I'm a Vipassana Meditator. I saw visions of being impaled, crushed, broken, slit, beheaded and so on (killed or not in so many different and even creative ways - once a Hindu Diety killed me who I thought was going to protect me) 100s of times regularly for few months. It was tens of succh experiences every 50-60 minutes sit. Then they were gone. I believe it was during the time when I was going thru Dukkha nanas. After getting a little stable in Equanimity I do not see those images any longer, not ever .  Those images were accompanied with lot of visceral pain, sadness, desperation, anger, disgust etc. . I still experience sadness, anger, annoyance sometimes ( a little) but that kind of despair and visceral pain not any longer.

I do not know what it means for Jhana meditator but all I can say is these are Imparmanent.

Metta,
Anicca

Hi. Sometimes dukkha arrives with its difficult feelings, they can be very dense and heavy like trying to wade through treacle. Sometimes dukkha comes with a strong visual element like how you describe. 

I'm hesitant to add any more as it seems you've got a healthy interpretation that being they are impermanant. 

Thanks for your kind words Bardo, even though I still cycle thru Dukkha sometimes, these kind of images are gone.
This thread was in reply to someone seeing images of getting impaled, they deleted their userid I guess.

Metta,
Anicca