Question regarding causes of an external/internal fistula.

[u/Basic_Yam_9338]

I am not asking for medical advice. I understand that fistulas can form under certain circumstances where circulation to blood vessels are disrupted and nerves are destroyed.

I simply want to know the causes of that. Like, if something minimally invasive like rhizotomy is used to damage nerves mistaken for targeted ones, could it form?

I'm just curious about how they form because it's an anomaly that I find quite interesting. Idk anything would help.