HEAD AND NECK SURGERY Ann R Coll Surg Engl 2012; 94: 585–587 doi 10.1308/003588412X13373405386538 How safe is diathermy in patients with cochlear implants? SJ Frampton1,2, H Ismail-Koch2, TE Mitchell1,2 1The South of England Cochlear Implant Centre, UK 2University Hospital Southampton NHS Foundation Trust, UK ABStRACt INTRODUCTION Cochlear implants are surgically inserted electrical devices that enable severely or profoundly deaf individu- als to interpret sounds from their environment and communicate more effectively. As a result of their electrical nature, they are susceptible to electromagnetic interference and can be damaged by excessive electrical energy. Surgical diathermy is one source of such potentially damaging energy. The British Cochlear Implant Group guidelines advise that monopolar diathermy should not be used in the head and neck region in patients with cochlear implants and that bipolar diathermy should not be used within 2cm of the implant (http://www.bcig.org.uk/site/public/current/safety.htm). METHODS A questionnaire was provided to 36 surgeons working in different specialties in the head and neck region, inquir- ing as to their knowledge of the safety considerations when using diathermy in cochlear implant patients. Thirty-five surgeons provided responses. RESULTS Overall, 77% of the respondents were unaware of the existence of published guidelines. Even when given an option to seek advice, 11% erroneously felt it was safe to use monopolar diathermy above the clavicles with a cochlear implant in situ and 49% felt that there was no restriction on the use of bipolar diathermy. CONCLUSIONS There is a significant deficit in the knowledge of safe operating practice in the rapidly expanding population of patients with cochlear implants which threatens patient safety. Through this publication we aim to increase awareness of these guidelines among members of the surgical community and this paper is intended to act as a point of reference to link through to the published safety guidelines. KEYwoRDS Cochlear implants – Electrocoagulation – Electrosurgery – Equipment failure Accepted 10 July 2012 CoRRESpoNDENCE to Mr Steven Frampton, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK T: +44 (0)23 8059 3522; F: +44 (0)23 8059 9608; E: [email protected] Cochlear implants are surgically inserted electrical devices spiral ganglion cells at different points in the cochlea. designed to stimulate the auditory nerve and bypass the Surgical diathermy employs high-frequency alternating defective hair cells of the cochlea. The implant consists of a current, which produces heat when applied to tissues, to receiver-stimulator package that is secured under the peri- cut, desiccate or coagulate them. Bipolar diathermy allows osteum of the cranium, above and behind the ear, connected current to flow only between the opposing tines of the in- to an array of electrodes (Fig 1). This electrode array is sur- strument while the current in monopolar diathermy passes gically inserted into the cochlea via a route drilled through from the handpiece, through the body, to the return elec- the mastoid bone. Sounds from the patient’s environment are trode plate, which is applied to skin distant from the surgi- received by a microphone worn either behind the ear or cal field. The presence of electrical current in the vicinity of elsewhere on the body and transformed into a digital elec- a cochlear implant can be damaging and may necessitate trical signal by a speech processor in the same unit. replacement of the damaged implant with the associated The digital signal is transferred to the implanted risks of further surgery and significant additional expense. receiver-stimulator package via a coil that sits on the sur- The British Cochlear Implant Group (BCIG) safety face of the skin over the package and that is connected by a guidelines advise that monopolar diathermy should not be wire to the speech processor. The coil is held in place over used in the head and neck region in patients with cochlear the implanted receiver-stimulator by a magnet and a radio implants. Bipolar diathermy can be used safely but should frequency signal is transmitted across the skin. The speech not be used within 2cm of the implant. processing software mimics the tonotopic organisation of The aim of this study was to assess the awareness of the human cochlea so that different frequencies of environ- these guidelines among surgeons operating in the head and mental sound are relayed to the brain by stimulation of the neck region, and to raise their profile in the surgical com- Ann R Coll Surg Engl 2012; 94: 585–587 585 2515 Frampton.indd 585 16/10/2012 11:57:01 FRAMpTON ISMAIL-KOCH MITCHELL How SAFE iS DiAtHERMY iN pAtiENtS witH CoCHlEAR iMplANtS? Of the nine surgeons who had knowingly operated on Coil patients with cochlear implants, five (56%) were unaware of published guidance on the use of diathermy. Of the same Reciever-stimulator nine surgeons, one (11%) stated that he or she would have package been happy to use monopolar diathermy above the clavi- cles in these patients while five (56%) knew that monopolar diathermy should not be used. The remainder stated that they would have sought advice. Two (22%) of these nine surgeons correctly felt that bipolar was safe to use a speci- fied distance from the implant, one (11%) felt that it could be used anywhere at a lower power setting, and two (22%) would not restrict their bipolar use in any way in cochlear implant patients. The remaining four (44%) would have sought advice. Microphone Discussion and speech Electrobe array processor The first cochlear implant was attempted in a living human in 1957.1 The crude single channel device has undergone sig- Figure 1 Schematic diagram of cochlear implant in situ nificant technological development over the past 50 years to become an efficient and reliable2 device produced by several manufacturers. In 2011 there were approximately 11,000 co- chlear implant users in the UK alone3 and at the end of the munity in order to reduce the risk of iatrogenic damage to previous year there were 219,000 users worldwide.4 these expensive and sensitive devices. Technology appraisal guidance from the National In- stitute for Health and Clinical Excellence (NICE) currently exists for cochlear implantation in the UK National Health Methods Service (NHS).5 With careful patient