I just took a spill last week and got a mild concussion and whiplash.
I just bought a $170 that had only been worn 5 times. It still looks in good shape except for the visor. BUT---
I still bought a new one. The helmet probably saved my melon a ton. I don't look at is as $170 down the drain, I look at it as $170 well spent. I still have a headache a week and half later. I can only imagine what would have happened if I wasn't wearing a helmet OR a helmet that wasn't in 100% perfect condition.
I am not risking my head wearing that helmet again.
Haven't worn my new one yet, still waiting for headache to go away before I head back up.
I agree with other people--if you have to ask, its done. don't risk it.