"What are the odds that something goes wrong?" I asked.

"It's a very safe procedure," my surgeon assured me. "It will drastically improve your quality of life in the long term, and the odds of failure are only about one in twenty."

"Okay," I said, "let's do it."

When my surgeon said "one in twenty", my external reaction was calm and logical, but internally, it was anything but. A 95% success rate would be pretty great for most things - imagine if you got 95% of the jobs you applied for. 95% accuracy in a game show would be unheard of; even the legendary Ken Jennings hasn't done that. And if I could write 95%-bug-free code, I could retire early, a rich man.

But not all things are created equal, and a 95% success rate (or a one in twenty failure rate, as my doctor put it) seemed scarily low considering that the procedure in question was a craniotomy - brain surgery.

When thinking about any medical condition or procedure, we unconsciously think of risk in terms of one among thousands. So it took me aback a bit when "twenty" wasn't followed by another, larger, number.

One day, early in June of 2015, I came to work early. That wasn't abnormal; sometimes I just did. I put down my bag, set up my computer, and got a cup of coffee out of the kitchen. I came back to my desk and got ready for the day's work, but found that I wasn't able to log into my computer.

My left arm began tensing and spasming in a way I'd never felt before. It was almost like the sensation of it falling asleep - a bit tingly. But it wouldn't go away, and as the minutes passed, I sat there, panicking silently.

Was something wrong? Should I just wait this out, or should I call a doctor? I hadn't had an actual checkup in years, so it could be indicative of something I had neglected.

Eventually, the episode stopped, and I decided to ignore it, at least for right then. Maybe I just cut off circulation somehow on my way into the office. Maybe it was just a one time thing. It'd probably never happen again.

But it did. And it got worse. Instead of just my arm, my face would go numb, and I'd feel tingling creeping up the back of my neck.

A couple weeks and over ten episodes later, I had to give in. I scheduled an appointment with my primary care provider. He declared me in general good health, with a couple minor exceptions, and referred me to a physical therapist; they could determine if the issue might be due to a pinched nerve.

The PT was kind and pleasant, and went through several steps with me. But she couldn't find anything physically wrong, which scared me all the more.

You see, I troubleshoot complex systems for a living - usually, that involves finding a single root cause that explains all the symptoms. And, while a pinched nerve might have explained the issues with my arm, it'd be a bit harder for me to pin the blame for my facial numbness and twitching on it.

The problem is that if you try to figure out things that can cause issues in both the face and in the arm, the list of things they even have in common is incredibly small. The most likely culprit, as well as the scariest, is the brain. And if you're talking about issues with the brain, the root cause that springs to mind is cancer.

Back I went to my PCP. Back with an increased sense of fear and trepidation. Back again – still without an answer.

My PCP decided that it'd be best for me to see a neurologist to see if they could get to the bottom of the issue. At this point, I had stopped having symptoms, but I was too terrified to stop the search for answers. I had to know what was going on.

So, I hopped on the train, rode to Harvard Square, and walked the half-mile or so to Mount Auburn Hospital. The neurologist was kind and professional, and reassured me that he didn't see any of the telltale signs of cancer. He explained that typically, a brain tumor would result in facial distortion, which wasn't there.

It was a relief, but after doing the physical tests, we still didn't know anything. So, sensing that I was still concerned, the neurologist offered to send me in for an MRI - "just in case," he said. My insurance would need to sign off on it, but it'd get us a clear picture of my brain, and would give us a final determination of if there were any physical abnormalities.

So, I went home and waited for the approval to come. It was a difficult time. Sarah and I were both stressed to the limit, waiting to find out what our future would hold: would I still be around this time next year? The neurologist thought it wasn't cancer, but he couldn't know for sure. If it was, it might take me quickly, or it could be the beginning of a years-long journey.

The MRI was a strangely peaceful experience. Just knowing that I'd soon know what was wrong, after months of waiting, soothed me, and as I lay in the tube, the thumping noises lulled me towards sleep. Periodically, I'd be pulled out to have something adjusted, or to have additional contrast dye injected into my arm.

But like all things, it too passed. The thumping stopped, and the motors whirred to pull the bed out of the machine. When I got out, the technician operating the machine wouldn't meet my eye.

