Monday, June 7, 2010

Righty Tighty, Lefty Loosie?

Getting a CI is rather like checking items off a shopping list.

1. Do I even want a CI? check.
2. Am I a good candidate? check. (more about this later)
3. Which type of device should I get? check.
4. Which ear do I implant? ummm...

The last question was the most ambiguous to answer. Most CI recipients are implanted in one ear at a time - and, out of those people, only a few go bilateral. The reasons for this are varied, but mostly because research has shown that the second implant usually provides only a marginal benefit compared with the first. Indeed, I have a few friends and relatives who are deaf in one ear but have normal hearing in the other - and they function like regular hearing people for virtually all purposes. The only major benefit of having two ears, rather than one, is better three-dimensional localization of sound. (Biology nerd moment: the brain compares the sound input - loudness, temporal sequence in reception of sound waves - from each ear, then integrates them into a mental "mapping" of where the sound is coming from. We don't even notice this intricate process - it seems to come to us automatically, as we turn to look at an unexpected noise. But, without the input of two ears to compare, it's much harder to perform such calculations.)

I never seriously considered going bilateral from the beginning, to be honest. First of all, there's the impracticality of bilateral CIs for surgery and recovery. When I talked with a friend (who had recently been implanted) about the idea of bilateral implantations, he explained that surgeons are averse to it. They're reluctant to operate on one side of a patient's head, then flip that patient over on the surgical table, on top of a fresh wound, in order to operate on the other side. Just thinking about that made me shudder and agree wholeheartedly. I'm already going to face difficulties with sleeping immediately post-surgery, when I can only lie down on one side - imagine if I couldn't put pressure on either side of my head!

My second reason for not going bilateral has to do with my lingering reservations about the CI. As ridiculous as this might sound at this point, I view my upcoming CI as an experiment. If I do not like it, if it does not work out the way I hope it will, at least by going unilateral I'll still have one ear left. Seeing that my major objection to CIs has always been that I do not want to destroy my cochlea, why would I destroy both of them at the same time? Then, in the case of catastrophe, I would truly be stuck in a world of silence. If I do like the one CI that I get, I can always get another later.

Okay, I did not want to go bilateral: check. Now the decision came down to a game of eenie-meanie-miney-moe. Which ear to implant? Which one would allow me to hear the most?

At first, I honestly considered flipping a coin. Both ears are so bad that did it really matter which one I implanted? Look:

This is an audiogram that I got a few years ago. The thick line near the top, at 20 dB, is considered "normal" hearing. My threshold is far, far below that - 90 dB at the most, and that only for lower frequencies. Once you go along the chart to higher frequencies, I almost do not hear at all. (Just for comparision, the threshold of pain for hearing people - the point at which sound becomes unbearable and causes permanent damage to the auditory nerve - is 115 to 120 dB. At this point, without hearing aids, I am only just starting to hear. Another fact: decibels are logarithmic units, so what I hear is thousands of times below what hearing people hear.)

This absymal performance is, in the end, what prompted the doctors, audiologists, and other CI evaluation specialists to unanimously agree that I'm an excellent candidate for an implant. Of course, I'd be a better candidate if I were younger, but that's neither here nor there. Their decision did not come as a surprise - after all, was there ever any doubt in my, or anyone else's mind, that I really am deaf? Ha.

Again, with this audiogram in mind, does it matter which ear I implant? In the end, probably not really. It is true that my right ear has always been slightly better than my left (though you can't see much difference on the above graph). In listening and auditory training exercises, this is always the ear I prefer to listen with, and during audiograms it is the ear that always makes me most confident that I am actually hearing tones and sounds - rather than imagining them. In a random sentence comprehension task for my pre-CI evaluation, I scored 15% out of the right ear (most of that by guessing). My score for my left ear was only 7%.

Which is the better strategy, implanting the better or the worse ear? Several people gave me different advice. Some said to implant the worse ear - that way my margin of improvement will be greater. Others said to implant the better ear, because that's the ear I feel most comfortable with anyway. Still others had more unexpected opinions. Among them was implanting the right ear because it's on the side that passengers will be talking into while I'm driving a car. A valid point, and one I would not have thought of otherwise. (But what if I move to the UK?)

In the end, my decision was more or less a crapshoot. I decided to go with the left ear, in hopes of bringing that ear up to par. The right side can always join the party later down the road, if I so choose.

A last word: this will probably sound maudlin, but I'm sad to leave my right ear behind. I'm right-handed, right-eyed, right-legged (at least from skipping around the yard) - why not right-eared? In truth, this will be the first time that I have any dominant faculty on the left side of my body. I find that weird.


  1. Rachel,

    I’ve been reading your blog, and as always, I’m so impressed with your remarkable writing skills. I feel that I can appreciate the monumental decision you’ve made after reading your personal insights. And I can honestly say that I felt some trepidation myself at the risks. But I have a really positive and hopeful feeling at the same time, and I won’t minimize the work that lays ahead for you, but I am very excited for you. Just let me know how I can support you, and I look forward to lunch this summer as soon as you’re ready.

    Fondly, Jenny

  2. That way I can walk/sit on your left side and we'll both be good! =]
    Meanwhile, I should practice my sign haha.

  3. Do we actually favor a side of our audio reception? Never thought of that. Being left handed, left legged, is actually a muscular adaptation we have in our nerve impulse to our limbs. Being left handed means to many being right brained. Many lefties are considered talented in the arts. Many of my interior designers that work for me are lefties, but not all. But the majority are.

    Could that be tested? Hmmmm.


  4. Well, to be honest, you are most likely left-brained. So your left-earedness is joining you left-brainedness, it won't be all alone! :)