selection, most of the Surgeons operating in the head and neck region in adults individuals implanted have improved sound perception and children in one teaching hospital and one district gen- compared with their prior use of hearing aids. Although eral hospital were asked to complete a short questionnaire the percepts of sound are very different from those created using only their existing knowledge. Surgeons trained in naturally in a normal hearing ear, with learning they can the insertion of cochlear implants were not included in the be interpreted effectively so that over 70% of implanted in- study. dividuals can understand speech using the telephone.6 The remainder gain considerable benefit from the use of sound to augment lipreading comprehension and from the aware- Results ness of environmental sounds. Implantation in young chil- There was a 97% response rate (35/36) from individuals dren, typically around 12 months of age, can allow normal who were approached. Surgeons from the departments of speech and language development, which would otherwise otolaryngology, oral and maxillofacial surgery, dermatology, be impossible. This improves their educational potential plastic surgery and paediatric surgery contributed to the dramatically and allows many children to enter mainstream survey. Sixteen surgeons were consultant grade, two were education.7 associate specialists and seventeen were middle grades Approximately 370 children are born in England and (specialist registrars, staff grade or specialist doctors). Wales each year with severe-profound deafness and by the Only 8/35 surgeons (23%) operating in the head and age of 3 years roughly 1 in 1,000 children experience this de- neck region were aware of the existence of any guidelines gree of hearing impairment.5 The newborn hearing screen- on the use of diathermy in patients with cochlear implants. ing programme, introduced in England in 2006, has facili- Four surgeons (11%) erroneously felt that monopolar tated earlier identification of newborn children requiring diathermy was safe to use in the head and neck region in more detailed audiological assessment and early implanta- patients with cochlear implants while eleven (31%) cor- tion where appropriate. In 2010, 500 children in the UK with rectly felt that it was unsafe to use and the remainder chose severe-profound hearing loss received cochlear implants.3 to seek advice. Of the adult population in the UK, 613,000 have severe or Only two of the surgeons questioned (6%) correctly felt profound hearing loss including 3% of the population aged that distance from the implant was important when using over 50 and 8% of those over 70.5 In 2010, however, only 500 bipolar diathermy but none knew the recommended distance. adult patients in the UK underwent cochlear implantation.3 Seventeen (49%) stated that they would use bipolar dia- It is likely that this number will increase significantly in the thermy without restriction in patients with cochlear implants future. and three (9%) stated that they would use a lower power set- The first cochlear implant in the UK was performed in ting. The remainder stated that they would seek advice. the 1980s.8 Currently, NHS funding is available for unilateral 586 Ann R Coll Surg Engl 2012; 94: 585–587 2515 Frampton.indd 586 16/10/2012 11:57:02 FRAMpTON ISMAIL-KOCH MITCHELL How SAFE iS DiAtHERMY iN pAtiENtS witH CoCHlEAR iMplANtS? Conclusions implantation in adults and bilateral implantation in children who meet NICE audiological criteria. The current cost of While responsibility for caring for an implant is shared be- assessment, implantation, and the first year of tuning and tween the patient and subsequent caregivers, many patients support is approximately £30,000 for unilateral adult im- do not understand the concept of diathermy and do not feel plantation and £45,000 for bilateral implantation in children. able to advise medical professionals regarding surgical Unfortunately, the implanted portion of these devices oc- technique. Many implant recipients do not carry their co- casionally fails. Minor electronic problems can sometimes chlear implant identification cards, which could otherwise be ‘tuned out’ or the programme in the speech processor re- act as a reference point for medical staff. This study indi- set but problems may be progressive, necessitating removal cates that there is insufficient awareness among surgeons of the implant and the insertion of a replacement. This is of the published safety guidelines and of safe practice using not only financially punitive but also exposes the patient to diathermy in the head and neck region in these patients. risks of repeat surgery including facial nerve injury, taste The unsafe use of diathermy risks irreversible damage disturbance, vertigo, tinnitus and wound infection. to the implant, which may necessitate costly reimplanta- Cochlear implants, being complex electrical devices, tion with the inherent risk of permanent and significant using small currents, are particularly sensitive to elec- surgical complications for the patient. Furthermore, cur- trical interference. Even the static charge released from rents transmitted to the cochlea may theoretically per- some articles of clothing can be sufficient to corrupt the manently damage inner-ear neural tissue, negating any speech processor electronics or damage implant compo- benefit of reimplantation of a new device. All surgeons nents9 and interference can be experienced from electrical operating in the head and neck region should be aware devices such as mobile phones or overhead power lines.10 of the existence of these guidelines and consult them, or It is therefore not surprising that the electrical currents seek advice, when presented with a patient fitted with a used in surgical diathermy can permanently damage the cochlear implant. implanted electronics, causing device failure. Furthermore, such currents may produce irreversible damage to the References cochlear tissues, negating any potential benefit gained from 1. Ramsden RT, Wheatley H. Developing surgical techniques in cochlear reimplantation.9 implantation. Cochlear Implants Int 2000; 1: 67–81. 2. Venail F, Sicard M, piron Jp et al. Reliability and complications of 500 The use of monopolar diathermy below the clavicles consecutive cochlear implantations. 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