Report

This review examines the appropriateness of performing cochlear implant procedures in outpatient clinical settings including ambulatory surgical centers. A cochlear implant is a prosthetic device used to produce the sensation of sound through the generation of electrical signals, which are perceived as an analog of environmental sound waves.(1). Most patients with profound sensorineural deafness (no useful hearing) have lost the hair cells that transduce acoustic vibrations into electrical activity in the auditory nerve. Of the 15 million persons in the United States with significant hearing impairment, fewer than 1 are considered potential candidates for a cochlear implant.(2). Cochlear implant systems employ an externally worn microphone, signal (speech) processor, and transmitter to receive sound and produce electrical signals. (3). The prosthesis includes a surgically implanted receiver and electrode to excite the remaining auditory nerve fibers electrically according to a speech-processing algorithm that is driven by the signals picked up by the external microphone, thus inducing sensations of sound in the patient.

A multichannel device with as many as 22 electrodes (electrode arrays), each of which can be stimulated independently, has been developed. Two multichannel devices are approved for marketing by the Food and Drug Administration: the 3M Company device (for adults only) and the Nucleus device from Cochlear Corporation (for children and adults). Only the Nucleus device is currently being implanted.

Approximately 300 to 500 cochlear implant procedures are performed each year in the United States. A small but growing number are being performed as outpatient procedures, and Medicare has recently added cochlear implantation to its list of covered surgical services provided at ambulatory surgical centers. There is no evidence that any cochlear implant operation has been performed in an ambulatory surgical center.

The implantation procedure, considered delicate but not complex or risky, enables the surgeon to fasten an electrode array in the vicinity of auditory nerve fibers while maintaining the integrity of both the inner and middle ears. The operation is performed under strictly aseptic conditions, and a general anesthetic is used. The surgical procedure includes the creation of a large scalp flap; a mastoidectomy is then performed utilizing an approach through the facial recess to the middle ear that exposes the round window of the cochlear base. A seat (bed) is formed in the mastoid, parietal, and/or occipital bones to retain the signal-receiving and stimulation device, which is from 1.5 to 2.5 cm in diameter and about 0.5 cm thick. The electrode array is inserted into the scala tympani via the round window, and the receiving coil is fastened in its surgically formed recess. This procedure usually takes from 1.5 to 3 hours.(1,3). The surgical implant operation for children is similar but requires modifications of the surgical technique.(4). A transorbital radiograph of the patient, to document and ensure electrode position, is taken immediately after the surgery. In most cases patients are hospitalized (observed) for 24 to 48 hours after surgery.

Possible medical complications include all those associated with general anesthesia. Published data regarding inhospital cochlear implantation indicate few postoperative complications.(1,5). Major complications are usually related to surgical technique, and they include flap necrosis, improper electrode placement, and rare facial nerve problems. Minor complications include dehiscence, infection, facial nerve stimulation, and dizziness.(5).

According to Kveton and Balkany,(1). clinical trials with two cochlear implant devices in almost 500 children produced significant complications in 2.4 in the 3M series and 3.5 in the Nucleus series. Complications included infection and extrusion, pain and inflammation, delayed wound healing and extrusion, skin flap complications, transient drainage, electrode displacement or misplacement, and facial nerve damage. Complications were successfully resolved, except in one patient with an unresolved but improved facial palsy.

The recent review by Cohen and Hoffman(5). of the surgical experience of 696 adults and 309 children in the United States found that there have been no deaths attributable to implantation of these devices, few serious major complications, and relatively few minor complications. (Major medical-surgical complications are those that require additional surgery and/or hospitalization, and minor complications are those that are treated with medication alone.) Complications were less frequent in children than in adults but were more likely to occur in younger children than in those older than 7 years of age.

A review of 459 implants with the Nucleus device in adults(5). found 23 (5) major complications and 32 (7) minor complications. Major complications included scalp breakdown requiring implant removal; compressed or incorrect electrode position; perilymph fistula; severe seventh nerve stimulation leading to implant removal; and one life-threatening case of meningitis, which resolved under treatment. Minor complications included flap problems; seventh nerve weakness or stimulation; and transient dizziness.

There are no published data that specifically address the operative morbidity or clinical effectiveness of cochlear implantation in outpatient settings. Opinions from acknowledged leaders in the field or cochlear implantation were sought in lieu of the data needed to compare the safety and clinical effectiveness of inpatient and outpatient procedures.

According to Maureen Hannley, Director of Research, American Academy of Otolaryngology-Head and Neck Surgery, cochlear implantations can be performed safely and effectively in outpatient settings, including ambulatory surgical centers. The procedure is considered not especially difficult nor more complicated than other procedures presently performed by otolaryngologists in outpatient settings. Professional judgment on the part of the clinician should determine which patients are not suitable for outpatient surgery. Some patients may require an impatient procedure because of coexisting morbidity (e.g., diabetes or epilepsy).

Some of the leading otolaryngologists performing cochlear implantation in the United States believe that the safety of the patient as well as the clinical effectiveness of the procedure are not diminished by implantation in an outpatient setting when protocols and guidelines are established to maintain safe and effective surgical outcomes (personal communications, Juliana Gulya, Georgetown University; Thomas Balkany, University of Miami; Noel Cohen, New York University; and Richard Miyamota, University of Indiana).

Adequate training in cochlear implantation, regardless of the setting, is essential. An overnight stay is considered a minimal requirement for appropriate care and observation and to allow for recovery from anesthesia and any dizziness that may occur, the detection of infection, and the removal of drains. A Public Health Service official at the National Institutes of Health, who is recognized as a national expert in the field of deafness, was consulted. In his opinion, cochlear implantation can be performed safely and effectively in an outpatient setting and should include an overnight stay to provide proper patient management and observation.

In regard to outpatient cochlear implantation, there is no evidence, based on the information obtained by this Office, that the safety of the patient and effectiveness of the procedure would be compromised as long as the same protocols and guidelines utilized for inpatient procedures are practiced. Such practices would also include allowing the patient to remain in a medical facility overnight for postoperative observation and treatment deemed clinically necessary, as well as providing for additional observation time or hospitalization as required.

References

1.

Kveton J, Balkany TH. Status of cochlear implantation in children. J Pediatr. 1991;118:1–7. [PubMed: 1986072]

2.

Concensus Development Panel. National Institutes of Health Consensus Development Conference Statement on Cochlear Implants. Arch Otolaryngol Head Neck Surg. 1989;115:31–36. [PubMed: 2642379]

3.

[no authors listed] Cochlear Implant Devices for the Profoundly Hearing Impaired Health Technology Assessment Report 1986No. 2, Rockville, MD: National Center for Health Services Research and Health Care Technology Assessment.

4.

Clark GM, Cohen NL, Shepherd RK. Surgical and safety considerations of multichannel cochlear implants in children. Ear Hear. 1991;12(4):15S–24S. [PubMed: 1955086]

5.

Cohen NL, Hoffman RA. Complications of cochlear implant surgery in adults and children. Ann Otol Rhinol Laryngol. 1991;100:708–711. [PubMed: 1952660]

AHCPR Pub. No. 92-0072