The Xomed Monopolar Cranial Nerve Stimulator Electrode: A Surprising Handy Tool for Deep Dissection of Epidermoid Tumors.

Gopalakrishnan M Sasidharan

doi:10.7759/cureus.2058

Abstract

Epidermoid cysts are notorious for their propensity to sneak into deep recesses between cranial nerves in the posterior fossa. Attempts to achieve complete excision using ordinary instruments when tempted by the seeming ease of dissection is known to cause unacceptable deficits. The Xomed monopolar stimulator electrode probe of the nerve integrity electromyography monitor has several advantages when used as the primary dissection tool for deep-seated epidermoid cysts. Cerebellopontine angle epidermoid is the classical prototype of a strategically placed deep-seated epidermoid tumor.The author describes the use of the monopolar stimulator electrode of the nerve integrity electromyography monitor as the primary dissection tool for excising epidermoid cysts of the cerebellopontine angle. Thin profile, rounded nontraumatic tip, and springiness of the body of the monopolar electrode aid the dissection.The monopolar electrode was used to tease and scoop out the flakes aided by a fine suction. An initial internal decompression allowed the capsule to be folded away and separated from neurovascular structures using the dissector. The thin profile of both the instruments allowed good visualization and delicate control over the dissection in depths of the resection cavity without undue traction or impacts on superficially dissected cranial nerves. This novel use of the monopolar electrode was employed in the surgical excision of epidermoid cysts of the cerebellopontine angle in nine patients.Total or near total excision was possible in eight of the nine patients who underwent excision using this technique. In three patients, mild deficits primarily of the fifth nerve sensory function were noted.The Xomed monopolar stimulating electrode of the nerve integrity electromyography monitor is an ideal instrument for deep dissection of epidermoid cysts in areas where neurovascular structures are at risk.

Highlights

Epidermoid tumors are known for their ability to insinuate among neurovascular tissues and expand into deeply cavernous recesses around the cerebrum and brainstem
Despite the fact that literature is replete with warnings of severe deficits even in the hands of high surgical volume experts, patients continue to get injured when surgeons pursue the temptation of a complete resection of adherent epidermoid cysts [2,3]
The monopolar stimulating electrode probe was used as the primary tool for dissecting the tumors in nine patients with cerebellopontine angle based epidermoid tumors that the author had operated between 2011 and 2014 (Figure 1)

Summary

Introduction

Epidermoid tumors are known for their ability to insinuate among neurovascular tissues and expand into deeply cavernous recesses around the cerebrum and brainstem These pearly beauties are so notorious for their ability to seduce even good surgeons into following them to places where many dangers lurk, that they can truly be called as the sirens among brain tumors. The monopolar stimulating electrode probe was used as the primary tool for dissecting the tumors in nine patients with cerebellopontine angle based epidermoid tumors that the author had operated between 2011 and 2014 (Figure 1). Flakes of the epidermoid cyst were removed by gently teasing out the clumps with the rounded tip of the monopolar electrode probe and by suctioning out the material disengaged by the maneuver using finely controlled size 1 French suction cannula (Day Bailey locking suction, Mizhuo Medical Inc, Tokyo) (Figure 2).

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