In cases where medications and therapy have failed to provide relief, corticosteroid injections may be indicated. These injections can target a specific nerve (selective nerve root block) that is inflamed or generally bathe the nerves in the medicine (epidural injection). At times these injections provide relief that may last a few days to a few months. In other instances they provide no relief. In cases where there is severe spinal stenosis, injections may be less effective.