@lexilulu - Here's an article from 2016 that might shed a little light on the topic.

"Is small fiber neuropathy fatal? -- When those deposits build up, peripheral nerves start to malfunction, and the patient experiences peripheral neuropathy. The disease eventually involves sensory, motor and autonomic nerves, and it is fatal.” --- The Fire Within - Johns Hopkins Medicine: https://www.hopkinsmedicine.org/news/publications/hopkins_medicine_magazine/features/fall-2016/the-fire-within