Highlights

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    We aim to investigate the operative anatomy of SPVC in MVD and discuss the surgical strategy of cases.

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    After dividing SPVC into 4 types, we selected personalized approaches and used decompression management based on different compressive veins.

  • •

    The accuracy recognition of anatomic variation of SPVC is crucial for the management of classical trigeminal neuralgia caused by venous compression.

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    Selecting appropriate approaches and using reasonable decompression methods can bring complete postoperative pain relief.

Background

Microvascular decompression of the trigeminal nerve is the most effective treatment for trigeminal neuralgia. However, when encountering classical trigeminal neuralgia caused by venous compression, the procedure becomes much more difficult, and failure or recurrence because of incomplete decompression may become frequent. This study aimed to investigate the anatomic variation of the culprit veins and discuss the surgical strategy for different types.

Methods

We performed a retrospective analysis of 64 consecutive cases in whom veins were considered as responsible vessels alone or combined with other adjacent arteries. The study classified culprit veins according to operative anatomy and designed personalized approaches and decompression management according to different forms of compressive veins. Curative effects were assessed by the Barrow Neurological Institute (BNI) pain intensity score and BNI facial numbness score.

Results

The most commonly encountered veins were the superior petrosal venous complex (SPVC), which was artificially divided into 4 types according to both venous tributary distribution and empty point site. We synthetically considered these factors and selected an approach to expose the trigeminal root entry zone, including the suprafloccular transhorizontal fissure approach and infratentorial supracerebellar approach. The methods of decompression consist of interposing and transposing by using Teflon, and sometimes with the aid of medical adhesive. Nerve combing (NC) of the trigeminal root was conducted in situations of extremely difficult neurovascular compression, instead of sacrificing veins. Pain completely disappeared in 51 patients, and the excellent outcome rate was 79.7%. There were 13 patients with pain relief treated with reoperation. Postoperative complications included 10 cases of facial numbness, 1 case of intracranial infection, and 1 case of high-frequency hearing loss.

Conclusions

The accuracy recognition of anatomic variation of the SPVC is crucial for the management of classical trigeminal neuralgia caused by venous compression. Selecting an appropriate approach and using reasonable decompression methods can bring complete postoperative pain relief for most cases. NC can be an alternative choice for extremely difficult cases, but it could lead to facial numbness more frequently.

Introduction

Classical trigeminal neuralgia (TN) is a common neurovascular compression (NVC) syndrome defined as a specific category of TN in which magnetic resonance imaging demonstrates vascular compression with morphologic changes of the trigeminal nerve root. Microvascular decompression (MVD) of the trigeminal nerve is the most effective treatment for classical TN.1 Compression and distortion of the trigeminal nerve by the surrounding veins, although less frequent than arterial compression, also is found in TN.2, 3, 4 MVD is acknowledged as the best treatment for classical TN associated with arterial compression, with long-term cure rates above 90% reported in recent publications.5, 6 However, when encountering classical TN caused by venous compression, the MVD procedure becomes much more difficult, and postoperative symptom recurrence caused by incomplete decompression may become frequent, and the total pain-free rate is approximately 80%.7, 8 The mechanism and management for venous compression, although studied and described by a number of researchers, are not well illuminated, and still remain controversial.9

The superior petrosal venous complex (SPVC) is the most frequently encountered venous structure during approaches to the posterior fossa, and although it has been studied and described,10 the anatomic relationship of the SPVC and trigeminal nerve is still an intricate network because of their high variability.11 MVD of classical TN caused by venous compression is widely acknowledged as much more difficult than that in arterial cases.12 In this paper, we aim to investigate the operative anatomy of the culprit veins in our surgery procedure of MVD for veins, divide representative venous patterns into several classification, and discuss the surgical strategy for those cases.

Section snippets

Patient Population

A total of 1456 consecutive TN cases, who had medically intractable TN on the unilateral face, received MVD in our center, during January 2012 to January 2017. After excluding those cases lost to follow-up, 64 cases (4.4%) with classical TN caused by venous compression were finally included in this study and retrospectively analyzed. Among these, 13 (0.9%) had a venous conflict alone, and 51 (3.5%) had one combined with arteries. There were 23 men and 41 women, and the age ranged from 28 to 69

Approach Consideration Based on the Novel Anatomic Classification

The most frequently encountered vein in our study is the SPVC, in accordance with the results of Rhoton.10 The tributaries include the TPV (which was the most common one in our study) and the pontotrigeminal veins, the veins of the cerebellopontine fissure and the middle cerebellar peduncle, and the common stem of the veins draining the lateral part of the cerebellar hemisphere. We used the venous corridor to reach the REZ of the TR, and the approach was chosen based on our classification: type

Discussion

MVD is the only surgery treatment without lesions to vessels or cranial nerves, and an appropriate and safe approach to sufficiently expose the TREZ is essential in the operation procedure.1, 18 Because the SPVC is the largest and most frequently encountered vein in the posterior fossa, which always indents the TREZ,4, 10 the selection of surgical approaches should mainly depend on the SPVC morphology and anatomy of its relationship with the TR. Although the microsurgical anatomy of the SPVC

Conclusions

The anatomic variation in the SPVC appears to differ from both tributary distribution and attachment form of classical TN caused by venous compression. An adequate surgical exposure for the TREZ was achieved via the STA or ISA without scarifying veins. Management of interposing or transposing by use of Teflon can solve most cases. Trigeminal NC can be an alternative choice for extremely difficult cases but could lead to a higher rate of facial numbness.

References (22)

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    • Cited by (0)

    Conflict of interest statement: Authors Wu M, Fu X, Ji Y, Ding W, Deng D, Wang Y, Jiang X, Niu C declare that they have no conflict of interest. This work was funded by the Science and Technology Project of Anhui Province, China (Grant number: 1606c08235).

    Drs. Jiang and Niu contributed equally to this work.

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