Final answer:
To determine the first test for a patient with myelopathy and bladder involvement, a thorough neurological examination should be conducted.
Step-by-step explanation:
The doctor can assess the patient's motor function by asking them to perform certain movements and testing muscular strength by providing resistance. For sensory assessment, the patient can be tested for their ability to feel the tip of a pen on various parts of their body.
Based on the symptoms reported by the patient, a problem with the sensory systems between the spinal cord and the brain is suggested. Before a CT scan is performed, further evaluation and appropriate tests should be done.