The character, Apollo, experiences tremors in his left hand and forearm, especially when he is under stress. Tentatively, it's called Trembler's disease. There's no known cure and the only way to control it is with narcotics. By the time the story gets rolling, Apollo is already an addict.
The mental disease plays into a larger theme in the story about Apollo and his cousin, Joseph, both secretly hearing the voice of God, their reactions to him, and the consequences for the galaxy.
RE: experiences tremors in his left hand and forearm, especially when he is under stress. GEEZ... I have this disease, it's called CIDP. There is no known permanent cure, however there are treatments. I received a REPORT TO MEMBER (Blue Shield) recently, concerning the treatment, the cost for one month: $42,970. I've had 25 months of treatments, and need these treatments for the rest of my life.
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I can't stop the treatment (IvIgG) or I revert back to a whining garden slug who can't take a breath or shit or escape the pain. The tremors are called fasciculations and they look like snakes continuously crawling under the skin (24/7/365), or sometimes a single snaking twitch that travels all the way up and down a muscle system for days on end. ALS has the same fasciculations, but these can't be stopped or cured. With treatment my fasciculations calm down to become tiny little earth worms crawling under my skin with no permanent damage, again 24/7/365. Still, I look like a freak with my shirt off as I have fasciculation in symmetrical configurations (from hell!) mainly in my deltoids and trapezoids and lesser ones elsewhere.
There is a rare mental component to CIDP, and I know exactly what it is and how it happens. In ALS there is definitely a mental component of the disease. Horrible beyond belief I think... BTW- I was diagnosed with ALS, but revised to CIDP.
When I relapse (about 8 days each month) I hear the voice of God telling me to grin and bear it... but I usually can't! I take massive amount of pain killers, but the pain for those 8 days is beyond anything that you can image PAIN is or could be.
Gee, I really went off on a tirade here... guess I needed to.