They probably meant ciática:
Del lat. tardío sciatĭcus, der. de scia 'cadera'.
- f. Med. Neuralgia del nervio ciático.
The condition is called nearly the same in several languages, e.g. in English it's sciatica.
But how could someone die from sciatica? Are you sure the word didn't mean something else in the 19th century?
Yes, I am 100% sure esciatica and ciatica are the same thing: sciatica.
A search in the NTTLE shows us that this ailment has been called like that for 500+ years (ciatica for Spanish dictionaries, sciatica for Spanish-English dictionaries):
About the "cause of death" part, it seems like "death by sciatica" was not unheard of in the 19th century. Just google
sciatica as cause of death and you will find some info and conjectures, like those found in this Reddit thread.
The gist of it would be:
- Death, not because of the actual sciatica, but of complications from a surgical intervention to try alleviate the pain.
- Death from rheumatoid arthritis, which may have been mistaken for sciatic arthritis back then.