Cochlear implant surgery is very safe. The risks are similar to having your appendix or gallbladder removed. The need for another operation following cochlear implant surgery is very low.

General expectations:

• Despite attempts to preserve hearing, loss of residual acoustic hearing can occur. If this happens, you are still likely to do better with a CI than a hearing aid (see below).
• Change in taste or numbness on the side of the tongue occur in a minority of patients. This can take a year to resolve.
• Pain or numbness at the incision site.
• Postoperative tinnitus and vertigo rarely occur. It usually subside over the next few days. It is rare for either to be permanent.
  

Not getting the performance you expect.

This can be divided in to two situations:

• No improvement or worsening of hearing. Basically, you do the same with a hearing aid as you do a cochlear implant. This occurs about 2 out of 10 cochlear implants.
• It is rare to do worse with a CI than with a hearing aid. This occurs 1 out of 100 cochlear implants. The frequency is higher for those who are born with hearing loss.

Scientific researchers are still working to understand why this occurs.

Rare complications

These complications occur less than 5% (5 times out of every 100 cochlear implants).

• Infection requiring surgery. Any type of infection occurs about 1 in 20 CI surgeries. Infection severe enough requiring removal of the CI occurs 1 in 100 surgeries.
• Failure of the internal device also occur rarely (1% or 1 in 100 CI surgeries). Sometimes this requires removal and replacement of the device.
• Issues with the incision or skin over the CI.
  

Exceedingly rare complications

These happen fewer than 1 out of every 100 CI surgeries. In other words the rate is between 1 in 200 to 1,000 CI surgeries).

• Facial weakness.
• Brain fluid leak.
• Brain infection (meningitis).

Yes, surgery is scary. But...

It is becoming increasingly clear that untreated hearing loss has a severe impact on brain health. Delaying a cochlear implant is undertreating hearing loss. Between 1 to 9% of patients with untreated hearing loss will develop dementia. The risk of dementia may exceed the risk of serious cochlear implant complications.