Unknown uniform seen in upsetting programme's medical episodes (8)

'medical episodes' is the definition.
Although both the answer and definition are plural nouns, I cannot understand how one could define the other.

'unknown uniform seen in upsetting programme's' is the wordplay.
'unknown' becomes 'z' (algebra).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'seen in' is an insertion indicator.
'upsetting' says the letters should be written in reverse.
'programme's' becomes 'series' (series is a kind of programme).
'series' written backwards gives 'seires'.
'z'+'u'='zu'
'zu' going into 'seires' is 'SEIZURES'.

Can you help me to learn more?