Good Morning, 

Without photos and further descriptions, I am not sure I could pinpoint exactly what the issue with your raspberries is - but a few points that may help: 

- How old are your plants/when were they planted? Some varieties produce fruit on the first canes out of the ground (primocanes) and some only produce fruit on second year canes (florocanes) and some on both. Older canes can die back at the end of a season- were you still getting fresh green new canes that came up? Were the new canes dying as well as the older ones? Was the dieback happening during fruiting? Before? after? 

- Pest damage is possible, but would need to know what the damage looked like. When you mentioned a white worm and hollow stems, I did think about the possibility of raspberry cane borers which could be found in the stems of raspberries in larval form: Raspberry Cane Borers - What You Can Do This Fall (umn.edu)

- Fungal disease of the canes is also a possibility, but fits the white worm discovery less. More info on potential fungi/diseases is provided in the list below

- I've linked additional resources below that cover other potential causes for cane dieback on raspberries, possible diseases and pests, and general care for raspberries that may help avoid problems in the future. If you can provide photos of damage or detailed descriptions, definitely send a follow up message and we can see if there is anything to be done for narrowing down the issue! 

Resources: 

Growing raspberries in the home garden | UMN Extension

Raspberry diseases | UMN Extension

Raspberry cane diseases | UMN Extension

Hopefully this all helps - and feel free to reach back out if you gather further information or see any new or worrying symptoms! 

Best, 
Kristin Hubbs