"Your neurologist will be contacting you with the results," she said, and then took me back to get dressed. So I got dressed, signed out, and went to work. I probably could have gone home instead, but I didn't want to yet. I hadn't told anyone at work yet, and I didn't want to just vanish.

About an hour after I got back to work, I got the call.

"You have what's called a vascular lesion in your right post-central gyrus. We caught it bleeding on your MRI; it's been causing tiny seizures. We're putting you on anti-epileptics right away; what pharmacy do you use?"

So, now I knew what it was. A vascular lesion is less fear-inducing than cancer, and much less fear-inducing than simply not knowing. Essentially, before I was born, even, a small set of blood vessels in my brain didn't form correctly – they bundled themselves into a tangle shaped like a raspberry.

That tangle, for most of my life, didn't do anything. But last June, it started leaking. Not a lot; not enough to be life-threatening, but enough to upset my brain's delicate balance. Enough to produce the symptoms I had experienced.

The neurologist said that he'd refer me to a neurosurgeon at MGH, but that it was likely no further action was necessary. He'd prescribed levetiracetam, and while I would likely need to take it for the rest of my life, it would prevent any further symptoms.

So, that was a relatively calm time. We knew what it was, we knew how dangerous it was, and we had a plan for what we were going to do. Life slowly moved towards normal.

Which brings us to the day the surgeon said "one in twenty".

He was a kind man, and his credentials spoke for themselves - UCLA med school, and recently tapped to lead vascular neurosurgery at MGH, the #2 brain surgery clinic in the nation. He spoke in a calm, soothing tone, which Sarah and I both appreciated.

He explained that while surgery wasn't absolutely necessary, if we didn't do it, it was extremely likely that the symptoms would return at least once more in my life - possibly to a much greater degree.

He explained that at 24, I was healthier and a better fit for surgery than I ever would be again; if I was going to have the operation performed at any time in my life, now would be the time to do it.

And while he explained, I thought about the last few months, and the fear and uncertainty and panic and breakdowns and how, above all else, I never wanted to worry about this ever again.

So when he said "one in twenty", although I was terrified and unready and not actually all that okay with the risk, I said four words.

"Okay, let's do it."

Time passed. When it's not an emergency situation, it can take a while to get things set up, and no one wants to rush brain surgery in the first place.

To verify the low risk the procedure would carry (one in twenty failure, and not one in ten or one in five), I had an fMRI to map my brain and determine which active regions the lesion was nearby.

Fear crept back into my life; it had gone away when we found out what was causing my symptoms, but now, rather than fearing the unknown, I feared that horrifying one in twenty chance of something going horribly wrong.

I started telling people what was going on. I had told a few other people before, but at this point, there were no more secrets. There was a who (me), a what (brain surgery), a where (MGH), a when (December 9th at 7:30 in the morning), and a why (to remove the lesion).

I was touched by the people who reached out to me. To comfort me, to support me, or even just to talk with me. I didn't sleep well; as surgery got closer, I would sleep less and less. I'd go to bed at eleven, lie awake for an hour, and drift off before jerking awake at three or four in a cold sweat.

As that one chance in twenty started looming larger, I began putting my affairs in order. I didn't have a will, nor did I need one, with Sarah as my spouse and only heir, but I did other things.

I collected bank account and student loan details. I gathered usernames and passwords. I contacted the people I needed to contact, and made sure I didn't have any loose ends. I convinced my employer to add life insurance to the set of employee benefits; as I was no longer in good health, my only hope was to get on a group plan.

In Python, when a function finishes executing, its state vanishes forever and is cleaned up. You can't go back after the fact to get any information out of it. I became aware of how possibly few "lines of code" I had left to execute, and tried to "save my context" elsewhere, so that if the worst were to happen, as little would be lost as possible.

Eventually, the day came. I got up early, and Sarah drove me in to MGH. I was checked in, stripped, dressed, hooked up to a variety of IVs, electrodes, sensors, and wiring harnesses. I honestly don't remember much; time passed as in a dream.

I remember the arterial line being put in my arm; the young doctor apologizing as I winced. I remember the anesthesiologist checking to see if I had any known allergies. I remember having the oxygen mask put over my face, and I remember joking nervously as I felt the drugs being pumped into my system take effect.

And then, I don't remember anything.

I remember waking up. I remember seeing Sarah's face. I remember feeling giddy with relief to be alive.

It's been a year since I first had symptoms, and I am finally free.