A patient's history includes paresis of the right hand improving by the afternoon. What does this suggest?

The suggestion of paresis of the right hand that improves by the afternoon aligns with the characteristics of a transient ischemic attack (TIA). TIAs are often referred to as "mini-strokes" and can cause temporary neurological deficits that resolve typically within a few hours and, in this case, by the afternoon.

This transient effect, particularly affecting the right hand, indicates that it is likely related to an issue in the left hemisphere of the brain, which is responsible for motor control of the right side of the body. The key here is the temporary nature of the symptoms, which is a hallmark of a TIA, distinguishing it from a full-blown stroke where symptoms tend to be more permanent or prolonged.

In contrast, a stroke in the right hemisphere would lead to sustained symptoms on the left side of the body, since the right brain controls the left side. Neuropathy would generally cause symptoms that don't resolve spontaneously and usually affect the distribution of the nerve over a longer time, not specifically tied to a time of day. Cerebral hemorrhage typically results in sudden and often severe symptoms that do not improve so quickly. Therefore, the characteristics of improvement in paresis throughout the day align most clearly with a TIA affecting the left hemisphere.