Complications of Cochlear Implant Surgery: A Public Implant Centre Experience

Objectives: To determine the prevalence of complications of cochlear implant surgery in children with congenital profound sensorineural hearing loss. Methods: This study retrospectively & consecutively reviewed charts of children who underwent cochlear implantation from July 2015 to July 2019 at Cochlear Implant Centre of Otolaryngology Department of Capital Hospital, Islamabad Pakistan. These included cases of both genders aged one to 12 years operated at least one year before the time of data collection. Basic demographic data, complications including major and minor complications and treatment received was noted and statistically analyzed using SPSS-23. Results were presented using descriptive statistics. Results: Current study included a sample of N=251 having a mean age of 4.05±2.15 years including 154(61.4%) males and 97(38.6%) females revealed a prevalence of complications of 16(6.4%) with 4(1.6%) major and 12(4.8%) minor complications. Wound infection and acute otitis media with frequency of 3(1.2%) each were the commonest complications, followed by , facial nerve twitching, tinnitus and vertigo, infection and extrusion; and device failure in 2(0.8%) each. However, there was no significant association of complications with age group and gender with P=0.344 and P=0.519 respectively. Conclusion: Present public sector implant program is characterized with a very low prevalence of complications of 16(6.4%) with 4(1.6%) major and 12(4.8%) minor complications. Wound infection and acute otitis media were the commonest complications.


INTRODUCTION
Severe to Profound Hearing Loss has a prevalence of 6.7% in clinical population and 0.7% in general population as reported for United Kingdom's National Health Service clinic 1 and a prevalence of 1.6 per 1000 cases with profound hearing loss alone has been reported from Pakistan. 2 Cochlear implantation is arguably the best possible option for non-serviceable sensorineural hearing loss (SNHL) with appropriate case selection having paramount importance. 3 A big population is now receiving cochlear implants with 78% of deaf children receiving cochlear implants in Belgium alone 4 and according to US Census 2000, there were 12,816 children aged 1 to six years eligible for cochlear implantation. 5 In cases with severe or profound hearing loss (HL), quite a high prevalence of inner ear malformations (IEMs) of around 15 to 20% has been reported in a study. 6 Though cochlear implantation in cases with IEMs has favorable surgical and speech results 7 and is a safe procedure in experienced hands, 8 however difficulties and intraoperative complications do occur. 9 Complications ranging from pain, minor bleed, infection, breakdown of skin, facial palsy, taste changes, vertigo, cerebrospinal fluid leak, device failure as well as mal-placement, skull base and brain damage to complete deafness and death may occur. 3 Hence knowledge of associated risks is very important since it is not a lifesaving procedure rather it is responsible for reduction of disability and hence significantly improves quality of life (QoL). 10 Cochlear implant surgery started in Pakistan in the year 2000, in the private sector alone and the only available small published study gave a complication rate of 11.5% for private sector program. 11 With a high prevalence of congenital hearing loss in Pakistan, 12 dearth of local literature on the subject and recent development of cochlear implant facility in the public sector in Pakistan was the stimulus to conduct this study on a larger population hailing from all over the country with the objective determine the prevalence of complications of cochlear implant surgery in children with congenital profound sensorineural hearing loss.
This study is important since it will cover the local literature gap being the only study of its type in Pakistan and will be helpful in provision of reliable local data regarding complications of cochlear implantation in patients with congenital HL and planning of effective management strategies.

METHODS
This study retrospectively conducted chart reviews of children who consecutively underwent cochlear implantation for congenital sensorineural hearing loss, over a period of four years from July 2015 to July 2019. These included cases of both genders aged one to 12 years who were operated at Cochlear Implant Centre of Otolaryngology Department of Capital Hospital, Islamabad Pakistan. All cases were more than one year postoperative at the time of data collection, hence cases operated after 30 th June 2019 were not included in the study. Basic demographic data, complications including major and minor complications and treatment received was noted.
Complication of Cochlear Implant surgery was labelled when there was any medical issue arising due to the surgery, which was not expected, resulting in increased morbidity or mandating addition surgical procedure. 13 Also these were classified as major when there was significant medical problem requiring removal of implant, re-exploration, facial nerve paralysis or paresis or other complication which was serious with continuous dysfunction or discomfort; while minor complications were those requiring no intervention or minor one, resolve by themselves, or easily overcome by little medical or audiologists management. 14 Study was initiated after obtaining ethical approval of the research from Ethical Review Committee of Capital Hospital PGMI, Islamabad vide Registeration No. 2020-03-003 dated 10 th March, 2020. Following data collection, tabulation was done in Microsoft Excel and statistical analyzed performed using Statistical Package for Social Studies (SPSS) Version-23. Statistical analyzed were done using descriptive statistic including frequencies, percentages, mean, and standard deviation. Chi-square test was used for assessment of age and gender association. Data was further examined besides national and international literature and deductions made were finally discussed.

