It does seem to be a stroke. The tests they are running are to find out the cause as well as the areas of the brain affected.
Stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis or embolism, or due to a hemorrhage(bleed in the brain).
Risk factors for stroke include advanced age, hypertension (high blood pressure), previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, cigarette smoking.
If he has ahistory of any of these it almost confirms the diagnosis.
Stroke is occasionally treated with thrombolysis ("clot-buster"), but usually with supportive care (physiotherapy and occupational therapy) and secondary prevention with antiplatelet drugs (aspirin and often dipyridamole), blood pressure control, statins and anticoagulation.
How much of fuctioning he will re-gain and rate of recovery varies from person to person.