The NIH stroke scale it used to identify the severity of stroke like symptoms, and should be scored on the patient's initial presentation, without coaching or duplication. It is important to be consistent when scoring all patients, and identify all deficits. 

NIH stroke scale scores patients 0-42, with higher scores indicating increased severity.

Training for appropriate use of the NIH stroke scale is free, at http://nihss-english.trainingcampus.net/

iPhone applications, such as StatCoder, are available and free.

Adapted from Rosens, chp 16. 

Testing to consider in an elderly patient with altered mental status
ABG: hypoxia, CO2 retention, SOB
BMP/CMP: electrolyte abnormalities, hepatic encephalopathy
UA: infection, DKA, ingestion
PT/INT: hemorrhage, anemia, hypercoagulable
Lactate: ketotic state, ingestion, ischemia
TSH: thyroid storm, hypothyroid
Cardiac Enzymes: MI, ischemia, cardiogenic shock
CXR: infection, pneumothorax, CHF
CT head: hemorrhage, mass
MRI: edema, mass, ischemia
CTA: pulmonary emboli, aortic dissection
LP/CSF: infection, ICP

The Himmelfarb librarians have built an extensive reading list for internal medicine sub-specialties, from Cardiology to Infectious Disease. These are a great resource for studying up on both bread and butter as well as zebras.