In the video for verse 25, Dr. Plummer says that this hypotactic style is "unusual for Mark." Since I don't have much experience in reading the original Greek of the New Testament, I'll have to take his word on that, but in studying these verses, I realized that this hypotactic style has a function here.
The subject γυνὴ in verse 25 doesn't receive a verb (ἥψατο) until verse 27. In between are various participles.
25 Καὶ γυνὴ οὖσα ἐν ῥύσει αἵματος δώδεκα ἔτη(Here's a link to the interlinear.)
26 καὶ πολλὰ παθοῦσα ὑπὸ πολλῶν ἰατρῶν καὶ δαπανήσασα τὰ παρ᾽ αὐτῆς πάντα καὶ μηδὲν ὠφεληθεῖσα ἀλλὰ μᾶλλον εἰς τὸ χεῖρον ἐλθοῦσα,
27 ἀκούσασα περὶ τοῦ Ἰησοῦ, ἐλθοῦσα ἐν τῷ ὄχλῳ ὄπισθεν ἥψατο τοῦ ἱματίου αὐτοῦ·
The distance between the subject and the verb provides an illustration of the twelve years during which this woman has been in this condition. Along with giving detail, it represents duration. Her touching Jesus' garment simultaneously completes this clause ("the woman... touched") and heals her discharge of blood (as verse 29 describes). The end of her suffering coincides with this grammatical completion.
