Even though no information about the physical examination is available, the likely lesion localization can be inferred from this patient's history alone. The abnormal sensory and motor function below a level in the mid-abdomen indicates a focal lesion in the spinal cord, at the thoracic level or above (RULE #3).
Since the symptoms are progressive, this is a mass lesion.
The time course is subacute.
A focal, subacute lesion is typically inflammatory, specifically, an abscess.
Comment: An MRI scan of the cervical and thoracic spine failed to demonstrate an abscess, but a lumbar puncture revealed a pleocytosis in the spinal fluid. All cultures were negative. The patient was thought to have transverse myelitis, and inflammatory (possibly autoimmune) disorder that behaves like a mass lesion within the spinal cord. Her symptoms gradually resolved without treatment. This is another example of how the rules can fail. In this case, they pointed to the correct diagnostic category but the wrong specific diagnosis. As it happens, it is often impossible to distinguish between transverse myelitis and a spinal cord abscess on clinical grounds alone, so it is appropriate to direct the evaluation at the possibility of an abscess, which would require urgent treatment.