Hi bigfrank,
PM&R is an ILL-DEFINED specialty. It is basically divided into inpatient and outpatient. The types of patients and problems you'll see in each setting are usually VERY different. Inpatient often resembles a nursing home--the difference is that patients on inpatient rehab have insurance that will pay for it. Physiatrists say they take care of patients with spinal cord injuries or traumatic brain injuries,etc. The reality is that there are only ~8,000 new spinal cord injuries per year in the U.S. and most are cared for in major academic centers. A substantial number of inpatients for most physiatrists are dumps from internal medicine--people with CHF, terminal illness, and a suprising number of people with dementia who are admitted for "family training." Inpatient physiatry is a combination of "controlled" internal medicine and social work.
Outpatient physiatry is pain management, occupational medicine, potentially some sports medicine, EMG's, medicolegal work, etc.
The characteristics and talents that would make one an excellent outpatient physiatrist are vastly different from those that would make an excellent inpatient physiatrist. Many in PM&R, including some "big shots," think (fear?) that the two areas may someday split into 2 different residencies.