Christa Pike Speaking in Full Sentences After Botched Execution

Christa Pike is making significant strides in her recovery after surviving a botched execution in Tennessee ... but doctors are still trying to determine the extent of any lasting psychological and cognitive damage ... TMZ has learned.

An attorney for Christa tells TMZ ... she's continuing to improve physically and is now able to walk more on her own. The attorney says Christa's speech has also improved, and she's now able to communicate more clearly and form full sentences.

However, her attorney says her cognitive and psychological functioning are still being monitored and it could take another month or longer before there's a clearer picture of any potential long-term effects from the ordeal.

The latest update marks a major improvement for Christa, who was initially left unconscious and unable to communicate after surviving two doses of lethal injection drugs during her September 30 execution attempt.

As we reported ... Christa was eventually able to take a few steps and speak after regaining consciousness, though her attorneys previously said she was struggling with confusion, memory issues and significant physical injuries.

Her recovery also follows troubling revelations about the emergency response to her failed execution.

According to 911 dispatch recordings, it took 31 minutes for prison officials to confirm that a request for emergency medical assistance was legitimate ... after confusion between prison staff and first responders delayed the response.

Christa was later released from the hospital and returned to prison, where she has continued receiving medical care.