from what i have seen neurologists not only see patients they also do some investigative procedures for which they receive payment.
These include EEG , EMG ,Nerve conduction studies etc. These procedures are done by neurologists themselves. Secondly most of followups of neurologic disease are done by neurologists , including stroke , epilepsy , parkinsons, alzheimers etc.
Neurologists with fellowships in stroke and who work in a stroke units are billed differently and i guess are paid more than a general neurologist( since they also remain on call for strokes and do intensive care).
Those with epilepsy fellowships would be doing other studies as video EEG monitoring and would be billed differently.
Like you said volume is money , there is a lot of neurologic disease. There are 700,000 new cases of stroke each year. Imagine emergency and intensive care management of 700,000 new cases every year and follow up of all previous cases with 700,000 new cases adding each year.
ER guys stabilize the patient and manage untill neuro takes over.
People are relatively less well informed of neuro subspecialities.
Stroke neurologists also do Transcranial dopplers or TCDs ( carotid dopplers are also done by cardio people) for which they also charge ( just like cardio guys do echo) . This is a relatively new trend , but is a must for all stroke units. Similarly almost all stroke fellows are trained in carotid doppler (which is extracranial doppler). In fact i was reading in a textbook that doppler studies are becoming a good tool for the stroke neurologist.
I spoke to some people regarding this. For example a stroke pt in intensive care develops recurrent ischemia do TCD find about ischemia and do needful. Pt with SAH dev weakness (vasospasm)or deterioration do TCD because it is a portable and more managable and gives quick insight into territory of ischemia or vasc damage. Vascular neurology fellowships are also getting board certifications now.
I know more about cerebrovasc dis because of my interest , but i am sure other neuro subspecialities also have cetain things.
This is apart from consults .