Earliest Reference to "Series of 3" Epidural Injections?
So far, this is the earliest reference I could locate: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1708522/?page=1 The article is from 1925- a caudal canal approach that used 20 ml of 1% novacaine (procaine) followed by 50-80 ml of saline or petrolatum. Remember this preceded the discovery of corticosteroids by 12 years and the clinical use of corticosteroids by nearly 22 years. (Source: Student Doctor Network)
Source: Student Doctor Network - February 14, 2017 Category: Universities & Medical Training Authors: algosdoc Source Type: forums

SIS and other experts advocate for Oregon patients
SIS and 10 other medical societies have warned the Oregon Health Authority (OHA) that a cascade of unintended consequences can be expected from their significantly flawed coverage decision on corticosteroid injections for low back pain. The multi-society response highlights significant flaws in OHA’s coverage guidance methodology, includes citations on the effectiveness of injections, and warns of expected negative consequences of eliminating access to interventional spine procedures... SIS and other experts advocate for Oregon patients (Source: Student Doctor Network)
Source: Student Doctor Network - December 13, 2016 Category: Universities & Medical Training Authors: drusso Source Type: forums

Dispensing of oral corticosteroids (systemic) is even more dangerous.
(Source: BMJ Comments)
Source: BMJ Comments - December 7, 2015 Category: Journals (General) Source Type: forums