Magnet dislodgement in cochlear implantation: Correction utilizing a lasso technique

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Summary

Objectives

Magnet displacement is recognized as an uncommon, major complication following cochlear implant surgery. This complication necessitates operative intervention exposing patients to further surgical risk and morbidity. The purpose of this paper is to describe a unique surgical technique for securing internal magnets which have dislodged from their silicone housing within the internal receiver-stimulator.

Methods

A case involving a 5-year old cochlear implant patient is reviewed. This patient experienced magnet displacement on two separate occasions. A new lasso technique for re-securing the internal implant magnet is described in detail.

Results

The patient's implant remains fully functional with a securely placed internal magnet 36 months post-operatively.

Conclusions

When compared to other surgical options, the “lasso” technique represents a simple, safe, efficient and cost-effective surgical option with minimal morbidity.

Introduction

Advancements in cochlear implantation continue to increase success in reversing hearing impairment in patients with bilateral, profound sensorineural hearing loss (SNHL). To date, over 120,000 individuals have been granted access to sound through placement of cochlear implants (Industry data, 2007).

Despite advances in cochlear implantation, surgical complications remain a reality. Complications have been labeled as major or minor depending on the degree of intervention required for their treatment. Specific complications are seen more frequently in the pediatric population. A child's naivety and curiosity promotes regular, uninhibited exploration of their surroundings. Poor motor control places young children at risk of frequent episodes of inadvertent trauma [1]. Accidental head trauma has been identified as a profound influence on the performance of cochlear implants in the pediatric population. Migration of the implant's internal magnet represents but one complication associated with head trauma [2].

Magnet migration has only recently been described as a complication of cochlear implantation [2]. The surgical solution to this problem remains a challenge. The purpose of this paper is to describe a case in which an internal implant magnet became displaced on two separate occasions. The management of these complications is discussed and a new technique for securing implant magnets is described. This new “lasso” technique represents an efficient, cost-effective less invasive and safer surgical option which poses minimal risk to patients.

Section snippets

Case presentation

An 18-month old male with Waardenburg syndrome was implanted with a Nucleus contour 24R device in January 2002 because of bilateral SNHL. Three and a half months post-implantation, the patient suffered inadvertent, minor head trauma. This resulted in migration of his implant magnet out of its housing within the internal receiver-stimulator (IRS). The magnet was palpable antero-inferiorly relative to the internal prosthesis. Findings on physical examination were confirmed with plain radiographs

Discussion

Cohen and Hoffman [3] classified complications of cochlear implantation into major and minor categories. “Major” complications are those requiring surgery and/or hospitalization for treatment. “Minor” complications exhibit either spontaneous resolution or improvement without operative intervention or hospital admission. Complications can be further subdivided into early and delayed categories. Early complications occur from the immediate post-operative period up until 3 months after surgery.

Conflict of interest

None.

References (8)

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    The 8 other case reports/series addressed RS/magnet migration. Six of these studies indicated that patients' CI magnets were dislodged from the silicone holding pockets and inappropriately located near or on top of the RS titanium housing, confirmed with plain radiographs of the head [4,11–15]. Table 1 shows the mechanisms of injury resulting in displacement for each case.

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    Revision surgery was necessary to replace and secure the magnet. Mickelson and Kozak [10] utilized a “lasso” technique to correct magnet displacement. And the new technique was regarded as a simple, safe, efficient and cost-effective surgical option with minimal morbidity.

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