More: Loki passed away a few years ago from Lou Gehrig's disease. While it isn't a cancer it is a nervous system disease that weakens muscles and impacts physical function. In this disease, nerve cells break down, which reduces functionality in the muscles they supply. The cause is unknown. The main symptom is muscle weakness. Medication and therapy can slow ALS and reduce discomfort, but there's no cure. It was heartbreaking. I miss him every day.