An EMG is commonly done if an examination suggests decreased muscle strength. Results of an EMG will allow your doctor to decide if your muscle weakness is caused by an injury to a nerve attached to the muscle or an underlying neurological disorder.
Your doctor will request an EMG if your diagnosis suggests peripheral nervous system disorders including carpal tunnel syndrome, peripheral neuropathy, diabetic neuropathy, cervical radiculopathy, lumbosacral radiculopathy, sciatica, plexopathy, or nerve injury from trauma or fractures.