Doom II GBA Tenements - Invisibility sphere not possible to get?

Playing through DOOM 2 on the Gameboy Advance and just went through Tenements MAP17 (technically MAP18 in this port). In the western room with the Blue Key there is that little door that opens in the southwest corner when you go up the southeast stairs. It reveals a blue soul sphere. Behind it is a half wall with at least two blue health vials and an Invisibility sphere.

I tried for a while but found no way to get to this! On the PC version there is that Blue river that runs through most of the western side of the map. This allows you to get to the other side of that small southwest room off of the blue key room. This river does not seem to be present in the GBA version though. I know they had to shorten some maps for the GBA to handle them, but for the most part they don't seem to leave areas completely inaccessible.

Think this was an oversight or was there some way I missed to get there?

Sorry for the bump, but someone recently emailed to ask the same thing; and since I wasn't 100% sure, I Googled around and found the unanswered question above.

Anyway, as far as I know it's an oversight, and there's no deliberately designed way to get back there. As stated above the normal access route was removed, and after spending time searching for other paths (including hidden or re-purposed teleport lines, switches, or impact-activated panels), I've come up empty.  But without the map data itself handy, I can't guarantee the answer.

If anyone does know for sure (Kaiser?), a confirmation one way or another would be welcome.

Cheers :)