Can nerve damage from a stroke always be found in an emg test?

Not necessarily: Sometimes tiny infarcts in the brain do not affect the electric conduit and therefore the eeg may not show an abnoramilty.

No: Strokes cause problems in the brain and that isn't tested with an emg.

Not always: Depending on the amount of damage to the brain tissue, abnormalities on EMG may not always show up. This is especially true in instances where there are upper motor neuron issues, say something dealing with coordination or movement, may not demonstrate changes in emg. Also, there has to be enough time for nerve damage to progress to show abnormalities in peripheral injuries. Hope that helps!

No, not directly: Emg is able to detect damage to the nerves that run from the spinal cord to the muscles, but not from damage to the brain itself, as in a stroke. There is a pattern of "decreased activation" on EMG that results from stroke, but there are many other things that can also cause this pattern.