Spinal nerve compression whether due to disc protrusion or bony canal narrowing can produce symptoms of pain, numbness and weakness. Collateral nerve innervation, referral pain and anatomical variations however can make diagnosis of specific nerve compression difficult especially when patients present with indistinct symptoms. Where as MRIs frequently reveal anatomical abnormalities that are more than clinically relevant, and EMGs are prone to false positives and negatives, SNRB is diagnostically more specific and functionally correlatable. SNRB of a single nerve-root with anesthetic and cortisone mixture is both diagnostic and therapeutic. Immediate pain relief from the anesthetic clinches the nerve’s involvement in causing pain. This helps to guide further therapy. The cortisone is beneficial as an anti-inflammatory medication.