RESULTS
N=251 cases of cochlear implantations performed at this public Cochlear implant Centre rom July 2015 to July 2019, were included in the study. With a mean age of 4.05±2.15 years, the study population comprised 154(61.4%) males and 97(38.6%) females. The prevalence of complications was 16(6.4%) (Fig.1).
Minor complications were predominant with frequency of 12(4.8%), followed by major  (Table-I).
Major complications included implant infection & extrusion and Device failure in 2 (0.8%) cases each. There was no significant association of complications with age group and gender with P=0.344 and P=0.519 respectively.

DISCUSSION
Current study being the largest study from Pakistan involving 251 cases of Government funded cochlear implant surgeries in the public sector revealed a prevalence of complications related to cochlear implant surgery among one to 12 year old children being 16(6.4%) with no death report and with 4(1.6%) major complications and 12(4.8%) minor complications. In contrast an Egyptian study by Sefein IK, 15 revealed a high complication rate of 18.75% with 8.03% minor and 10.71% major complications with no death. Another study by Farinetti A et al. also reported a high complication rate of 19.9% with minor complications in 14.9% and major in 5% cases. They also noted significant higher complication rate in adults. 16 Achiques MT has reported a prevalence of 11.38%. 17 While, Awad AH et al 18 reported complication rate of 10.43% with 6.75% minor and 3.68% major complications. Dodson KM et al reported a complication rate of 9.3%, with 59% related to device failure and 3 intracranial complications including two with minor dura leak which was repaired with fascia and one with acute hematoma treated by evacuation. 19 In a previous study conducted in Pakistan, in the private sector comprised of only 52 cases and revealed much higher prevalence of complications of 11.5% with 3.8% failure rate of the device. 11 Current study has the advantage of being conducted for a population in which implant and surgery was government funded resulting in a sample hailing for all provinces and areas of Paksitan, while the previous study was in the private sector in which funding was a substantial issue. 11 The difference in the complication rate of the two studies might be due to better audiological, surgical and follow up of cases in current study. In a study by Saunders & Barrs,20 to make recommendations for implantation in developing countries, while studying challenges in developing nations, authors reported that most respondents (83%) agreed that audiologist was most important requirement and limitation of audiological services was the most important postop concern compared to postoperative care and infection. It must also be noted that over the years, Pakistan has developed better audiological services. In quite similarity to our study, Binnetoglu A et al. in a large study with 2597 cases and mean  22 It has also been highlighted that vertigo with non-improvement in hearing should arouse suspicion of mal-placement of electrodes. 23  Some other complications may also rarely occur. Facial Nerve stimulation occurred in just 0.8% of our cases and was not related to IEM's, According to Kubo T et al this commonly occurs in ears with anomalies and can be dealt with reprogramming some electrodes, however decrement in speech recognition may occur. 22 Rarely, auditory nerve may give poor response as a result patient becomes aware of only environmental sounds and avoids implant use. 22 Also rarely complications like periorbital ecchymosis can occur, hence avoidance of undue extensive periosteal elevation and dissection of other subcutaneous tissues. 28 Depending on specific individual anatomical considerations of patient preoperative planning and adoption of soft surgical techniques result in reduction of surgical complications. 24 Preoperative protocol followed, safe surgical techniques and post-operative care are responsible for reduction in complications. 26 Hence continued surgeon education and training is emphasized. 25

CONCLUSIONS
Present public sector implant program is characterized with a very low prevalence of complications of 16(6.4%) with 4(1.6%) major and 12(4.8%) minor complications. Wound infection and acute otitis media were the commonest complications.