Definitions matter

[The Blue Flower]

Spasmodic: occurring or done in brief, irregular bursts: "spasmodic fighting continued"

Dysphonia: is when your voice sounds rough, raspy, strained or breathy. Hoarseness may affect how loud you speak or your voice’s pitch (how high or low your voice sounds). Many things cause hoarseness, but it’s rarely a sign of a serious illness.

So calling jr's voice 'spasmodic dysphonia' is just a technical way to say he sometimes sounds really bad. It's a description, not a disease.