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' (represents an unknown value in algebra).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'seen in' indicates putting letters inside.
'upsetting' says the letters should be written backwards.
'programme's' becomes 'series' (series is a kind of programme).
'series' back-to-front is 'seires'.
'z'+'u'='zu'
'zu' inserted within 'seires' is 'SEIZURES'.

Can you help me to learn more?