A psychiatric inpatient becomes unresponsive and immobile over several hours, but on recovery accurately recalls conversations that took place around her during the episode, including details she should not have been able to register if her consciousness had genuinely been impaired throughout. Before revealing the answer: does this fit akinetic mutism?

No, this does not fit akinetic mutism well. The failure to register new memories, and the resulting total amnesia for the episode, is a specific and important distinguishing feature of akinetic mutism from psychiatric stupor — and here the opposite is true: she has accurately retained memories from during the episode, which points toward preserved, clear consciousness throughout rather than the genuine underlying lowering of consciousness that akinetic mutism requires. This pattern is much more consistent with catatonic stupor, which typically occurs with clear consciousness despite the profound reduction in movement and responsiveness.