What is it like to be locked into your body, to be alive but not living? I’m dying — fast. My lungs are at 20 percent of vital capacity and it’s a matter of time before the nerves supplying my breathing muscles degenerate. I have a rapid form of ALS — amyotrophic lateral sclerosis, or Lou Gehrig’s disease. Two years ago, I was running around with my kids, hiking with my wife. All that is over. My body no longer moves. I cannot talk — my only voice is the one in my head, telling me over and over that I am going to die. Soon. I can’t even breathe for myself anymore — I am tethered to a ventilator that breathes for me.

I don’t want you to feel sorry for me. At all. It is just ironic, this new, condensed life of mine. I went into medicine to take care of patients with brain diseases. Now, I have one of the diseases that I study. Even with this lethal disease, I continue to find neurology fascinating and beautiful.

I wish you knew the old me. ALS has completely destroyed my body and parts of my brain. The new version has stripped me of control over regulating my emotions. I laugh and cry inappropriately during movies, and even during conversations. The cognitive parts of my brain are still working perfectly fine so I’m able to get through the day. But because swallowing has become increasingly difficult, eating and drinking are a battle: continuous bouts of choking, vomiting, crying, sweating, drooling — until finally, it goes through. It is not a pretty picture.

What is it like to be locked in?

When I swallow, I imagine my childhood in India — driving with my parents and sister in our sky-blue Maruti minivan through the wide roads of New Delhi, relishing my grandmother’s sambar, a savory soup of lentils and vegetables. In my mind, I am always in Boston where I lived for 15 years during college and then medical school and for my doctorate in neurobiology. In my mind, which is all I have left, I am playing house music records at Satellite Records in the Back Bay or trying the Persian eggplant dish at Lala Rokh with my wife or going out with my friends to River Gods or the Enormous Room in Central Square. I am so good at imagining the old me that I see, taste, hear, touch everything. And relive every single detail.

I miss my yesterdays.

Now I spend most of my time in front of the computer, which is my lifeline to the world. My best friend and I have rigged up several different devices that interface with a laptop so I’m still able to do many things. I rely on a combination of eye gaze and head motion to help me maneuver around my screen. A single sentence takes me five minutes to compose. I don’t waste words.

Without this setup, I am locked in and have to rely on a unique system of communication. Eye blink means yes, and head nod is a no. To spell out words, someone goes through each letter and I blink for the right letter. I dread nights when I’m in bed alone for a few hours because I have no way to communicate my needs. No one can hear me scream: I want out of this body.

But then, there is the beauty of my world. Every morning, my kids wake me up and I open my eyes to see them. At age 5 and 3, they are too young to understand what is going on and they have come to know me as the father who sits in a wheelchair and watches them. In my mind, I lift them over my head, kiss them and tell them in my old voice that everything is going to be okay.

Sadly, my children know words that no child should ever know — ventilator, Hoyer lift, PEG tube and ALS. I now live for the moments that my kids come home from school and snuggle up to me when they are watching their shows. If I could smile, I would.

My wife, an internal medicine doctor and scientist, is my everything — doctor, nurse, best friend and emotional pillar. She has lost the man she fell in love with. She never signed on to be my caregiver and a single mom. The guilt is killing me. Still, our love is boundless. I’m most at peace when my wife holds me at night.

My parents have lost their son. I see the immense grief in their eyes when they hold my hands. They always say I will get back to my old self. I blink yes, but we all know the truth.

As a clinician-scientist and now as a patient, I’m disappointed in modern medicine. I don’t know why we can’t solve ALS but I wonder if we are asking the right questions. Although every clinical trial for ALS has “failed,” if you look carefully at the raw data you will find that a subset of patients who were treated showed slower disease progression. Instead of lumping all patients into one group, why not focus on this group of responders so we can figure out the genetic, cellular and clinical characteristics of these individuals? What if we had all the data we need to find cures but didn’t have the right tools to see it?

I am sitting in this wheelchair, lifeless yet alive, pondering these questions in my mind every day. My laboratory at UCSF meets with me every week and we mine through data from millions of people trying to find answers.

It is hard to let go of the anger and injustice at what has happened to me that I feel. There are days when I’m not struggling to stay alive and I am at peace. But most of the time, the sadness is unbearable and I can’t find the strength to face it. I hide behind the electronic music that I’m still able to compose, and my work. I know how Sisyphus felt every day rolling the rock up the hill. I understand the labyrinth of solitude. That’s what being locked feels like.