Fenestrated Aneurysm Clip Trigeminal Decompression after CyberKnife Treatment Failure

We have read with great interest the paper of Graffeo et al describing a novel and alternative method of microvascular decompression (MVD).[1] In their article, the authors highlighted the use of an aneurysm clip for neurovascular decompression, specifically in the context of refractory trigeminal neuralgia. The offending vessel was secured to the tentorium cerebelli with an aneurysm clip. The inclusion of an illustrative case example and an operative video significantly enhanced the clarity of the presented methodology. We commend the authors for their valuable contribution to the field. Moreover, we wish to contribute by sharing our institutional experience with MVD and discuss two alternative approaches that employ sutures or slings.

Separating the compressing vessels from the nerve is the basic concept of MVD. In many cases, prostheses are used as interpositions between the offending vessel and nerve.[2] Polytetrafluoroethylene (Teflon) is a popular prosthesis, but we prefer the use of polyvinyl alcohol sponge (Ivalon) due to our subjective experience that scar formation occurs more frequently with Teflon. Furthermore, Teflon granulomas and subsequent scarring have been reported with an incidence ranging from 1.1 to 7.9% ([Fig. 1C, D]).[3] [4] [5] Others have described the use of Surgicel and fibrin glue for MVD;[2] however, we do not endorse the use of Surgicel due to the excessive amount needed for it to act as an adequate interposition, swelling, its absorbable nature, and the low pH irritating nerve structures.[6] This can lead to excessive scar formation and increase the risk of recurrence. When symptoms recur, patients may need redo surgery and the recurrence of symptoms is likely caused by granulation and scarring. Removal of the interposition material may be difficult due to the encapsulation of the material on the nerve, leading to increased risk of permanent nerve damage ([Fig. 1A, B]).

Fig. 1 (A) A difficult to remove Teflon granuloma tightly adhering to the trigeminal nerve (B) After removal, tear damage to the nerve is visible. (C, D) Histological images showing foreign body reaction and granuloma formation around Teflon particles.

In cases of refractory neuralgia, especially in cases where excessive scarring is present, transposition of the offending vessel is the preferred treatment strategy. In our institution, we have successfully utilized sutures to secure the adventitia of the compressing artery to the tentorium cerebelli, as depicted in [Fig. 2A]. Care must be taken to fully release the offending vessel from the arachnoid to gain mobility before securing the artery to the tentorium. Additionally, the offending vessel can be elevated using a sling as illustrated in [Fig. 2B], with favorable outcomes. For the sling, a piece of synthetic polyester aorta graft (Dacron) was cut, looped under the vessel, and secured to the tentorium cerebelli. The sling essentially acts as a hammock for the offending vessel, creating an adequate transposition. A similar technique describes cutting a strip of the tentorium that is consequently used as a sling to transpose the vessel.[7] This technique obviates the need for introduction of a foreign body (except for a Weck clip) and thus limits reactive inflammatory response. Care must be taken not to tear the dura and maintain a split-thickness pedicle. A downside of using a Weck clip or aneurysm clip is the metal artifacts on magnetic resonance imaging. This can make imaging evaluation more difficult, especially when patients present with recurrent symptoms after surgery. Other techniques describe slings using only sutures; however, thin sutures wrapped around an artery risk cutting into or constrict the artery.[8] [9] The “birdlime” technique uses TachoSil soaked in fibrin glue for sutureless vessel transposition.[10] However, we have our reservations concerning this technique. First and foremost, both hemostatic materials are at least largely absorbable. Theoretically, this increases the risk of recurrence when these materials are absorbed. Although no recurrences related to transposition were described at a mean follow-up of 28.8 months, we are eager to see the long-term results (>5 or >10 years) of this method.

Fig. 2 (A) The adventitia of the offending vessel is sutured on the tentorium cerebelli with an 11–0 monofilament nylon suture (Ethilon). (B) A piece of polyester aortic graft (Dacron) is used to elevate the offending vessel away from the nerve and is consequently sutured to the tentorium cerebelli.

We want to thank the authors for their clear description, illustration, and operative video of the technique and their contribution to advancing MVD techniques. We share the opinion of the authors, especially in cases with refractory compression, transposition of the vessel is preferred. The technique used should be simple and safe to perform, as demonstrated in their paper.

Publikationsverlauf

Artikel online veröffentlicht:
08. Mai 2024

• References

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